Drill Bit / screw sizes
 

Will stare drilling holes for the boat hardware soon. Can anyone tell me where I can find a chart which shows what size drill bit to use for drilling fiberglass for each screw size. Have such a chart for wood. However, it is not applicable for drilling fiberglass.
Warner

Drill Bit / screw sizes
 

Will stare drilling holes for the boat hardware soon. Can anyone tell me where I can find a chart which shows what size drill bit to use for drilling fiberglass for each screw size. Have such a chart for wood. However, it is not applicable for drilling fiberglass.
Warner

Re: Drill Bit / screw sizes
 

Don't have a chart, but I know that you need a pilot hole slightly larger than what you'd use in wood.

Re: Drill Bit / screw sizes
 

Don't have a chart, but I know that you need a pilot hole slightly larger than what you'd use in wood.

Re: Drill Bit / screw sizes
 

i use an 1/8" pilot hole for everything, if the screw is too hard to go in, I "waller out" the hole a little more with the same bit. If its too loose with the 1/8, then you use that Marine Tex stuff

Re: Drill Bit / screw sizes
 

i use an 1/8" pilot hole for everything, if the screw is too hard to go in, I "waller out" the hole a little more with the same bit. If its too loose with the 1/8, then you use that Marine Tex stuff

Re: Drill Bit / screw sizes
 

I try and use a bit that is the size of the screw minus the threads. For example if you removed the threads off the screw the bit would be the same width as whould be left on the screw. If the hole is too small you stand a chance of spider cracks (I think thats what they call them). The main thing is to seal those things up real good.

Re: Drill Bit / screw sizes
 

I try and use a bit that is the size of the screw minus the threads. For example if you removed the threads off the screw the bit would be the same width as whould be left on the screw. If the hole is too small you stand a chance of spider cracks (I think thats what they call them). The main thing is to seal those things up real good.

Re: Drill Bit / screw sizes
 

I do the same thing but if I'm real worried about the work or location I'll scoot a little 5200 in the holes and under the hardware.

Re: Drill Bit / screw sizes
 

I do the same thing but if I'm real worried about the work or location I'll scoot a little 5200 in the holes and under the hardware.

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

Re: Drill Bit / screw sizes
 

Should have given more information. When reattaching Teak I use Petrolium jelly on the screws. When attaching hardware I put Boat Life in the holes as well as on the threads. May be a little over kill. See a lot of silicone that has seperated from the fiberglass. Maybe it wasn't marine grade.

Re: Drill Bit / screw sizes
 

Should have given more information. When reattaching Teak I use Petrolium jelly on the screws. When attaching hardware I put Boat Life in the holes as well as on the threads. May be a little over kill. See a lot of silicone that has seperated from the fiberglass. Maybe it wasn't marine grade.

Re: Drill Bit / screw sizes
 

within alot of the old drill cases is a drill index that will give you tap clearance sizes etc.. i got an old steel one from Radnor with all the info punched into the holding brackets.

Re: Drill Bit / screw sizes
 

within alot of the old drill cases is a drill index that will give you tap clearance sizes etc.. i got an old steel one from Radnor with all the info punched into the holding brackets.

Re: Drill Bit / screw sizes
 

A drill index is priceless...do they still make 'em?...

Re: Drill Bit / screw sizes
 

A drill index is priceless...do they still make 'em?...

Re: Drill Bit / screw sizes
 

They sure do!!

Re: Drill Bit / screw sizes
 

They sure do!!