# 1964 10EE lathe



## rabler (Feb 27, 2021)

The CK I posted about in another thread is a great lathe, certainly sturdy.  But it is not the machine for spinning anything over 1000rpm.  I'd been working with a 10x22 import lathe and realized a spindle speed faster than 1000 is certainly useful for carbide on small diameters.  And I decided I really like fixing up the older machines.  About a year ago I ran across a Monarch 10EE for sale in Wisconsin.  Pretty rough shape, but running.  5HP DC motor, that had been modified with an after market "Danfuss" controller that wouldn't run the spindle up over 1000rpm. 

DC motors are a bit strange in that there is both an armature and field, basically a rotating electromagnet and a fixed electromagnet.  The rotating electromagnet (armature) gets driven through brushes that activate the appropriate orientation to push against the fixed magnet (field).  To vary speed in this type of DC motor the voltage to the armature is increased from zero to maximum, and then to go faster, the current to the field is decreased.  (Sorry to any power/motor experts if I'm butchering this).   That requires a fairly complicated set of controls feeding the DC motor.  Monarch went through quite a bit of variation in doing this over the 4+ decades that the 10EE was mass-produced, and the control electronics have always been the Achilles heel of these lathes.

Anyhow, this lathe was meant to spin up to 4000rpm on the spindle, but the existing controller would only get up to about 1000 rpm.









I'll add more to this thread soon ...


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## rabler (Feb 28, 2021)

I did quite a bit of reading om practical machinist on fixing the DC mechanism in these.  Two possible routes became obvious, basically replacing the DC controller, or replacing the DC motor with an induction (standard AC) motor and vfd.

The monarch 10EE is a bit unusual for a lathe in that the spindle is ungeared.  It is a straight through shaft and however fast the belt drive turns that end is how fast the chuck or whatever is mounted on the working end will turn.  And yet you get this incredible range of useable speed, like 10 rpm to 4000 rpm on mine.  This is done via a DC motor which has torque over a fairly broad range of rpm, plus a reduction gear mounted on the motor, giving direct motor rpm out, or IIRC a 5:1 reduction.

The challenge with the induction motor plus vfd route is even with a good vfd, 10-4000 rpm on the spindle is a 400:1 range of rpm to operate. Many vfd machines we see today run 20-2000 rpm, 100:1, by using two or three geared speed ranges.  Also, a vfd driven motor roughly creates the same torque at speeds less than the design speed of the motor.   HP = rpm * torque * constant, where constant is a number which depends on units used.  So if torque is constant, than as rpm drops, so does HP.  On a lathe if you are looking for a certain SFPM cutting speed, you go slower on bigger (larger diameter) parts.  Larger diameter means less leverage for the motor, so the motor needs more torque to give the same force at the cutting tool at that SFPM.  So a VFD isn’t to optimum configuration for getting power to a machining tool as we reduce rpm below the motors rated speed.  On the other end, as we increase rpm above the motor’s rated speed, vfd’s have to reduce the torque as speed increases (above the 60Hz speed of the motor), to keep the motor from exceeding its rated HP output. This matches well with what we want for most machining.   Turning faster is associated with smaller endmills or smaller diameter workpieces in the lathe.

One takeaway from this is if you have a vfd machine with multiple speed ranges and you need the most cutting power, you should opt for the lowest speed range that will give you the desired cutting speed.  So if your lathe has ranges 50-500 and 200 to 2000, and 400 rpm is your desired cutting speed, you are better off using the 50-500 rpm range.  The high range will of course still give you the option of 400 rpm, but less cutting power.  Just like you can use third gear at 20mph in your manual transmission car, but if you want to accelerat, downshift to 2nd or first.

Ok, rhe point of all that explanation is that a VFD driven motor isn’t going to give you good cutting performance over a spindle rpm range of 10-4000 rpm.  There are two ways to help this along. One is to use some gearing.  The other is to use an oversize motor.

The 10EE does have that reduction gear in its design.  The challenge is that the reduction gear is part of the DC motor assembly, between the DC motor and the drive pulley.  So you can’t just take the pulley off and put it onto a VFD driven motor without losing the reduction gear.  Quite a few 10EEs out there have been converted in just that way, the reduction gear is discarded along with the old motor.   Even with a ridiculously oversized motor (commonly up to 10HP) the low rpm performance suffers.  Singke point threading is one area that this can become an issue.  Since that is one area where the classic 10EE shines, it is a shame to sacrifice capabilities in that area.

A very good solution to this is to re-use the original reduction gear unit.  This is somewhat complicated to do in that the original DC motor is not a simple keyed shaft but rather a splined shaft into the reduction gear.  This has been solved many ways, such as making a keyed shaft to spline adapter, or more commonly just cutting off the spline end of the original DC motor and putting a keyway on the cut end, along with a coupling.

So, a large (5-10HP) AC induction motor, reduction gear adapter and VFD is probably the cleanest solution.  That’s not necessarily cheap, unless you can find a bargain on a good used AC motor and suitable VFD.

The option I took was to preserve the whole motor assembly and build a new DC motor control system.  In retrospect that certainly wasn’t the quickest solution to a functional lathe, and is only practical in that I do have a background that includes electronics.  I also wanted to run the whole thing off single phase rather than a phase converter.


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## Shootymacshootface (Feb 28, 2021)

A 10EE is on my bucket list!
Good luck with your project.


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## rabler (Feb 28, 2021)

Shootymacshootface said:


> A 10EE is on my bucket list!
> Good luck with your project.


Thanks!  I like your profile/avatar quote.  But my favorite version of that is "I made a small fortune out of a big one", which may be just as applicable to hobby machining


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## extropic (Feb 28, 2021)

That OP summarized considerable research into a few paragraphs. It should help many readers understand the trade-offs. Thanks for posting.


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## rabler (Feb 28, 2021)

Instead going the VFD and AC motor route, I decided to try building a new DC motor controller.  I wouldn't really recommend this approach, but there are some reasons that Monarch used a DC motor in these things.  Two primary reasons are: DC motors can cover a wide RPM range, and DC motors have a lot of low speed torque.  Drill/drivers of the cordless or even of the older corded era are a good example.  Spin fairly fast, and under load the slow down but can develop a lot of torque to turn in a screw or turn a large drill bit.  Starter motors on your car are also DC motors, again low end torque, but there your battery is also DC so that makes it an easy match.

My 10EE came with a 5 HP DC motor.   Here is a copy of the data plate,cropped a bit closer than the above picture:


Volts: 240,
Amps: 18.1
RPM: 1150/3450
Fld Amps 1.19/.272
SEP EXC 120V MACH TOOL DUTY

This means it wants 240VDC on the armature, at 18.1 Amps, to achieve 1150 RPM.  At 1150 RPM, the field needs 1.19 amps at 120V.  To achieve 3450RPM, we need to REDUCE the field current to 0.272 amps.
To get less than 1150RPM it'll need to be fed a voltage less than 240VDC on the armature.

So basically this thing needs two variable output DC power supplies.  One for the field and one for the armature.
Converting AC to DC is why these things get complicated.  Monarch went through a lot of variations in making this work.  Some of the earliest 10EE's used an AC motor to turn a DC generator to run the DC motor.   They went through a couple generations electronic approaches, mostly using old fashion vacuum tubes.  I'm sure those of us over a certain age can remember when every hardware store had a tube tester and stocked a few vacuum tubes, but those have gone the way of 8-track tapes.  Or is that cassette and VCR tapes?

240VDC is not straightforward to generate from your 240V single phase AC circuit.  While theoretically 240VAC is actually the RMS (root mean square) voltage and the AC line sinusoid actually peaks out at 240 * sqrt(2), roughly 340 volts, RMS voltage is used so that RMS voltage * RMS amperage = average power.  (AC current is also measured RMS).  Volt meters and current meters are calibrated in RMS volts or amps.  Anyway, converting AC to DC isn't perfect so typically you can't get 240VDC out of 240VAC for a high powered circuit.  (Remember we need 18.1 amps).  All we need is 20 car batteries in series, right?

Why didn't they use a DC motor with a smaller voltage requirement?  You can build a 5HP motor that uses less than 240V, but the trade off is the motor gets bigger.  So obviously they were trying to keep the motor to a size to fit in the base.   To get the enough DC voltage, the easiest solution was to use a transformer to raise the AC voltage up higher than 240V.  (Transformers don't work for DC).    Monarch used at huge 6.8KVA transformer to boost the AC voltage up to 580 volts AC (that is not a typo).




I'd guess that transformer weighs at least 100lbs.  I have it on my bench.  Unfortunately the leads on it are corroded beyond usable. So it makes a good doorstop I guess.

I did some reading and searching, and found a few people had successfully used Parker/Eurotherm DC controllers, namely a 514-32 and a 506 or 507 as the two DC power supply controllers for 10EEs using single phase 220V.  Here is the basic power circuitry schematic I came up with for using those for the motor in my 10EE (note that there are several different DC motor options, 3HP DC was more common than 5HP).


The "boost transformer" on the far right is the replacement for the above Monarch original.  The Parker 514 is a solid state unit and a bit more efficient than the older tube electronics so I only need around 340VAC into the 514 to get full rated power out of the existing DC motor.  Her's what that schematic looks like in implementation:




This is the panel that lives under the lathe bed behind a door on the front lower right of the lathe.  The top left contraption is a 3 pole (3 phase) switch that protrudes through the door and has a large on/off handle.  That switch is the only original equipment on that panel.  The smaller panel in the lower left has the original on, off, and coolant switches.  Note that the original panel had a nice easy to press protruding "On" switch, while the Off switch is recessed.  Obviously modern safety standards have changed.

The blue boxes on the right side are the two Parker DC controllers, purchased used off of Ebay.  The 514 was not cheap, $400+ used.    (Did I mention that the VFD route made a lot of sense as long as the reduction gear was retained?)  Obviously this panel doesn't include the DC motor itself, nor does it include the boost transformer.  (Actually the motor can be spun up without the boost transformer, just doesn't deliver full power).

This doesn't cover a completely working setup yet.  The 507 and 514 need some control inputs that tell it what voltage and current to deliver to the motor to give the desired RPM.


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## rabler (Mar 1, 2021)

DC motors are a bit weird.   As I mentioned above the field current is reduced to increase RPM.  Taking that to the extreme, once spinning, some DC motors will actually spin up to self destruction if the field current goes to zero.  So, if the smaller 507 field controller fails for some reason, the 514 needs to be shut down immediately to prevent this type of runaway motor.  I've been told by one person that they tested this on one of the 3HP Monarch supplied motors and that it max'ed out before self destructing.  Not going to test that myself.

Further, to control this we're controlling two DC power supplies, the Parker 514 and the 507.  The approach I've heard used is to use a separate potentiometer for each one, along with a few relays to be sure they power up/down together.  You then dial in the both to get the RPM you want.  Basically you need to understand how to set both power supplies to get a desired RPM.  I really didn't like the sound of this approach.  Especially as reversing the spindle is then also controlled by one of those pots.  Just too much to think about while trying to go forward/backwards for say, threading.

So here is where I went overboard.  I decided to build a microcontroller circuit to manage all of this.   I had the guts of my 10EE spread out on my welding table, electronics, plus all the mechanical bits of the apron, carriage, gearbox, etc.







To start with, that meant I needed an electronics bench in my shop.  I had some maple flooring left over from a previous house, so I ripped the tongue and groove off of those and glued up a nice heavy maple bench.  Weldeded up a frame, added a upper shelf for measurement instruments, and a plywood back.





Add some bins for parts, put the oscilloscope, bench power supply, soldering iron on there, and my shop now has a very useful electronics station, instead of my usual worktable being tied up with electronics work as it was when I first started the electronics side of this.  I like to be able to hop between parts of a project or different projects so this was critical for me.


