Boxford TCL , Spindle motor problem

[John11668]

John you may find that the worn brush and loose connection has sent spikes back to the controller over a period of time and stressed some components on driver board. Knocking may have been the instantaneous changes in speed. It also may have damaged some segments of the commutator or has carbon shorting out in slots. You can clean segments out with a groundown back of hacksaw blade and run along slots to remove carbon. If commutator worn you can lathe down commutator and scrape out the insulation to below segments using sharp end of hacksaw blade as mentioned above---old trick used in automotive industry before throw away society became the norm. Can you check if commutator still arcing with new brushes by leaving the cover off to test. You may be able to reach in and clean slots without disassembling motor.

I have done all of this johnny ( Just had motor apart a second time to re-bed brushes again this time with 320 grade paper and now running in again)
Makers tech rep suggested that I run the motor with a current limit of half capacity (set about 2 amps ) and use the belts to gear down. I tried this now normal running is at about 0.8 amps, 100 volts max at 9.7v dc input, but it still stalled on screwcutting. No signs of any motor problems , no arcing at the com , . Motor runs sweet just no torque boost when needed.
And as I have said before it was fine initially and handled all the loads I was going to put on it . Frustrating!

[JohnnyK]

That is frustrating. The motor should be able to draw up to 7 amps if its the original DC motor. The original lenze 534 controller was set at 8 amps max. Are you using the Lenze driver module.... if not whatever you replaced it with may have a problem with the ramping circuit something like a feedback resistor or amp has reduced gain due to damage from earlier brush problem. It responds but slow in outputting extra amps under load.

[John11668]

I ran the motor today on a separate 42v power supply and of course it would only run at about 500 revs but at that I could take a millimeter off diameter in a single cut without stalling. So the motor seems to have the guts for the job.. Speed drops a tad and current goes up but the torque is there despite low voltage.
I reckon the drive has fallen over . Now waiting to hear what suppliers will do about it .
Drive is supposed to be self protecting so should look after itself if a brush wears out (you would think anyway)

[John11668]

So Drive unit is heading back to the makers for testing.
Watch this space!
I expect they will find a problem with it . Just hope they accept it as warranty problem. I am confident I did nothing wrong

[John11668]

So they said no fault , but they did me a deal on a 12,2 amp upgrade . (???)
Still no improvement and motor would only draw about 1.5 amps max settling down to 1.2 . I have concluded that brushes may be limiting the current input . No arcing , but brushes did not seem to be giving a "witness" over their full face width.
The brush width spans 3 comm segments so maybe only 1 in 3 being fully supplied .
Motor stripped again, segments cleaned and brushes bedded in another lathe using a jig. Then re-assembled taking care to keep the same brush orientation.
Seems better already although back to running in again, so will keep you posted .

[JohnnyK]

Hey John. Are you still using the LENZE 534 driver module? I'm not sure if motor can handle 12.2 Amps as Boxford set max to 8 Amps ,,,but learning learning. My LENZE 534 has stopped working and I am trying to trace fault. I had to replace capacitor across the mains input but it still does not function. I am trying to work out how the Simplatron DCVT-2 interface board controls the input of the LENZE driver. I have traced fault to output of DCVT-2 board. I just need to know if the DCVT-2 generates the 10v reference from A (white wire) on DCVT-2 connected to Pin 9 labelled +VCC in Useless LENZE manual. Can you disconnect white wire and report if 3 to 10 volts dc is present between A and C terminals on DCVT-2 board or that 10 volts is generated on pins 7 and 9 on LENZE board---with white wire disconnected. That would help a lot thanks.

I have checked that 180 volts is present and the IXYS Half Controlled Single phase Rectifier Bridge is fine and waiting for dual Gate control to start motor.

[John11668]

Sorry Johnny but my Lenze unit died so I cant test anything for you.
My Sprint 340i was not even giving its full 3.4 amps unless I stalled the spindle, but Sprint felt that 680i might be under-rated hence recommending 1220i.
It is however governed down to an I max of about 50% or 6 amps .
Having said that, since I rebuilt the motor torque is much better but I have not seen the motor draw more than 1.5A.

But as I said on another thread there are a couple of GEC gemini dc controllers on Ebay at the moment .
Looks like Boxford used these as an alternative to Lenze

[JohnnyK]

Thanks John