[How do I?] Drill Bits Or Diamond Cut Burr For Fiberglass?

EmilioG

EmilioG

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I need to drill clean holes through 1/2" of fiberglass without cracking or melting.
I've looked at all kinds of offerings, like carbide tipped drills, brad points, diamond cut drill point burrs
from OnsRud and McMaster carr. Does anyone here have actual experience drilling holes through fiberglass
and/or composites, carbon fiber, plastic? I've seen where the drill needs to be dubbed for plastic and brass,
will that work for opening the hole in fiberglass? Start with an 1/8" drill bit? Thanks
 
I have considerable experience with FRP materials.
First, how many holes, 10, 100, 1000, 10,000 or 100,000, this chooses your tooling for you.

Also, do you have the ability to accuratley interpolate a hole that size, this would probably be the best method with diamond tooling and a 30,000 RPM spindle machine.
 
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Thank you.
I will be using a cordless drill, hand held. Only 25 holes at a time through 1/2" thick fiberglass.
Final size: 5/16" and 7/32" holes. Should I start with a smaller drill? I've seen people drill fiberglass by running the
handheld cordless drill in reverse.
 
Pitch the cordless drill idea, those things even the good ones have so much run out (wobble-o-matics) you are not likely to get a decent hole drilled, certainly not through that thick material. And you would have to have quite a few batteries. Get yourself a good old fashioned cord drill with a real keyed chuck. I have a Milwaukie 1/2 inch with a right angle handle to hold onto. Its decent.
 
If you want a clean hole, you definitely don't want to run in reverse. I would use a very small pilot hole. This will lessen the chance of the drill grabbing and pulling the drill through. Use backing if possible to also lessen the chance of breakout as the drill clears. If you can't back the piece up, drilling halfway from both sides will also aid in controlling breakout. Carbide will keep an edge. HSS will dull rathe quickly but with resharpening, should work. By carbide, I mean a carbide or carbide tipped twist drill, not a masonry bit. Practice on some scrap first, if you can to develop your technique.

Bob
 
coolidge said:
Pitch the cordless drill idea, those things even the good ones have so much run out (wobble-o-matics) you are not likely to get a decent hole drilled, certainly not through that thick material. And you would have to have quite a few batteries. Get yourself a good old fashioned cord drill with a real keyed chuck. I have a Milwaukie 1/2 inch with a right angle handle to hold onto. Its decent.
Click to expand...

If you have a good drill you should have no problems, fit a good quality chuck and with a fresh battery it should last a few hours.

Brad point drill bits work great to reduce tearout in fiber materials. They score the edge of the hole before it pulls out the chip. I bet it would work pretty good in fiberglass.
 
How accurate does the hole need to be? I have roughed out holes then used a heated, partly tapered, rod to get to the final dimension. I used a high melting temperature wax as a lube, and it worked great. However, I was working on boat, mounting a stabilizer. I think we had .02 tolerance on the final dimension.
 
I spoke to some friends about this and they told me that they use dagger drill, solid carbide, 3/8" with no issues.
Using a hand held drill. And that they use reciprocating air saws to trim the edges of the work.
I have to go with this because they've been doing it for years. Dagger drills in 3/8" are not easy to find but I did find
one place. The holes are for securing bolts with wingnuts.
Thanks
 
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