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JIS screwdrivers and bits

"Henry F. Phillips (1890–1958) was a U.S. businessman from Portland, Oregon." -- wikipedia.org



[edit] Background

On behalf of all Oregonians (especially from Portland), I hereby apologize for our part in bringing the plague of stripped screw heads to the world. John P. Thompson was the inventer in 1933, with Henry F. Phillips the assignee. One of the wonderful features of the Phillips design was that after a certain torque was reached, the bit would "cam out" of the screw head. This was a fine feature for manufacturing where it was difficult to control torque on the new powered drivers. In 1936, Cadillac chose to use the new screw-head design, and by the end of World War II, the design was ubiquitous, and most screw manufacturers had a licence to produce the screw.

On these thirty- and forty-year-old dirt bikes, the "cam out" feature can be frustrating. If the thread is a somewhat rusted in place, the Phillips bit usually cams out a bit early and destroys what remains of the screw head socket.


[edit] The JIS specification

But most Japanese dirt bikes do not use a Phillips socket! The Japanese designed a straightforward socket and tool that does not cam out. The history is quite complicated, and the International Standards Organization got involved, too, but it's enough for us merely to know the JIS term. Some JIS screw heads are marked with a single raised dot. The JIS bits allegedly work in a Phillips socket as well as or better than a Phillips head bit.

[edit] Finding these tools

These tools are completely obscure in the U. S. For JIS hand screwdrivers, Hozan seems to be the cherished name. These are offered all over the internet. Hozan started making tools in 1951 and incorporated into their present form in 1955. They seem to sell a lot of bicycle tools, too.

Now (late 2015) Go Fast Innovations in Canda sells a three-tool JIS screwdriver set. Their blue and white colour scheme will look great next to a 1972 TS185!

Go Fast Innovations JIS screwdriver set

[edit] But for the corroded hulks that are our machines

An impact driver with bits (courtesy of wikimedia.org)

Many forum members recommend loosening screw heads with an impact driver, that is, a tool with a bit on one end that is smacked on the other end with a hammer. This imparts an impact and a bit of a twist to the bit to shock and encourage the screw to turn. Nicer impact tools allow tightening and loosening shocks via a twist adjustment on the driver.

Hilmi recommends smacking a screw head tighter first before attempting to impact it in "loosen" mode. This makes some sense to me as tightening might allow the screw to turn in "new" non-corroded threads. When it comes time to loosen, the screw has a bit of a running start on clean threads before being forced to cut through the corrosion that is likely present toward the screw head. I suppose also that upon tightening, the tension of the screw could be increased, and this extra energy released when the "loosen" impact impacts.

[edit] JIS impact bits exist!

"VESSEL was founded in 1916 as Japan’s first volume manufacturer of screwdrivers." I have no idea whether their hand screwdrivers are as lovely as the Hozan brand or newcomer Go Fast Innovations, but Vessel also offers impact bits on an 8 mm hex shaft (which is practically identical to a 5/16-in. hex shaft).

I have not yet dealt with this company, but if you can find a hand impact driver which accommodates an 8 mm hex shaft, here are your bits!

Vessel bits buy page

Please let the TS/TC/TM forum know of other sources for these tools and whether you notice better results with real JIS-spec tool bits. Perhaps these tools are common in your part of the world.

[edit] Vessel tools creates the Holy Grail of tools!

Finally, a screwdriver that you can pound on with a hammer!! These are somewhat pricey, but they are offered with JIS ends, so knock yourself out! You know you have always wanted to bash away on the end of a screwdriver!

May I present the Megadora Impacta screwdriver: