How to cut a hole in the roof for antenna cable bundle.
Your mounting procedure is very similar to installing the dish TV Winegard Trvlr. My experience was that the fiberglass roof is very thin and the wood substrate is less than 1/8", so first find the cross bows with a stud finder so you don't drill into them:
1. don't use a cone dril bit the tip of the bit may go through the interior ceiling before the 1" dia of the drill bit makes contact with the fiberglass roof.Secondly, the cone bit has but one cutting edge, when it first breaks through the fiberglass, the cutting edge can jam against the circumference of the uncut portion of the hole and tear out a chunk of your roof. A spade bit with two cutting edges will do the same damage.
2. Use a hole saw that has very fine teeth. If you happen to have a hole saw for tile or masonry that has an abrasive (no teeth) cutting edge, use it. Take the center drill bit out of the saw, it can come through the ceiling similar to the cone bit.
3. Use a variable speed drill motor.
4. Be patient, don't push on the drill motor, let the weight of the motor apply the cutting force. Use very slow motor speed. Because there is no centering bit (you removed it, step 2) the circular cutting blade will want to wander around, tilt the drill motor and make a partial cut that will help keep the circular blade stable as you return the drill motor to vertical. If your roof is arched, make the cut at the highest point.
I was surprised at how thin the roof is. There is styrofoam directly below the substrate.
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