Exciter motor brush springs

I am looking for a supplier for exciter motor brush springs on my 1954 10ee. Please let me know if you know where to purchase them. Thanks!

Axel said:

I am looking for a supplier for exciter motor brush springs on my 1954 10ee. Please let me know if you know where to purchase them. Thanks!

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Oy! Dunno if we've even seen this need before. Modern coils abound. These are "tamper" style, are they not? My "loose" MG is sort of buried right now as far as going to take a look.

Do you have at least one in good enough shape to use as a guide for making your own?

Anybody here already set up to do so? 9100, maybe?

UPDATE: Helwig Carbon, maker (as far as I know) of the brushes Monarch presently sells, also does constant-force springs:

Constant Force Spring Assemblies - Helwig Carbon

But only claim to do 35 'types', though they can refurbish old spring (assemblies) as well as make new ones, from scratch.

Monarch is the most likely entity to have such as a source or even in-stock. Ex; Their brushes, best I can determine, are not listed directly by Helwig. Monarch may have an older specification in Helwig's files for holders and springs, as they do for brushes.

Might be best to start with an email or phone call to Monarch:

Contact Us | Monarch Lathes

Monarchist, Thank you for the reply. I have already contacted Monarch and they said the part is unavailable but there is a retrofit they offer. I asked for additional information on that and have not yet recieved a reply.

I also contacted a local Reliance dealer and they are currently looking for the part. I originally called it a spring but have since seen it referred to as a rocker. I have seen others like mine for sale online but I figured I look for an oem replacement first.

The rocker somehow fell off my brush and was rubbing on the commutator and galled it up a bit. I think it's going to be ok though.

On a side note, do you think a guy could make brushes out of graphite for edm electrodes? I will keep you updated with what I find.

Axel said:

On a side note, do you think a guy could make brushes out of graphite for edm electrodes? I will keep you updated with what I find.

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No, not effectively. Wrong material entirely.

Motor brushes are not "just" Carbon, they are a mixture that includes various metals and other modifiers, more binder choices than just one. Their electrical, thermal, physical, and lubrication characteristics are tailored into classes used for different applications. Note, for example, Helwig's chart even on different spring characteristics.

You should take Monarch's retrofit, as it will have been tested and proven by experts - probably Reliance and/or Helwig working together, then advising Monarch.

Holders and springs CAN last over 70 years if nothing untoward borks them. You probably won't need to deal with these twice.

Brush life is typically 2,000 power-on-hours. For a retiree/hobbyist, and even most small shops that do not use their 10EE all that often, the 40-hour week times one year that 2,000 approximates can easily translate to TEN years - sometimes more. IOW - brushes don't really cost much at all, amortized.

Worth it to buy more than one set, save a bit on shipping, have spares in your own place.

Same again with new bearings. Though less need of spares, motor & generator bearings are among the least-costly one can buy.

Not, so, the spindle bearings, though!

The Motor company I am in contact with is still awaiting reply from Baldor so I may still have a chance at getting the rocker. I got more information on the retrofit. It's a box that you mount on the machine that completely replaces the the exciter motor. Problem is its a thousand dollars. I read a post on here about somebody replacing the exciter with a home built transformer. I don't know much about this subject but I'm learning as I go. Seems like there should be a cheaper solution.

Axel said:

The Motor company I am in contact with is still awaiting reply from Baldor so I may still have a chance at getting the rocker. I got more information on the retrofit. It's a box that you mount on the machine that completely replaces the the exciter motor. Problem is its a thousand dollars. I read a post on here about somebody replacing the exciter with a home built transformer. I don't know much about this subject but I'm learning as I go. Seems like there should be a cheaper solution.

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Sure as Hell IS a cheaper solution! Several of them!

I thought you were after doing what I call a "Museum Grade" restoration - where everything is preserved as originally shipped.

Even were I NOT replacing the MG entirely, I'd use a small solid-state DC Drive intended for small medium motor Armature (and Field) supply. Specifically the Eurotherm/Parker-SSD 507, The 506 and 508 will do also, as will nearly any other small DC Drive. About $25 to $80, used. KB-Penta's less sophisticated DC Drives are OK as well, and cheap enough brand-new with warranty that used ones are not worth ten minutes of risk.

This - off 240 VAC input - 180 VDC or LESS at the output, adjustable to a maximum limit, assures having the full 115 VDC, with a decent waveform and other adjustable features, including limit presets, alarms, and ease of safe, low-power control.

