Re: X pedestal side panels
Posted: Mon Jun 24, 2013 9:03 pm
Another option that I like to use (it's simple, and the results are professional), if you have enough thickness and integrity of fibreglass, is to drill and tap. The tools are inexpensive (a drill, a countersink, a HSS tap, and tap handle, maybe a guide block to keep things square), and the skill is easily learned, if you're a careful sort. You can also use your existing stripped-out holes if you use the corresponding next size up tap drill that cleans up the hole.
Although the thread depth on wood and sheet metal-type screws is usually fairly deep (deeper than say, a machine screw), they will fracture and split their way through fibreglass at the edges of the pilot hole, especially at the entry and exit points, leaving a poorly-formed and small surface contact area for the threads. And we all know it's hard to tell when you've reached the point of over-torquing until you're already past it. Plus the situation worsens with each install-remove cycle.
With a tap-threaded hole, on the other hand, the thread profile and height is actually cut and better-formed, more predictable, and can withstand more torque. The more precisely made machine screw helps retain the integrity of the threads after a handful of install cycles, or infinitely more if you're careful to not over-torque.
If the screw strips out after fifteen years of cycling, simply go to the next size up machine screw to drill and tap.
I've had success so far with 8-32 threads into fibreglass on my Mac. (Use stainless screws).
- Brian.
On edit - so an 8-32 screw will get you 7 or 8 threads in 1/4" material, depending on how large your chamfer on the hole is (keep it small).
Although the thread depth on wood and sheet metal-type screws is usually fairly deep (deeper than say, a machine screw), they will fracture and split their way through fibreglass at the edges of the pilot hole, especially at the entry and exit points, leaving a poorly-formed and small surface contact area for the threads. And we all know it's hard to tell when you've reached the point of over-torquing until you're already past it. Plus the situation worsens with each install-remove cycle.
With a tap-threaded hole, on the other hand, the thread profile and height is actually cut and better-formed, more predictable, and can withstand more torque. The more precisely made machine screw helps retain the integrity of the threads after a handful of install cycles, or infinitely more if you're careful to not over-torque.
If the screw strips out after fifteen years of cycling, simply go to the next size up machine screw to drill and tap.
I've had success so far with 8-32 threads into fibreglass on my Mac. (Use stainless screws).
- Brian.
On edit - so an 8-32 screw will get you 7 or 8 threads in 1/4" material, depending on how large your chamfer on the hole is (keep it small).
