10EE Spindle pulsing (not spinning at same RPM)

My 10EE with motor/generator set started doing something strange yesterday.

While turning a socket, the machine started to sort of pulse or spin irregularly. I was turning the spindle slowly so I thought maybe something weird due to that. I turned up the speed and still the machine behaved this way although the effect is much worse at lower spindle speeds. It did not seem to matter if I was cutting or not. I would say it pulses (running slower)about once every 1-2 seconds. I can turn down the speed such that the spindle completely stops.

I saw a clip where someone had the contactors in the DC control box come apart (from a power resistor going bad). I took the cover off to see if this was happening but it was not. I have replaced those resistors in the past.

My first suspicion was to go clean up the brushes on the exciter. Am I going down the right rabbit hole?

Thanks for any help.

-Walt

I had a piggyback MG lathe do that and the cure was just wiggiling the brushes on the exciter to make sure they are free. Power off, naturally. You should see some sparking across the width of the brush. If it only has one bright line from one edge of a brush, that is the problem.

Bll

OK, Bill, you got me . . . what's a piggyback MG, and how does mine (1941 model) fit into the grand scheme of things?

jbeech said:

OK, Bill, you got me . . . what's a piggyback MG, and how does mine (1941 model) fit into the grand scheme of things?

Click to expand...

maybe lets start with some pictures of what is under the "hood"?

1941 may have an inline exciter MG vs piggy back, but the issue could be the same with some brushes that need some loving. An intact MG set be it inline or piggy back will all have three sets of brushes....that need servicing.

thermite,
I'm informed mine is a 1942 (serial #EE 15178) and because it's stamped with a US Army Ordinance Corps logo on the bed, worked toward the war effort. Does this change your response regarding whether it'san inline exciter or piggyback? And where do i stick the camera to post a photo?

No, no, thermite, you misunderstand. My 10EE isn't pulsing in synchronicity with MachinistBlue's. My 10EE is perfectly behaved. Instead, I'm merely lurking in hopes of learning something because the OP hasn't replied.

Regarding being informed about the year my 10EE was made; I'd actually been under the impression it was a 1941 but a vague memory led me to poke around within the serial number thread: Monarch Serial Numbers
. . . from when another fellow shared the manufacture date for two of his machines (post #34). This data implied mine was actually made in 1942.

So back to where I'll look, since the TS is presumably the tail stock end, and while you said photos aren't necessary, maybe they'll servo a good purpose for someone else so I took one anyway. This is what I see, and yes, it's got a v-belt, so is this a piggyback setup? Strikes me as such but without anything else for comparison, I leave it to you to help me identify the components I'm seeing.

Sounds useful. How about sharing that list? Also, what have you got presently? A 10EE I presume, but what year, and with stock MG, VFD-conversion, or . . .? Finally, with respect to Cal, I sent a PM recently thanking him for all the valuable help he provides here. Stand up guy is my impression.

Do you confirm mine is a piggyback configuration?

And where do these fall on the spectrum ranging from easy to live with to impossibly difficult?

And when they give trouble, where do they usually?

And when do people bail on them and fit a new motor and VFD?

Yes, that's a piggyback setup. The belt-driven unit on the top is the exciter, which provides power for the relays in the DC control panel as well as the fields of both the generator and the spindle motor.

Motor/generator (MG) 10EEs are almost bullet proof. The thousands of them that are still in service after three quarters of a century is proof of that. The main point of failure seems to be the exciter; square-dial DC panels also have an issue with the big resistors in the upper corner of the panel burning out. The exciter can be easily replaced with a simple rectifier circuit. Brushes are a periodic maintenance issue with any DC machine. Beyond that, normal problems with the wiring, a burned out relay coil, etc., pop up. In general, the problems that an MG machine has are easy and inexpensive to fix, providing you know what you're doing. I've walked lots of guys through troubleshooting and repair.

I think that most people who go the VFD route just don't want to take the time to understand how the MG system works. Instead, they spend a huge amount of time and effort adapting an AC motor to the back gear unit and installing the VFD.

Cal

Cal . . . thank you as always! So far (knock on wood) mine is operating fine. Thus far it's academic curiosity with a helping of better learn sooner rather than later.

thermite . . . thank you, also. Your unique slant is the icing on the cake!

In summary, keep what I have as long as it's working and when it's not, it's repairable. That, and PM is sufficiently mature to have become a font of wisdom. Check!

