Monarch 10EE and VFD conversion

Found a 10EE in the SF Bay Area on Craigslist, http://sfbay.craigslist.org/sby/tls/2034511321.html
Generator model, says ready for VFD conversion.
What all is involved in doing this conversion and what is it likely to cost me assuming I don't have lots of time to shop for bargains on any needed components?
Will the 10EE cut metric threads native, or does it require transposing gears? If the latter, how hard is it to locate the required parts?
Anyone here see this lathe in person and know anything about it's overall condition? The trip down would burn a day for me and I've got lots of work. Looking for an engine or toolroom lathe and there's a few on CL that look promising. Might come down to what comes with the most tooling ready to run. I've always wanted an HLVH, but a 10EE is something I think I could live with... <G>
Jon
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If it's an MG setup, that's a DC motor in there, not the 3-phase needed for a VFD. You'd end up gutting it, finding a 3-phase motor that would fit, then hooking up a VFD to that. That's if the DC motor were a complete wreck, they can usually be overhauled reasonably easily, if needed. If the machine was really cheap and in really good shape, it might be worth it. Old electromechanical DC motor controls are usually pretty robust, they don't take an EE degree to fix. No way to really know that without a personal inspection, though. Unless it's got a metric leadscrew, it's not going to cut metric without conversion gearing. Most older US-made lathes don't have metric leadscrews, at least the ones that weren't exports to start with.
Stan
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On Nov 3, 11:38 am, snipped-for-privacy@prolynx.com wrote:

Would a Variac and rectifier be enough?
jsw
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    [ ... ]

    Not a single one. I'm not sure what the voltage the motor wants is, but you need two controls to duplicate what is built into the system once you have the ability to generate sufficient voltage. (Since the thing has a three-phase motor turning a generator to produce the needed DC, there are no bets as to what the voltage is. They may have gone for low voltage DC or high voltage (each has its own benefits and drawbacks), but you need two variable voltages -- the one for the motor's rotor (increased up to a certain maximum speed and then you start turning down the voltage (and thus the current) applied to the motor's field to get even higher speeds.
    If the motor/generator and the spindle's DC motor are all in good shape, you can just put a rotary converter on the input instead of a VFD and use the lathe as it is. But the fact that he is pushing it as "VFD conversion ready" suggests that there are problems with the motor-generator or the DC spindle motor.
    Good Luck,         DoN.
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On 11/3/2010 7:38 AM, snipped-for-privacy@prolynx.com wrote:

Just got off the phone w/seller. All are DC, this one is the generator type, not the tube type. It came out of the optics lab at Stanford. There was some speculation from the guy running the lab that the problem was just a switch, but since nobody knows, it's being sold as a retrofit.
He mentioned two approaches to retrofitting these, one is to do away with the gearbox and drive the spindle direct, this loses back gear. The other is to machine some sort of adapter to fit a 3ph motor to the gearbox. If I were to go for this, I'd prefer the latter and would love to hear from anyone that's done it. But would like to solicit input on the two approaches.
I need another project machine like I need a hole in the head, but this might turn out to be a decent deal...
Jon
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Do you think that you would be limited by its very short bed?
I would personally pass.
i
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On Wed, 03 Nov 2010 11:34:13 -0500, Ignoramus3281

Bingo!
Same here.
Hope you got your armor ready Iggy.....
"Confiscating wealth from those who have earned it, inherited it, or got lucky is never going to help 'the poor.' Poverty isn't caused by some people having more money than others, just as obesity isn't caused by McDonald's serving super-sized orders of French fries Poverty, like obesity, is caused by the life choices that dictate results." - John Tucci,
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On 11/3/2010 9:25 AM, Gunner Asch wrote:

