Kyoto Tool Company (KTC)

Table of Contents

Introduction

The Kyoto Tool Company (in Japanese 京都機械工具 or "Kyoto Kikai Kōgu"), generally known as KTC, is probably the best known and most celebrated Japanese toolmaker. The company offers high quality tools for professional use under the KTC and Nepros brands.

Background information on the Japanese tool industry can be found in our page on Japanese Tool Makers.

Company History

The Kyoto Tool Company (京都機械工具) was founded in 1950 by Kiichi Saitō (斉藤喜一), Sojiro Yamazaki (山崎宋次郎), and Masayuki Ushiro (宇城正行), all of whom had previously been key employees of the tool division of Kyoto Kikai. The company's initial business contract was with Toyota Motors to supply tools for vehicle tool kits, and the company's early factory was at 38 Hinagajo-cho, Minami-ku in Kyoto City.

The Toyota contract had previously been held by Kyoto Kikai, but followed the founders to their new company.

We were quite interested to learn of the formation of KTC by ex-employees of Kyoto Kikai, rather than as a business succession via spinoff or as a newly independent subsidiary. KTC's own history dwells at some length on the early history of Kyoto Kikai, leaving an impression that KTC is the heir by succession of the earlier company's heritage.

In the U.S. and other Western countries it's fairly common for employees to leave one company and set up a competing business, but in Japan at that time it was probably unusual.

The Karasuma Factory at Higashikujo

In 1951 the company moved to a new factory at 36 Torimaru-cho, Higashikujo, Shimogyō-ku, Kyoto City (京都市下京区東九条鳥丸町 36) and began manufacturing commercial tools. The company referred to this as the Karasuma (鳥丸) factory.

Early JIS Certification

On November 11, 1952 KTC received JIS certification 1977 for class B4630 (open-end wrenches) at the Karasuma factory. The record for this certification can be seen in the section on the 1952-02 Monthly Report for Class B4630.

The Oike Factory at Nakago-cho

In 1952 the company built a new factory and moved to Nakago-cho, Nakagyo-ku in Kyoto. This factory was referred to as the Oike (御池) factory after a nearby famous area in Kyoto.

On October 21, 1954 the company received JIS certification 3487 for class B4614 (combination pliers) at the Oike factory. The record for this certification can be seen in the section on the 1955 JIS Summary for Class B4614.

On November 22, 1954 the company received JIS certification 3523 for class B4604 (adjustable wrenches) at the Oike factory. The record for this certification can be seen in the section on the 1955 JIS Summary for Class B4604. (This certification was later upgraded to include both normal and strong grades, but we don't know the exact timing.)

On September 6, 1955 the company received JIS certification 4247 for classes B4636 (socket wrenches) and B4637 (extension bars) at the Oike factory. The record for this certification can be seen in the section on the 1958 JIS Summary for Classes B4636, B4637, and B4639.

On the same date the company received JIS certificate 4251 for class B4632 (box-end wrenches) at the Oike factory. The record for this certification can be seen in the section on the 1958 JIS Summary for Class B4632.

The 1955 Factory Name List reports that the JIS 1977 certification for class B4630 had moved to the Oike factory, but we haven't found a record documenting the move.

On August 10, 1959 the company received JIS certification 6853 for classes B4638, B4640, and B4641 at the Oike factory. The record for this certification can be seen in the section on the 1962 JIS Summary for Classes B4638, B4640, and B4641.

[Editor's note: these JIS certifications are not mentioned in the company history.]

Kyoto Kōki Subsidiary

In 1960 KTC acquired Nakagawa Kōki and formed Kyoto Kōki as their first subsidiary. Nakagawa Kōki had been founded by Eiji Nakagawa and made slip-joint pliers as its main product.

Contract Production for Fuller Tool

KTC's published history has an interesting story noting that in 1960 Bernard Fuller of the Fuller Tool Company came to visit the KTC factory, and afterwards took sample wrenches back to the United States. The result was a 1961 export contract between KTC and Fuller Tool, which is known to have included adjustable wrenches, open-end wrenches, and combination wrenches. KTC continued to supply tools to Fuller for many years.

A further anecdote from the 1960 visit is that after returning home, Fuller sent some of the sample wrenches to Sears to be tested, and this set in motion events that would lead to the Sears "BF" line of Japanese import tools.

The Fuller tools supplied by KTC were of very high quality, much better than the "hardware store" grade that might have been expected. The early open-end wrenches were similar to KTC's own JIS-certified wrenches, with a recessed panel design and crisp forged-in markings noting chrome vanadium steel. In addition, the wrenches were marked with the KTC-Oval trademark rather than passing as generic production.

Although the Fuller wrenches would have been expensive to produce due to the need for custom dies, the Fuller production could be regarded as a calculated investment on KTC's part, with each wrench advertising the capabilities of the producer. The 1961 Fuller export contract was important enough that KTC specifically mentions it in the history timeline of their website.

The KTC-Oval Logo

In the early 1960s KTC began marking their tools with the KTC-Oval logo, a trademark that had been registered in the 1950s. Initially the tools retained the older Nijūmarukyo logo marking as well, and this transitional period continued for at least several years.

We have found two generations of box-end wrenches marked with both logos, and an example can be seen as the KTC [MOB-1012] 10x12mm Offset Box-End Wrench. We hope to find other examples of tools from the transition period.

Not all tools have been observed with transitional markings, and in particular adjustable wrenches seem to have gone directly from the older style with the Nijūmarukyo logo and "maru" jaws to the newer KTC-oval logo with "spear-type" jaws.

New Factory in Fushimi-ku

In 1964 the company relocated to a new factory at 40 Shimo toba, Nagatamachi, Fushimi-ku, Kyoto, and the new facility became designated as a "model factory".

On December 16, 1964 JIS certificate 3523 for adjustable wrenches was transferred from the Oike factory to Fushimi-ku.

Contract Production for Sears Roebuck

By 1964 KTC had begun supplying tools to Sears Roebuck under the "BF" manufacturer's code, initially with "Sears" brand adjustable wrenches and carbon steel drop forged wrenches. The carbon steel wrenches were designed as copies of the Sears "Dunlap" brand wrenches of the late 1950s, and an example can be seen as the [KTC] Sears "BF" 9/16x5/8 Open-End Wrench.

In addition, KTC probably supplied slip-joint pliers through its Kyoto Kōki subsidiary, but we are still gathering evidence for this production.

Pipe Wrench Development

In the mid 1960s the company began an intensive project to develop pipe wrenches for the export market, which is covered in some detail in KTC's published history. The project began with a request from the Fuller Tool Company, and Fuller sent samples of Ridgid-pattern pipe wrenches to KTC for analysis and study.

At that time most heavy-duty pipe wrenches were being made with cast malleable iron bodies, but after analysis KTC decided to use ductile cast iron instead, which had strength similar to steel and would allow reduced weight. KTC was able to find a foundry run by the Shimadzu Corporation which could make the required ductile castings, but because of the greater cost of the material, it required six months of research and development to find the right balance between strength and cost.

The result was a heavy-duty (Ridgid pattern) pipe wrench constructed with a ductile cast iron body, which was well received by the market. KTC reported selling 700,000 units in the U.S. and Australia in the first three years.

KTC's history doesn't provide a timeline for the pipe wrench program, but if we work backwards from the listing for heavy-duty pipe wrenches in the 1968 Craftsman catalog, the wrenches were probably ready for production by late 1966 or early 1967. (Sears would have needed some time for testing and catalog preparation.)

The pipe wrenches were initially offered by KTC and Fuller, and by 1968 KTC was supplying "Sears" brand heavy-duty pipe wrenches. These wrenches have been observed marked with the KTC logo and a "BF" code, an example of which can be seen as the Sears 30852 "BF" 14 Inch Pipe Wrench.

The development project also produced a Stillson-pattern pipe wrench, which was offered by Fuller and by Sears beginning in 1969.

The "1966" Catalog

In the late 1960s KTC published a catalog in English noted as "Catalog No. 8" on the inside cover. This catalog is an important reference and provides the first listings for "spear type" adjustable wrenches and heavy-duty pipe wrenches, as well as many other tool listings. This was also the first catalog to show the KTC-Oval logo as a marking on tools.

Unfortunately the catalog does not have an explicit date, and the only connection with the 1966 date estimate is a foreword noting 1966 as the start of a five year rationalization and expansion plan. But since it's a five year plan, any year between 1966 and 1970 would fit this period.

We examined the catalog carefully for clues to the publication date, and one promising lead is the mention of three years of sales for the heavy-duty pipe wrenches, along with sales figures for the U.S. and Australia. KTC had a documented project to develop pipe wrenches (see the section above), and from that project we think that pipe wrenches were probably first offered in 1966, or at the very earliest possibly in late 1965.

