Monarch machining centers

[HuFlungDung]

Does anyone around these forums have any experience with Monarch VMC's? The reason I ask, is because I see some of this 70's vintage cnc equipment around and its relatively cheap. Granted, it might deserve a new controller, but for 27,000 lbs of machine at a couple of thousand dollars, it makes my ass twitch right where my credit card sits

I know the loading and freight would be considerable of course, and it needs a building that it will fit into, too. But, apart from that, if anyone has actual experience with Monarch VMC's I'd like to hear about it.

Thanks.

[CNCAddict]

Yeah, I see these machines on ebay all the time. I bet it wouldn't be hard to slap on some new servo motors and hook them up to Mach 2 for a really nice setup at prolly 1/30 the cost of a new 10ton machine. I really like rigid tapping though...and I don't believe anyone has tried to add this feature to an old machine. The ATC would also be a huge problem, and is necessary if you're trying to do any production work.

David B.

[HillBilly]

I know one of the major down falls is there bastard tooling.
It is a Cat taper but it has a bunch of little spline fingers around the flange instead of the two keyways.

HillBilly

[ynneb]

Granted, it might deserve a new controller, but for 27,000 lbs of machine at a couple of thousand dollars, it makes my ass twitch right where my credit card sits

The medical term for this is hemorrhoids

[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

[HuFlungDung]

Thanks for that report, Mike, I appreciate the details.

I especially like that story of the 2" hogging mill. I wanna do (and hear) that.

Obviously, if I bought an older machine, it would be a retrofit candidate immediately. I suppose a person could dispense with some of the complexities of the head if going to a modern controller, like going to rigid tapping and a VFD spindle drive.

I wonder if a person would have to replace all the servo drives, or whether they are "good enough" for a new cnc. I suppose they used resolver feedback? Any idea what size servo motors would be on a massive machine like that?

BTW, with this floating tap feature, how the heck would you maintain accurate Z position between holes?

[3t3d]

My first machine was a Brown and Sharpe VC1000 with the Bendix A5M control. About 16,000 lbs smooth as silk.
Retrofit? that was/is a great operator friendly control! It had resolver feedback to the control, and tach feedback to the servo drives. The servo drives were GE HiAk drives. They take +- 10 volt signals. As does the spindle drive, GE Valutrol. All very friendly for newer controls. The motors were 2hsp GE DC motors, 90 volts servo power supply. Encoders could be fitted instead of the resolvers, not a problem. The resolver circuit in the Bendix control is awesome how it worked, it could also detect a bad or intermittent signal from the resolver. Try THAT with an encoder circuit!
The Bendix control, like the Bostomatic was based on a Data General computer. Having worked on Data Generals for years, it was like an old friend electrically. Easy to troubleshoot to the chip level.
The fourth axis used inductosyn scales fro feedback, and positioned to 360,000 parts of a circle. The inductosyn uses printed circuit "antenas" (?) and is very simular to the resolver in operation, in fact it used the resolver circuitry with an extra op-amp for feedback.
IF you have the room, that old iron can be had for less than scrap value, and is much more massive, stiffer and slower than modern VMC's. The key is really the room it takes up, and the floor thickness to support it. Moving it was not too hard to do. That was my first big machine, and was easy with a couple bottle jacks and a borrowed pair of skates from a local shop. A local cement (cistern) factory supplied a boom crane for about $120 to lift it and move it... Get creative, if you have the room.
Pete

[HuFlungDung]

I'm not thinking of real highspeed machining capabilities, because I'm "old school" I guess Mainly what I would like is perhaps feed capabilities of up to 200ipm (that should do me till I retire ) and as high a block processing speed as is required to attain that feed (maybe 20,000 blocks/sec). I'd prefer to save some roughing time on a machine that won't complain when setting the tool into steel.

Hmm, I wonder if anyone has done a Camsoft (or other) retro on a Monarch. I'd wonder how difficult they found the toolchanger to interface?

[3t3d]

200 ipm? You might need more spindle rpm. With Cat 45 tooling the spindle bearings are big enough to fill a lunch box. 4000 rpm is the norm for max rpm....
With a 4 flute, at 4000 rpm that's a chip load of .0125" per tooth... The machine migh not mind, but the tooling <might> notice.
On the B&S the rapids were 400 ipm, and feeds were up 100+ ipm, if you had tooling and cutting to match...
Also consider an old Cincinatti.
The hydraulics on those old machine were really something! Buy O-rings by the 100's and learn to rebuild seals, pistons, and couplers, and valves.
The tool changer on the B&S was amazing, about 3000 lbs worth. Those tools went up, down, sideways, and flipped, just to get to the changer arm. Sure worked nice and smooth though, once I adjusted it all to new specs.
The tool changer was contolled by a drum cam, with about a dozen hydraulic valves along the drum for all the cylenders and actuators for the tool change.

Pete

[greggv]

Good machines, altho somewhat weird here and there. Had a "floating" z axis at times, some had hydraulic toolchangers (good), others air powered tool changers (not too good)
They all had Heindehain scales for feedback(a good thing) Shop I worked at had 3 of them, with the pallet changer system, and only 1 of them used the strange tool holders. I would think maybe worth retro fitting, but it would be a big job!

[Al_The_Man]

One like this? http://cgi.ebay.com/ws/eBayISAPI.dll...ayphotohosting
They were a well built (beefy) us made machine, This one has the GE 2000 control which I believe was the last GE before it became GE Fanuc. You would definately want to upgrade the control. (you could always part it out on ebay).
Machinery Values does get good deals on shipping to Canada etc.

[NcDave]

Hi,

Yeah I got and use a old Monarch VMC 150 , its super tough
and rigid but slow compared to newer machines, my biggest headake
is the Allen Bradley Control, its seems to have a lot of problems
to keep it running, anyway the spindle on mine uses Cat 45 taper,
thats easy to find cheap in many places, i like the big size so I can
put many parts at a time on the table for machining... but I would
really like to find someone who did a retrofit like Camsoft makes just
to see how well it works.

Dave.