Is there a chart available that lists which size drill bit to use for screws in fiberglass? I'm always afraid of using too small a bit and damaging the gel coat when running a screw in.
Is there a chart available that lists which size drill bit to use for screws in fiberglass? I'm always afraid of using too small a bit and damaging the gel coat when running a screw in.
I'm sure there is. But I don't have one.
I take the screw and insert it in my hole sizer down to the last one it will go into. Most normally I'll use the next smaller size bit. I also put a piece of tape over the spot to be drilled and be slow and deliberate.
I always go way to small with drill bit and I have snapped a few Stainless steel screws trying to force them in (stainless is weaker than normal screws). I am getting better at going close to the screw size and also felling it as it goes in and if it needs more than average one handed force stop back it out and go bigger. I got search for a chart and I do need to by one those bolt and screw test boards like you find at the store they are not that expensive.
https://www.amazon.com/Metric-Gauge-.../dp/B016J3Z49I
Best chart I could find for wood? I would say start with hardwood???
Last edited by trashmanssd; 10-29-2020 at 11:49 AM.
2020 Ranger 521L, Merc 250 Pro XS
fastener size clearance hole Pilot hole (FG) Pilot hole (wood)
#4 9/64 3/32 5/64
6 11/64 7/64 1/16
8 13/64 1/8 7/64
10 15/64 9/64 1/8
12 1/4 5/32 9/64
14 (1/4") 9/32 3/16 5/32
countersinking the gel coat is recommended. I've never done it, haven't seen any cracking... YMMV
Thanks for the help! I don't know why I hadn't thought of using the hole sizer then going to the next smaller bit.
Countersink hole a bit help prevent cracking of gel
2013 Pantera 2
200 Pro XS (2b009069)
Ghost Trolling Motor
Run the drill bit in reverse first.
As stated...tape the hole, run drill in reverse to start.
BULLET 20 XRD/250 Merc Sport XS
www.ncboatguy.com
I always run the bit in reverse. I guess my real problem has been drilling the hole too small and that can cause some gel cracking or breaking off a screw.
Easy enough to do..
depending on screw size and thickness of place drilling I will go two sizes smaller to start with.. if the screw gets hard to insert just back it in and out a few times, often just cleaning the threads will allow the screw to cut the grooves without clogging up. another trick is to drill it two sizes smaller then very carefully drill it part way with the next size bigger.
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