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## rabler (Mar 1, 2021)

If you look at the first picture in my previous post, you can see that the lathe is pretty dirty.  These 10EE's have all sorts of cavities in the base.  I really wanted to clean it up, but getting down on my knees on a concrete floor wasn't appealing.  I wanted a height that I could sit on a stool or 5 gallon pail while scrubbing and painting.  So I fabbed up a stand complete with wheels to lift the whole thing up about 16".  You can see here I've also done some work on cleaning and painting.  I used the lighter blue for interior surfaces, so anything in the light blue/gray eventually get covered up.  But it makes those compartments a little brighter and easier to see into, helpful for finding that nut or bolt that fell.  And it was leftover from the 12" CK project, basically a reject color.  I do like the darker blue, so you'll see I'm using it on all three lathes.


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## extropic (Mar 1, 2021)

Beautiful !!!     You do NICE work.

Please show what you used to lift the lathe onto the work platform.


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## Karl_T (Mar 1, 2021)

savarin said:


> Have you considered going with a monotube flash steam boiler?
> If it blows there is not much water or steam to damage anyone.
> Almost instant steam.





rabler said:


> I did quite a bit of reading om practical machinist on fixing the DC mechanism in these.  Two possible routes became obvious, basically replacing the DC controller, or replacing the DC motor with an induction (standard AC) motor and vfd.
> 
> ...   ....
> 
> So, a large (5-10HP) AC induction motor, reduction gear adapter and VFD is probably the cleanest solution.  That’s not necessarily cheap, unless you can find a bargain on a good used AC motor and suitable VFD.



Very good summary. I do think there is one more important point on the  3 phase motor. Get one with 4 (1800 base RPM) or 6 (1200 base RPM) poles, NOT a 2 pole (3600 base RPM). For a given slow speed the 4 pole has twice the torque, the 6 pole has three times the torque of a 2pole motor; and it won't hurt them at all to spin up to 3600 or even a bit more RPM.

I will be using a 6 pole C frame 7.5 Hp 3 phase motor on my 10EE that i plan to rebuild late this spring.  The VFD will be set to spin the motor and spindle from 60 to 4000 RPM .  Back gear gives another 6:1 reduction.  i already have another 10EE that was rebuilt this way.


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## macardoso (Mar 1, 2021)

rabler said:


> I did quite a bit of reading om practical machinist on fixing the DC mechanism in these.  Two possible routes became obvious, basically replacing the DC controller, or replacing the DC motor with an induction (standard AC) motor and vfd.
> 
> The monarch 10EE is a bit unusual for a lathe in that the spindle is ungeared.  It is a straight through shaft and however fast the belt drive turns that end is how fast the chuck or whatever is mounted on the working end will turn.  And yet you get this incredible range of useable speed, like 10 rpm to 4000 rpm on mine.  This is done via a DC motor which has torque over a fairly broad range of rpm, plus a reduction gear mounted on the motor, giving direct motor rpm out, or IIRC a 5:1 reduction.
> 
> ...



One thing to think about is modern high end VFDs will offer Field Oriented Control (FOC). When you use this control mode *with *an encoder on the motor, you can see 1000:1 torque range.

Here is an excerpt from an Allen Bradley whitepaper (publication DRIVES-WP002A-EN-P). 



			https://literature.rockwellautomation.com/idc/groups/literature/documents/wp/drives-wp002_-en-p.pdf
		





Note that Field Oriented Control (FOC) is branded by AB as "Force Technology". Without an encoder, you get about a 20% gain on a sensorless vector controlled (SVC) VFD. Adding the encoder gets you to the 1000:1 constant torque speed range, in line with a DC drive, as well as much better speed regulation. They also offer better torque bandwidth and regulation than a comparable DC drive.


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## rabler (Mar 1, 2021)

Karl_T said:


> Very good summary. I do think there is one more important point on the  3 phase motor. Get one with 4 (1800 base RPM) or 6 (1200 base RPM) poles, NOT a 2 pole (3600 base RPM). For a given slow speed the 4 pole has twice the torque, the 6 pole has three times the torque of a 2pole motor; and it won't hurt them at all to spin up to 3600 or even a bit more RPM.
> 
> I will be using a 6 pole C frame 7.5 Hp 3 phase motor on my 10EE that i plan to rebuild late this spring.  The VFD will be set to spin the motor and spindle from 60 to 4000 RPM .  Back gear gives another 6:1 reduction.  i already have another 10EE that was rebuilt this way.


Karl,
Another way to look at that is torque at 60Hz.  Since HP = torque * RPM * (conversion constant):
A 2 pole motor produce 1 HP spins twice as fast as a 4 pole 1 HP motor.  The two pole motor has 1/2 the torque.
But you can put a 2:1 pulley on the 2 pole motor and get the same RPM and torque as the 4 pole motor.  Ignoring pulley loss you haven't really gained anything.  It's really just a matter of matching the RPM of the motor you're replacing to avoid having to add that extra 2:1 pulley.

A 6 pole motor is a close match to the original Monarch torque curve. And by going from the typical 3 HP to 7.5 HP you've thrown in a good bit of extra torque to make up for the fact that AC motors don't usually deliver good torque at really low RPM.  With the back gear you are set.  I think I already alluded to the fact that If I were starting over I would go this route.


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## rabler (Mar 1, 2021)

macardoso said:


> One thing to think about is modern high end VFDs will offer Field Oriented Control (FOC). When you use this control mode *with *an encoder on the motor, you can see 1000:1 torque range.
> 
> Here is an excerpt from an Allen Bradley whitepaper (publication DRIVES-WP002A-EN-P).
> 
> ...



Yep, VFD's are getting more and more advanced.   I wouldn't get too wrapped up in claims by a company about the performance of their product, this white paper certainly has a bit of marketing spin. Ironically the Parker 514 has an encoder option that adds stability and speed range too, so this is not a completely new concept.  Any engineer will tell you that feedback improves stability.  All of these technologies are basically trying to estimate the actual speed (or slip) of the motor.  Going to a direct measure instead of an estimate gives a more accurate measurement to work from.  Either way, via the Parker or Allen Bradley approach, adding an encoder is an additional complexity.   The more modern hall-effect encoders make this much easier than it was in an earlier era.

