Quote:
Originally Posted by flatbutt
3/8"
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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.