PDA

View Full Version : SEM DC Motor Issues



Chaz
25-09-2016, 04:01 PM
Hi,

So my Denford's spindle motor has been giving problems and recently blew fuses on my drive. I managed to get it going again but the motor seemed to lack torque.

Tried to machine a part this afternoon, motor struggled and smoke came out where the brushes are.

Took the motor out and split it as far as I can. The brush lenghts look OK although the one snapped off the wire when I tried to remove it. The comm is also fairly black. Two of the thinner wires (I assume the field winding), one is burnt off. Might explain the lack of torque.

So, what are my options? Ebay has a slightly smaller motor (mine is the MT30U4-36) for sale. This is an option, ideally a straight swap.

Repair mine, cost might be high. Find a suitable replacement, same issue. I dont intend keeping my Denford long term and I do need parts made for Thor, so a bit snookered. I was looking to move to a high speed spindle but Ill need a machine to make the bracket, unless I just do something manually to get going.

Thoughts? By any chance has anyone got one of the motors spare from an older machine?

Thanks

Chaz
25-09-2016, 04:46 PM
Checked the wiring diagram. The wires that are damaged go to a temp sensor, clearly the motor has overheated. Could this have been caused by a brush gone bad and/or a dirty comm?

m_c
26-09-2016, 11:52 PM
Try cleaning the commutator up, and see what happens.
Have you been aware of the motor running hot?

It could be a sign of the drive itself failing, as it shouldn't be putting out enough power to cook the motor, and the blowing fuses can be caused by a faulty drive.
If possible hook up an ammeter so you can see how much current the motor is using, and one so you can see how much the drive is using.

JAZZCNC
27-09-2016, 12:20 AM
Chaz I've got 3 x MTS30U4-36 working motors with 2 working Anilam SMA7215-1 drives and one dead one I'll sell.
The dead drive I think is probably easy repair or could even just be fuseed internaly but not checked. It Was working while I was messing around with it on bench. Turned it off then wouldn't come back on. Got new AC servos so never botherd with it just thru it in box.

Encoders on motor are 1000 line single ended but I've got some new 2500 quad Differential was going to fit so I'll sell those as well.

See pics. (Ignore Controller board)

If interested got my email make me an offer.

Chaz
27-09-2016, 11:22 AM
Chaz I've got 3 x MTS30U4-36 working motors with 2 working Anilam SMA7215-1 drives and one dead one I'll sell.
The dead drive I think is probably easy repair or could even just be fuseed internaly but not checked. It Was working while I was messing around with it on bench. Turned it off then wouldn't come back on. Got new AC servos so never botherd with it just thru it in box.

Encoders on motor are 1000 line single ended but I've got some new 2500 quad Differential was going to fit so I'll sell those as well.

See pics. (Ignore Controller board)

If interested got my email make me an offer.

Thanks Dean. Ill drop you an email.

Are the motors using tacho feedback at all (ie, voltage for a specific speed)? Trying to work out if I can use my current drive (Sprint 1220i).

Chaz
27-09-2016, 11:24 AM
Try cleaning the commutator up, and see what happens.
Have you been aware of the motor running hot?

It could be a sign of the drive itself failing, as it shouldn't be putting out enough power to cook the motor, and the blowing fuses can be caused by a faulty drive.
If possible hook up an ammeter so you can see how much current the motor is using, and one so you can see how much the drive is using.

I will do that and see. Waiting to hear about brushes but the normal supplier is out of stock.

I dont think the motor itself has been running hot. Ill post some pics later.

The drive is fairly new, Sprint 1220i that I bought when my 1200 had issues and could not be connected directly to the CS Labs board. The big thing I dont have is a current reading which I should do, its nice to know specifically when it sounds like the motor is loaded (or not).

Ill email Sprint and ask for some info.

Ive ordered some pulleys as I believe I can get my 1.5KW Servo motor (destined for the Y Axis on Thor) as a temporary measure.

Chaz
27-09-2016, 01:44 PM
Chaz I've got 3 x MTS30U4-36 working motors with 2 working Anilam SMA7215-1 drives and one dead one I'll sell.
The dead drive I think is probably easy repair or could even just be fuseed internaly but not checked. It Was working while I was messing around with it on bench. Turned it off then wouldn't come back on. Got new AC servos so never botherd with it just thru it in box.

Encoders on motor are 1000 line single ended but I've got some new 2500 quad Differential was going to fit so I'll sell those as well.

See pics. (Ignore Controller board)

If interested got my email make me an offer.

Email sent. Thanks

andy_con
27-09-2016, 09:46 PM
It's normally the brushes in the top compartment that cause the issue.
You get a build up of carbon in there which conducts, blows fuses and burns

Chaz
28-09-2016, 07:43 AM
It's normally the brushes in the top compartment that cause the issue.
You get a build up of carbon in there which conducts, blows fuses and burns

Top (looking at the motor mounted with the shaft in the lower position)? Just ensuring we are speaking of the same thing.

I am hoping a clean and brush replacement will work.