Broken or stripped screws

[latexeses]

I've been tearing down and cleaning the carbs for the SF one at a time and everything was going along just fine until I got the the LAST CARB...
Number one carb has the little bracket for the "choke" lever. First screw came out perfect. The second screw was placed by Murphy or maybe Hulk Hogan. Tapping lightly on the screw to loosen it up.. nothing, same with heat, same for penetrating oil, same for inpact driver.
Ultimately I had buggered the phillips head to the point of utter frustration.
I fell back on the last resort in my book. The screw extractor.
I've had it for years and I have NEVER lost a scew or a bolt. Bought it from Snap-On tools out here in Ca. EXDL10 is the number on the box.
The key to this kit is the fact that it uses Cobalt left hand twist drills. Same for the extractors. Maybe 25% of the broken bolts I have used this set on brought the broken part out when I was drilling the pilot hole!
I can't recomend this set enough. Plain and simple it has worked every time I have had to bring it out to go after a busted fastener.

[tarzan]

I have a set of extractors too.Craftsman.I dont much care for craftsman anymore because their tools quality has gotten a lot worse over the years.But this kit works great.It has a left handed centerdrill on one end and extractor on the other.It has saved me several times too.

[Ken Talbot]

Re: Broken or stripped screws

Originally posted by latexeses
Ultimately I had buggered the phillips head to the point of utter frustration.

That's why, with phillips head screws of unknown heritage, it is often wise to start with the impact driver. Crack it a good one right from the get-go, and you can often prevent the stripped-out head scenario and having to dremel a fresh slot.

BTDT

[prometheus578]

"Tips for next time"

Put a little dab of "coarse valve lapping" compound on the screw head first. The carbide grit, or whatever it is, helps to prevent the screwdriver tip from slipping and stripping.
Mac Tools sells a bottle of great stuff for $10.
The Mac guy said I could also use valve lapping compound... (naturally, he said this after had I bought the bottle of stuff from him)

[Just In Case]

About screw heads... aren't JIS screw heads slightly different than Phillips? I remember someone somewhere saying they got a JIS screwdriver set and stripped screwheads were vastly reduced.

And as Ken says, a good whack with an impact driver means the problem doesn't even arise

Dave

[prometheus578]

"Craftsman will strip..."

...but the #2 Phillips from Mac Tools is a perfect fit ($14)

[latexeses]

Both of the little screws were pretty well worked over from the PO. The very first thing I did was take the screwdriver bit form the impact set and give each of the screws a good rap, without the driver.
I was really surprised at how soft the metal seemed. Acted like Babbitt metal or something. Really soft.
Using the imact driver first would have saved me a bunch of time. Sort of "Go or go home".
If I'm not mistaken doesn't the JIS have a shallower "hole"? The screwdriver is more blunt?
I have a driver that fits the "healthy" screws very well and was the first to try the bum screws.

Prom-
Thanks for the tip on the lapping compound.

Thanks to everyone for the input. Hopefully I won't run into too much of this once I get past the carbs. HA!