Overkill, technologically, but all the work is already done but for setting a switch and a few trimpots. Needs no transformer, and gives one back the time to go fix things not so easily bought already packaged.

At the BFBI but cheaper end, a basic isolation transformer, salvaged free or bought cheap, plus a full-wave-bridge at $3 to $6 can work, too.

If one goes THAT route, it may be better to use TWO of them. One for powering the variable field supply, the other to power the contactors and relays at a fixed 90-115 VDC.

That way, the actuator coils are assured of more stable power, as their source is is divorced from side effects of changing the field Voltage and Current for the variable need.

I don't keep the MG or the DC control panel, but others have done.

Cal Haines and Peter - over in London - also worked through one a while back where the MG and exciter were BOTH shed, but the DC panel with contactors was retained and made to work with a solid-state DC drive.

Variacs plus basic rectifiers have also been utilized. Lots of options, IOW.

There is a minor downside, though.

Such "compensation" - RPM regulation for varying load - as existed in the MG-era 10EE, was significantly dependent on the exciter DC generator's intentionally non-linear characteristics. It was more than ONLY a DC source - it had a dynamic role to play in the larger picture.

The final-drive motor had no compensation above the inherent stability of a straight shunt wound DC motor. The exciter for it - "piggyback" especially - DID have compensation built-in.

Once into the Feld Weakened RPM band - most of what a 10EE owns - that matters.

If 4Q Solid State drive has replaced the MG outright, regulation is their job, and built in. If not, one may MISS the compensation of that exciter, even if not by very much.

The piggyback exciter MG remains the smoothest of all 10EE at least until 3-Phase-only "Monarch Sidney" and competing 3-Phase Solid-State DC Drives entered. All single-phase-input DC drives have an uphill climb to be smooth, even with a ripple filter.

That isn't obvious until one long-lines the MG outdoors or the other side of a sound-deadening wall, then notices how quiet and turbine-smooth the MG-fed final drive motor really is - even under load - with all the distracting noise of the MG out of the immediate zone.

Restoral of an MG to original still has merit. Lots of merit.

And they can be serious rugged and enduring bastards once given that renewal of life. Proved that a long time ago. Haven't quit yet.

Your 10EE, your call.

Free for the shipping cost an entire 1942 MG & exciter set yours if you want it. Needs cleaned up, but was in working order when retired.

Intact ONLY, however. I am not for stripping it for components, nor even separating the exciter. I like to see that those who wish to do so be able to preserve the MG system, entire.

My own 'call' was Eurotherm/Parker SSD, after all - so I'm weary of tripping over the MG as well as apologetic for my sins. Weelll s**t-eating GRIN "apologetic". I DO have ripple filtering, and lots of it!

3 HP version of the 5 HP one here. Different boost transformer, but same electronics and even near-as-dammit same setup settings, otherwise. They were in the damned Eurotherm MANUAL the whole time:

http://www.practicalmachinist.com/v...-10ee-modular-332092-post2932496/#post2932496

Axel said:

... I got more information on the retrofit. It's a box that you mount on the machine that completely replaces the the exciter motor. Problem is its a thousand dollars. I read a post on here about somebody replacing the exciter with a home built transformer. I don't know much about this subject but I'm learning as I go. Seems like there should be a cheaper solution.

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There are lots of motor/generator 10EEs using a simple bridge rectifier circuit to provide DC for the system. One way to do it is to bring in 5-wire service to the machine: the three "hot" phases (one of which will be the artificial phase, if using a rotary phase converter), the grounded "neutral" (or white wire) and the green safety ground. By going from one of the real hot leads to the neutral, you have 120 VAC to feed into the rectifier, which produces about 90 VDC, which is good enough for most users. It's best to install a GFCI in front of the rectifier, in case the rectifier shorts out, and you definitely want the machine and the GFCI well grounded. This also gives you a 120 AC outlet at the machine for a work light or what have you. I addition to the rectifier, you need some slow-blow fuses and an MOV to protect the rectifier from switching transients.

Let me know if you need more information on that.

Cal

Thanks guys. Give me some time to digest all the great information you have provided me.

Cal Haines said:

have 120 VAC to feed into the rectifier, which produces about 90 VDC, which is good enough for most users.

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Specifics - one loses, but not by much:

- 90 VDC is OK for the contactors.

- 90 VDC drops torque at base RPM and below.

A strong field is the torque contributor. 115 VDC, not 90 VDC (over 20% down, if it is even close to "linear" and it may not be linear.)

