[mrainey]

Hu,

I worked with a VMC75 for several years in the early 80's. Had a Bendix 5 control.

The machine is quite rigid, but not a lot of HP (~10-12). I remember one job we ran a lot - 2" hog mill 2" deep in steel, full-width cut for thirty minutes per part - couldn't even hear it cutting.

Proprietary toolholders, as previously mentioned. Had to keep a rubber mallet at the the machine to whack the tools - toolchanger would stick. Have seen this in other shops with Monarchs. No harm done, just a nuisance. Ours held twenty tools.

Tapping wasn't "rigid" in the way the term is normally used. You could hold a tap in an ordinary toolholder, no tapping head. The tapping was "floating". You gave a G84 with R and Z values, but no feedrate. The tap fed itself to depth. There was even an M code for high-pressure tapping (large NPT taps, etc.). The system worked very well.

You couldn't specify a precise spindle RPM. Machine had four speed rangs, with a dozen or so speeds selectable within each range.

G83 deep hole drilling cycle was a little odd. You couldn't specify a peck depth. It was controlled by the operator using a knob on the control. Not too good.

Had a large, rigid quill with about 10" of Z travel. Beyond that, the entire head could be repositioned, manually or in the program, in 1" increments for especially high or low setups.

Had a G86 command for milling, which would activate quill clamps to keep the quill from pulling down in a heavy cut. Don't know how useful it is. The shop I'm at now has an old VMC150 and they never use G86 - but don't do any heavy milling, either.

The VMC75 seems to have a million valves, servos, etc. which are constantly getting stuck. We found it essential to run a warmup program every morning to "exercise" them.

Boards in the control seemed to vibrate loose pretty often. Reseating them was frequently the cure when control faults showed up out of nowhere.

Never could hold a repeatable thousandth with a boring bar on the VMC75, even with a new spindle.

Ours had a Hiperdex indexer, which was massive and accurate for positioning. Lots of Monarchs had the Hiperdex in those days.

Make sure you get the executive tape if you buy one.

Enough for now. Good luck if you get one. I have a lot of fond memories of the machine.



Mike