The Craftmans Shop > New from Old

Yet another Beaver resurection (TC20F)

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JeffK:
I guess all 3 plates are mounted on the main spindle motor body, though 2 are together on one end and the other (main) is at the other end of the assembly. As I said I have very little knowledge of these type of motors so it may well be that one plate relates to the cooling fan (which is at the same end as what I call the field plates) and the other to the main motor.
I have been doing a bit of internet searching and realise that there are several different tacho's, encoders etc to monitor position etc on the main motor but am a bit lost with this.
My gut feel is pull the whole thing off, clean it and see what is worn out. That is ok with a V8 petrol engine but with servo motors I am afraid I might do more damage than good with settings etc for encoders.
I can certainly check in the morning if the motor fan runs but will be away from tomorrow night for 2 weeks so don't want to pull too much apart just now. The whole thing is pretty clagged up with gunge so a clean mat well do some good but....

Again thanks for all of the replies. I am a bit out of my depth here so don't want to mess too much up.....

cheers

Jeff

awemawson:
Assumptions here Jeff, but I THINK what you have there is a fairly normal 3 phase motor driven by a probably pretty big inverter whose speed can be controlled. As it is needed to run fairly slowly at times it has a separate cooling fan. Embedded in the motor is a tacho to let the controller know what speed it's turning at.

At a pinch you could probably run that motor at a fixed speed directly off 3 phase so long as the voltage is ok

JeffK:
I will hopefully dive into it tomorrow and get the motor off the lathe then try to see what is going on. As I said I will be away for a couple of weeks after tomorrow so apologies for the discontinuity but will get back after it when I get back. I think you are right with the separate cooling fan but will confirm when I get it in bits. As for the tacho / main motor I am a bit less confident there. However I guess if it is broke then the worst thing that can happen is that its broke. If I am lucky it may end up fixed... nothing ventured nothing gained...  into the unknown. :D

cnc-it:
I would test the motor without removing it to save a lot of hassle as it looks heavy!.. then if it's ok service the drive.  I've had lots of spindle and servo drives go down but never had a motor go bad. Could be a bad capacitor or other component that has failed due to age?

JeffK:
Well - I got back from my travels (eventually) and though time to dive into the lathe again....
Pulled off the fan motor at the back of the spindle motor (Andrew was right with his diagnosis of the spec plates) and found it totally choked up with caked on crudd. https://madmodder.net/Smileys/default/confused0068.gif I though this must be the problem - overloading the motor and causing the thermal switch to trip..... Once upon a
time there used to be a filter at the inlet to the cooling fan but that had long since gone....
After much solvent, scraping etc I relieved the fan blades and casing of a significant weight of sticky gunge. Tested the motor and all was well so re-assembled and put it
back on the machine confident I had fixed the problem. I even fabricated a new filter out of fishtank filter mesh.
Alas on starting up again the same thermal trip problem :doh:
More head scratching and chasing wiring revealed nothing new so I decided to get some new classD breakers and a new thermal switch. Off to ebay and picked up everything
at a bargain price.... Installed the new breaker and changed out the thermal switch - got to be it now.... Not a chance.
I was now getting really frustrated so thought back to basics. Lets do what I should have done at the start and get the multi-meter out.....
With power on I was getting strange voltage readings at the switch across phases.... 130V, 330V and 415V. Can't be right methinks.... Worked my way back to the main fuses
to find voltage ok upstream of them.... one 80amp fuse blown and the fan motor was trying to run on 2 phases..... this had not affected the PLC side of things or anything else
that was kicking in prior to the thermal switch tripping.... I thought I had better check all of the 5 main fuses and found 3 out of 5 had blown - obviously when the whole
main breaker thing had gone. Back to ebay and found 5 surplus used fuses (these are not cheap new...) so bought them all. They arrived middle of last week adn I duly installed
them and - hey presto all was working again...... :D
I guess the excercise was not all a waste of time as otherwise I would have kept running with a bad cooling fan with no filter so at least that got fixed but just shows sometimes it
is better not to jump to conclusions and to check the basics first.....
Got the first metal cut on Thursday in MDI mode so just got to figure out Symbolic FAPT now..... Off to order some new tooling......

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