20 % torque hit, somewhat lower RPM stability under load when in Field-Weakened range is "Good enough for most users", yes. Fully-functional piggyback exciter still wins if one can restore that.

Pushing the limits a tad, OTOH:

I run a 140 VDC field, full-up. Harmless to the motor as an SSD is easily switched OFF when idle.

Low-end performance improves, including extended minimum useful RPM. VERY MUCH extended, but the IR regulation of the 4Q SSD on the Armature is a player there as well.

In combination, the SSD's also bump that 690 RPM base upwards and improve HP and torque when in the field-weakened range (Armature is at 265-275 VDC rather than 230 VDC).

Current-mode Field Regulation and its interdependent feedback scheme still "to do". The "legacy" pre-packaged solution in our size-range from Eurotherm-SSD is long out of production and half the size of a microwave oven as well. Larger current model drives it is but an option card, ELSE built-in as standard.

BFBI works for now.

2CW

Your 10EE, your goals, your choice of method. "I got mine"

Axel said:

Thanks guys. Give me some time to digest all the great information you have provided me.

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BTW . IF (and I do not know..) that $1,000 box, is a genuine "Field Regulator", and not just a raw Power Supply or basic regulated and filtered Power Supply?

That is a fair price. They are righteous critters, can improve the stability when in Field Weakened mode, and very much so. The "tell' is what it does with/to the twinned control Rheostats.

Connections to a Field Regulator appear to work bass-ackwards until groked.

Control input goes to the FIELD. The Regulator's own resources then command the Armature supply as is needed to balance its control feedback input from BOTH Armature and Field as RPM requested is sought, then held as load varies.

Put another way - a Field Regulator will have more than just two wires for AC in, and two wires for DC out.

2CW

Monarchist,
I tried to pm you but your inbox is full

Axel said:

Monarchist,
I tried to pm you but your inbox is full

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I try to keep it that way.

[email protected]

1-703-473-7011

I kinda figured you were going to say that.

Axel said:

I kinda figured you were going to say that.

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Not about slings and arrows. I don't get "private" bitch-slaps hardly ever. Public, rather.



You'd have to guess how clumsy it is keeping a PM-PM box clear when even buying a bit of tooling may use-up several messages each way, and both ways count against a tiny ration.
I'd keep losing shipping addresses and PayPal info when trimming it.

SMTP Email? Around a dozen GigaBytes in more than one IMAP server, 25+ years.
Space is not a problem. I can find an address many years later, too.

And.. I do answer the phone, BTW. Any hour of any day, or near-as-dammit.

Well here's the status of my lathe as of today. I never recieved any information from that Baldor rep that I spoke with. I contacted Helwig and they wouldn't help with the spring but would make new brush holders.

I spent some time the other night with my damaged spring. Not realizing before how soft that spring material actually was I rebent it and pulled some extra length out of it. I put it back together quickly and tried it. It functioned fine for the few minutes I played with it.

The next day I pulled the brushes out, cleaned up the commutator and dressed the brushes. Tried it again and it was back to the way it was when I started having issues. Surging spindle with the contactor going on and off. I checked the electrical, read a little, and found that my resistors in the dc panel are shot.

I am very interested in the DC drives Monarchist has fitted into the machines. Definitely something I will be looking at when the time comes.

Could you guys explain a little more on how the motor generator compensates rpm with varying load and also what role the ripple filter plays in the proper function of the lathe when using the Ssd.

Axel said:

I spent some time the other night with my damaged spring. Not realizing before how soft that spring material actually was I rebent it and pulled some extra length out of it. I put it back together quickly and tried it. It functioned fine for the few minutes I played with it.

Click to expand...

It isn't actually hard to make springs. The materials are available. Same again with brush-holders. More about metal-bending than "machining", but still.. one can "fixture" an ignorant vise with dowel-pins to do the do.

Could you guys explain a little more on how the motor generator compensates rpm with varying load

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The "large frame" 3 HP final-drive motors used in MG era 10EE are four-wire, straight shunt. The four wires being Armature A1,A2, Field F1,F2.

There is "inherent" compensation, of sorts, in the motor itself. Shunt-wound motors are stable critters.

More dynamic compensation depends on the "exciter", a DC generator "tuned" to match the needs of the final-drive motor. Shedding that for an ignorant rectifier exacts a penalty.

As to the ripple filter:

With single-phase input direct-off-the-line thyristor DC drives one has technically but two pulses per cycle. When fixed to line @ 60 Hz, that's 120 to the second, and the drive cannot change that.