A three years sales period for pipe wrenches would then place catalog No. 8 in 1968 or 1969, which we think is a more reasonable estimate for the publication date.

Craftsman Combination Wrenches

By 1969 KTC was supplying "Craftsman" combination wrenches, an important milestone as the first "BF" series tool for the Craftsman brand.

The Hokuriku KTC Tool Company

In 1970 the company established the Hokuriku KTC Tool Company in Hakui City, Ishikawa Prefecture, which provided additional production capacity. The Hokuriku KTC factory was located at 150-1, Yanagida-cho 70, Hakui City.

Hokuriku KTC was a quasi-independent company and received JIS certifications under its own name, but since it provided production for KTC, we are treating it as a factory for KTC.

Pipe Wrench Certification

Sometime between 1967 and 1972 class B4606 (pipe wrenches) was added to KTC's JIS 3523 certification, but without changing the date, so that we don't know the exact date of the pipe wrench certification. The record for this certification can be seen in the 1972 JIS Summary for Classes B4604 and B4606.

New Factory at Kumiyama

In 1979 the company started relocating production to a new factory in Kumiyama-cho, Kuse-gun, Kyoto Prefecture. The factory at Fushimi-ku continued production of certain tools for some years afterwards, but eventually was closed.

On June 26, 1979 JIS 3523 for class B4604 and JIS 4247 for class B4636 were transferred to Kumiyama. [Editor's note: Get the MR for this recertification.]

JIS certification for Kyoto Kōki

On June 26, 1979 the Kyoto Kōki factory received JIS 579037 for class B4614 (combination pliers). The record for this certification can be seen in the 1982 Summary for Class B4614.

After Kyoto Kōki received JIS certification, KTC transferred production of combination pliers to its subsidiary. Kyoto Kōki used a K-Circle mark as its JIS ID code.

Mirror Tools

In 1984 the company released its line of Mirror tools with a highly polished finish.

In 1985 Hokuriku KTC received JIS certificate 474026 for combination wrenches (class B4651). Documentation for this certification can be found in the 1999 Summary for Super-Class B027.

In 1988 the head office moved to Kumiyama-cho.

In 1988 Hokuriku KTC received JIS certificate 488006 in classes B6404 (adjustable wrenches) and B4606 (pipe wrenches). Documentation for this certification can be found in the 1999 Summary for Super-Class B013.

The Nepros Line

In 1995 the company released the Nepros line of "Mirror" tools.

In 2003 the KTC Manufacturing Technology Museum was opened to the public.

Continuing Operations

KTC continues in operation today at Kumiyama-cho, and the company maintains a website (in Japanese and English) at KTC Kyoto Tool [External Link]. Our history was adapted from the historical timeline on the Japanese site.

Patents

The table below shows some of KTC's early patents that are mentioned in the catalogs.

Trademarks

KTC registered trademarks in both Japan and the United States.

Fig. 1. Japanese Trademark 26-10594.

The scan in Fig. 1 shows Japanese trademark 26-10594 for KTC's "nijūmarukyo" (二重丸京) logo, published on Showa 26.7.28 or July 28, 1951.

JIS Certification History

KTC received JIS certifications for classes B4604 (adjustable wrenches), B4606 (pipe wrenches), B4614 (combination pliers), B4630 (open-end wrenches), B4632 (box-end wrenches), B4636-B4641 (socket wrenches), B4643 (bolt cutters), and B4651 (combination wrenches).

Factory locations were in Higashikujo (Karasuma), Nakago-cho (Oike), Yanadiga-cho, and Kumiyama-cho.

View Company History with Factories for KTC.

View JIS Certification Events for KTC.

Kyoto Kōki received a JIS certification for class B4614 (combination pliers). The factory location was Oyamazaki-chō.

View Company History with Factories for Kyoto Kōki.

View JIS Certification Events for Kyoto Kōki.

Background information on the JIS program can be found in our article on Japanese Industrial Standards.

Tool Identification

Tools from Kyoto Tool are typically marked with the KTC-Oval logo consisting of "KTC" inside an oval. This symbol was registered as a US trademark in 1991.

Early tools were generally marked with the KTC-Double-Circle logo, known as "nijūmarukyo" (二重丸京) in Japanese.

In addition to selling its own brands, the company also provides extensive contract manufacturing services for a number of customers, and KTC-made tools can be found under many other brands.

KTC-Double-Circle Logo

Fig. 2. KTC "Double Circle" Logo.

Fig. 2 shows the KTC-Double-Cirle logo, known as nijūmarukyo (二重丸京) in Japanese.

This was the early logo used by KTC from 1950 until the early 1960s.

KTC-Oval Logo

Fig. 3. KTC-Oval Logo from Trademark #1,663,191.

Fig. 3 shows the KTC-Oval logo as it was presented for trademark #1,663,191.

The KTC-Oval logo was registered as a Japanese trademark in the 1950s and its first use on tools appears to have been for combination wrenches in the late 1950s or early 1960s. The logo was gradually phased in during early to mid 1960s as a replacement for the older nijūmarukyo logo.

Fig. 4. KTC-Oval Logo from Fuller Wrench.

Fig. 4 shows the KTC-Oval logo, as stamped on a Fuller 3/4 combination wrench shown in a later figure.

KTC Standard Forged Markings

KTC provided extensive contract production for the Sears "BF" series tools, which included a line of carbon steel drop-forged wrenches with forged-in markings. The next set of figures show the standard marking style on these wrenches, which included several variations. These markings should serve as a reliable means to identify KTC production.

Based on the observed examples, the "standard" markings underwent some evolution, and these changes may assist with estimating the production date for a tool.

Fig. 5. KTC Standard Forged Markings, Early Split Version, ca. 1964 to Mid 1960s.

Fig. 5 shows the earliest version of the KTC Standard Forged Markings, as observed on a Sears "BF" 13/16x7/8 Open-End Wrench.

In this example the "BF" and "JAPAN" markings have been split by "DROP FORGED", and the panel does not repeat the size markings from the other side. Some further variations include "B.F" at the left.

This first generation of the standard markings has been observed on open-end wrenches and combination wrenches.

Fig. 6. KTC Standard Forged Markings, "BF JAPAN" Joined, ca. Mid 1960s to Mid 1970s.

Fig. 6 shows the second generation of the KTC Standard Forged Markings, as observed on a Sears "BF" 5/8 Combination Wrench.

In this example "DROP FORGED" is in the center with size markings at both ends of the panel, and the "BF" and "JAPAN" markings have been joined at the right.

This second generation of the standard markings has been observed on open-end, combination, and box-end wrenches.

Fig. 7. KTC Standard Forged Markings, Later Forged Version, ca. Mid 1970s+.

Fig. 7 shows the third generation of the KTC Standard Forged Markings, as observed on a Sears "BF" 9/16x5/8 Offset Box-End Wrench.

In this example "DROP FORGED" has been replaced by "FORGED" in the center of the panel, with "BF JAPAN" in smaller letters to the right, and size markings at both ends.

This third generation of the standard markings has been observed on open-end, combination, and box-end wrenches.

The examples above show that the markings evolved through three generations, during which the "BF Japan" marking was consolidated after being split apart in earlier versions, and "Drop Forged" changed to "Forged".

We can roughly estimate the date ranges for the generations by noting that the third generation was in use by the mid 1970s. This suggests that the first generation ranged from 1964 to the mid 1960s, the second generation ranged from the mid 1960s to mid 1970s, with the third generation from the mid 1970s onward.

References and Resources

Photographs and observations of particular tools are based on items in the Alloy Artifacts Collection.

Catalog Resources

Selected Tools

Currently many of our examples of KTC's tools are contract production for other brands, including Toyota, Nissan, Fuller, and Sears, but we also have some examples of production for KTC's own brands.

Wrenches

KTC offers a wide variety of wrenches in open-end, box-end, and combination styles, as well as specialty wrenches for particular service applications.

Open-End Wrenches

Early KTC "トヨタ" 12x14mm Open-End Wrench

Fig. 8. Early KTC 12x14mm Open-End Wrench, with Insets for Back Side, Side Vew, and Marking Detail, ca. Early 1950s.

Fig. 8 shows an early KTC 12x14mm open-end wrench with raised longitudinal panels, marked with "Kyoto" and "K.T.C." plus the Nijūmarukyo logo forged into the front panel, with "Nickel-Chrome-Vanadium" forged into the back panel.

One of the back faces is also stamped with the Toyota "トヨタ" Katakana logo, as seen in the lower inset.

The overall length is 5.7 inches.

The finish is nickel plating, with extensive losses revealing the copper underlayer. We cleaned the wrench carefuly to polish the copper without removing the remaining nickel layer.

