Oliver 25 Wood Lathe DC motor rewind help and advice please
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  1. #1
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    Default Oliver 25 Wood Lathe DC motor rewind help and advice please

    I recently purchased an Oliver No. 25 pattern makers lathe with the original direct drive DC 2hp Motor. The lathe was manufactured in 1914. The motor is integral to the machine so can't be replaced with a modern motor. I included some photos. It has a modern variable speed motor control. The motor is rated from 400-2000 rpm.
    It runs but as the speed is increased,the brushes arch severely at the commutator, it also does not have the power it should have. I currently have it at a motor shop which was recommended to me. They have checked everything, grounds etc. They checked the drive and ran the lathe direct from line DC. They turned the commutator and seated the brushes this didn't help, nothing has helped. They partially unwrapped one of the interpoles and a field coil and the wire insulation is breaking down and can be scrapped of with a fingernail, so their next step would be to rewind the two fields and the four interpoles. The shop wants $1500 to rewind the six coils, plus $500 for the comm turning, testing and reassembly, "about" $2000 total. If this does not work, they would send the armature out to be rewound. The shop they would send it to is reluctant to even do it because they claim if it needs a new commutator, it alone would have be custom made by a shop in Europe costing at least 2k, then the armature rewinding.... I am already in deep, including lugging this 3000# 12' lathe to the very back of my shop. Help!

    Any thoughts regarding the estimates (seems high?) or any suggestions(except for scraping)would be much appreciated. Thanks in advance!

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    Thats not out of line, dc motor rebuilds are a significant labor undertaking, its one of the reasons there less and less common, a std induction motor is a far far simpler beast. Whats more your going ever further towards the slippery slope, anything short of a full rebuild on a motor that age becomes ever more a when not if failure wise.

    if you can accept loss of originality, making up a complete new head-stock and belt driving it would be a lot less outlay, for a new good 2hp electric motor and drive you could have change from $500 another $1500 would easily cover building a new wood lathe spindle and head-stock, that would get you back to turning wood, other options to learn how to rewind the motors coils your self, its not hard, its all to be found online, but you will have weeks into it time wise.

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    That comm appears to be the problem, they wanted to source a new one from Europe
    .
    Kirkwood Commutator didn't have anything ?

    The labor to remove and install a new comm is not easy/short.

    If your not into keeping it antique, I would go at the motor with a torch/air arc
    and gut it, keeping the end bells/bearings, hole in the bottom for a belt.

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    That wheel at the end of the motor. Could not that be removed and a pulley put in its place to be driven by another motor? I have an Oliver 20 inch jointer, where the motor is part of the machine. I think Oliver is known for doing that.

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    Quote Originally Posted by ejfm View Post
    I recently purchased an Oliver No. 25 pattern makers lathe with the original direct drive DC 2hp Motor. The lathe was manufactured in 1914. The motor is integral to the machine so can't be replaced with a modern motor. I included some photos. It has a modern variable speed motor control. The motor is rated from 400-2000 rpm.
    It runs but as the speed is increased,the brushes arch severely at the commutator, it also does not have the power it should have. I currently have it at a motor shop which was recommended to me. They have checked everything, grounds etc. They checked the drive and ran the lathe direct from line DC. They turned the commutator and seated the brushes this didn't help, nothing has helped. They partially unwrapped one of the interpoles and a field coil and the wire insulation is breaking down and can be scrapped of with a fingernail, so their next step would be to rewind the two fields and the four interpoles. The shop wants $1500 to rewind the six coils, plus $500 for the comm turning, testing and reassembly, "about" $2000 total. If this does not work, they would send the armature out to be rewound. The shop they would send it to is reluctant to even do it because they claim if it needs a new commutator, it alone would have be custom made by a shop in Europe costing at least 2k, then the armature rewinding.... I am already in deep, including lugging this 3000# 12' lathe to the very back of my shop. Help!

    Any thoughts regarding the estimates (seems high?) or any suggestions(except for scraping)would be much appreciated. Thanks in advance!

    img_4718.jpg
    img_4817.jpg
    img_4818.jpg
    img_4819.jpg
    The presence of interpoles, the RPM range, etc. hint that the windings have the sort of mesh interleave as Reliance was to call a "Type T". Built for smooth low RPM under load and a wide RPM band at the expense of reduced conversion efficiency.

    See elevator and hoist motors, and the 3 HP "Large Frame" Reliance of the 10EE's MG-era, a 670 RPM => 2400 RPM motor.

    IOW - your rewind estimate is likely to prove LOW, ELSE you are being given it at cost out of the interest in just. .. being able to say they could still DO it.

    "The good news is".. SCR-Drive optimized DC motors of Type T (Reliance RPM III, AKA "Rectified Power Motor" ) are physically smaller, and you could "hide" one in that housing. A pre-RPM-series "small frame " Reliance might fit as well.

    The bad news is .. that the uber-low RPM, massive torque units went serious rare after the "large frame" era. The newer ones have base RPM's around 1100 to 1700 or so and cannot directly match the performance curve of the OEM one you have. The torque just isn't THERE at low RPM - there is a fixed mathematical relationship back of that torque/RPM/HP trade-off.

    No easy answers there.

    Might be some food for further research and/or "scouting" for other applications that used a more compatible motor as might provide a closer matching donor.

    Reliance motors of the 1930's onward have had an astonishingly good average longevity, BUT.. more modern insulation had been developed and applied well AFTER your one was built. General Electric's own well-funded research labs developed "Glyptal" out of necessity just to name one.

