Issues drilling fiberglass

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gsanders

EastCoaster
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Does anyone have any tips when it comes to drilling through fiberglass? It always seems to "flare" the fiberglass filaments when the drill bit goes through the inside body tube.

Thanks in advance.

Gary Sanders
 
"back up" where you are drilling holes, with a scrap coupler....wooden dowel....PVC pipe.
Any thing that will keep some pressure just below/inside, where bit comes through.
Use high speed bits and drill "slowly" through the tube.

The issue is with all the new spiral wound tubing. It "pre-stresses'' the tube during the winding process on mandrel, any cut...hole...slot, etc. want to splinter as winding pressure is released as the bit comes through to other side of hole.

Older convolute wound fiberglass tubes [where glass cloth is wrapped around a mandrel ] never did that.
 
If it is for a vent or other situations where an exact diameter isn't necessary, I first drill a small hole and then open it up with the Dremel tool and a tapered grinding bit. It leaves a smooth, perfectly round hole every time.
 
I use brad point bit specifically made for composites from McMaster. Also use high rpms and little to no force and let the bit do the work.
 
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