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Drilling holes in 2pak painted fibreglass - any dramas?
I'm going to run out of time to obtain and attach lots of fittings (bonnet straps, wing mirrors, blinkers, etc) before the car is painted. Are there any dramas in later drilling through 2pak (no clear coat) to attach these parts, e.g. chipping around the edge or flaking? Thanks
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Peter, not sure whether this applies to 2pak but the times I've seen it done they always lay down some masking tape before drilling, which I guess prevents the paint lifting around the edge of the hole.
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As Sambo said, tape is good.
Provided paint has stuck properly and cured, you shouldn't have any trouble. You may get some minor chipping (1mm sort of stuff) but in most cases this isn't an issue as the item you are attaching will cover it. Sharp drill bits are best and where possible drill from paint side not from the back. |
Good point if you have to drill from back, drill small pilot hole then drill reqired size hole from front
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Also take your time, don't force it through.
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I had to drill through an angled panel at the front for the bumpers with a hole saw. Was scared when I started, but it didn't grab or chip. best to drill it smaller, then enlarge the hole with a tapered stone on a die grinder. It ended up that good, I didn't use grommets for the bumper rods.
JD |
low tack tape stops excess clean up later
& a reverse circle to catch the swaf helps too |
All good advice, try to take some weight off the drill as it breaks through the surface and use a pilot (smaller drill first, I like to use 3mm). Helps with accuracy. Depending on application, I like to use nutserts.........but you do need to be careful with them. Have fun.
Cheers Chris |
My technique for drilling finished fiberglass is to start with a very small pilot hole so any chips it makes are within the size of the final hole. Then, with the final size drill bit, run the drill in reverse until you are well down into the fiberglass. This makes the hole more by erosion than by cutting and avoids the grabbing that sometimes happens when you drill conventionally.
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With fiberglass topped with gelcoat and paint - after the hole has been carefully drilled to final size in a series of steps of increasing diameter - I typically take a larger bit and run it backwards to put a pretty good camfer at the top of the hole through the paint and gelcoat. This helps prevent lifting of the gelcoat and paint as the screw is threaded in. The threads on the screw try to lift the gelcoat off of the body as it's run in - thus the chamfer.
Also, I have found you have to drill the hole sufficiently large to prevent the screw from siezing up as you try to run it in, as that will start lifting gelcoat and paint. If the screw starts to get tight while running it in, pull out and drill one more size larger. You can't just force a screw into fiberglass like you might metal or aluminum plate. |
Drilling holes
As has been mentioned run the drill backwards to avoid the bit grabbing and the inevitable chip and tear.
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I have seen step drill bits used with very good success. They are far less prone to grab the edge of the hole and tear the fiberglass.
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As stated above run drill in reverse use pilot bit first. After hole is complete I also dab the outer rim of hole with clear coat to prevent any future fracturing.
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Use a W shaped drill bit, they cut the outside diameter of the hole cleanly with no splintering before cutting the hole, not sure on what sizes are available, ive got one in 12mm, they are used for drilling holes in timber cleanly without splintering the grain so that a timber plug of the same wood can be plugged to cover the fixings on decorative finishes.
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