We acquired this wrench as an example of early KTC production, but got an unexpected bonus: the stamped Toyota Katakana logo reveals that KTC's early production for Toyota was dual-branded!

KTC S116 Six-Piece Open-End Wrench Set

This next figure shows an example of a KTC wrench set, consisting of six wrenches in a patented metal holder.

Fig. 9. KTC S116 Six-Piece Open-End Wrench Set, with Insets for Top View and Marking Detail, ca. Mid 1960s.

Fig. 9 shows a KTC S116 six-piece open-end wrench set in its metal holder, embossed with the KTC-Oval logo on the front, with the Nijūmarukyo logo and "M. Pat No. 422209" stamped on the back.

The wrench sizes are 8x9mm, 10x12mm, 12x14mm, 14x17mm, 19x21mm, and 23x26mm.

This set closely resembles the illustration on page 9 [External Link] of KTC catalog No. 8 from 1966. The set was identified as model S116 based on the wrench sizes.

All of the wrenches are marked with the KTC-Oval logo, and five of the six have "Kyoto Tool Co." forged into the front. However, one wrench has an older marking with the Nijūmarukyo logo between "Kyoto" and "K.T.C.", suggesting that the set was assembled while the markings were in transition.

Each wrench is marked with the JIS-Circle+S logo, a reference to KTC's JIS 1977 certificate. The "S" suffix refers to the "spear-type" jaw outline of the wrenches.

The patent notation refers to publication number S29-11799 for utility model patent 422209, issued on January 30, 1955. The document describes a wrench holder with a leaf spring to support the wrenches.

The next group of figures will show the individual wrenches in the set.

KTC 8x9mm Open-End Wrench

Fig. 10. KTC 8x9mm Open-End Wrench, with Inset for Back Side, ca. Mid 1960s.

Fig. 10 shows a KTC 8x9mm open-end wrench with recessed oval panels, marked with the KTC-Oval logo and "Kyoto Tool Co." forged into the front panel, with "Nickel-Chrome-Vanadium" and an "82" code forged into the back panel.

The front panel is also marked with the JIS-Circle+S logo, a reference to KTC's JIS 1977 certificate. The "S" suffix refers to the "spear-type" jaw outline.

The overall length is 4.3 inches, and the finish is chrome plating with polished faces.

This wrench was acquired as part of a KTC S116 Six-Piece Wrench Set in a metal holder.

KTC 10x12mm Open-End Wrench

Fig. 11. KTC 10x12mm Open-End Wrench, with Inset for Back Side, ca. Mid 1960s.

Fig. 11 shows a KTC 10x12mm open-end wrench with recessed oval panels, marked with the KTC-Oval logo and "Kyoto Tool Co." forged into the front panel, with "Nickel-Chrome-Vanadium" and a "90" code forged into the back panel.

The front panel is also marked with the JIS-Circle+S logo, a reference to KTC's JIS 1977 certificate. The "S" suffix refers to the "spear-type" jaw outline.

The overall length is 5.0 inches, and the finish is chrome plating with polished faces.

This wrench was acquired as part of a KTC S116 Six-Piece Wrench Set in a metal holder.

KTC 10x12mm Open-End Wrench

Fig. 12. KTC 12x14mm Open-End Wrench, with Inset for Back Side, ca. Mid 1960s.

Fig. 12 shows a KTC 12x14mm open-end wrench with recessed oval panels, marked with the KTC-Oval logo and "Kyoto Tool Co." forged into the front panel, with "Nickel-Chrome-Vanadium" and an "87" code forged into the back panel.

The front panel is also marked with the JIS-Circle+S logo, a reference to KTC's JIS 1977 certificate. The "S" suffix refers to the "spear-type" jaw outline.

The overall length is 5.5 inches, and the finish is chrome plating with polished faces.

This wrench was acquired as part of a KTC S116 Six-Piece Wrench Set in a metal holder.

KTC 14x17mm Open-End Wrench

Fig. 13. KTC 14x17mm Open-End Wrench, with Inset for Back Side, ca. Mid 1960s.

Fig. 13 shows a KTC 14x17mm open-end wrench with recessed oval panels, marked with the KTC-Oval logo and "Kyoto Tool Co." forged into the front panel, with "Nickel-Chrome-Vanadium" and an "89" code forged into the back panel.

The front panel is also marked with the JIS-Circle+S logo, a reference to KTC's JIS 1977 certificate. The "S" suffix refers to the "spear-type" jaw outline.

The overall length is 6.3 inches, and the finish is chrome plating with polished faces.

This wrench was acquired as part of a KTC S116 Six-Piece Wrench Set in a metal holder.

KTC 19x21mm Open-End Wrench

Fig. 14. KTC 19x21mm Open-End Wrench, with Inset for Back Side, ca. Mid 1960s.

Fig. 14 shows a KTC 19x21mm open-end wrench with recessed oval panels, marked with the KTC-Oval logo and "Kyoto Tool Co." forged into the front panel, with "Nickel-Chrome-Vanadium" and an "87" code forged into the back panel.

The front panel is also marked with the JIS-Circle+S logo, a reference to KTC's JIS 1977 certificate. The "S" suffix refers to the "spear-type" jaw outline.

The overall length is 7.8 inches, and the finish is chrome plating with polished faces.

This wrench was acquired as part of a KTC S116 Six-Piece Wrench Set in a metal holder.

KTC 23x26mm Open-End Wrench

Fig. 14B. KTC 23x26mm Open-End Wrench, with Inset for Back Side, ca. Mid 1960s.

Fig. 14B shows a KTC 23x26mm open-end wrench with recessed oval panels, marked with "Kyoto" and "K.T.C." plus the Nijūmarukyo logo and KTC-Oval logo forged into the front panel, with "Nickel-Chrome-Vanadium" and an "80" code forged into the back panel.

The front panel is also marked with the JIS-Circle+S logo, a reference to JIS 1977, first received by KTC in 1952. The "S" suffix refers to the "spear-type" jaw outline.

The overall length is 9.0 inches, and the finish is chrome plating with polished faces.

This wrench was acquired as part of a KTC S116 Six-Piece Wrench Set in a metal holder.

This wrench is different from the other wrenches in the set in that it includes the older Nijūmarukyo logo between "Kyoto" and "K.T.C." on the front side, instead of the "Kyoto Tool Co." marking found on the other wrenches. The presence of both the older Nijūmarukyo logo and the KTC-Oval logo suggests that the set was assembled during the transition from the older marking style.

Box-End Wrenches

In 1955 KTC received JIS certificate 4251 for box-end wrenches (class B4632).

Transitional KTC [MOB-1012] 10x12mm Offset Box-End Wrench

Fig. 15A. KTC 10x12mm Offset Box-End Wrench, with Insets for Back Side and Side View, ca. Early 1960s.

Fig. 15A shows a KTC 10x12mm offset box-end wrench, marked with "Kyoto" and "K.T.C." plus the Nijūmarukyo logo forged into the front, with "Special-Alloy-Steel" and a "41" code forged into the back.

The front is also marked with the KTC-Oval logo at the left and JIS-Circle logo at the right.

The overall length is 7.9 inches, and the finish is nickel plating.

This wrench is not marked with a model number, but the 1963 KTC catalog offered metric offset box wrenches in this style and size as model MOB-1012.

The presence of both the KTC-Oval logo and the older Nijūmarukyo logo indicates transitional production.

Transitional KTC MOB-1716 17x192mm Offset Box-End Wrench

Fig. 15B. KTC MOB-1719 17x19mm Offset Box-End Wrench, with Insets for Back Side, Side View, and Marking Detail, ca. 1964-1965.

Fig. 15B shows a KTC MOB-1719 17x19mm offset box-end wrench with recessed panels, marked with "Kyoto" and "K.T.C." plus the Nijūmarukyo logo forged into the front panel, with the model number and "KTC, Alloy-Steel" forged into the back panel.

The front panel is also marked with the KTC-Oval logo at the left and JIS-Circle logo at the right.

The overall length is 11.0 inches, and the finish is chrome plating with polished ends.

The 1963 KTC catalog listed the model MOB-1719 offset box wrench, but in a style with oval shanks and forged-in markings. The 1966 KTC catalog illustrated box-end wrenches in this style with recessed panels, but by that time the model number had changed to M25-1719. The older model number suggests that the present example was made between those dates, leading to a production date estimate of 1964-1965.

Adjustable Wrenches

Adjustable wrenches were an important product for KTC, and we are planning to present a number of examples to show the development and evolution of these tools.

Background Information

In 1954 KTC received JIS certificate 3523 for adjustable wrenches at its Oike (Nakago-cho) factory, and in late 1964 JIS 3523 was transferred to the new factory at Fushimi-ku.

