Re: Drill Bit / screw sizes
 

You are fine drilling one or two sizes smaller then the screw, but you MUST counter sink the hole to stop spider cracking!!!

Re: Drill Bit / screw sizes
 

You are fine drilling one or two sizes smaller then the screw, but you MUST counter sink the hole to stop spider cracking!!!

Re: Drill Bit / screw sizes
 

I take the screw and hold a bit up to it...if I can see "a little bit of the edge of the threads" stickin' out wider than the bit-shank, that's the one ... and use a cone-shaped bit or counter-sink edge of hole like MJ says above...fiberglass does not take screws like wood does... ;) ...

Re: Drill Bit / screw sizes
 

I take the screw and hold a bit up to it...if I can see "a little bit of the edge of the threads" stickin' out wider than the bit-shank, that's the one ... and use a cone-shaped bit or counter-sink edge of hole like MJ says above...fiberglass does not take screws like wood does... ;) ...

Re: Drill Bit / screw sizes
 

Thanks To All Who responded,
Thought for sure there was a fiberglass screw/drill bit chart. There should be one. Have seen to many people crack their fiberglass by forcing a screw. Appears that a 1/32 to 3/64 of an inch less than the thread diamater will be about the right size pilot hole. Always remember to put petroleum jelly on the screw threads.

Re: Drill Bit / screw sizes
 

Thanks To All Who responded,
Thought for sure there was a fiberglass screw/drill bit chart. There should be one. Have seen to many people crack their fiberglass by forcing a screw. Appears that a 1/32 to 3/64 of an inch less than the thread diamater will be about the right size pilot hole. Always remember to put petroleum jelly on the screw threads.

Re: Drill Bit / screw sizes
 

The petroleum-jelly sounded good at first...but most screws that go in boats should be coated w/ marine grade silicone... or at least that's the way I do it ...nothin' works for everybody ;) ...

screw-threads in fiberglass...it doesn't take much BITE to get a good, firm hold :D ...

Re: Drill Bit / screw sizes
 

The petroleum-jelly sounded good at first...but most screws that go in boats should be coated w/ marine grade silicone... or at least that's the way I do it ...nothin' works for everybody ;) ...

screw-threads in fiberglass...it doesn't take much BITE to get a good, firm hold :D ...

Re: Drill Bit / screw sizes
 

I kept dropping my countersink bit in the water, in a pinch, i took the screwdriver bit and used it to bevel the hole before I ran the screw in, worked pretty good

Re: Drill Bit / screw sizes
 

I kept dropping my countersink bit in the water, in a pinch, i took the screwdriver bit and used it to bevel the hole before I ran the screw in, worked pretty good