Which reminds me, I will be 85 in a few days. I have overhauled two inline MG panels and made various coils. Most of them are not difficult- I have wound lots of them on a South Bend lathe and now have a computer controlled coil winder. Cal and I briefly discussed willing it to him, along with the coil specs I have.

The main failures are brushes, coils, and contacts. Brushes are available from Monarch and in a pinch you can grind down larger ones to fit.

I have a Reliance MG and a Modular control panel, which supplies samples of the majority of coils needed.

As to contacts, they can be replaced. The earlier inlines used Struthers-Dunn relays and they used the same style of contacts on a lot of other relays so it may be possible that they are still available.

I need to get all this together and archive it, probably with Cal.

Bill

thermite said:

Hardly ever, "these days".

Not now that PM's Monarch forum has examples and people with helpful expertise to repair any original drive from Sundstrand hydraulic onward.

So long as you still have ANY ONE of the OEM DC motors?

- First and best- usually also least-cost in both time and material, is to repair the OEM drive. Any of them. Be it Sundstrand, MG, WiaD, or Modular drive.

- Next best is to replace an outright MISSING MG, WiaD, or Modular "power system" with a packaged DC drive that can supply not less than the 230 VDC a 10EE motor requires. Any of several 3-Phase-only DC Drives. "At least" The Parker-SSD 514C single-phase.

Annnnd you haven't had to downgrade from DC power to a VFD at all.

MISSING a DC motor? Well.. if you cannot find a used one? Typically $500 or less.
ABB/Baldor/Reliance has NEW 5 HP DC motors starting a bit under twelve thousand dollars.. US. No. I didn't misplace the decimal.

Only then... would that stiff price cause one to consider a repurposed CNC spindle Servo motor and servo control amplifier.

So why do some folk use a VFD instead?

Clear out of better options "back in the day" before the PM / Monarch community had finally "made it easy" to stay with the goodness of OEM DC power.

Or for the same reason a dog licks his anatomy.

He is able to.

No one really cares to interfere.

VFD's work. They just don't work as well as OEM DC. Right out of the starting blocks one has to provide not less than 50% higher HP rating. Double would be closer to a match. And now yah need a bigger VFD. Perhaps bigger yet if it was not rated for single-phase.

Making chips is about TORQUE. TORQUE is about DC.

Then, too, few DIY converters to VFD use the higher-grade 3-P "industrial-grade" goods as Monarch Lathe use for rebuilds, either.

The "good stuff" Monarch uses is not cheap. Just cheaper than $12,000 DC motors!

Click to expand...

I put a pair of Scissio's solid state thyratron replacements in a Modular 10EE. They work very well, but their uniform firing highlights the problem with AC. It will run at a slow spindle speed, holding a constant speed, but it is a series of jerks, 120 per second. A three phase VFD will do better, but the AC is still in there.

The 3 hp spindle motor in the piggyback MGs looks like a huge clunk, but it is as smooth as a servo motor. The designer used every trick in the book, three windings per slot, opposite brushes offset slightly so both do not switch bars at the same moment, etc.

Bill

Bill . . . thank you also, sir. Going to turn 85 soon, eh? According to my father, that's still pretty young (I recently turned 62 and he's 89). Anyway, your plan to include Cal in your plans seems sound to a nobody like me. especially in light of how much he helps folks, I can't think of anyone better, in fact.

Also, thanks for taking time to make the observations regarding these machines. I count myself fortunate to be late to the game as it's allowed a lot of knowledge to accumulate and be tallied in this forum.

I'm still not clear about the details of function regarding my machine. The motor beneath the tailstock with the piggyback exciter is an AC motor, yes? And the exciter powers the fields of the DC motor beneath the headstock, which has a gear box. And the electronics, such as they are, are for effecting variable speed of the DC motor via a humongous rheostat like thing (electrons aren't my strong suite so please forgive my ignorance). Also, the AC motor beneath the tailstock is connected to the DC motor in the headstock via a shaft, right? I'll have to pull my machine out to confirm this but this is what's in my memory banks. Anyway, while everything is operating nicely is, I believe, the time to confirm a few things like the condition of the brushes. Again, thank you!

jbeech said:

Bill . . . thank you also, sir. Going to turn 85 soon, eh? According to my father, that's still pretty young (I recently turned 62 and he's 89). Anyway, your plan to include Cal in your plans seems sound to a nobody like me. especially in light of how much he helps folks, I can't think of anyone better, in fact.