After receiving certification, most companies would add JIS markings to their adjustable wrench production. In Japan of the mid 1950s and later, JIS certification was generally required for sales to commercial, government, and military customers, and since KTC is a major tool company, we would expect to find numerous examples of KTC adjustable wrenches marked with its JIS certification.

However, the CWC site reports that KTC adjustable wrenches marked with the company's own JIS certification are somewhat rare, and that adjustable wrenches with KTC's brand are frequently marked with another company's JIS certification, indicating contract production for KTC. (Recall that JIS marked tools must be traceable to the actual maker.)

The observed contract makers are Hokuyo Sangyo ("Sanki") for production of the late 1960s to 1980s and Yamaco for the Nissan OEM wrenches of the 1950s.

This extensive use of contract production is somewhat puzzling, and we did some investigation in an attempt to understand KTC's balance of in-house and contract production during the mid 1950s to 1980s time frame.

A Mercari Search

To investigate this issue further, we decided to do some research using Mercari, a popular Japanese online marketplace for tools and other products. A recent search (October 2024) for "KTC monkey wrench" turned up many examples of adjustable wrenches.

We restricted our attention to the "classic" style of adjustable wrench of the 1950s to 1980s and ignored the many modern wrenches with cut-away shanks and super-wide openings. The wrenches we examined were all marked for KTC's name and logo, but (as expected) most had forged-in markings indicating production by Sanki. Fortunately we were able to spot some examples with direct relevance to our question.

• An Early Nissan OEM Wrench

  One example that stood out from the rest was marked with the Nissan logo and a JIS symbol, along with KTC's early "nijumarukyo" logo and the company name. The construction of the wrench closely matched the illustration on page 11 [External Link] of the 1966 KTC catalog, which shows some very distinctive production characteristics. Note in particular the rounded inside corner of the fixed jaw, the inset convex cutaway of the movable jaw, the wide tailpiece of the movable jaw, and the hanging hole without a ridge.

  A photograph of a similar wrench can be found on the CWC site as the KTC "Nijumarukyo" OEM for Nissan [External Link]. The CWC site actually shows two Nissan OEM wrenches, the first of which was made by Yamaco as contract production for KTC, with the second example made by KTC itself. These wrenches allow us to understand the origin of KTC's style for adjustable wrenches.

  In the early 1950s KTC had a production contract with Nissan, and Nissan apparently requested JIS-certified adjustable wrenches as part of the contract. At that time KTC was not yet certified for adjustable wrenches, so it subcontracted with Yamaco to produce the first generation of the Nissan OEM JIS wrenches, which were marked with Yamaco's "YK" identification mark. (Yamaco had received JIS 2356 on June 20, 1953.)

  Since the tools produced for Nissan were supposed to be marked with KTC's name and logo, Yamaco made the wrenches with markings for KTC, plus the small "YK" code required for JIS traceability. The first wrench displayed by the CWC link above shows an example of Yamaco's production, with a "YK" code visible to the right of the JIS symbol.

  On November 22, 1954 KTC received JIS certificate 3523 for adjustable wrenches, and presumably shortly afterwards began its own production of Nissan OEM wrenches. Since the wrenches made up to this point had been made by Yamaco, KTC copied Yamaco's style for its own wrenches. The second wrench in the CWC link above shows KTC's own production, in the same style as Yamaco but without any additional marks near the JIS symbol.

  We can accept the Nissan OEM wrench as proof that KTC made JIS-certified wrenches in this style.

  Although the Nissan OEM wrench is very similar to the illustration in the 1966 KTC catalog, there is one difference worth noting. The Nissan OEM wrench has jaws with a round or "maru" (丸形) outline, but the 1966 catalog shows the jaws with a "spear type" (ヤリ形) outline. This difference may be helpful in estimating the production date for some adjustable wrenches.

• JIS 9786

  The next significant observation on Mercari was a wrench marked with KTC's name and logo along with a JIS symbol and "9786" forged into the front, with "KTC, FORGED ALLOY" plus a small "SA" marking forged into the back. JIS 9786 was registered to Hokuyo Sangyō, so this wrench was definitely produced by Sanki, and it shows that the "SA" marking indicates Sanki production.

  The wrench construction closely matched the KTC catalog illustration in the jaw details and the absence of a ridge around the hanging hole, which proves that Sanki was able to replicate the "KTC Style" in adjustable wrenches.

• The Remaining Examples

  After examining these first two examples from Mercari, we now know what a KTC JIS-marked wrench looks like, but we also know that looks alone won't distinguish a wrench from a close copy.

  Most of the other listings we examined were very similar to the Sanki example, with a forged-in "SA" on the back and in some cases marked with the full JIS number. However, we did find two listings that appeared to not have the "SA" marking, but were otherwise similar in construction to the other wrenches. (We say "appeared" because the photos were not completely clear.)

  Our hypothesis is that these two wrenches were actual KTC production, and that distinguishing KTC production from contract production must be based on the absence of the seemingly insignificant "SA" mark.

• Conclusions

  From this exercise it is immediately clear that KTC wrenches produced by Sanki represent a substantial majority of the used wrenches available for sale now. To draw further conclusions, we have to start with the assumption that the relative abundance of products in the online marketplace is proportional to their original sales. With this assumption we can make a rough estimate of the proportion of sales by noting that after examining at least ten listings, only two represented possible KTC production. This leads to an estimated 80% market share for Sanki.

  This might seem to be a surprising result, but by the mid 1960s KTC is known to have had at least three major contracts requiring adjustable wrenches, for customers including Nissan, Fuller Tool, and Sears Roebuck. The excess demand from these contracts, in addition to the normal sales volume to other customers, may have greatly exceeded the production capacity of KTC's factory.

Based on the evidence here, we will assume that KTC made extensive use of contract production for adjustable wrenches, with Hokuyo Sangyō as the primary outside producer, but possibly with others as well.

We will update this section as new information becomes available.

Construction Details

In this section we'll look at some important construction details applying to KTC adjustable wrenches. KTC's wrenches underwent various evolutionary changes from the 1950s to 1970s, and the example chosen for the illustration below is representative of mid to late 1960s production.

Fig. 16. Annotated Close-up of Jaw Detail for KTC 200mm Adjustable Wrench.

Fig. 16 shows an annotated close-up of the jaws of the KTC 200mm Adjustable Wrench shown in a later figure.

The annotations have highlighted the rounded transition of the fixed jaw and the corresponding inset convex cutaway on the movable jaw. This was KTC's preferred construction from the mid 1950s onward.

The annotation at the left notes the full width of the tailpiece of the movable jaw, a feature found from the mid 1950s through the 1960s. Production changed to a tapering tailpiece sometime in the 1970s.

The annotation at the top notes the "spear type" outline of the jaws, a feature adopted in the mid 1960s to replace the "maru" outline used up to that point.

Fig. 17. Close-up of Jaw Parts for KTC 200mm Adjustable Wrench.

Another important detail to note is that the pin securing the worm gear is threaded on the inside end. Most other manufacturers also used inside threads, but Toho Kōki and Nippon Riki are known to have used threads on the outside (slotted) end on the pin.

Fig. 17 shows a close-up of the disassembled jaw parts from the KTC 200mm Adjustable Wrench. From top to bottom, the parts consist of the movable jaw, the worm gear, a small spring, and a threaded pin.

Note that the threads are on the right (inside) end of the pin, opposite from the slot on the left (outside) end.

Fig. 18. Close-up of Jaw Parts for KTC 300mm Adjustable Wrench.

Late Update! We recently (2025) acquired a later KTC adjustable wrench and were very surprised to observe that the pin securing the worm gear was threaded on the outside end!

Fig. 18 shows a close-up of the disassembled jaw parts from a KTC 300mm Adjustable Wrench. From top to bottom, the parts consist of the movable jaw, the worm gear, a small spring, and a threaded pin.

Note that the threads are on the left (slotted) end of the pin. The pin diameter was measured at 5.46mm in the interior and 5.75mm in the threaded section.

This is the first time for us to find that a manufacturer has changed the thread position. The wrench in question is believed to have been made in the mid 1970s or later and corresponds to the third generation in our table of styles.

One construction detail not shown in the photos is that KTC generally used a plain hanging hole (without a ridge) from the mid 1950s into the early 1970s, although some contract production was supplied with a ridge around the hole. By the mid 1970s KTC had adopted a ridge around the hole as its standard construction.

The next section will provide more detail on the differences between "maru" and "spear type" jaw outlines.

Understanding "Maru" (丸形) and "Spear Type" (ヤリ形) Jaw Styles

Early open-end wrenches were typically designed with approximately round heads, but eventually some manufacturers developed wrenches with slightly elongated jaws that became known as "spear type". The JIS standard for open-end wrenches (B4630) eventually accepted "spear type" jaws as a sub-type designated by an "S" suffix, and afterwards wrenches were described as either "maru" or "spear type".