Modern production CNC equipment designers will probably want to take a close look at this type of technology ("Force Technology").   What is the sweet spot for home/hobbiest machinists, or even job-shop machinists that want a good manual lathe?  I'd guess right now the oversized motor and vector control VFD w/o any other technology is probably the best on the basis of cost, and easiest to maintain for the home shop, less confusing if you attempt resale.  In another 10 years I'm sure that will change.


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## rabler (Mar 1, 2021)

extropic said:


> Beautiful !!!     You do NICE work.
> 
> Please show what you used to lift the lathe onto the work platform.


I have a small gantry crane that I made many years ago, using a 2" x 3" x 3/16" A36 rectangular tube frame.   It bolts together.  Unfortunately I don't have any pictures of it and it is currently disassembled.   Honestly it is not suitable for lifting that much weight with a safe "overhead" lifting margin, even though I'd stripped quite a bit of the weight off.


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## rabler (Mar 2, 2021)

So I made the very questionable decision to keep the DC motor and install a new controller based around the Parker modules.  From there I decided to jump off the deep end and build a microcontroller-based circuit to keep everything straight and give a simple one dial speed control.  This particular machine has what Monarch called a "Electrical Lead Screw Reverse" (ELSR).  Or may they used "Electronic"?  That sounds pretty fancy but it is really just an "off switch" driven by adjustable stops.  A fancy mechanical adjustable limit switch.  The tailstock end of the lathe has a dial that selects between forward, neutral, or reverse for the motor and therefore the spindle.



Monarch also offered some 10EE variants/options that allowed you to set a different speed for forward and reverse.  This can be helpful for cutting threads, where you may want to move quickly while out of the cut, and then run a cutting pass more slowly.  I figured WTH, I'll add this to my design.  

So I'm going to throw low voltage digital control circuits in with lots of high AC and DC voltage, including inductive (motor) loads and high frequency switching in the Parker controllers.  That has the ingredients for serious RF interference problems so I figured I'd better design my digital circuitry with care.  Digital circuits are generally not tolerant of signals that are even briefly greater voltage than the 5V or 3.3V power supply, or less voltage than ground (any negative voltage).  Not tolerant, in this case doesn't just mean a bad logic value, it means the digital circuit dies.  So while the basic logic needed is pretty simple, keeping things robust is more complicated.  Only time and use will tell if I'm doing this right.

I picked the Arduino family of microcontroller development environment.  My background is offended by that world of trying to gloss over the all the details and reduce programming to what they call "sketches".   I've worked professionally with Motorola 68701, 68HC11, Microchip 16C and 17C series, Texas Instruments MSP430 microcontrollers, as well as a fair amount of embedded linux 32-bit systems.  But the advantages of the Arduino environment are free development software based on C/C++, USB port interface to a programming computer, and low cost microcontrollers that are available in packages conducive to through-hole circuitry.  Actual microcontroller chips tend to come in surface mount packages with .025" lead spacing, or other bizarre package/mounting options.  While I've seen a few projects where people have done that with a home soldering iron, my eyes and soldering skills would be hard pressed to do that reliably.  The Atmel 8-bit microcontrollers are pretty decent capability, have a good C-compiler port, and at $10 or less for a microcontroller break-out board for the 20MHz Nano every, are a good value for this project.




I design up a circuit with a lot of protection for the interference issues discussed above.  Optical isolation buffers (opto-isolators) to keep the high voltage noise/transients from damaging the circuits.  RC low pass filters to reduce noise, as well as debounce switches (I hate software debouncing, offends my sense of good design).  Zener diodes as transient protection.

The main control into the Parker 514 is an analog voltage input between +10 and -10volts.  The 514 provides a +10V and -10V output, so a potentiometer (variable resistor) can be easily set up.    Of course, forward is selected by 0 to +10volts and reverse by 0 to -10v.  I really don't like the idea of a speed dial on the lathe also selecting forward vs reverse.  (Ever run a carbide insert backwards?  Be prepared to change out the insert.)   I won't go into more details on the 514 and 506/7 interface, it gets a bit messy.  I also wanted an interlock circuit.  Monarch's original design had lots of good safety features, like the ELSR needs to be in neutral to power on the lathe, and won't spin up if the spindle lock is set.  

I wanted the digital part of my circuit to fit in the original on/off switch panel, an area roughly 2.75" x 11".  (See the previous post with the protruding on button and recessed off button for a picture of that original switch panel).    So I designed up replacement panel accordingly.




The e-stop and square red-green buttons go directly the main power contactor.  The large knob on the right goes through a bushing to a digital encoder (or rotary pulse generator).  I didn't want a delicate little knob for speed control, so this is more in size with other working controls on the machine.  The center LCD screen displays my two speed set-points, 100rpm forward and -100rpm backwards.  The letters reflect "S"top/"G"o, "F"orward/"R"everse.  The P is a diagnostic for the lathe "state", in this case "P" stands for power-up.  This is still on the bench test stage obviously.


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## macardoso (Mar 2, 2021)

rabler said:


> Yep, VFD's are getting more and more advanced.   I wouldn't get too wrapped up in claims by a company about the performance of their product, this white paper certainly has a bit of marketing spin. Ironically the Parker 514 has an encoder option that adds stability and speed range too, so this is not a completely new concept.  Any engineer will tell you that feedback improves stability.  All of these technologies are basically trying to estimate the actual speed (or slip) of the motor.  Going to a direct measure instead of an estimate gives a more accurate measurement to work from.  Either way, via the Parker or Allen Bradley approach, adding an encoder is an additional complexity.   The more modern hall-effect encoders make this much easier than it was in an earlier era.
> 
> Modern production CNC equipment designers will probably want to take a close look at this type of technology ("Force Technology").   What is the sweet spot for home/hobbiest machinists, or even job-shop machinists that want a good manual lathe?  I'd guess right now the oversized motor and vector control VFD w/o any other technology is probably the best on the basis of cost, and easiest to maintain for the home shop, less confusing if you attempt resale.  In another 10 years I'm sure that will change.



