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Need Wiring Help - Enco Mill 100-1525

Discussion in 'ELECTRICAL ISSUES - POWER YOUR MACHINES & SHOP' started by GT Mills, Nov 7, 2016.

  1. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    I just bought an Enco 100-1525 knee mill (c1991) for $1800 plus $250 delivery. It is in great shape. It came with Phoenix Rotary phase converter. I smoked the motor this evening. Please help if you can.

    First off, the switch was no good and I rebuilt it without too much trouble. I got the mill running. I drilled some hold down holes in a 1-1/2" aluminum plate to start milling it today, running it on low speed. No problems.

    I set it up to start milling, and turned it on to high speed. It ran for a few minutes, then the motor started speeding up. I looked up and a puff of smoke came out of the motor - I snapped off the switch immediately, of course.

    On this mill, the wires are labeled (apparently by the manufacturer) such that 5 of the 6 are labeled differently at each end. They go like this, switch end/motor end: 1U/1U; 1V/1W; 1W/1V; 2U/2W; 2V/2U; 2W/2V

    When I checked the wiring at the switch against what I had written down before I took things apart to repair the switch, I found that I had swapped two wires at the switch: 2U and 2V. But I don't think that is the problem.

    The wire map shows that for Low Speed, power goes to 1U, 1V, 1W and 2U, 2V, 2W are open. For High Speed, it shows 1U-1V-1W tied together, and power to 2U, 2V, 2W. (At the motor, there is a double-side terminal strip, 1 UVW and 2 UVW. All the wires and their markers match at the motor terminal strip.)

    But that ain't how things were switching! I disco'd all the wires at the motor and did a continuity check at the switch connectors. This showed another oddity: On Low Speed, power went to 1U, 2V, 1V with the rest open; and on High Speed 1U-2V-1V tied together and 2U 1W 2W had power.

    BTW, the motor was turning in the right direction.

    It is a simple matter to straighten out the wiring at the switch terminals w/o tearing apart the switch again.

    But now I am wondering if it matters which way the wires from the converter to the switch are run to which terminal? Two wires from the single phase go to the converter and also the switch, and a third wire from the converter goes to the switch. Should this third wire be the one that does not switch for directional control? I thought it didn't matter, but now I am wondering.

    I checked the motor with a digital ohm meter. On the scale for 200k ohms, it reads within 5-10% of a readout of 0.35 between all motor leads on the #1 side, and again on all leads on the #2 side. I'm hoping the motor isn't destroyed...is there any hope?

    Any thoughts or suggestions before I try to power it up again?
     
    Last edited: Nov 7, 2016
  2. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    Does anyone know the HP rating on the ENCO 100-1525 variable speed head? (waiting for my photos to be approved.)
     
  3. lens42

    lens42 United States Active User Active Member

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    I have the same mill, though mine's not originally variable speed. It's been a long time since i was deep in the motor wiring of my mill. I put on a VFD. I remember it had to be an odd hookup because to motor was not a normal 2-speed. The ratio between high/low was something like 4 or 5 to 1. If you post pics, get a clear one of the motor nameplate.
     
  4. markba633csi

    markba633csi United States Active Member Active Member

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    Smoke is bad, one of the windings may be burned and there could be an inter-winding short, or one may develop soon. It sounds from your description that the correct connection would be the first one: 1u 1v 1w powered for low and 2u 2v 2w powered for high.
    Here's the proper way to approach it, first you need the correct wiring diagram for the machine, second you need to positively identify the motor and switch wires with the help of a ohmmeter or continuity checker. Third you should try to check for shorts in the motor between windings or from windings to ground (the frame) again using a meter.
    Then reconnect and cross your fingers. If you shut it off quickly enough when you saw smoke you might be OK. You should check the phase converter too for equal voltages. Be careful, don't get shocked. Been there, done that. Still here. Smarter.
    Mark S.
     
  5. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    I re-wired things and fired it up, it runs in their both directions and at the right speeds. I milled at low speed for 20 minutes and the motor got pretty hot to the touch. Is that normal?

    Where can I find a replacement motor? I doubt this one is going to last long now that I smoked it.
     