Oh heck, not going to flame anyone here! I'd REALLY rather have an HLVH, but a -lot- of people rate the 10EE very highly, and I know in good running condition they are worth a lot. He's got accessories for it that would probably cost as much to buy as he's asking for the whole thing. So it's at least worth considering. I'm thinking the project aspect of it is going to kill the idea. I'll have enough of a project just moving things around to get the manual chucker out of the garage and bring in anything, let alone haul (another) project home.
Hmm, ok, looked at the PM link. Looks like the mods for a gearbox conversion really call for an engine lathe, which I don't have, and don't have access to. Not one good enough for this sort of work anyway. Looks like it's a pass for me.
Now, if that was a low hours HLVH out of a Stanford lab and needed the vari drive rebuilt, I'd jump on it for $2500..., and wouldn't be asking questions here that might alert a potential competitive buyer... <G>
Jon
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On 11/3/2010 8:34 AM, Ignoramus3281 wrote:

Given money and space, I'd really want an HLVH and a 16x60 engine lathe. Given that I don't have money and space and can only fit one lathe, no matter what I get, I'm going to be limited.
An HLVH or 10EE won't handle big stuff, a good size engine lathe isn't going to give me the precision and RPM I often need.
I'm likely to encounter mostly farm type work in Oz, but that's if I decide to really go into business there. That would call for the engine lathe. But if I am going to (finally) have my shop just for me and my hobby tinkering, then I want the tool room lathe.
The issue of greater importance is how long is it going to take me to get this thing up and running. I do have an Omniturn, but I absolutely must have a manual lathe available, so even if it's a good deal, if it's going to take several months to convert, I'd have to pass. Decisions, decisions...
Jon
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On 11/03/2010 12:16 PM, Jon Anderson wrote:

The tube kind can be difficult to fix, it has 4 thyratrons that can be close to impossible to get replacements for.
The all electromechanical type is quite a bit simpler. You have two control systems. One reduces motor field for the high-speed range, the other regulates the generator field for the lower speed range. Both are generally just big rheostats in series with the respective field windings.
Jon
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    So -- you could luck out and be able to fix it easily to run from real three phase or a rotary converter, and not need a VFD.
    My suspicion is that it is a problem with brushes in the generator or DC spindle motor.

    This latter is the approach the friend in the local metalworking club took. It was not a quick project, but he did a beautiful job.

    A heavy (but good) decent deal.
    Good Luck,         DoN.
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On Wed, 03 Nov 2010 08:09:42 -0800, Jon Anderson

This may be of interest to you.....
http://www.practicalmachinist.com/vb/monarch-lathes/vfd-conversion-started-187915/
Gunner
"Confiscating wealth from those who have earned it, inherited it, or got lucky is never going to help 'the poor.' Poverty isn't caused by some people having more money than others, just as obesity isn't caused by McDonald's serving super-sized orders of French fries Poverty, like obesity, is caused by the life choices that dictate results." - John Tucci,
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On Wed, 03 Nov 2010 08:09:42 -0800, Jon Anderson

Btw...Leigh down at MarMachine just took in an absoultely georgious 13" Clausing Colchester and will be putting it up before long.....Its an 8015 as I recall..and is loaded with everything..including a DRO....
Which in my professional opinion..while not as "cool"..is a superior lathe.
Gunner, donning his flame proof suit and ceramic armor....
"Confiscating wealth from those who have earned it, inherited it, or got lucky is never going to help 'the poor.' Poverty isn't caused by some people having more money than others, just as obesity isn't caused by McDonald's serving super-sized orders of French fries Poverty, like obesity, is caused by the life choices that dictate results." - John Tucci,
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    The generator sort of Monarch 10ee has a three phase motor at the line side, spinning a generator which produces DC of the needed voltage and current, and then the speed control feeds voltage separately to the rotor and the field -- first increasing the rotor voltage as the speed is turned up, then holding it constant and reducing the field current, resulting in faster and faster spinning.
    Later ones use electronics to produce the DC for the spindle motor -- and some are more difficult to fix because they use tubes which are rather rare and expensive these days.
    The latest have solid state electronics which are also expensive to fix.
    The simple form of conversion mentioned is simply putting a VFD between the three phase input and the single-phase power line.
    A much more complex one involves removing the three phase motor, generator, and DC motor, and installing a higher horsepower three phase motor in place of the DC motor. A friend in the local metalworking club did this -- and had to do a lot of metalworking to come up with a proper mount for the three phase motor.
    Or -- Monarch will do the conversion for you -- for lots of money. This may be what he is talking about. And if so, it means that the current motor/generator and DC spindle motor may be bad, thus the factory conversion is the best bet.