For sure, whitepapers *are *marketing tools for us nerds  But I do not believe the specifications to be inflated. DC drives hold a very special place in the portfolio of motor control as they have been able to do things that AC drives are just starting to match (and AC drives can do things DC drives can't touch).

The encoder is included for applications where the highest speed range is required, or more commonly, the smoothest and most accurate application of torque is required.

These drives are not specifically designed with machine tools in mind. More or less, our technological needs are very basic. The motor drive is put to the test when super precise control of the load is needed. One example is using a roll to set the tension in a continuously moving web of product (packaging, printing, etc.). Any variation in applied torque will be visible in the end product. 

Technology trickle down is a great thing. Someone with a crazy application *must *have the absolute best motor control, 20 years ago, and now the controls we have access to today includes that same technology as a standard option. Pretty cool.


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## rabler (Mar 2, 2021)

Here's a better picture of the 10EE when I got it.  It did come with a tailstock, of which the quill lock handle is barely visible sitting in the back right corner of the chip pan.


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## macardoso (Mar 2, 2021)

rabler said:


> Here's a better picture of the 10EE when I got it.  It did come with a tailstock, of which the quill lock handle is barely visible sitting in the back right corner of the chip pan.
> View attachment 357714


What a cool machine.


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## francist (Mar 2, 2021)

Looking great, rabler. I have to admit I tend to glaze over when discussions turn to microvolts and optoisolators but you’ve got a way of writing that keeps even us fools engaged. Thanks for that! 

-frank


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## Winegrower (Mar 2, 2021)

Man, rabler, your analysis and design direction is excellent.   Possibly like you, this project would be a cross section of my professional career, and something that would be exciting to take on, and I applaud you for it.   

Please continue showing us your progress.   I suspect for 10EEs, the price is about to go up and the availability about to go down, with all the drooling going on out here in cyberspace.


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## Shootymacshootface (Mar 2, 2021)

Winegrower said:


> Man, rabler, your analysis and design direction is excellent.   Possibly like you, this project would be a cross section of my professional career, and something that would be exciting to take on, and I applaud you for it.
> 
> Please continue showing us your progress.   I suspect for 10EEs, the price is about to go up and the availability about to go down, with all the drooling going on out here in cyberspace.


Yes, this has the makings of one of those  HM historic go to threads! No pressure.


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## rabler (Mar 2, 2021)

I've been alternately working on the electronics and the mechanical parts of the 10EE.  I jump back and forth depending on what mood I'm in, and what I have on hand.  Often something ends up hold while waiting for parts, often via mail-order, or just waiting for a coat of paint to dry enough for a part to be reasonable to handle which often takes a few days.  I'm trying to write this up with some idea of a timeline, without jumping back and forth quite as often as I do between various aspects of this project.

I got the body of the lathe painted, and put it together a bit to just keep the pieces from creating too much clutter.  It's pretty dusty here (some woodworking/sanding going on).    Maybe not the best angle for a photo but I'm not willing to move it around to get it's "best side".  Pictures probably make the paint look a bit better than reality but it certainly looks better than the original worn off paint.




I've gone over the gearbox.  At this point I'm going to put it back together without completely disassembling it.  Other than a needing really good cleaning the gearbox seems to work well.  I took the apron side faceplate off as the bearings for the leadscrew and feed rod felt a bit rough and I wanted to replace them.  I also needed to drill out one of the taper pins to separate the feed rod from that faceplate.  I had tried to pull the faceplate off without removing the gearbox from the lathe, but the two capscrew holes on the right as shown here are not accessible with the gearbox in the lathe, as it sits partially recessed into the bed under the headstock.




Each of the two rods (leadscrew and feed rod) uses two opposing taper bearings to eliminate any play in those.
Here's the picture of the gearbox sitting on the bench.  I used diesel fuel in a 1 gallon garden sprayer to thoroughly flush the gearbox and wash all the residue out from the bottom of the inside.





I've put a first coat of paint on the face of the gearbox, and I bought some 1/32 gasket material from McMaster to make replace gaskets.   These gaskets tend to leak and can't be replaced without pulling the gearbox off.

Note that I didn't take all of the control handles off, while that would make repainting easier I opted to just do what I can without stripping it all down.  My goal is to have a functional lathe with a bit of attention to cosmetics, not to make a prize winning showpiece.  I will be putting a second coat of paint on the gearbox, as I think that'll last longer.   The lathe body has two coats also.  The second picture below shows the faceplate reassembled to the body of the gearbox, with the leadscrew and feed rod bushings installed with the new bearings. The third and last picture is the backplate of the gearbox re-installed with a new gasket, apparently this is a very common source of leaking on these lathes, and frustrating as pulling the gearbox is not trivial.


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## rabler (Mar 3, 2021)

While I haven't finished painting and remounting the gearbox, I went ahead and pulled the apron apart.  With all the levers/controls it is hard to do a good job of painting without disassembly, but more importantly, the apron on most Monarch lathes contains an oil pump which lubricates the apron, as well as the carriage, bed ways, and cross slide.  Cleaning out that oil pump, and the corresponding copper lines to everything is necessary as they often get plugged up over the years.





It seems to worked best to start from the headstock side of the apron, taking the shafts and components out from that end and working toward the tailstock end.  These are from my disassembly notes pictures sequence. so they're not the best framed pictures, but the sequence of pictures, and the placement of the parts in the pictures, helps me figure out how to put it all back together.  I also use a lot of ziplock bags to keep small parts together, labeled and numbered in sequence.




Fortunately on this apron the whole bottom comes off too.  My CK that I had previously redone the apron did not have a removeable bottom, it was all one casting.  Obviously this was a real mess.  Note that you can see the oil pump on the bottom of the apron.  It sits in the bottom so it was trying to pump up oil through this mess.  (And probably failing).