Following a similar path, early adjustable wrenches were typically designed with approximately round heads, then in the mid 1960s KTC developed a "spear type" variant with the goal of changing the weight and balance of the head. However, unlike the case for open-end wrenches, the JIS standard for adjustable wrenches (B4604) did not recognize "spear type" jaws as an offical variant, but left the design choice to the manufacturer.

To illustrate the differences between the "maru" and "spear type" designs, we have taken photographs of wrench heads and annotated them with a circumscribed circle just outside the jaws of the wrench.

Fig. 19. Close-up of "Maru" Jaw Design for "Strong HIT" Adjustable Wrench.

Our first example is a typical "maru" design for Japanese adjustable wrenches.

Fig. 19 shows the jaws of the "Strong HIT" 200mm Adjustable Wrench with a circumscribed circle.

Note that the outline of the fixed jaw closely tracks the red circle, and that the circle covers most (but not all) of the wrench head.

Fig. 20. Close-up of "Spear Type" Jaw Design for Fuller "KTC" Adjustable Wrench.

Our second example is an early "spear type" design made by KTC for Fuller Tool.

Fig. 20 shows the jaws of the Fuller "KTC" 12 Inch Adjustable Wrench with a circumscribed circle.

Note that the outline of the fixed jaw has less curvature and deviates from the circle, and that the circle extends well beyond of the wrench head.

We can see that the elongated jaws of this design require a relatively larger circumscribing circle.

Stylistic Generations of Adjustable Wrenches

KTC's adjustable wrenches went through a number of production changes over the years, and the following table is an attempt to summarize the changes, with estimated production dates.

In the table we have identified three stylistic generations, beginning with the early Nissan OEM contract production by Yamaco around 1953. For some generations the production was shared with another manufacturer, as noted parenthetically.

In the last generation production was transferred to KTC's Hokuriku subsidiary, which received its own JIS certification in 1988.

It's possible that there may be a generation missing from our table, depending on whether KTC started using the KTC-Oval logo while still using maru-style jaws. We have not observed such a wrench, but if one shows up we will revise the table.

First Generation Adjustable Wrenches

KTC's first-generation adjustable wrenches were characterized by the use of the Nijūmarukyo logo, a maru-type jaw outline, and a plain hanging hole.

The most readily available examples of this generation are the dual-branded wrenches made as Nissan OEM tools, which were apparently made in huge quantities and remain common today.

But as luck would have it, we were also able to acquire an example of KTC's production for its own brand bearing the company's "3523" JIS number.

Early KTC "JIS 3523" 200 mm (8 Inch) Adjustable Wrench

We'll open this section with a first-generation KTC adjustable wrench marked for JIS 3523 in "N" grade.

Fig. 21. Early KTC "JIS 3523" 200mm Adjustable Wrench, with Insets for Back Side, Side View, Construction Detail, and Marking Detail, ca. Late 1950s.

Fig. 21 shows an early KTC 200mm adjustable wrench, marked with "KYOTO" and "K.T.C." plus the Nijūmarukyo logo forged into the front, with "Special-Alloy-Steel" forged into the back.

The front of the wrench is also marked with the JIS-Circle+N logo and "3523", as seen in the small upper inset.

The lower inset shows a close-up of the open jaws, illustrating the rounded transition at the corner of the fixed jaw and the inset convex cutaway of the movable jaw. Note also the full width of the tailpiece of the movable jaw.

The overall length is 8.2 inches and the maximum opening is 1.0 inches. The head thickness was measured at 0.49 inches.

The finish is chrome plating, but it appears to be just two layers (chrome over nickel). Modern chrome finishes have a copper base followed by nickel and then chrome, but close inspection of the areas where the finish has chipped off does not reveal any signs of a copper base. (See the tip of the jaws in the middle image.)

The "3523" marking is KTC's JIS certificate number for adjustable wrenches, first received in November of 1954. KTC's initial certification was apparently only for "N" ("Normal") grade, as the earliest record for "H" grade is not until the 1962 Certified List. (We have not found the exact date when the company received JIS "H" certification.)

We disassembled the wrench for cleaning and observed that the pin securing the worm gear is threaded on the inside end.

Estimating the production date for this wrench requires weighing several factors. The measured head thickness at 0.49 inches is thinner than any of the KTC-Nissan examples we have examined, a factor that suggests later production.

The chrome plating is an early two-layer (chrome over nickel) finish rather than a fully modern three-layer finish, but still suggests later production than the nickel finish of the KTC-Nissan examples. But since this wrench is for KTC's own brand, the company would be expected to use a higher-grade finish if possible.

By 1962 KTC had received JIS "H" grade certification, but we don't have a record of the exact date. The JIS "N" certification for this wrench suggests earlier production.

After weighing these factors we think that the wrench was probably made in the late 1950s, and we may be able to improve this estimate if the JIS "H" certification date can be found.

Early KTC "JIS H" 200mm Adjustable Wrench

Fig. 21B. Early KTC "JIS H" 200mm Adjustable Wrench, with Insets for Back Side, Side View, Construction Detail, and Marking Detail, ca. Late 1950s to Early 1960s.

Fig. 21B shows a similar early KTC 200mm adjustable wrench, marked with "KYOTO" and "K.T.C." plus the Nijūmarukyo logo forged into the front, with "Special-Alloy-Steel" forged into the back.

The front of the wrench is also marked with the JIS-Circle+H logo near the hanging hole, as seen in the small upper inset.

The lower inset shows a close-up of the open jaws, illustrating the rounded transition at the corner of the fixed jaw and the inset convex cutaway of the movable jaw. Note also the full width of the tailpiece of the movable jaw.

The overall length is 8.2 inches and the maximum opening is 0.9 inches. The head thickness was measured at 0.54 inches.

The finish appears to be chrome plating over a copper base, and traces of the copper layer can be seen in the lower inset.

We were not able to remove the pin securing the worm gear, but observed that it is threaded on the inside end based on the smooth walls of the bore.

This wrench closely resembles the illustration on page 18 [External Link] of the 1963 KTC catalog, which shows the JIS+H logo.

Currently we don't have a record of when KTC was first certified for "H" grade in class B4604. The first published record is in the 1962 Certified List, but we think it's likely that the certification came well before then. In the 1950s the JIS Monthly Reports did not have a format for publishing the "notes" field needed to report suffixes such as "H" grade, and as a result some tests may have gone unreported.

[Yamaco] KTC-Nissan "53 N" 200mm Adjustable Wrench

This next figure is representative of the first-generation KTC adjustable wrenches, made under the Nissan OEM contract but with production by Yamaco.

Fig. 22. KTC "Nissan" 200mm Adjustable Wrench, with Insets for Back Side, Side View, and Construction Detail, ca. Mid 1953 to 1959.

Fig. 22 shows a KTC 200mm adjustable wrench, marked with the Nissan logo and "Boron Steel" forged into the front, with "KYOTO" and "K.T.C." plus the Nijūmarukyo logo forged into the back.

The wrench is also marked with a "53 N" code forged into the front, with the JIS logo and "Y.K" forged into the back.

The lower inset shows a close-up of the open jaws, illustrating the rounded transition at the corner of the fixed jaw and the inset convex cutaway of the movable jaw. Note also the full width of the tailpiece of the movable jaw.

The top inset shows a side view of the wrench, illustrating the relatively thick head. The head thickness was measured at 0.51 inches.

The overall length is 8.2 inches and the maximum opening is 0.9 inches. The finish is nickel plating with polished faces, with minor losses due to rust.

We removed the pin securing the worm gear and verified that it is threaded on the inside end.

This wrench has a rather complex history, which we can begin to explore by examining the markings.

The front of the wrench seems relatively simple, with the Nissan logo indicating an OEM wrench probably intended for an in-vehicle tool kit. The "Boron Steel" marking is a bit unusual though, as boron is not a common alloying element, but a small amount of boron (less than one percent) can increase the hardness of carbon steel.

The back of the wrench offers a big surprise though, with "KYOTO" and "K.T.C." flanking the "Nijūmarukyo" logo, the same markings found on KTC's standard production! This kind of double-branding is rather unusual for contract production, as usually both the customer and the manufacturer would prefer not to draw attention to the maker.

The surprise continues with the JIS-Circle marking. The JIS industrial standards were very new in the early 1950s, and this wrench was probably first JIS-certified tool to appear in a mass-market vehicle tool kit.

One more surprise can be found in the small "Y.K" code to the right of the JIS mark. This is the JIS ID code for Yamaco, indicating that this particular wrench was actually made by Yamaco.