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    I have the AC version of that lathe, with an equally massive 4 speed motor. The direct drive machines are very quiet and smooth, but when those complicated motors go south, very expensive to fix.

    I've seen 25's with the motor gutted as digger doug suggests. Get rid of all the windings and get some sort of multi sheave pulley on the spindle and drive it with another motor.

    You might want to post on the Old Wood Working Machine site, you'll find folks with the same machine and maybe the same problem,
    Old Woodworking Machines - Old Woodworking Machines

    You can also conbtact Eagle Machinery, they repair and rebuild Oliver machines, and can supply parts.
    Eagle Machinery

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    Thinking a bit more, you could gut the motor (and save the spindle) with no torch work.

    Take the end bells off, remove all the stator poles (they just bolt on)
    The armature, to keep the shaft intact, press off the punchings (with the windings).

    Many times the shaft has a step in it, the punchings are pressed up to it as a hard stop.
    The comm is pressed up against the other side of the stop.

    Put the armature in a lathe and using a parting tool, cut the windings between
    the punchings, and the comm piece risers.

    Now the comm is separate from the windings.

    Some times, when you press off the comm, it will fall all apart, the copper bars
    and mica sheets between them are held together using the end cones.

    Some times the comm is retained by a large nut on the shaft, remove it.

    As far as the frame (now a gutted tube) put in the mill and mill a oval
    thru the bottom for the belt.

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    Thank you all for your thoughts and advice regarding this motor. It is good to know that the field rewinding quote seems inline and even perhaps low. Now that I know about Kirkwood Commutator I can quiz the shop regarding this.

    I had thought about gutting the motor and cutting out the bottom of the housing for the belt to allow mounting of a modern motor below the bed and installing a step pulley on the shaft of the armature but even this seemed quite involved... I had not thought about simply adding a pulley on the outboard side of the head stock. This way I could leave the original motor intact. This will be last resort.. still need to decide whether to gamble the $1500 on rewinding the coils.

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    Quote Originally Posted by digger doug View Post
    As far as the frame (now a gutted tube) put in the mill and mill a oval
    thru the bottom for the belt.
    One could Do this with a simple single-speed belted ratio. I'd use a fairly WIDE PolyVee belt. About triple the "rib count" the HP ask. That's for not slipping under the gobs of low RPM torque.

    And you "get there" by planning the remoting of the new motor such that you can utilize a HIGHER than 2 HP DC motor that still IS a "Type T".

    A 3 HP to 5 HP that has twice or thereabout the "base" RPM also has double the Do Not Exceed RPM. Up around 4500 - even 5,000 RPM.

    At somewhere between a 2:1 and 3:1 step-down ratio, the torque and RPM, net-net, are back where they were, and easily as smooth.

    The newer motor comes out of the box with "SCR Duty" insulation.

    An SCR-class DC drive will not eat the insulation alive as it can do (and seems to HAVE DONE) on the older "rotating power" design motors.

    If also Reliance "RPM" class, the optimized lamination shape and arrangement come with the package as well. Gild that particular lily by adding a ripple filter inductor and the low-end of the RPM band is extended and made smoother-yet. It also gets QUIET again as the SCR growl at partial power is integrated before it hits the motor windings.

    Needless to say, the big fat ripple-filters inductors AKA "choke" also kills-off the last of the switching artifacts VERY effectively, also extending motor life.

    Very close to "rotating power" DC source for smooth, but with far better load regulation than BFBI Iron and Copper ever had.

    It might want some surgery to camouflage such an alteration, cosmetically, but the original goodness would be preserved, operationally.

    How-to?

    Seek a 180 VDC wound Reliance RPM III motor. The medium-priced KB-Penta 4Q regenerative drives already poop-proofed in handy mount-anywhere NEMA 4X "washdown" rated enclosures will be good enough.

    Higher Volage DC motors want 3-Phase power and 3-Phase-only DC Drives, else a boosted drive Isolation transformer or array-of, and one of the few single-phase drives that can deal with around 300 VAC to 500 VDC input to output 230 VDC to the motor.

    Parker SSD 514C series. 4Q, but no enclosure nor on-box controls as the KB arrive with.

    Better to select the lower-voltage motors to begin with, even though they are larger and heavier for any given HP than the higher-Voltage ones.

    I didn't buy-up ALL of them in the NOS /recent rebuild market. Only about 8 or 9, actually, so there are some still "out there". ERC up in Ohio is where about five of mine came from. They may still have some.

    2CW

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    I hae rewound DC motors. Stators are easy, armatures are not. Rewinding armatures is like getting a Phd in basket weaving. Two armatures needed replacement commutators A local repair shop had one in stock and got me a second one.
    The motor shop was surprised when I came back with four stators and four armatures. They were even more surprised when they tested them and they worked. The shop varnished them and offered me a job there!
    Stearns,Perry and Smith in Quincy, MA may be able to help you. They are an old line, very old line shop.

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    Quote Originally Posted by Rollerman View Post
    Stearns,Perry and Smith in Quincy, MA may be able to help you. They are an old line, very old line shop.
    "Old line" is exactly what's needed.

    Time was, these complex windings were not as uncommon, lifts, hoists, derricks, and anything else as needed a "mode" or range where it was able to "creep" slow and silky-smooth while doing that was a candidate. More of those got overloaded and NEEDED redone than machine-tools usually saw the need of.

    Even if what they have includes no recent tasking, only old files, a competent younger practitioner can grasp what is different and work to it. Just not fast nor cheaply.

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