Discussing the viability of Belleville washers for use as a holding force is probably off topic for this thread. I'm trying to keep it focused. It isn't that I'm not interested, it is that I'm hoping to help some other poor wayward soul in the future when they have a similar problem and stumble on the thread. This way they'll be able to get the data as quickly as possible without going through a ton of pages. This is partially why I've tried to summarize all of my steps in a few co-located postings.
However, I will say that although I agree with you that hydraulics might be a superior solution, I think the important thing to realize is that designers are trying to economize as much as possible. Belleville washers are used extensively, I believe, in this application. My guess is that in the grand scheme of function versus dollars, the low cost of Belleville washes wins out. As for how best to test the 'strength' of the pull... I hear what you are saying, but I have some additional thoughts. The pull force measured by something like the Clamprite is a pretty standard paradigm. But, the issue here is that the force is not linear. My guess is that the problem with my system is that the washers are likely a tad thinner. Add that up over 80 washers and you end up with insufficient deflection of the washers when in retention mode. But this, ultimately, is what is going to address fretting. Although it might take 5000 lbs to actually pull the tool out, I'll end up with all sorts of chatter (and then fretting) if I only have 100PSI at the tools static (retained) state. Well, that is my thought. I'm sure someone can poke holes in this as I specifically do not claim to be an all knowing machine tool designed. And, frankly, I think you and I are addressing the same concern.
My guess is that I need to add some shim washers to decrease the total length of the cylinder holding the Belleville washers. This is all assuming that the original washers were a tad thicker. Decreasing the length of the cylinder would increase the compression of the washers, thereby increasing the pull force on the stud. The balance here, of course, is that if I compress too much, then the bottom clamping collet will not drop far enough to allow the ball bearing to retract; the result would be an inability for the retention knob to clear the retention bearings (aka a stuck tool).
Adding the following to the archive... Earlier in this thread, someone mentioned that they had some washers from Dyna. They provided the measurements from those washers. I took the P/N listed (which matched something that I got from the ex Dyna guy), AM-201010, and did some searching on the internet. I got a hit that provided all the specs, so I thought that would be something to keep in this thread:
Attachment 436872
Finally, here are the part numbers for the whole retention assembly (note the ball bearing sizes in there too, in case you lose one!):
Draw bar DM4400M ( 19-0042 )
1.- T00201011-6 Draw bar = 1
2.- T0112-04004 hex-screw= 1
3.- T0899-03016 steel ball 3/16"= 6
4.- T0201013 Washer = 1
5.- T0268-201010 Disk Spring = 80 pcs.
6.- T00201014-1 Guide top chuck =1
7.- T0639-01800-P O-ring P18 = 1
8.- T0639-01200P O-ring P12 = 1
9.- T00201017-5 Stud Chuck = 1
10.-T00201018 Set Screw M4 = 1