Our hypothesis is that when KTC first signed the OEM contract with Nissan, KTC itself had not yet received JIS certification for adjustable wrenches, and as a result Yamaco was brought in as the contract producer. Yamaco received JIS certificate 2356 for adjustable wrenches in June of 1953, and presumably the Nissan production would have begun sometime after that.

KTC received JIS certificate 3523 in November of 1954 and presumably would have begun its own production of the Nissan OEM wrenches shortly afterwards. KTC's Nissan wrenches are nearly identical to the Yamaco example here except for the omission of the "Y.K" marking.

The Nissan OEM wrenches were produced in great quantities and are still quite common today (2024) 60 to 70 years later. Observations of online photographs show that the Yamaco and KTC variants are both common, suggesting that Yamaco continued as a production partner.

KTC-Nissan "31 N" 200mm Adjustable Wrench

Fig. 23. KTC "Nissan" 200mm Adjustable Wrench, with Insets for Back Side, Side View, and Construction Detail, ca. Late 1954 to 1959.

Fig. 23 shows another KTC 200mm adjustable wrench, marked with the Nissan logo and "Boron Steel" forged into the front, with "KYOTO" and "K.T.C." plus the Nijūmarukyo logo forged into the back.

The wrench is also marked with a "31 N" code forged into the front, with the JIS-Circle logo forged into the back.

The lower inset shows a close-up of the open jaws, illustrating the rounded transition at the corner of the fixed jaw and the inset convex cutaway of the movable jaw.

Note also the full width of the tailpiece of the movable jaw.

The top inset shows a side view of the wrench, illustrating the relatively thick head.

The overall length is 8.2 inches and the maximum opening is 0.9 inches. The head thickness was measured at 0.59 inches.

The finish is nickel plating with polished faces.

We disassembled the wrench for cleaning and verified that the pin securing the worm gear is threaded on the inside end.

This wrench is very similar to the previous Nissan OEM example and most of our comments there apply here as well, but the JIS logo without an extra ID mark indicates that this wrench was produced by KTC itself.

A comparison with the KTC "JIS 3523" 200mm Adjustable Wrench above shows that KTC's production for its own brand was very similar, except that the markings on the back were moved to the front, and the back was marked "Special-Alloy-Steel".

Despite being made for an OEM customer, because of the dual branding we consider this to be a first-generation KTC adjustable wrench. (See our Table of KTC Stylistic Generations above.)

While cleaning the wrench we noticed a few spots where the nickel finish has worn off to reveal a copper base layer. The reddish copper layer can be seen on the tailpiece of the movable jaw in the lower inset, and another spot can be seen near the hanging hole in the middle inset.

The presence of the copper layer indicates a two-layer nickel over copper finish for this wrench, which is more refined than the finish on the previous example. Modern chrome plated finishes typically have three layers, with a copper base followed by nickel and then chromium.

The JIS marking for KTC indicates production some time after November of 1954, and the nickel finish suggests production in the 1950s.

A comparison of the Yamaco and KTC production for Nissan confirmed that the wrenches are very similar, but there were some discernible differences. For example, the head of the KTC wrench is substantially thicker than the Yamaco example (0.59 inches vs. 0.51 inches), and both in turn are substantially thicker than the 0.46 inch thickness measured for the second-generation KTC "Spear Type" Adjustable Wrench.

We examined several more examples of KTC-Nissan wrenches, and this particular wrench turned out to have the thickest head.

Another difference is the more refined two-layer nickel over copper finish noted for the KTC wrench, compared to the plain nickel plating of the Yamaco version.

We found another noticeable difference in the pin securing the worm gear. Both manufacturers use inside threads, but the KTC example has a rather short pin that does not clear the hole even when fully unscrewed. (We had to rap the wrench sharply on the workbench to knock the pin out.) In contrast, the Yamaco pin clears the hole when unscrewed and can be pulled out.

Additional examples of KTC-Nissan wrenches can be found in the section on Production for Nissan.

Second Generation Adjustable Wrenches

In this section we'll look at KTC's second-generation wrenches, which were characterized by the presence of the KTC-Oval logo and the use of a new "spear type" jaw outline.

The earliest known catalog reference for the second generation wrenches is in the 1966 KTC catalog, where the wrench can be seen on page 11 [External Link]. This style was still being offered in the 1971 KTC Price List No. 13, where it can be seen on page 21 [External Link].

KTC "Spear Type" 200mm Adjustable Wrench

Fig. 24. KTC 200mm Adjustable Wrench, with Insets for Back Side, Side View, and Construction Detail, ca. Mid to Late 1960s.

Fig. 24 shows a later KTC 200mm adjustable wrench, marked with the KTC-Oval logo and "Kyoto Tool Co." plus the JIS-Circle+H logo forged into the front, with "KTC, Alloy Steel" and a "12" code forged into the back.

The lower inset shows a close-up of the open jaws, illustrating the rounded transition at the corner of the fixed jaw and the inset convex cutaway of the movable jaw.

Note also the full width of the tailpiece of the movable jaw and the "spear type" jaw outline.

The top inset shows a side view of the wrench, illustrating the relatively thin head made possible by alloy steel. The head thickness was measured at 0.46 inches.

The overall length is 8.0 inches and the maximum opening is 0.9 inches. The finish is polished chrome plating.

We removed the pin securing the worm gear and verified that it is threaded on the inside end.

This wrench closely resembles the adjustable wrench illustration on page 11 [External Link] of the 1966 KTC catalog. Note in particular the details of the jaw construction, the "spear type" jaw outline, the full width of the tailpiece of the movable jaw, and the absence of a ridge around the hanging hole. More information can be found in the section on KTC Construction Details.

Based on our Table of KTC Stylistic Generations, this would be a second-generation KTC adjustable wrench. The principal change with the second generation was the adoption of the "spear type" jaw outline, a feature found in all subsequent generations.

Third Generation Adjustable Wrenches

The defining change for KTC's third generation of adjustable wrenches was the use of a ridge around the hanging hole, a design that had already been adopted by most other makers of adjustable wrenches.

Some additional minor changes occurred part way into the generation. For one, the company name marking was changed from "Kyoto Tool Co." to the slightly simpler "Kyoto Tool".

Another change occurred in the tailpiece of the movable jaw, which was modified so that it tapered to the cylindrical base rather than retaining the full width.

By observation, the change to the shorter company name occurred before the change in the tailpiece of the movable jaw.

In addition to the changes in design, the third generation was notable in that production was shared with Hokuyo Sangyo ("Sanki") from the beginning, and there is some evidence that Sanki may actually have initiated this generation.

KTC "119 SA" 200mm Adjustable Wrench

We'll begin this section with an early example of a third-generation KTC adjustable wrench.

Fig. 25. KTC "119 SA" 200mm Adjustable Wrench, with Insets for Back Side, Side View, Construction Detail, and Marking Detail, ca. Early 1970s.

Fig. 25 shows a KTC 200mm adjustable wrench, marked with the KTC-Oval logo and "Kyoto Tool Co." plus the JIS-Circle+H logo forged into the front, with "KTC, Alloy Steel" and a "119 SA" code forged into the back.

The lower inset shows a close-up of the open jaws, illustrating the rounded transition at the corner of the fixed jaw and the inset convex cutaway of the movable jaw.

Note also the full width of the tailpiece of the movable jaw and the "spear type" jaw outline.

The top inset shows a side view of the wrench, illustrating the relatively thin head made possible by alloy steel.

Note that the hanging hole is fully enclosed by a ridge, the defining feature for KTC's third generation.

We removed the pin securing the worm gear and verified that it is threaded on the inside end.

The "SA" mark on the back is the JIS ID code for Hokuyo Sangyō (Sanki), which indicates that this wrench was made by Sanki. Some production by Sanki also carries the company's 9786 JIS number forged into the front, but it appears that this wrench doesn't have room for the number, due to the width of the markings on the front.

A comparison with the second-generation KTC 200mm Adjustable Wrench above shows that this wrench is nearly identical except for the ridge around the hanging hole. Sanki has obviously taken great care to make a faithful copy of KTC's own production, as is expected for Japanese contract production.

This wrench has two features that suggest early contract production by Sanki for KTC. The first is that the tailpiece of the movable jaw retains its full width at the end, the same feature found in KTC's second generation (and earlier) wrenches. In later production of the third generation the tailpiece tapers to the cylindrical base, as can be seen in the figures below.

A second feature suggesting early production is that the company name is marked as "Kyoto Tool Co.", as was done in KTC's second generation. This marking was simplified to just "Kyoto Tool" in later production, as can be seen in the figures below.

KTC "16" 300mm Adjustable Wrench

The next two figures show later examples of third-generation KTC 300mm adjustable wrenches, with subtle differences in the marking and construction.

Fig. 26. KTC 300mm Adjustable Wrench, with Insets for Back Side, Side View, and Construction Detail, ca. Mid 1970s to 1980s?

