Shop Press

Shop Press is the news and idea hub for everything related to working on cars and trucks, focusing on repair, technology, and wrenching lifestyle.

From the creative minds at:


Hot Off the Press

Catalytic converters are the coolest car parts that get no respect

The air in Detroit during the 1960s was so polluted that mothers were scared for their children to play outside. In certain places, you couldn’t see the sun at noon, and buildings had to be cleaned or repainted every six months. Some people wrote letters to...

Is perseverance in the service bay a feature or a bug?

I am a proficient mechanic. I have long said my proficiency comes partially from skill, but mostly I’ve achieved good results due to my perseverance. I am generally unwilling to toss in the towel on something until it works correctly. “Too stupid to know when to quit”...

May Automotive Horoscopes

Aries: Your service writer will be keeping you busy this month, and you’ll need to keep your focus to avoid burnout. Pay special attention to the effects of distractions around you. Some coworkers have a way of keeping you from your work for a little longer than you...

Right to Repair gains momentum in Maine

The state motto of Maine, “Dirigo,” Latin for “I lead,” is being embraced by the members of the Maine Right to Repair Coalition who find themselves at the vanguard of a movement to ratify legislation that protects independent repair shops. Last February, a referendum...

Tool review: ICON 3/8” ratchet

About a year ago, I was reefing on some fastener, and my trusty old Armstrong ratchet let go and spun free. It did it again a few bolts later, and at that point I set the tool down before I got hurt. I had purchased a few 3/8” ratchets years earlier after some junkers...

The other “Phillips” head screwdriver you might not know about

by | Dec 9, 2021

Not every Phillips head fastener is a Phillips head fastener.

I believed this was common knowledge until today, when I was speaking with another tech who had no idea what I was talking about, and I relived a lesson from my salad days of wrenching.

Many moons ago, when rebuilding the carburetors on Japanese motorcycles, I would replace all the hardware for the bowls and carb tops on CV units, for they were constantly stripping. I used to poke fun at them. I said they were made of cheese.

An old mechanic saw me doing this on a nice older bike, and told me I was an idiot. Quite naturally, I asked him why. He told me I was using the wrong tool on them. Nonsense! It’s a simple Phillips-head! Why, I had drawers full of them. He laughed and told me to bring him one of the screws I was throwing away. With his tobacco-stained pinky nail, he pointed to a small dot in one of the corners of the cross.

Dimples in a screw denote they are JIS.

See the dimples? Those are JIS shorthand for, “Walk back to your box and get the correct tool!” Photo by Lemmy.

“See that?” he asked. “That punch mark is to tell you not to use a Phillips-head driver on it. This is called a JIS screw. Japanese Industrial Standard.”

I thought he was breaking my horns. Then I looked into it. Turns out, he was correct. A true Phillips head screw “cams out” at a fairly low torque reading—exactly why I thought they were stripping (and why you’ve probably stripped them too). No one is sure if the design was developed that way, but the patent was updated in 1949, when that very cam-out “feature” (useful for machine-driven fasteners in those days) was described.

JIS screws are a little different but look similar. Many, many items made in Japan use JIS screws, which have a different profile in the “cross” area, as well as a more vertical angle of attack in the head of the fastener. They’re also flat in the bottom, whereas a Phillips bit is not, so it stands out of the slot when inserted, decreasing the contact area between driver and fastener.

JIS screwdrivers prevent damaged JIS fasteners, and they also can be useful for a Phillips fastener that’s been marred—sometimes prudent use of a JIS driver can extract the Phillips fastener. (And if you get it out, replace it with something fresh so you don’t sweat the same thing twice!)

Phillips screwdriver next to a JIS screwdriver

Not all screwdrivers (nor fasteners, for that matter) are created equal. The one on the right is a JIS driver. Photo by Lemmy.

I’ve got a few brands of these kicking around in my box, but I think Vessel makes some really nice ones. They’re expensive and always have been, and they are worth every penny. I recommend them.

The articles and other content contained on this site may contain links to third party websites. By clicking them, you consent to Dorman’s Website Use Agreement.

Related Articles

Shop Press Comment Policy

Participation in this forum is subject to Dorman’s Website Terms & Conditions. Please read our Comment Policy before commenting.

Notify of
Oldest Most Voted
Inline feedback
View all comments

Get Articles In Your Inbox

Subscribe to receive a monthly email summary of our latest Shop Press stories.

Shop Press

Thanks! You're now subscribed.