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## Chipper5783 (Mar 3, 2021)

rabler said:


> Karl,
> Another way to look at that is torque at 60Hz.  Since HP = torque * RPM * (conversion constant):
> A 2 pole motor produce 1 HP spins twice as fast as a 4 pole 1 HP motor.  The two pole motor has 1/2 the torque.
> But you can put a 2:1 pulley on the 2 pole motor and get the same RPM and torque as the 4 pole motor.  Ignoring pulley loss you haven't really gained anything.  It's really just a matter of matching the RPM of the motor you're replacing to avoid having to add that extra 2:1 pulley.
> ...


Question for Rabler or Karl.
I'm resurrecting a small radial arm drill.  The spindle has a 1.5HP 3 phase motor (the elevate motor is a small 3 phase motor).  Though I have 3 phase in my shop (PhasePerfect) my intent is to bring 3 phase to the drill, for the elevate motor via conventional contactors and to power a VFD for the spindle.  The rational for the VFD is two fold: 1. I like some easy speed range on a drill press (I have a good sized post drill with a VFD and I like it) 2. to increase the speed range.  The drill has a 3 speed gear box, I'm keeping it (to help with the turn down issues you described with a VFD).  The spindle motor is a 2 speed motor (830 & 1630) - seems like a lot of slip for 8 pole - 4 pole 60 hz motor.  Per the machine name plate, right now I have 6 speeds from 130-900 rpm.  From the motor's point of view, do you see any issue running it to 3600rpm (about 125Hz on the Hi setting)?


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## rabler (Mar 3, 2021)

Chipper5783 said:


> Question for Rabler or Karl.
> I'm resurrecting a small radial arm drill.  The spindle has a 1.5HP 3 phase motor (the elevate motor is a small 3 phase motor).  Though I have 3 phase in my shop (PhasePerfect) my intent is to bring 3 phase to the drill, for the elevate motor via conventional contactors and to power a VFD for the spindle.  The rational for the VFD is two fold: 1. I like some easy speed range on a drill press (I have a good sized post drill with a VFD and I like it) 2. to increase the speed range.  The drill has a 3 speed gear box, I'm keeping it (to help with the turn down issues you described with a VFD).  The spindle motor is a 2 speed motor (830 & 1630) - seems like a lot of slip for 8 pole - 4 pole 60 hz motor.  Per the machine name plate, right now I have 6 speeds from 130-900 rpm.  From the motor's point of view, do you see any issue running it to 3600rpm (about 125Hz on the Hi setting)?


The two issues when using a VFD on a motor are cooling, and some weird arcing effects associated with the high switching frequency coming out of the VFD.  

 Cooling is only a problem if you push the lower end because the motor fan is also turning slower.  For a higher speed (>60Hz) it isn't a problem. You might shorten the life of your bearings some by cranking up higher speeds, and I'd probably consider putting new bearings in the motor if there is any doubt to their condition.

The high switching frequency issues can be mitigated to some extent by keeping the wiring from VFD to motor as short as possible, and by programming the VFD to a lower switching frequency.  IIRC, my TECO VFD for example goes up to 15KHz and uses that as a default, I dropped it to 11KHz.   Going too low tends to produce an audible whine or high pitched hum, depending on your hearing, so if it is annoying trying bumping the frequency up a bit.  Note that switching frequency is NOT the same as the motor speed frequency, it has to do with how fast the VFD pulses the power on and off to try to emulate a sine wave.     "Inverter" rated motors are designed with this issue in mind.  A lot of people are using non-inverter rated motors successfully.  Might be shortening the motor life to some extent?  But if your old motor dies next week, for the average end user it is hard to tell if the VFD killed it or it was just old.


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## Chipper5783 (Mar 3, 2021)

rabler said:


> The two issues when using a VFD on a motor are cooling, and some weird arcing effects associated with the high switching frequency coming out of the VFD.
> 
> Cooling is only a problem if you push the lower end because the motor fan is also turning slower.  For a higher speed (>60Hz) it isn't a problem. You might shorten the life of your bearings some by cranking up higher speeds, and I'd probably consider putting new bearings in the motor if there is any doubt to their condition.
> 
> The high switching frequency issues can be mitigated to some extent by keeping the wiring from VFD to motor as short as possible, and by programming the VFD to a lower switching frequency.  IIRC, my TECO VFD for example goes up to 15KHz and uses that as a default, I dropped it to 11KHz.   Going too low tends to produce an audible whine or high pitched hum, depending on your hearing, so if it is annoying trying bumping the frequency up a bit.  Note that switching frequency is NOT the same as the motor speed frequency, it has to do with how fast the VFD pulses the power on and off to try to emulate a sine wave.     "Inverter" rated motors are designed with this issue in mind.  A lot of people are using non-inverter rated motors successfully.  Might be shortening the motor life to some extent?  But if your old motor dies next week, for the average end user it is hard to tell if the VFD killed it or it was just old.


Thank you for the tips.  I don't see demanding much torque (50 Hz is still a decent motor speed) and I'd have a drill speed of about 110rpm.  I can't think of many applications where I'd need good torque at significantly lower speed.  If it seems the case, then a RAD is probably not the right machine for the task.  I've heard that about keeping the motor leads short (in this case they'll be about 2' long).

The previously mentioned post drill is using a non-inverter rated motor, the leads are short, it has been working great (in fairness, it really doesn't see much use - it it lasts another 12 operating hours, that is probably more than I'll use it in the next 15 years).


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## rabler (Mar 7, 2021)

The casting for the apron has been painted.  Some cleanup of overpaint is still needed here. Also, here is a better picture of the control knob mounting arrangement I built.


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## rabler (Mar 21, 2021)

I was working on the electronics side of this, got the motor hooked up to the control board to do some testing and code debugging.  Had to fix a few code issues, but the DC motor turns both forward and reverse.  But it turns pretty rough, bad enough that I'm not going to be able to do the needed tuning on the two Parker DC power supplies.