    Last edited: Nov 7, 2016
  6. lens42

    lens42 United States Active User Active Member

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    If we do have the same oddball motor, I can try to retrace my wiring to confirm. I'm sure mine is correct since I've had no problems on my VFD in several years of use. This points to a benefit of VFDs over rotary converters in that you will usually get a VFD shutdown and error code before you doing anything bad to the motor.


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  7. markba633csi

    markba633csi United States Active Member Active Member

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    Have you tried the high speed at all? And does it get evenly hot all around or just one particular spot on the case?
    Mark S.
     
  8. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    I ran the mill at low speed for about 1/2 hour...then tried high. After a couple of minutes it fried itself completely.

    My local electric motor shop said their price to rewind it is $1200-$1500, he suggested I just get a new motor.

    I found www.use-Enco.com, called and they have a replacement in stock $821.33

    Then I found www.MSCDirect.com, called and they have one in stock for $726.67 so I ordered, it should be here in a day or two.

    Sadly, the 8/2 pole motor I had is lost. The replacement part is only the 4/2 pole motor. The 8/2 is far more desireable, it has slower spindle speeds on low switch settings, down to 100 RPM. It also makes changing from milling to drilling much easier, since you don't have to change the belt steps.

    Oh well.

    On a happier note, I got my photos posted to my album on here, so I can include pix here for anyone interested.

    I'll have to come up with something more elegant for the vac hose hanger, until then my rope is good for a giggle. Also, I haven't yet bothered to get some flex conduit for the wiring protection. One thing that is nice, I was able to put the noisy vac and RPC in a storage room behind the door, and run the wiring and hose through the wall. So I shut the door and the only thing I hear is the mill. I like that, a LOT. When I was training using my friend's mill his LOUD vac was right next to the mill. Not thinking, we didn't have ear protection and I got tinitus in my left ear. It has faded with time, but there for about 8 months it was terrible, especially first thing in the morning. It comes back now and then but doesn't seem to last as long and isn't such a bother.

     
    Last edited: Nov 8, 2016
  9. lens42

    lens42 United States Active User Active Member

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    Sorry to hear about the motor's demise. What I would do is get a standard 56C frame 3 phase motor off eBay and make an adapter plate to fit it to the machine. Then get a VFD and toss the RPC. I know the urge might be to get a single phase motor but resist. Knob controlled speed is too nice. On eBay, a good name-brand (sometimes even new) 3-phase motor can be under $100. Don't worry about getting one that's "inverter rated". Any modern 3-phase motor will be fine on a VFD in a home shop environment. For the VFD, I probably wouldn't bother with eBay because new ones are not that expensive. A nice Hitachi is around $200.


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  10. JimDawson

    JimDawson Global Moderator Staff Member Director

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    You might be able to find an exact replacement motor on ebay. This motor might just drop in: http://www.ebay.com/itm/REPLACEMENT...ING-MACHINE-VSM3-SP-STEP-PULLEY-/401200615543

    Mill motors are normally ''special'' in that they have a non-standard end bell for mounting and an odd shaft length (extra length) and diameter. Many are a roughly equivalent to a NEMA 145TC frame motor or the metric equivalent.

    I suspect your motor is a 2HP. First measure the shaft then compare to a NEMA 145TC frame motor. It also may be a metric motor.

    You absolutely need a reversing motor, when you shift into back gear, the spindle rotation reverses relative to the motor.

    I would go with a 3 phase motor and a sensorless vector VFD, that way you get a very wide speed range.
     
  11. kingmt01

    kingmt01 United States Active Member Active Member

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    For $100 I'd probably just buy one but at $800 I'd use a video camera to unwind & learn to rewind one myself.
     
  12. markba633csi

    markba633csi United States Active Member Active Member

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    So the motor was actually miswired when you got the mill, so really YOU didn't smoke the motor, the previous owner did.
    Shame on them. Dummies. Good reason to recheck wiring when you buy used machinery. Don't assume anything is correct.
    Mark S.
     
  13. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    Ya know, the thought crossed my mind. But how would I make an adapter with no mill?
     
  14. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    This is good advice, I will follow up on this and see what I can find.
     
