JIS vs Phillips: Japanese Screwdriver Sizes and Tip Length

Short answer: a JIS screwdriver is one ground to JIS B 4633, Japan’s cross-recess driver standard — shorter and more pointed at the tip than a US Phillips. On a #2, JIS requires a minimum tip length of 3.70 mm against ASME’s 4.83 mm, plus a pointed 17–19 degree end. It seats deeper in a shallow Japanese recess, which is why a US Phillips rounds those heads.

The short version, before the folklore

Phillips was not designed to cam out. JIS B 4633 has not been withdrawn. And the dot beside the cross on a Japanese fastener does not mean “JIS recess” - it means the thread is ISO pitch. What is true is that a US-ground Phillips driver often fits a Japanese fastener badly enough to round it, because Japanese drivers are ground shorter and more pointed. Here is the documented version.

What the Phillips patents actually say about cam-out

The story goes that Henry Phillips deliberately built slip into the recess as a poor man’s torque limiter. The patent record says the opposite. US 2,046,343 (Phillips, filed July 1934, issued July 1936) describes the objective as a recess that can be produced by a simple punching operation and that engages a driving tool firmly - with, in the application’s own framing, no tendency of the driver to cam out. Preventing cam-out was the stated goal.

What is documented is the sequel. A later patent in the same family, US 2,474,994 (applied for December 1942, granted 1949), discusses the recess’s vertical contact angles and argues that a zero-cam-out geometry had proved unsatisfactory on assembly lines, where torque-limiting clutches were unreliable. Cam-out was a property the industry learned to live with and then rationalised - not a feature drawn on the first napkin.

JIS B 4633 exists, and it is current

JIS B 4633, “Screwdrivers for cross recessed head screws,” was established 30 January 1954, last revised 20 March 1998, and confirmed 22 October 2018. It is active in 2026. The persistent claim that it was declared obsolete in 2008 and replaced by ISO 8764 is wrong.

What confuses people is that JIS B 4633:1998 is a modified adoption of ISO 8764-2:1992 and ISO/DIS 8764-1:1996 - aligned, within ISO tolerances, but written with its own numbers. For the H-type tip:

• Point (wing taper) angle: No.1 = 7 degrees, No.2 and No.3 = 5 degrees 45 minutes, No.4 = 7 degrees, each with a tolerance of 0 to minus 45 minutes.
• Flute angle: No.1 = 138 degrees, No.2 = 140 degrees, No.3 = 146 degrees, No.4 = 153 degrees, plus or minus 45 minutes.
• Marking: the driver must carry the recess type symbol (H or S), the size number, and the maker.

The number that matters day to day is tip length. On a #2, JIS requires at least 3.70 mm, ISO at least 4.37 mm, ASME at least 4.83 mm. JIS also calls for a pointed end (17 to 19 degrees) where ASME and ISO permit anything from flat to 19. A US-spec driver is longer and can be blunter; in a shallow Japanese recess it sits proud, loads the wrong part of the wall, and skates.

The screw side: H-type, S-type, and JCIS

The recess in the screw is governed by JIS B 1012, “Cross recesses for screws,” confirmed as recently as 2021. It defines two forms:

• H-type - the common one, M1.6 and up, 7 degree or 5 degrees 45 minutes wing angle. Conforms to ISO 4757.
• S-type - M2 and smaller (and small-head M3 and smaller), 4 degree wing angle.

That undercuts the popular version of the story: the ordinary Japanese cross recess is the ISO recess. The H-type is not a secret rival geometry. Divergence lives at the small end - the S-type, and separately JCIS, the Japan Camera Industry Standard covering micro screws in camera and lens bodies. JCIS is not JIS. Inside a film-era Nikon or Canon, that is the standard you are fighting, and a Western #00 Phillips will chew it.

JIS vs Phillips vs Pozidriv

Pozidriv is the one that really is a different geometry. Its extra 45 degree ribs and near-parallel flanks roughly double the contact surfaces, and its screws carry visible tick marks between the cross arms. Either driver in the other’s screw is a genuine mismatch.

The dot is not what you think

The small hemispherical dimple beside the cross on Japanese fasteners is the ISO thread mark. It was specified in the 1972 edition of JIS B 1111 to distinguish screws cut to the new ISO metric pitches from the older JIS pitches - M3 went 0.6 mm to 0.5 mm, M4 0.75 to 0.7, M5 0.9 to 0.8. Mixing the two cross-threads parts, so the dimple warned mechanics.

The requirement was abolished at the end of November 1977. Japanese makers kept stamping it anyway, which is why you still see it, and why Honda-supplied fasteners in particular carry a dot or raised plus across all sizes. It says nothing about the cross recess. A dotted screw is not “a JIS screw” in the sense the internet means.

Check Vessel Megadora 900 series on Amazon

So why does your driver still round the head?

Because fit is cumulative. A US #2 with a long, blunt, slightly worn tip, pressed a few degrees off axis into a shallow recess on a 30-year-old corroded fastener, will slip. A JIS-ground #2 seats deeper with more wall loaded, so the same hand pressure becomes more torque before it skates. The advantage is real. “Different geometry” is not the reason for it.

The drivers worth owning

Vessel is the name most people land on, and its own catalogue backs the marketing: the Megadora 900 series is described by Vessel as recommended for JIS screws, in +No.1, +No.2 and +No.3, with magnetised black-point tips. Sensible default.

The Megadora 980 Impacta is the one for motorcycles. It fits #2 JIS and US Phillips, and its Tang-Thru construction lets you strike the handle with a hammer, rotating the tip 12 degrees counter-clockwise while driving it into the recess. Shock plus axial load breaks loose seized engine-cover and carburettor screws that a normal driver only rounds.

Check Vessel Megadora 980 Impacta on Amazon

Hozan sells a four-piece JIS cross-point set, the JIS-4, that lands in the US regularly and covers the small end better than most Western precision sets. Anex is strongest in precision and JCIS-range drivers - camera work rather than engine work.

Check Hozan JIS-4 set on Amazon

What to actually buy

Japanese motorcycle: a #2 and #3 Megadora Impacta, plus a #2 in the plain 900 series for ordinary work. That covers most of a carburettor, a side cover, and a chain guard.

Japanese cameras or lenses: skip general sets. You want JCIS-range precision drivers in +00 and +0, where the geometry actually does diverge from Western Phillips.

Check Anex No.930 precision drivers on Amazon Japan

Japanese appliances: a single #2 JIS-ground driver solves essentially every screw you will meet.

Identifying a JIS tip is easier than identifying a JIS screw. Look for the H or S symbol and size number stamped on the blade, which JIS B 4633 requires. Do not go by the dot on the fastener.

Summary

The cam-out legend is not supported by the Phillips patent language. JIS B 4633 is alive, confirmed as of 2018. The H-type recess conforms to ISO 4757. The dot is a thread-pitch mark from a rule that expired in 1977. What survives the debunking is the practical point: Japanese drivers are ground shorter and more pointed inside the standard’s tolerances, they seat better in Japanese fasteners, and Vessel, Hozan and Anex all sell them into the US.

Hand tools have no import problem - no voltage, plug, or frequency issue, so buy the Japanese driver without a second thought. That only becomes a question with powered tools, covered in our Japanese tools 100V voltage guide. More Japan-market gear coverage is in our English section.

Related guides

• Q-max Is a Half-Second Number
• Japan’s Heatwave Survival Kit