Also, thanks for taking time to make the observations regarding these machines. I count myself fortunate to be late to the game as it's allowed a lot of knowledge to accumulate and be tallied in this forum.

I'm still not clear about the details of function regarding my machine. The motor beneath the tailstock with the piggyback exciter is an AC motor, yes? And the exciter powers the fields of the DC motor beneath the headstock, which has a gear box. And the electronics, such as they are, are for effecting variable speed of the DC motor via a humongous rheostat like thing (electrons aren't my strong suite so please forgive my ignorance). Also, the AC motor beneath the tailstock is connected to the DC motor in the headstock via a shaft, right? I'll have to pull my machine out to confirm this but this is what's in my memory banks. Anyway, while everything is operating nicely is, I believe, the time to confirm a few things like the condition of the brushes. Again, thank you!

Click to expand...

There is one more DC generator. The AC motor drives a DC generator at a constant speed. The piggyback generator supplies 100 VDC to operate relays and things plus supplying DC to the spindle motor field. The DC generator is controlled by the large rheostat, which you will note is two sections. One section controls the DC up to circa 250 volts, then for the rest of the rheostat's rotation holds it at that while the second segment reduces the spindle motor's field current. Somewhat against first impressions, reducing the field makes the motor run faster.

Bill

jbeech said:

Bill . . . thank you also, sir. Going to turn 85 soon, eh? According to my father, that's still pretty young (I recently turned 62 and he's 89). Anyway, your plan to include Cal in your plans seems sound to a nobody like me. especially in light of how much he helps folks, I can't think of anyone better, in fact.

Also, thanks for taking time to make the observations regarding these machines. I count myself fortunate to be late to the game as it's allowed a lot of knowledge to accumulate and be tallied in this forum.

I'm still not clear about the details of function regarding my machine. The motor beneath the tailstock with the piggyback exciter is an AC motor, yes? And the exciter powers the fields of the DC motor beneath the headstock, which has a gear box. And the electronics, such as they are, are for effecting variable speed of the DC motor via a humongous rheostat like thing (electrons aren't my strong suite so please forgive my ignorance). Also, the AC motor beneath the tailstock is connected to the DC motor in the headstock via a shaft, right? I'll have to pull my machine out to confirm this but this is what's in my memory banks. Anyway, while everything is operating nicely is, I believe, the time to confirm a few things like the condition of the brushes. Again, thank you!

Click to expand...

.
NOPE no shaft from the AC motor to the DC motor for the spindle.

jbeech said:

Cal . . . thank you as always! So far (knock on wood) mine is operating fine. Thus far it's academic curiosity with a helping of better learn sooner rather than later.

...

In summary, keep what I have as long as it's working and when it's not, it's repairable. That, and PM is sufficiently mature to have become a font of wisdom. Check!

Click to expand...

Actually, I think that the motor/generator (MG) drive is more robust than the machine itself. The MG drive is built in such a why that it can be repaired forever (assuming that parts like motor bearings are available). But the lathe itself wears every time it's used and you can only regrind the ways so many times. Rivett's version of the 10EE, the 1020S, has replaceable tool-steel ways, so in theory it could be rebuilt to new condition over and over again.

jbeech said:

...
I'm still not clear about the details of function regarding my machine. The motor beneath the tailstock with the piggyback exciter is an AC motor, yes? And the exciter powers the fields of the DC motor beneath the headstock, which has a gear box. And the electronics, such as they are, are for effecting variable speed of the DC motor via a humongous rheostat like thing (electrons aren't my strong suite so please forgive my ignorance). Also, the AC motor beneath the tailstock is connected to the DC motor in the headstock via a shaft, right? ...

Click to expand...

Here's my explanation of how the motor/generator drive and all it pieces work:

And a slightly more technical version:

Cal

I pulled out the brushes on the exciter to have a look. During my adventures cleaning up my machine, I did pull those brushes out and sort of clean up the armature and such but I figured maybe I did something wrong. It looks like I decided to clean up the contact surfaces using sandpaper on a flat surface. I pulled everything apart again and did the finish work on a cylinder...hopefully getting a better match between the armature shape and the brushes. the problem was still there.

