Originally Posted by
Eric F
Please enlighten me....How are JIS Phillips bits different?
Philips bits have tapered blades and were designed to be torque limiting. That is why you have to push so hard on the driver when the resistance increases. They “cam-out” when you turn too hard.
JIS screws look like philips screws, but the faces of the blades are parallel. Using a philips bit in a JIS screw tends to damage the screw. Using a JIS screwdriver in a philips screw usually isn’t a big deal.
Nearly all derailleur screws are JIS. Most shops use JIS drivers, but most home mechanics don’t know that there is a difference.