I don't care to defend CHPWS in a specific case that I know nothing about but I will defend the material issues. an adapter plate is mostly a spacer. IT can be made out of anything and I'm surprised we don't yet have plastic ones to be lighter. 6061 is not too soft for this use under any possible engineering view. The yield strength is in the area of 40K and your trivial little 4-40 fasteners aren't going to threaten that. The threaded posts threaded in there ok we can discuss those for CHPWS. but a zillion other people don't use the posts at all and it all works just fine so its not a critical part of the design. You don't need a steel plate per se. and given the extra weight I wouldn't want one.

quote:

Originally posted by hrcjon:
an adapter plate is mostly a spacer. IT can be made out of anything and I'm surprised we don't yet have plastic ones to be lighter.

Arex just released a new line of optic-ready Deltas. Their optic plates are made of fiberglass-reinforced nylon - same material Spyderco uses for most of their knife handles. It'll be interesting to see how the Delta's plates far. If owners have problems w/ them, they will instinctively blame Arex for not using steel.

quote:

Originally posted by hrcjon:
I don't care to defend CHPWS in a specific case that I know nothing about but I will defend the material issues. an adapter plate is mostly a spacer. IT can be made out of anything and I'm surprised we don't yet have plastic ones to be lighter. 6061 is not too soft for this use under any possible engineering view. The yield strength is in the area of 40K and your trivial little 4-40 fasteners aren't going to threaten that. The threaded posts threaded in there ok we can discuss those for CHPWS. but a zillion other people don't use the posts at all and it all works just fine so its not a critical part of the design. You don't need a steel plate per se. and given the extra weight I wouldn't want one.

The original Aimpoint Micros were 6061 and it was easy to strip the threads in the M3 mounting holes until Aimpoint finally published a 6 in-lb limit with loctite. The H2/T2 have heli-coil inserts to allow 12 in-lb but loctite can't be used (the heli-coils can back out when you remove the screws if you use loctite). The CompM5 was upgraded to 7075 and the limit is 12 now in-lb with loctite - double that of 6061.

The RDS plate is not a spacer. The plate is fastened to the slide with screws, and the RDS is fastened only to the plate. So all you have to keep the RDS from flying off is two little M3 or M4 screws with enough torque and loctite to keep them from backing off. And there are lots of reports of screws loosening up on various mounts, especially the factory Glock MOS plates that have only a few threads engagement.

Very few plates are "just" spacers with through holes and screws that go into the slide. The only ones I know of are G43X/48 MOS riser plates to adapt the factory RMSc cut to a Holosun 407K/507K, and risers to adapt the Sig P320 Pro Series cut to an RMR, but using the factory drilled RMR holes while the plate only adds the bosses.

While insufficient torque can be compensated for by using loctite, all bolted joints should be designed so that the clamp load from the screws is enough to hold the joint together under all operating loads with no back off of the screws. Torque doesn't correlate really well to clamp load (angle of turn after a threshold torque is much better) but that's about all we can do with small screws and a torque screwdriver.

In many cases, the thread engagement on an RDS plate is insufficient to allow the required torque without stripping the threads. So you go to a lower torque and use loctite on the threads (or on the underside of the bolt head) to keep them in place.

Personally I prefer steel or 7075 (Bobro's M17 RMR plate) to allow max torque in a reasonably thin plate.