  15. JimDawson

    JimDawson Global Moderator Staff Member Director

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    Pull the motor off of your lawn mower and lash it up to your mill. :grin::grin:

    Sorry, I just couldn't resist that one.:p
     
  16. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    Or I could just shoot bullet holes through some aluminum plate...that's be more fun, and work out my blues to boot!
     
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  17. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    I found a motor dimensional chart on Grainger, that'll be a good reference to look over. I'll post it up along with the wiring schematic I drew up today for the switch and motor from my experience with this mill. As soon as the photos are accepted I'll post em up
     
  18. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    Arg. Arg, I say. Got the motor off, but the step pulley is stuck on the shaft and won't come off. It is blind on the end so I can't use a gear puller. Using a lever and sledge hammer didn't get it off. I guess I can try heating it up with a propane torch and then hitting a pry bar with the hammer again...
     
  19. lens42

    lens42 United States Active User Active Member

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    These little 8x36 mills are 1.5HP, not 2. My motor plate says "1 kW". Here's a decent looking eBay motor example:
    https://www.ebay.com/itm/131666749226
    Yes, you'd have make some adapter hardware, but it ain't $800.

    Re the stuck pully. Can you drill the blind cap so you can then use a puller? Might be less destructive and risky than beating on it with a hammer. It's pretty easy to crack the pully since I think it's cast.


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  20. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    Ya know...I could rough out a ring from 1/2" aluminum plate on my vertical bandsaw and drill/tap the two sets of holes needed for an adapter. After I get the mill running again I could make a decent adapter to replace the saw-cut one.

    Things that make ya go "Hmmmmm."

    I'm thinking about a propane torch and two ball-joint fork tools to pry the pulley off with, if that won't do it then yeah, I'll drill out the end of it and try a 3-leg puller, or a 20,000 # hydraulic bearing press that my buddy next door has in his auto shop. I'll get that sucker off one way or another.
     
  21. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    I took the advice above and checked the RPC and house voltage. Across the house power I get 244-249V. The 3rd phase coming off the generator shows 248 - 258V. This is keeping with my wall outlets which show 122V. Seems like the power company in SC is delivering max potential. Would 10-15 V too much current be enough to do damage? (I wouldn't think so)
     
  22. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    Last edited: Nov 9, 2016
  23. lens42

    lens42 United States Active User Active Member

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    Two other options for the pulley:
    1) get a new pulley
    2) take the motor apart (bandsaw if necessary) and cut off the pulley with a healthy length of the old motor shaft. You are probably going to need some shaft extension and coupler for the new motor anyway.


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  24. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    I went to the local Pep Boys and borrowed a ball joint kit with five forks. I pointed two forks head to head, wedged between the pulley and motor, butted one handle against my brick stairs, and hammered on the opposite one. Then I took the widest fork, pointed it straight down, and hammered it. That did the trick. After lots of wedging and hammering the pulley came off. It was stubborn to the last 1/2"!

    My new replacement motor arrived UPS about 7:15 PM, next day delivery. Two customers called late today wanting to know my schedule for their parts.

    HELP! I need to know if 250-255 V is going to fry the new motor, cuz that is apparently what is coming out of the RPC at no load. Coudl that actually have been what fried the first motor?
     
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  25. kingmt01

    kingmt01 United States Active Member Active Member

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    I have 250v at my house as well. My mill runs off a VFD tho. My lathe I taped the transformer leg for 250v. I have went throw several clothe dryer heating elements which I believe may be from the high voltage.
     
  26. JimDawson

    JimDawson Global Moderator Staff Member Director

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    You should be fine at 255, +/- 10% would allow 264. The loaded voltage out of the RPC is proabaly a bit lower.
     
  27. GT Mills

    GT Mills United States Mohawk Aero Registered Member

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    Great, thanks for posting! I ran the mill and made some cuts and everything is fine now. So here I go, now I just need to learn how to use it. Thanks to John Morgan for telling me about the FRIENDLY Hobby Machinist forum.

    Here's the switch schematic in case anyone ever needs it in the future, I drew it up on Visio. I can only post 600x600 pix so I've included larger shots so it's easier to read.
     
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