Fig. 26 shows a KTC 300mm adjustable wrench, marked with the KTC-Oval logo and "Kyoto Tool" plus the JIS-Circle+H logo forged into the front, with "KTC, Alloy Steel" and a "16" code forged into the back.

The lower inset shows a close-up of the open jaws, illustrating the rounded transition at the corner of the fixed jaw and the inset convex cutaway of the movable jaw. Note also the "spear type" jaw outline.

The top inset shows a side view of the wrench, illustrating the relatively thin head made possible by alloy steel.

Note that the hanging hole is fully enclosed by a ridge.

The overall length is 12.0 inches and the maximum opening is 1.4 inches. The finish is chrome plating with polished faces.

With the absence of any extra JIS ID codes, we can be certain that this wrench was made by KTC itself, and this example is representative of KTC's third generation, as described in our Table of KTC Stylistic Generations. The principal visible change for the third generation was the adoption of a ridge around the hanging hole.

This wrench incorporates some minor evolutionary changes within the third generation form. Note that the tailpiece of the movable jaw now tapers rapidly to the cylindrical section, rather than maintaining its full width. Another small change is that the company name has been simplified to just "Kyoto Tool".

In addition to the readily visible changes, this wrench revealed an unexpected change to KTC's manufacturing process: the pin securing the worm gear is threaded on the outside end, in contrast to the inside threads used on all previous generations. The details of this change can be seen as the KTC Jaw Parts in the section on KTC Construction Details.

Currently we don't have an exact catalog illustration for this model. The illustration on page 28 [External Link] of the 1973 KTC catalog No. 15 shows a wrench with a ridge around the hanging hole, but with the angled transition of the fixed jaw characteristic of the larger wrenches produced by Hokuyo Sangyō (Sanki). By this time Sanki was providing contract production for KTC adjustable wrenches, and the catalog illustrations show the Sanki large-wrench version, rather than the rounded transition used for KTC's in-house production.

KTC "49 SA" 300mm Adjustable Wrench

Fig. 27. KTC 300mm Adjustable Wrench, with Insets for Back Side, Side View, and Construction Detail, ca. 1980s?

Fig. 27 shows a similar KTC 300mm adjustable wrench, marked with the KTC-Oval logo and "Kyoto Tool" plus the JIS-Circle+H logo forged into the front, with "KTC, Alloy Steel" and "Japan" forged into the back.

The wrench is also marked with a "9786" code forged into the front below the "H", with a "49 SA" code forged into the back.

The top inset shows a side view of the wrench, illustrating the relatively thin head made possible by alloy steel.

The middle inset shows a close-up of the open jaws, illustrating the rounded transition at the corner of the fixed jaw and the inset convex cutaway of the movable jaw. Note also the "spear type" jaw outline.

The small bottom inset shows a close-up of the pin securing the worm gear, illustrating the cross-point drive end of the pin.

Note that the hanging hole is fully enclosed by a ridge.

The reader could be forgiven for thinking that these two wrenches look exactly the same, as the differences come down to two small markings, "9786" on the front and "SA" on the back.

The "9786" marking is the JIS certificate for Hokuyo Sangyō (Sanki), the contract maker of this wrench, and "SA" is the JIS ID code for Sanki. (Some production by Sanki for KTC carries only the "SA" marking on the back.)

Apart from the subtle differences in markings, there are also subtle differences in construction. For Sanki the pin securing the worm gear is threaded on the inside end, but the third-generation wrenches from KTC switched to having the pin threaded on the outside end.

In addition, the pin on this wrench has a cross-point drive end, a feature known only on later Sanki wrenches. This detail suggests production in the 1980s.

Pliers

KTC began producing combination pliers in the early 1950s and received JIS certificate 3487 for class B4614 on October 21, 1954.

KTC [JP-200] 200mm (8 Inch) Combination Pliers

Fig. 28. KTC [JP-200] 200mm (8 Inch) Combination Pliers, with Insets for Back Side, Side View, and Marking Detail, ca. Mid 1960s to 1970s.

Fig. 28 shows a pair of KTC [JP-200] 200mm (8 inch) combination pliers, stamped with "95" and the JIS-Circle logo on the front, with "Pat." and "399268" plus the KTC-Oval logo forged into the back.

The middle inset shows the back side of the pliers in the wider opening position, partially revealing one of the circular wells for the slip-joint mechanism.

The top inset shows a side view of the pliers, illustrating the raised dimples of the gripping pattern.

The overall length is 8.0 inches, and the finish is chrome plating with polished jaws.

These pliers were listed as model SP08 in early KTC catalogs, but as JP-200 in later editions.

The patent marking refers to KTC's utility model ("petty") patent M399268, registered on January 23, 1953. The patent describes a slip-joint mechanism in which a raised oval land forged into one handle operates within overlapping circular wells in the other handle, remaining locked in one well when the angle between the handles is small, but slipping between the wells (to change the adjustment) when the handles are opened wide.

It's the same idea as a standard slip-joint mechanism, but with the flattened bolt replaced by a much wider oval land, thereby spreading the reaction forces over a broader surface. The screw serves only to hold the pliers together and does not bear any force when the pliers are gripping an object.

KTC's patent is basically identical to the 1939 Palmer patent 2,152,563, which was used by the Palmer Brothers Company for a moderately successful line of "Welloct" (well-locked) pliers in the 1940s and 1950s. The Palmer patent would have expired in 1956.

KTC JPS-150 150mm (6 Inch) Slip-Joint Combination Pliers

Fig. 29. KTC JPS-150 150mm (6 Inch) Combination Pliers, with Insets for Back Side, Side View, and Marking Detail, ca. 1979+.

Fig. 29 shows a pair of KTC JPS-150 150mm (6 inch) combination pliers, stamped with the KTC-Oval logo and model number near the pivot.

The pliers are also stamped with the JIS-Circle logo and a K-Circle logo on the front, with "579037" and "Japan" on the back.

The top inset shows a side view of the pliers, illustrating the chevron (or herringbone) gripping pattern.

The overall length is 6.1 inches, and the finish is polished chrome plating.

The K-Circle logo indicates production by Kyoto Kōki, which received JIS certificate 579037 in 1979 for combination pliers.

These pliers use a standard slip-joint adjustment mechanism.

KTC [SPD-200] "MH" 200mm (8 Inch) Lineman's Side-Cutting Pliers

Fig. 30. KTC [SPD-200] "MH" 200mm (8 Inch) Lineman's Side-Cutting Pliers, with Insets for Back Side, Side View, and Marking Detail, 1978.

Fig. 30 shows a pair of KTC 200mm (8 inch) lineman's side-cutting pliers, stamped with "Kyoto Tool" and the JIS-Circle+H logo around the pivot, with the KTC-Oval logo across the center.

The pliers are also stamped with "MH" and "78G" on the back.

The top inset shows a side view of the pliers, illustrating the angled facets of the head and the gripping pattern with "KTC" in the center.

The overall length is 8.3 inches, and the finish is plain steel with a polished front face.

These pliers were illustrated in the 1971, 1973, and 1977 KTC catalogs with the same distinctive gripping pattern.

The "MH" marking indicates production by Maruto Hasegawa, a major maker of pliers in Niigata prefecture. The JIS marking refers to JIS certificate 1018, first received by Maruto Hasegawa on October 31, 1951.

The "78G" code on the back is believed to be a year/month date code, which would indicate production in July of 1978.

Although not marked with a model number, these pliers were listed as model SPD-200 in the KTC catalogs.

KTC [RP-150] "MH" 150mm Needlenose Pliers with Side-Cutters

Fig. 31. KTC [RP-150] "MH" 150mm Needlenose Pliers with Side-Cutters, with Insets for Back Side, Side View, and Marking Detail, 1985.

Fig. 31 shows a pair of KTC [RP-150] 150mm (6 inch) needlenose pliers with side-cutters, stamped with "Kyoto Tool" and the KTC-Oval logo around the pivot.

The pliers are also stamped with the JIS-Circle logo on the front, with "MH" and "85D" on the back.

The overall length is 6.3 inches, and the finish is plain steel with red hand grips.

These pliers were listed as model RP-150 (or sometimes as RP-160) in the KTC catalogs. The 1977 KTC catalog noted side-cutting pliers, diagonal cutters, and needlenose pliers as being JIS certified.

The "MH" marking indicates production by Maruto Hasegawa, a major maker of pliers operating in Niigata prefecture. Maruto Hasegawa received JIS certificate 370202 for class B3631 (radio pliers) in 1970.

The "85D" code on the back is believed to be a year/month date code, which would indicate production in April of 1985.

Pipe Wrenches

By the mid 1960s KTC was offering heavy-duty (Ridgid pattern) pipe wrenches, the result of an intensive development program initiated at the request of Fuller Tool.

