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View Full Version : Drilling into Fiberglass


KBryant2007
04-18-2012, 01:22 PM
I am upgrading my radio, and adding an iPOD port. The iPOD adapter that I bought requires a 3/4 inch hold for the jack to be installed. I plan to put it near the radio, but it will require me to drill a hole. What type of bit should I use, and what should I watch out for since I have no room for error.

cbryan70
04-18-2012, 01:23 PM
tape it, drill in reverse

SilviaMan
04-18-2012, 01:27 PM
I would use a hole saw for drilling and agree with the reverse at least until your through the gel coat.

willyt
04-18-2012, 01:37 PM
I believe your supposed to use masking tape as well

CantRepeat
04-18-2012, 01:51 PM
I believe your supposed to use masking tape as well

I always do and and if I can get to the back I mask off both sides.

The other nice deal if you have a friend, have the hold a vacuum to the area while you are drilling and vacuum up the dust.

cbryan70
04-18-2012, 01:51 PM
tape it, drill in reverse

I would use a hole saw for drilling and agree with the reverse at least until your through the gel coat.

I believe your supposed to use masking tape as well


There you go. And def use a hole saw. Tape it with masking tape, and use the hole saw in reverse. It will prevent chiping and cracking of the glass.

Double D
04-18-2012, 01:56 PM
tape it, drill in reverse

+2 on this answer......

FrankSchwab
04-18-2012, 05:08 PM
1. Tape over it
2. Mark your hole.
3. Using a small bit (1/8 or so), drill a pilot hole. Run the bit in reverse until you're through the gelcoat, then you can switch to forward.
4. Enlarge the pilot hole using a larger bit - based on the next step, a 1/4" bit would work. Start in reverse until you're through the gelcoat, then you can go forward. You could probably start with the 1/4" in reverse, but that's not how I did it.
5. Using a Step Drill (http://www.harborfreight.com/2-piece-titanium-nitride-coated-high-speed-steel-step-drills-96275.html), drill the hole. No need to go backwards with these; they make a very controlled hole through the gelcoat. When you get to the 3/4" step, run the drill backwards and use the edge of the next larger step to chamfer and smooth the edge of the gelcoat.

I've done several 3/4" holes on my boat installing pop-up cleats, and this is so smooth and easy that I've never considered using a hole saw, or trying to run a 3/4" twist drill in reverse. The first couple of steps make small holes, but also hold the bit solidly centered in the hole as the next larger step is biting in.

Barefooter92
04-19-2012, 07:40 AM
Great advise guys! Never thought this was going to be an issue. I am glad this thread cought my eye. I am going to drill two 5" holes in my glass for speaker install, and install some new rocker switches in front of my throtle. Thanks!!

ctjahn
04-19-2012, 08:58 AM
1. Tape over it
2. Mark your hole.
3. Using a small bit (1/8 or so), drill a pilot hole. Run the bit in reverse until you're through the gelcoat, then you can switch to forward.
4. Enlarge the pilot hole using a larger bit - based on the next step, a 1/4" bit would work. Start in reverse until you're through the gelcoat, then you can go forward. You could probably start with the 1/4" in reverse, but that's not how I did it.
5. Using a Step Drill (http://www.harborfreight.com/2-piece-titanium-nitride-coated-high-speed-steel-step-drills-96275.html), drill the hole. No need to go backwards with these; they make a very controlled hole through the gelcoat. When you get to the 3/4" step, run the drill backwards and use the edge of the next larger step to chamfer and smooth the edge of the gelcoat.

I've done several 3/4" holes on my boat installing pop-up cleats, and this is so smooth and easy that I've never considered using a hole saw, or trying to run a 3/4" twist drill in reverse. The first couple of steps make small holes, but also hold the bit solidly centered in the hole as the next larger step is biting in.

I agree with the step drill bit...