I've been doing more research on fiberglass. I learned that when drilling holes in fiberglass you have to use a countersink so it won't crack the gelcoat. How does a countersink prevent cracking? If I have a hinge and I drill a screw through the hinge and into the fiberglass would it cause cracking? Also people will drill the holes with the drill in reverse. Will that change how the holes are made in solidworks?
Are we talking about left hand drills here or are these "Friction Cutters"?
TMI Edit ...
Nowadays we use these bad boys (and we use them the way we're supposed to) ... Where it's a straight flute we get no pickup and the solid carbide simply lasts forever, or at least until somebody buries (sp?) it into the table.
John Pesaturo wrote:
... solid carbide simply lasts forever, or at least until somebody buries (sp?) it into the table.
Or drops it on the floor...
How to Drill Fiberglass | Hunker
"The problem with drilling through fiberglass is that the drill bit has a tendency to chip the edges of the hole. This is because fiberglass has a gel-coated surface, and the edges of a drill bit tend to get underneath this surface and then chip it off."
Eric, I don't work with fiberglass personally but if I had to guess why countersinks are required you can look at many different industries to find the same result.
Aerospace applications for instance typically have the same requirements and the reason behind it is what they call a "stress crack". Essentially, a crack is more likely to form around an edge that is considered "square" or "sharp". In the aerospace industry we see callouts for included radii or a corner round which is a convex radius on top of a hole. This isn't always something that is easily reproduced as it is modeled so occasionally countersinks are substituted.
As far as using a drill in reverse ... While it may be better to machine certain materials in this way (we do the same with Delrin©) the design of the hole should not be affected or compensated for due to the "technique" used.