The company later offered Stillson-pattern pipe wrenches as well.

KTC [PW-300] 300mm (12 Inch) Heavy-Duty Pipe Wrench

Fig. 32. KTC [PW-300] 300mm (12 Inch) Heavy-Duty Pipe Wrench, with Insets for Back Side, Side View, and Marking Detail, ca. 1970s to 1980s.

Fig. 32 shows a KTC [PW-300] 300mm (12 inch) heavy-duty pipe wrench, marked with "K.T.C." and "Top Quality" cast into the front, with "K.T.C." and the JIS-Circle+H logo cast into the back side.

The movable jaw is marked with "Drop Forged" and the KTC-Oval logo forged into one side, with graduation marks for the opening size on the opposite side.

The overall length is 10.6 inches closed and 12.9 inches fully extended. The finish is plain steel and red paint.

KTC received JIS certification for pipe wrenches sometime before 1972, but the exact date is not yet known.

The absence of a "Japan" marking suggests that this wrench was originally sold into the domestic market.

Production for Toyota Motor

KTC had a production contract with the Toyota Motor Company at the start of its operations in 1950, and Toyota remained an important customer for many years.

KTC is known to have produced open-end wrenches and pliers for Toyota, but it's an open question as to whether the company also made adjustable wrenches for Toyota. We are currently trying to find information and examples (if any) of early Toyota adjustable wrenches.

Later Toyota adjustable wrenches were made by Toho Kōki, and further information can be found in the section on Toyota Adjustable Wrenches.

Our current hypothesis is that Toyota adjustable wrenches made by KTC (if they exist) look substantially the same as the example from Toho Kōki, and can be distinguished by having inside threads on the pin holding the worm gear. If any of our readers have an example of such a wrench, please let us know via email.

Open-End Wrenches

KTC produced open-end wrenches for Toyota from 1950 to the 2000s and beyond. Over that span of time there were a number of production changes, and in the next section we will attempt to organize these changes into a series of generations.

In the 1950s and 1960s Toyota OEM wrenches were marked with "Nickel-Chrome-Vanadium", a reference to KTC's preferred steel for toolmaking at that time. The use of the same alloy steel strongly suggests that the OEM tools were being made to the same high standards that KTC applied to its own tools. The resemblance went further than just the use of the same steel, as the Toyota OEM wrenches with recessed oval panels closely resemble KTC's open-end wrenches of the 1960s.

Stylistic Generations of Toyota Motor Open-End Wrenches

As noted above, the Toyota Motor open-end wrenches went through a number of production and marking changes over the years, and the following table is an attempt to summarize the changes. Based on our present understanding, we have defined five stylistic generations with easily observed visual characteristics.

The table includes a column with a rough estimate of the production date range, and we will make updates as new information becomes available.

The production and marking attributes defining the generations are as follows:

• Shank. The style of the flat or paneled shank, as Flat, Recessed, or Raised.
• Markings. The type of markings, as Forged or Stamped.
• Alloy Marking. The alloy steel marking, as N-C-V, Special, or None.
• Name. The company name "Toyota Motor" or "Toyota" expressed as Long or Short.

Evidence for the date of the transition from the second to third generation (recessed panels to raised panels) can be found by examining KTC's contract production for the Fuller Tool Company. KTC supplied open-end wrenches with recessed panels to Fuller from the early 1960s until the mid 1970s, then switched to supplying wrenches with raised panels in two styles. Wrenches with raised parallelogram panels were marked with a higher-grade (or more specific) alloy, and wrenches with raised oval panels were marked for a non-specific alloy.

This is the same pattern that we see for the Toyota OEM wrenches, providing confirmation for our date estimates. The change from recessed panels with forged-in markings to raised panels with stamped markings was probably driven by a need to reduce costs.

[KTC] Toyota Motor 10x12mm Open-End Wrench

The next figure shows an example of a first-generation open-end wrench.

Fig. 33. [KTC] Toyota Motor 10x12mm Open-End Wrench, with Inset for Back Side, ca. Early 1960s.

Fig. 33 shows an early Toyota Motor 10x12mm open-end wrench, marked with the metric sizes plus "Toyota Motor" and the "トヨタ" Katakana logo forged into the front, with "Nickel-Chrome-Vanadium" forged into the back.

The overall length is 5.0 inches, and the finish is chrome plating with polished faces.

This style of wrench has been observed in a Toyota OEM tool kit with other components consistent with an early 1960s production date.

[KTC] Toyota Motor 14x17mm Open-End Wrenches

The next two figures show examples of second-generation open-end wrenches, with differences in the forged-in markings.

Fig. 35. [KTC] Toyota Motor 14x17mm Open-End Wrench, with Inset for Back Side, ca. Early 1960s to Mid 1970s.

Fig. 35 shows a Toyota Motor 14x17mm open-end wrench with recessed oval panels, marked with "Toyota Motor" and the Toyota Katakana logo forged into the front, with "Nickel-Chrome-Vanadium" and "Japan" forged into the back side.

The overall length is 6.3 inches, and the finish is chrome plating with polished faces.

This wrench closely resembles the KTC 14x17mm Open-End Wrench shown in an earlier figure.

The recessed oval panels of this wrench closely resemble the illustration on page 8 [External Link] of the 1966 KTC catalog, which shows the company's line of JIS-certified open-end wrenches. The catalog description notes that the wrenches were made of nickel chrome vanadium alloy steel, the company's preferred alloy steel in the 1950s and 1960s.

Fig. 36. [KTC] Toyota Motor 14x17mm Open-End Wrench, with Inset for Back Side, ca. Early 1960s to Mid 1970s.

Fig. 36 shows a similar Toyota Motor 14x17mm open-end wrench with recessed oval panels, marked with "Toyota Motor" and the metric sizes forged into the front, with "Nickel-Chrome-Vanadium" and "Japan" forged into the back side.

The overall length is 6.4 inches, and the finish is chrome plating with polished faces.

The absence of the Toyota Katakana logo may indicate a later production date for this wrench, but it's also possible that the Katakana logo might have been omitted for some regional markets.

[KTC] Toyota Motor 10x12mm Open-End Wrench

The next two figures show examples of third-generation open-end wrenches with raised square panels.

Fig. 37A. [KTC] Toyota Motor 10x12mm Open-End Wrench, with Inset for Back Side, ca. Late 1970s to 1980s?

Fig. 37A shows a Toyota Motor 10x12mm open-end wrench with raised panels, stamped with "Toyota Motor" and the metric sizes on the front panel, with "Special Alloy" and "Japan" on the back panel.

The overall length is 5.2 inches.

The finish is cadmium plating, with striations from fine grinding still visible on the panels and faces.

Wrenches with raised panels in this style have been observed in Toyota OEM tool kits of probable 1980s production.

[KTC] Toyota Motor 14x17mm Open-End Wrench

Fig. 37B. [KTC] Toyota Motor 14x17mm Open-End Wrench, with Inset for Back Side, ca. Late 1970s to 1980s?

Fig. 37B shows a Toyota Motor 14x17mm open-end wrench with raised panels, stamped with "Toyota Motor" and the metric sizes on the front panel, with "Special Alloy" and "Japan" on the back panel.

The overall length is 6.4 inches.

The finish is cadmium plating, with striations from fine grinding still visible on the panels and faces.

Pliers

KTC produced combination pliers for Toyota tool kits for many years. The pliers were offered in two sizes, 150mm (6 inches) and 200mm (8 inches).

For many years the 200mm pliers were basically identical to KTC's own production, even down to the forged-in marking for KTC's patent.

[KTC] Toyota Motor 200mm (8 Inch) Combination Pliers

Fig. 38. [KTC] Toyota 200mm (8 Inch) Combination Pliers, with Insets for Back Side, Side View, and Marking Detail.

Fig. 38 shows a pair of Toyota 200mm (8 inch) combination pliers, stamped with "Toyota" and "Japan" on the front, with "Pat." and "399268" plus the KTC-Oval logo forged into the back side.

The top inset shows a side view of the pliers, illustrating the raised dimples of the gripping pattern.

The overall length is 8.0 inches, and the finish is chrome plating with polished faces.

The patent describes a slip-joint mechanism in which a raised truncated cylindrical projection forged into one handle engages a circular recess on the other handle, thereby relieving all sheer stress from the connecting screw.

The 1963 catalog has an illustration of this patent, but the catalog shows the patent number as "399238" rather than the "399268" forged into the pliers. The published announcement document for the patent turns out to be 27-7597, issued on January 23, 1953.

The design shown in the patent is nearly identical to the 1939 Palmer patent 2,152,563, which was used by the Palmer Brothers Company for their line of "Welloct" ("well-locked") pliers.