For those into technical details, the Parker units are meant for powering DC motors, so they have some control functions built in.  Somewhat like a VFD, you give it a low voltage signal which it translate to RPM (armature voltage) for one, and field current for the other.  DC motors being somewhat odd, you start out with full field current, and increase the armature voltage to (roughly) increase the RPM.  When you reach peak rated voltage on the armature, you are not yet at the motor rated maximum RPM.  To increase the RPM further, you _decrease _the field current.  Interestingly, some DC motors, especially if unloaded, will self-destruct in overspeed if you decrease the field current to zero.  Which could happen if the field circuit or wiring fails.

The Parker 514 is a full armature controller, and understands how to monitor the current and voltage of the armature and control it appropriately to get desired RPM even with a changing load, and will provide braking (allowing current to flow back to the line) if the RPM gets dialed back.   It does take some tuning, it is essentially an analog PID controller, so various gain parameters need to be set.  But it doesn't know how to coordintate this with the 507 field controller.  Some people just use two separate inputs (pots) to control them separately, and it is up to the operator to know how to fiddle with two knobs to get the desired RPM.




I decided to build a digital controller front end that uses one knob to set the RPM I want, and that microcontroller figures out how to get there from where ever it is now.  All good in theory, but of course now three devices (microcontroller and two Parker DC supplies) that need to coordinate correctly.  Or really, I have to program the microcontroller correctly and tune the Parker's correctly.  But wait, there is a fourth player.  The motor itself.  This motor needs some help, as the commutator is not in great shape.  With a bad commutator and brushes making less than good contact, the motor struggles.

So the DC motor needs to come apart.  Sort of thought that would be a good idea anyway, new bearings and brushes was on the list.  Additionally, I'm going to need to turn the commutator, as in put in on a lathe and take a couple thou off to get a nice, round, even surface for best brush contact and life.  After turning the commutator, the mica insulation between the commutator bars needs to be undercut a bit, as otherwise the mica will not allow good brush to copper contact.







My workbench is a bit full of projects (pieces) so I've decided to get the apron reassembled before tearing into the DC motor.  So the apron is going back together.  I replaced the bearings that ride on the underside of the ways, and the thrust bearings on either side of the feed worm.  The other bearings seem to be in pretty good shape.  The pinion gear that rides on the bed rack is a bit more worn then I'd like but it isn't so bad that it won't engage.  I replaced the filter on the oil pump and cleaned that out.  This apron also has part of the ELSR (electronic lead screw reverse) which is really just a motor shut off.  That mechanism had one of the fittings commonly used for grease but intended for oil, so that mechanism was a mess of old solidified grease.    Picture is from a day or two ago, it is almost completely back together now, just waiting for a coat of touch up paint to dry enough to move it off the bench.   I have the QCGB ready to go back into the lathe too, so need to do that.  Shop is getting crowded with parts.  Then I'll tackle the motor.  Keep your fingers crossed that I'm able to clean up the commutator, and motor in general.  Otherwise .... VFD and oversized induction motor will be in this lathe's future.


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## rabler (Mar 21, 2021)

Here’s what the back side of the apron looks like, as well as the pinion gear.
The inner ring of teeth is overcut from cutting the gear teeth.  So the teeth right up against the apron aren’t fully cut, I assume that diameter is there to ride on the bearing
.


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## rabler (Mar 26, 2021)

Waiting on some 5/32 soft copper tubing to replace the oil lines in the apron.  Once those show up I'll be able to rehang the apron.  Then I get to tackle the DC motor.


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## rabler (Mar 27, 2021)

Here's what it looks like so far.  Quick change gear box (QCGB) rehung, most of the covers in place, even if covering empty space.  Second picture is the bench of parts left to go.  At least that is most of them, there are a few more in various corners of the garage, and the motor and electronics on the electronics bench, etc.


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## rabler (Mar 28, 2021)

The DC motor was obviously in need of some help, based on looking at the commutator.  (Note these pictures are "thumbnails" so you can click them for larger view.) So I hoisted the motor out from under my electronics bench and put it up on the workbench:




Took the motor apart with some help from my wife to manage the gear puller on one bearing.  This is what the motor shaft looks like going into the reduction gearbox, note the face of the motor is the backplate of the reduction gearbox.  Had to disconnect the two leads to the brushes.




Here's the plate the brushes sit on, and a closeup of one of the brush holders.  The brush itself is on the bottom right, barely protruding from the holder, desperately in need of new brushes:






I got the rotor chucked up in the Monarch CK and started to turn the commutator down.  Took about .075" off the diameter total to get it completely cleaned up.





I still need to clean up between the commutator bars, but that is a challenge for another day.  Another issue I have to address is that the fan rotor is about 3/8" out of true.  Looks like someone had pried against it to remove the rear motor housing.  (GRRRRRrrrrr).  I'm sure that's going to induce some vibration in the motor if I don't straighten and/or balance it.  You can see a gouge near 3 o'clock in this picture, and at about 7 o'clock there is a major bend.


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## extropic (Mar 28, 2021)

Great progress. Sweet machine.

In my projects, when I find things like your bent fan, I think of God's vengeance (lightening strikes and such) on the ill prepared (insert favorite descriptor) that did the damage and left it behind.

I would like to see a description and pictures of how you have (or intend to) relieve the insulators between the commutator segments.


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## rabler (Mar 28, 2021)

extropic said:


> Great progress. Sweet machine.
> 
> In my projects, when I find things like your bent fan, I think of God's vengeance (lightening strikes and such) on the ill prepared (insert favorite descriptor) that did the damage and left it behind.
> 
> I would like to see a description and pictures of how you have (or intend to) relieve the insulators between the commutator segments.



Thanks!  A lightning bolt sounds too quick.  I was thinking of using his fingers as the next pry-point.  

This is my first adventure cleaning up a DC motor.  I've heard from at least 2 sources that a hacksaw blade with the kerf ground off is a good tool to scrape between the commutator bars so I plan on trying that.  I left the rotor mounted in the CK so it'll be easy to access, and I can give the commutator a final polish after that to get a truly smooth surface to minimize wear on the brushes.


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## Shootymacshootface (Mar 28, 2021)

That 10EE is going to be so awesome!