I took a look at the tail end of the machine when the weird pulsing things was going on. I noticed a lot more weirdness happening at the generator brushes then at the exciter so I decided to apply the same method. Pulled the brushes out and did a general cleaning on the armature and guides for the brushes. That seemed to do the trick. The spindle runs smoothly now and I am able to go down to a very slow speed with no problems.

Thanks for the help figuring this out. Besides this issue, the machine has been working pretty well. I need to align the tail-stock to the spindle...I keep getting weird results when drilling on the end. I think I can only adjust the angle of the tail-stock and not the location. Does anyone know if that is true?

I am in the process of accumulating cutters and such. I came across a video where a guy uses broken drill bits to make small boring bars. He sticks a Dremel tool in the tool post and grinds the cutter in the spindle (held fixed). is this worth the effort? Seems like a big mess. YouTube

Re; Mr. Haines' response in post #24 above . . . the link is gold. The specific post referenced is #53, which within itself contains a link to a yet more detailed explanation. Thank you. I can honestly be gone and not bothering the forum for quite a while merely digesting this information. Folks, don't laugh, I'm serious when I say it'll require several read-throughs for this non-electron oriented fellow to 'maybe' get it. Anyway, thanks again, sir!

Walt . . . if I may serve to interpret what i believe thermite is saying, yes, what the YouTube video guys says works in a pinch, but you're probably better off buying a boring bar!

thermite . . . thanks as always, I raise a malty beverage to you, sir.

My takeaways; Walt has had an experience (spindle motor pulsing at low RPMs) that's worth sharing. Moreover, because he came back and reported a resolution (cleaning armature and facing the brushes) he's given a leg up to the next guy (maybe even me some day). Well done! As an aside, I see your experiences coming up over and over again and am learning vicariously through your experiences. is your machine now considered 'done done?

Summary; my overall takeaway is when (if) my MG setup goes south, the smart money is on taking time to repair the fault versus the yank and replace method (VFD) because in a non-24x6 wartime environment, this is a 'lasts forever' kind of system/machine (especially considering I'm 62, prone to pneumonia and odds are COVID-19 gets a shot at me). Meanwhile, I'm knocking on wood my machine continues functioning and taking due precautions vice my health. Cheers everybody!

I am glad to hear the thread for restoring my 10EE has been useful to others. I used a similar technique (an ongoing post) at a thisoldhouse.com discussion forum for a kitchen rebuild project with similar results. I used that method of documentation to keep my own thoughts straight but it seems others can use the embedded information to learn. I am happy that the threads have provided a unforeseen benefit.

I am a hobbyist machinist so all my comments should be viewed through that lens. I enjoy shaping metal but, quite honestly, the household benefits more from my interest in woodworking/cabinet making. I bought an old 10EE mostly because I thought I could recover my investments (or maybe not lose my shirt) if I HAD to. Turns out, I sort of fell in love with the machine in that the attention to the mechanical design is something special. The folks at PM convinced me to keep the machine close to the original so I followed that advice. No VFD and for the most part I kept things as originally intended. I did strip back the bad paint jobs and cleaned up the outer surfaces with new paint. Some argue I should have stopped at the original paint but I like shiny things.

Going through my restoration you can see there is a point where I had to decide where "enough is enough" I did not tear apart the head nor did I have the ways reground. I admire those who have the guts to go that far. This was my first deep dive on restoring a machine tool so I had to keep it within my needs and skill set. I do not need to hold .000005" roundness and if that performance were free I would take it. To get my machine to that level it would have required too much money and time for me to accept. I seem to get +/-.002" level of performance (without a DRO) and really that suits me fine.

I have been restoring a BP mill with a CNC controller and that too has taken time and money to get to a useful state. Right now both machines work well enough for my needs as a low skill level machinist. I like staying connected to the side of life that makes chips as most of my work life is in front of a computer. In general, machinists are incredibly smart people and I try to learn from them whenever I can. Machine tool builders/restorers are next level smart and are just a plethora of information...if you can get them to reveal their secrets :0)

-Walt

Which CNC equipped BP do you have? I wonder because I've got a Series II, which began life with paper tape NC and has been converted to CNC (not by me, that way when purchased). mine has a black box (motion control unit) by a company no longer in business. Works well enough and reasonably easy to convert to Mach or LinuxCNC (my preference being the former but in the end will more likely be the latter since I prefer a robust servo solution).