At - for example - 50% load, only half of each pulse is switched ON. The other half of the time-window has NO power. If/as/when the motor itself is the only inductor in-circuit, it must "integrate" that energy. Classical Integral Calculus equation applies, and a NOISY one. The big ripple filter inductor, AKA "choke" helps smooth those peaks and gaps.

Three-phase input, or "six pulse" DC Drives have a lesser challenge.

The better drives, single OR three phase, also simulate more pulses by playing games with firing angle phasing of a more complex array of pass elements. Eight pulses rather than two for 1-P, 24 pulses rather than six for 3-P.

The classical "quiet elevator" publication also uses capacitors WITH the choke. I have those. Testing didn't give me "enough" extra gain to add them. Capacitors have shorter lives than inductors do, so I'd have almost as "fragile" a situation as a VFD.

BTW: Read the manuals for the better-documented VFD. New caps are recommended at typically the 7 to 9 year mark. Few get those.

Most VFD are simply replaced, outright, rather than given new caps.

Solid-State SCR-class DC Drives don't have a capacitor bank, ergo they generally last longer than VFD do.

And, of course, they need no "de-rating". They are built for ONE OF single-phase or 3-Phase. ONLY.

Today I installed my new resistors and the start stop issue has so far been solved.

I have now surprisingly discovered another problem.

I was running the machine testing the new resistors and could see the drive motor brushes sparking more than normal, plus I could smell it too. When I run the drive motor the brush holder ring will actually rotate slowly with the commutator which I have learned will make the timing become off plus cause all the added sparking. It looks like the pinch bolt gap to hold it in place has 2 washers in it and I'll have to remove one to get more squeeze out of it. As for the brush timing, I read can be tuned in by energizing the field coil with 120 volts ac. Once energized, you rotate the ring until you achieve the lowest possible voltage reading taken at the brushes.

I have gotten this far with it but certainly do not want to mess anything up. Can anyone advise me in greater detail to how this tuning is performed. Like what wires I should be tapping into and how are the electrical readings made at the brushes. I have not found anything that specific on it but I will keep looking in the meantime.

Thank you again
Axel

Axel said:

Today I installed my new resistors and the start stop issue has so far been solved.

I have now surprisingly discovered another problem.

I was running the machine testing the new resistors and could see the drive motor brushes sparking more than normal, plus I could smell it too. When I run the drive motor the brush holder ring will actually rotate slowly with the commutator which I have learned will make the timing become off plus cause all the added sparking. It looks like the pinch bolt gap to hold it in place has 2 washers in it and I'll have to remove one to get more squeeze out of it. As for the brush timing, I read can be tuned in by energizing the field coil with 120 volts ac. Once energized, you rotate the ring until you achieve the lowest possible voltage reading taken at the brushes.

I have gotten this far with it but certainly do not want to mess anything up. Can anyone advise me in greater detail to how this tuning is performed. Like what wires I should be tapping into and how are the electrical readings made at the brushes. I have not found anything that specific on it but I will keep looking in the meantime.

Thank you again
Axel

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Brush timing has been covered on PM. IIRC, the least-risk of injury suggestion used a "doorbell" transformer at 24 VAC or so.

I time mine under DC power using insulated tools, Mark One Eyeball to monitor for minimal spark, and a Biddle mechanical tachometer to confirm RPM and bias, forward direction.

FWIW - UNLOADED RPM, both directions, will be higher than the nameplate, which is spec'ed at nameplate full normal load.

I'll not publish my RPM, as it is taken with boosted field of 140 VDC, rather than the specified 115 VDC. That is useful. Very. But not common.

I was able to get my brushes positioned tonight. I did not do the above mentioned yet but I found an article which showed me the physical orientation of the brush in relation to the commutator poles at the neutral position. I figured I could eyeball the brush position to the center of the pole nearest to the brush I could see easiest. It seems like I hit it right on. There is no visible sparking on the brushes and rpm sounds close to synced in forward and reverse. The article also gave instruction on the already mentioned field exciting procedure. Here is a link to that.

https://www.google.com/url?sa=t&sou...ghxMA4&usg=AFQjCNFafX2HGcPknOBvB8KDMtrtlPgxtQ

Monarchist,

What is your rpm differential from forward to reverse with the directional bias dialed in? Also I'm curious, whats the max spindle speed you have spun your tricked out machine up to? I have to admit I'm a little frightened standing at my machine with it wound up. All that potential just waiting to unload makes the mind wander into a "what if" type of place.