Having bolt-modded a few of these classics, I have gotten a pretty good feel for the "tricks of the trade" and where the pitfalls lie.
My goal is to end up with 2 Model Ms for myself: a super-heavyweight and a super-lightweight. Today I completed my "Super Heavy Weight" contender.
A few months ago I bought a very nice 1390131 on ebay. It was not badly used, and seemed to be in good condition throughout. The square aluminum badge was in perfect condition. It has been sitting in the garage waiting for me.
When I took it apart, I saw that the black "barrel plate assembly" or whatever you call the large plastic tray that holds the keys, was cracked slightly, longitudinally, in the numpad area. I had been planning to fix that with some sort of reinforced glue/epoxy repair, but a few weeks ago I happened upon an early-90s M, with missing stuff, at a cheap price. Opening it up, I found a beautiful solid beige barrel plate and decided to substitute that one for my project.
Fellow Geekhacker "demik" sold me some Unicomp keycaps and springs, so now I had all the optimal pieces for my project: case, plate, and electrics from the 1986 original, plus a clean solid barrel plate (I took great care in the shaving and drilling process) with my preferred bolting pattern, and a set of almost-new Unicomp spring/hammers.
After assembly and testing (always a couple of kinks to work out), I got out my roll of rubber padded drawer liner (from Target) and carefully lined the interior of the case, plus rolls and stuffing where I could fit it in (and, it took some hand pressure to make the case all fit together!).
I had tightened the plate modifying nuts by holding the socket itself in my fingers and twisting until just the first bit of resistance was overcome. I don't have a torque wrench, but I would guess that I was not applying more than a few ounces (100 grams?) of torque, just enough to nicely "snug up" the nuts, and no more.
I knew that I had done the "non-destructive" sound deadening as well as I could, and I had decided not to "floss" this specimen.
The sound is quite tolerable, even without flossing, even I am surprised at its solid, but low-key projection. This a "clicky" keyboard < BUT NOT > a loud keyboard.
Using US nickels for a quick and dirty Rip-O-Meter test, it seems that I am in the 75-80 g range for most of the keys I tested. I am surprised that it is not lower, and perhaps a little disappointed, but this keyboard is so absolutely "BAD-ASS" that I will not complain. If my fingers get tired I will get out my Leopold Cherry blue.
If I were not so utterly spoiled by my Model F 122-key terminal conversions, I might be tempted to rhapsodize as to this being the "ultimate" buckling spring keyboard experience. Otherwise, I am extremely happy with this board, and satisfied that it was worth the effort.
Special thanks to Ripster and Sandy for their clear and coherent instructions, that set me on this path nearly a year ago.
