Are limit screws JIS instead of Philips?
 

I have a theory. I've often noticed that derailleurs limit screws don't quite... work with Phillips screwdrivers. I've tried #1s and #2s, but they never seem to work right in those limit screws.

So, my theory is that those screws are the JIS heads and not Phillips. Am I right? I mean, Shimano is a Japanese company...

Correct. I've been meaning to get JIS #2 for them.

Actually most of the "Philips" screws you see in the USA haven't been Philips for years. The last stronghold for Philips was in the electronics trades and other applications calling for nice cosmetics.

Otherwise, most of those screws today are a variant of "Pozidriv". The key difference is that Philips drivers come to a point, and the more modern variations don't. Forming screws with the full depth to accommodate the pointy drivers is more difficult, so they don't bother.

There's an easy fix if you have a bunch of Philips screwdrivers that aren't working for you. Just grind the point back so the driver can settle deeper until it's supported on the blades. This isn't a technically correct conversion to Pozidrive or JIS, but it'll do the job.

Yes, it does seem so, IME. If you try a JIS screwdriver, you will be impressed with how much better it fits with the limit screws on Shimano derailleurs.

Shimano derailleurs are JIS-2. I expect that other brands are not.

Because you can't eat "JIS-1".



Sorry... bad pun.

A lot of limit screws will work with a bladed screwdriver as well, which gives you a better grip on the screw in my experience.

http://www.slowtwitch.com/articles/i...mit_adjust.jpg

Ugh. I feel just wrong looking at that picture. I can hear the words in my head "Using the wrong tool for the job will just end up making more work for yourself." Then again, I guess the phillips screwdrivers are also the wrong tool so...

I generally abhor flat bladed screwdrivers. I get annoyed when I have to deal with a flat headed screw, especially if it's one that I have to turn a lot. They're remnants of the past, and should only be used when absolutely necessary. But if you say they work better than Phillips, I may have to try it haha.

Interesting. I've noticed that most of my #1 Phillips are sharp, where most of my #2s are blunt.

Screws like the one in the picture are clearly made to use with either Phillips or bladed screwdrivers. I've never had a problem with a bladed screwdriver slipping or damaging the screw head. I've always found a Phillips to not fit right and honestly didn't know about the JIS standard for this. Learn something new every day here!

Ha!

Philips (and variants) should not be used for screws that adjust something, because you have to push on the screw to make the adjustment. Much better to use an allen head. I understand not wanting to force everybody to adopt a new tool, but those tiny philips heads on derailers and vee-brakes are a weird throwback, when every other screw on the bike has been modernized.

Thanks....

Interesting aside, many of those Phillips screw heads can also be turned using a Canadian invented Robertson screwdriver

Whut? Robertson is square drive.

90 degrees is 90 degrees. Pozidrive combines Phillips and Robertson. In Canada many consumer products allow you to use both and Robertson is mostly the default choice

Don'r forget Frearson aka Reed and Prince.

The dot in 1 quadrant is an indicator that it is a JIS screw and not a Phillips screw.

Shimano used to put their logo on these Jis #2 screwdrivers:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

This worked great - was working on a bike last night and grabbed a Philips screwdriver for an adjustment and of course it didn't fit. Remembered this comment and had a file sitting in my tool bag. Few strokes and removed the sharp point off the screwdriver and it fit perfectly.

Your Theory is Goofy. Its a Metric screw.

Spend Up on a Quality screwdriver , whose tips dont round off and so make a weak connection..

http://www.phillips-screw.com/pozidriv.php






./.

Well, a flat blade screwdriver is technically the wrong tool but limit screws require very little torque so the "wrong tool" does work and doesn't damage them. No harm, no foul.

Most hardware store flat screwdrivers are ground with a taper and tend to cam-out of the screw slot. Gunsmith screwdrivers are hollow ground and the tips are parallel. They stay put in the screw slot and are far less likely to damage the screw head.

Whether a screw is metric or not has nothing to do with JIS. It has to do wit the shape of the screwdriver tip. The best phillips head screwdriver in the world will likely strip or "Cam out" the head of a JIS screw. Here is why...



http://www.vesseltools.com/images/st...jisdiagram.pnghttp://www.vesseltools.com/images/st...ipsdiagram.png



Vessel makes outstanding JIS screwdrivers...

700/KIT-P123 | Screwdriver Sets | Screwdrivers | Hand Tools | VESSEL TOOLS



-Tim-

I had forgotten about this. Thanks for the reminder.

It's surprising that, AFAIK, Park doesn't make JIS screwdrivers. I've used a JIS screwdriver on Shimano limit screws, and it is clearly an "A" fit on Shimano limit screws, compared to the "B" fit with Phillips screwdrivers.