Quote:
Originally Posted by cochise
Usually it is the other way around: In unstable and flimsy material one uses coarse thread screws for better hold. Look at the so called "dry wall" screws. They are all coarse thread.
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Drywall screws are course tread because drywall is
thick. Each thread on the screw grips a larger amount of the material as it passes through. A fine thread screw used in drywall would simply pulverize the chalky drywall material and would fail to grip anything. The fact is, drywall screws are generally meant to pass
through the drywall and screw into the wood behind it. The TM has no such wood behind the aluminum.
Sheet-metal screws are generally a finer thread because the material is thinner. However, the sheet aluminum used on the TM is very thin and the fact that it is aluminum on top of that makes it a very poor medium for any screw (no matter how fine) to grip. It is better to use a fastener that opens up inside the wall (behind the aluminum panel) and grips from the other side.