How to NEATLY drill fiberglass

[flatbutt]

I want to mount a luggage rack on my trike and must drill thru the fiberglass trunk lid. I've never worked fiberglass before. So, first what type of bit should I use? Second...anything else I should keep in mind?

tia

[URY914]

Put a piece of masking tape over the spot and then drill it. Go very slow so you don't blow out the hole on the backside.

[look 171]

Brad point drill bit. How big is the hole? If blowout is a concern, drill half way from top, go under and drill from underneath. Basically score the hold from the bottom, finish drilling through from top all with the same bit.

[Por_sha911]

Start with a small pilot hole. Be sure to not let the fiberglass flex by putting a block of wood on the opposite side so for support. Go slow with very little pressure and let the bit do the work.

[flatbutt]

Thanks guys. A brad point wood bit it is.

[Tobra]

Wow, that was fast

[flatbutt]

People like to help an old guy like me.

[1990C4S]

I would try to sandwich the fiberglass between two pieces of wood, clamp them, then drill.

[URY914]

Also drill it smaller than needs to be and work it larger with a fine file.

[911 Rod]

Hold the drill tight so it does not skate across the finish.
A buddy of mine did this when drilling holes for speakers in his jet ski. The only time I have ever seen him cry. lol

[Tobra]

Does the mount for the rack have something to go behind the fiberglass to stiffen it, spread the load, so to speak.

The pictures are not coming up on my computer

Do you put resin on it to seal up the hole, like painting a hole in metal?

[Series900]

Two flute drill bits will always tear the fiberglass. Pilot drill is fine, rotary file , dremel , die grinder is the tool to use to enlarge the hole. A hand file still can fracture the edges.

[flatbutt]

How about these?

https://www.amazon.com/dp/B083Z482QK?tag=journeymanhq-20&linkCode=ogi&th=1&psc=1

[look 171]

Originally Posted by 911 Rod

Hold the drill tight so it does not skate across the finish.
A buddy of mine did this when drilling holes for speakers in his jet ski. The only time I have ever seen him cry. lol

Brad point bits will keep the bit from walking.

[look 171]

Originally Posted by flatbutt

How about these?

https://www.amazon.com/dp/B083Z482QK?tag=journeymanhq-20&linkCode=ogi&th=1&psc=1

I suppose that will work but eventually clog the diamond dust. How bit is the hole?

[ltusler]

After drilling seal the exposed fiberglass with some clear nail polish.

[flatbutt]

Originally Posted by look 171

i suppose that will work but eventually clog the diamond dust. How bit is the hole?

3/8"

[look 171]

Originally Posted by flatbutt

3/8"

3/8 brad point bit will do the trick. Be done in less then a min, two depending how long it takes you to measure and mark center. The hole will be perfect too instead of using a file and other rotary type abrasive to ream out the hole.

[look 171]

DeWalt 3/8 brad point bit from Amazon for only a few bucks.

[wdfifteen]

Originally Posted by flatbutt

3/8"

Too small for the method we used. We had to drill 1/2" holes for fiberglass trailer covers. We used a 1/2" hole saw, ran it backwards until we got through the gel coat, then ran it forwards slowly to get through the fiberglass. I don't think they make 3/8" hole saws. Even with a brad point bit I would drill forward until the flutes just touched the gel coat. Then run it backwards to get through the gel coat without chipping it. The big problem you face with trying to do it neatly is that the gel coat chips easily. The drill flutes cut into the surface and lift it up. Getting under the gel coat and pulling it up will causing it to chip. Cutting through the gel coat will cause a ragged hole, you need to abrade it.