    The gears and leadscrew produce inch threads normally. I don't know whether there is a place to put transposition gears or not. (I've not actually used one to that extreme -- just the old motor-generator one at work where I never needed to cut metric threads, so I never opened up the left-hand side of the headstock.
    But -- if so -- the threading dial will not work when doing metric threads (a common problem with any lathe with an inch thread leadscrew) -- you will have to stop and reverse the lathe spindle to back up as you wind the tool out of engagement with the workpiece while in reverse, and then wind it back in as you switch to forward. You can't release the half-nuts and expect to cut the same thread path on another pass.

    A lot greater distance for me. I would have to take two flights to get there and back in a single day (if I were lucky). :-)

    The 10ee is a very good machine. Even one as old as the motor/generator style. (But you may have to turn the commutators and replace badly worn brushes.
    Good Luck,         DoN.
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Can someone educate me a little bit. If the drive motor is DC, and has separate field and main windings, why can't it be controlled by two separate DC power supplies?
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On Wed, 03 Nov 2010 18:47:20 -0500, Ignoramus3281

Hey Iggy,
For starter's, why?? What's wrong with the as-designed method of supplying the DC voltage to the spindle motor rotor and field from the same source (in this case, an MG set)? Why two?
Probably not that it can't be done, but safety would dictate a lot of control circuitry so that the motor can't over-speed because of the loss of field excitation. Bad news on a lathe if it were to happen. The motor would probably fly apart within a few seconds, but imagine the chuck and work-piece speeds for that second or so. If you've never seen it happen, it's hard to imagine.
Take care.
Brian Lawson, Bothwell, Ontario.
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Ignoramus3281 writes:

I don't see why not. That's certainly how the off-the-shelf controllers operate, with an optional field winding supply.
I don't know about this particular DC motor, but in general DC motors with separate field windings can be wired in parallel or series and run off a single power supply, with varying torque-vs-speed characteristics for those two configurations.
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    The 10EE separately varies the rotor and field at different times to achieve the various speeds. Think two variable resistors (probably set up as rheostats in the early M/G types, and as potentiometers in the later electronic types. The rotor is increased until you reach a maximum voltage -- and then to continue increasing the speed, the field current is decreased.
    The separate variation si why not a single power supply. No wiring in either parallel or series in this case.
    Enjoy,         DoN.
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So, then, there is no real need to change to a 3 phase motor and VFD, all one needs is to make or buy a proper set of power supplies? That seems far easier than making all those shaft and mount adaptors and much more straightforward.
I made a power supply for my mill and it was completely trivial. It was not adjustable or regulated, though, but I do not think that it needs to be regulated. Adjustability, may be a bit tricky, but not totally impossible with a multitap transformer or something like that.
i
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    [ ... ]

    Assuming that the spindle motor has no problems. You may need to skim and re-groove the commutator and put in new brushes.

    The trick is getting all that to adjust at the right times. There is a single knob on the lathe which has the two rheostats or pots on a single shaft, which each have a range during which they do not change, as the other one changes.
    Doing this with switched taps -- or even a pair of Variacs -- gets a bit tricky.
    Yes -- you could use the two pots on the single shaft to control two power supplies -- with the proper control electronics and SCRs or triacs -- but you are then getting close to the original electronics in the later models. If you have one of the later models with a dead set of electronics, this might be the best way to go. But for a M/G version, I think that making that work as designed is the better approach.
    There is also a mechanical tach in the headstock to tell you the RPM you are currently using. (The one at work had that dead, unfortunately, so I never knew the actual speed -- just went for what felt right. :-)
    If the motor and generator still work -- or can be made to work fairly easily -- it is easier to go that way.
    When you come in to use the lathe, you bend over and hit a button which (IIRC) is near the floor on the tailstock end. You hear the motor generator spin up, and then it is ready to use. Then all you have to do is remember to turn it off when you are done.
    Enjoy,         DoN.
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