Drilling holes in A&C body with gel coat

[spdbrake]

Uni-bits are safe for Fiberglass, Composites, Plastics and and can't be beat for Plexiglas. No blowout, chipping or crazing.

The only real drawback can be the thickness of the material. In your case though a #3 Bit PN 10233 (max dia is 3/4") should do a great job.

Also Uni-bits can be laterally "walked" if you see you off a bit on center line.

https://www.irwin.com/uploads/produc...etal_eBook.pdf
https://www.irwin.com/tools/drill-bi...tep-drill-sets

If you do decide to use a hole saw. Once the pilot tip is thru run the drill in reverse while you cut thru the Gel-coat to help eliminate chipping. Then switch back to normal R/H drilling rotation. As others have said, its good idea to go to backside and score the hole with the the bit to prevent a lot of final hole blowout chipping.

[1BIG67AC]

Gents thanks for the info. Now it’s time to man up and just do it! I’ll let you guys now how it comes out. I’ll keep my finger crossed too!

[H-Rod]

Originally Posted by spdbrake

If you do decide to use a hole saw. Once the pilot tip is thru run the drill in reverse while you cut thru the Gel-coat to help eliminate chipping. Then switch back to normal R/H drilling rotation. As others have said, its good idea to go to backside and score the hole with the the bit to prevent a lot of final hole blowout chipping.

All the round holes I drilled in my car were with a holesaw spun in reverse.
Drill your pilot hole (in reverse) then use that as a guide for the drill in the hole saw.
I also laid down some painters tape while I did this.
No chipping, cracking or anything.

If you think drilling for the hood latches is a booger, wait til you drill for the roll bar.

[cycleguy55]

Originally Posted by H-Rod

All the round holes I drilled in my car were with a holesaw spun in reverse.
Drill your pilot hole (in reverse) then use that as a guide for the drill in the hole saw.
I also laid down some painters tape while I did this.
No chipping, cracking or anything.

If you think drilling for the hood latches is a booger, wait til you drill for the roll bar.

Reverse is okay for high speed steel hole saws, but not for carbide-tipped - they may survive that in fiberglass, but the carbide tips are designed and attached only for conventional drilling and could be ripped off if run in reverse.

Personally I wouldn't do it with carbide-tipped hole saws. Just my 2¢.

[saltshaker]

I’ve built a couple A&C’s... spade bit for the windshield wipes and hole saw for the rest from harbor freight. Tape the body, drill the pilot hole and reverse the hole saw to start it then go froward. I never chipped the body on any builds.
Jon

[Jaydee]

I haven't tried it, but would a stepped drill work?
JD