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## Winegrower (Mar 28, 2021)

It takes knowledge of a bunch of different disciplines to pull off this kind of restoration.  Terrific work, rabler.


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## rabler (Mar 29, 2021)

Winegrower said:


> It takes knowledge of a bunch of different disciplines to pull off this kind of restoration.  Terrific work, rabler.


Or the willingness to jump in and learn at the cost of a few mistakes along the way, which is a good way to acquire that knowledge.
Thanks!!


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## rabler (Mar 29, 2021)

extropic said:


> I would like to see a description and pictures of how you have (or intend to) relieve the insulators between the commutator segments.



The insulation was much less of an issue than the copper smearing. Hacksaw blade with the kerf ground off, and lots of patience.  Held the blade rocked at 45 degrees into the trailing edge from the cut. Polished with 180 then 320 grit sandpaper.  Cleaned up with compressed air.  Had to go back and hacksaw more and then polish again to get something I could live with. The harder and certainly nastier job is going to be getting all the grease mixed with carbon out of the frame.


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## rabler (Apr 3, 2021)

Winegrower said:


> Please continue showing us your progress.   I suspect for 10EEs, the price is about to go up and the availability about to go down, with all the drooling going on out here in cyberspace.


Missed your comment earlier.  I really hope the price doesn't go up.  I might mess this up and need to buy another one to start again.


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## rabler (Apr 15, 2021)

Well I've started cleaning out the carriage.  A couple hours of scrubbing in the parts washer.   Compressed air would not go through the oil lines, so I took the manifold and bijur flow restrictors apart and blew them out individually, alternating compressed air and WD-40 after cleaning the ports out individually with a bit of welding wire.  All but one of them are open/flowing at this point.  I left the blocked one soaking over night with WD-40 saturating the line.  I'm going to have to replace a couple of the copper lines as they are smashed flat.  I'll probably go ahead an replace the flow restrictor ports too.  Getting oil through here consistently is the most critical part of long term carriage/way maintenance, with keeping good way wipers a close second.




I'll have to get around to ordering brushes and bearings for the motor, but likely not until next week.  The trip to pick up the straight edge took up a full day.  Been trying to get some spring yard work done too.  Of course my idea of "yard work" includes spreading a couple dump truck loads of gravel.


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## Beckerkumm (Apr 15, 2021)

Great write up.  It's interesting how different companies dealt with oiling issues and how often they go bad when no one pays attention to the machine.  My Smart Brown oil comes from the apron but the design seemed to be flawed in that oil seldom got all the way to the back ways.  I found the plugged hole where the copper tube was inserted and drilled it out so now I can add some oil directly.  the Monarch system looks to be better if the tubes aren't smashed.  Dave


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## rabler (Apr 18, 2021)

Beckerkumm said:


> Great write up.


Dave,
Thanks.  Keeping these oil systems working, either as built or modified, is really helpful to longevity.  Monarch typically didn't provide automatic oiling to the compound. I have resorted to simply drilling through the compound, cutting some oil channels and inserting ball oilers on another lathe's compound.


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## rabler (Apr 24, 2021)

Left, old brush from the DC motor.  Right, replacement brush from Monarch.  The old one was worn to the point it didn't really have spring pressure.


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## rabler (Apr 30, 2021)

Looking at putt the DC motor back together, including the reduction gearbox.  Unfortunately the reduction gear needs to be repaired or replaced. Not much left of those teeth.  Its not extremely hard as it cuts with a file, although probably a bit harder that 1018.
Probably not straightforward or cheapest, but tempted to try cutting a replacement myself.

I’m going to put thisback in the gearbox for now so I can test out the DC motor after cleanup, but replacement needs to happen before putting a load on this gear ...


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## mksj (Apr 30, 2021)

May be worth looking at, this listing has been around for years. If they had a year similar to your motor you also may be able to salvage other parts. probably other sources, you might also check with Karl to see what he plans to do with his gearbox from his single speed motor retrofit.








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This is a direct link to there site, they may have other parts that they remove form the 10EE when they do their CNC conversions.





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QUALITY MACHINERY SALES FOR BRIDGEPORT MILL, HARDINGE, MONARCH, MACHINERY. When your ready for your next machine tool purchase come to TAS IRON LTD.




					www.tasironltd.com


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## rabler (May 3, 2021)

Another gotcha on the DC motor.  I was looking at reassembling the motor and hoisted the body of the motor back up onto the bench to clean.    I noticed the wires that attached to the brushes were in bad shape, cracked from heat and badly corroded under the cracked area.  Look closely where the lead with the eye is tied into the bundle.  I figured easy enough, these wires go to the brushes, so they should be the A1 and A2 armature leads in the motor junction box.   Not quite so simple, the A1 and A2 leads go two the two smaller poles in the motor, in series, then to the brushes.  The two larger field poles are laminated, and have 4 leads each.  The motor junction box has S1 and S2, F1 and F2, and  a2, a3.  a2 and a3 are connected in the junction box and taped over.  F1 and F2 are the series field.  S1 and S2 are presumable the shunt field as this is a complex wound DC motor. a2 and a3 are also part of the large field poles but no idea how.  I need to map all the wires out.  And then start replacing the heat damaged leads to the brushes.  This is going to require some solder and heat shrink splices.


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## rabler (May 9, 2021)

I'm going to eventually put this all together, although it is a bit more than I hoped to have to deal with.  I'm keeping my eye out for another 5HP DC motor with reduction gear from these things to have as a spare.  I know there is one source near Cleveland Ohio, that @mksj referenced above, of someone who swaps them out as part of a commercial 10EE rebuild.  Not in a hurry as I intend to fix this one, but I've invested enough in this that a spare seems prudent.


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## Karl_T (May 9, 2021)

I have one to sell, but shipping would be too much for our distance.


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## rabler (May 9, 2021)

Karl_T said:


> I have one to sell, but shipping would be too much for our distance.


I do drive through Minnesota twice a year, but sounds like yours is a 3HP.  I'd like to match the one I have.


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