Help establishing armature connection diagram of an electric motor.

[Flynth]

I have a widely used automatic table feed AL-310S made by ALSGS. Unfortunately the armature coils burned out (likely due to a manufacturing fault). Replacements are available only from China and are not cheap so I decided to have a go at rewinding it (especially that I already have all the supplies), but I need some help with the coil layout.

Specifically, this is a 2 pole universal motor. It has 16 slot (16 tooth) armature with a 32 connection commutator.

Here are some photos:



To me this looks like a lap winding with coils spanning from slot 1 to 9 and from 9 to 1 on the other side, then shift one and repeat.

This seems contrary to a common way how these are normally done (double flier lap winding supposedly being common and coil pitch is supposed to be slots divided by pole count, so 8 not 9).

However, those windings don't look like that. I'm pretty sure they use a pitch of 9 (span of 8) and "single flier" (if that makes sense). They look like if we number slots from 1 to 16 that it is wound 1 to 9, and 9 to 1(on the other side) , then 2 to 10 and 10 to 2, then 3 to 11, and 11 to 3, then so on... It seems a lot simpler than various arrangements described online. I can't shake an idea I'm misinterpreting it somehow. I even cut the windings on top and I traced them to make sure coils do go from slot 1 to 9. They do. Unfortunately it is not possible to trace the other side due to all the windings on top.

I looked for pictures to compare, but it is impossible to find any online. There is plenty of diagrams of various arrangements of windings, but no photos how those arrangements actually look like in reality to recognise shape etc.

If anyone can help me confirm this winding pattern I'll be very grateful. Some decades ago my dad did motor rewinding as a side job, but the motors he worked on were big three phase things, not tiny universal motors like this one. Also it was so long ago he doesn't remember much of the theory, winding patterns etc.

 

[tq60]

Can only suggest using a PAINT PEN to mark up the slots, does not matter how, but suggest finding whatever wire is on top and wherever it goes is number 1.

Make a map of commutator and maybe mark some.

Use a spreadsheet and camera.

Label first column 1 to how many steps you do.

Add next to record the task

Next is commutator pin START wire cut from.

Next 2 are the slots the wires go through
Start
Finish

Last is commutator other end FINISH cut from.

One line for each coil.

Unwind one at a time.

Save after each coil.

After done, copy tab as "reverse"

Click on first column and do reverse sort.

Next, reverse the labels in start and finish columns.

Now attach the wire to start, wind through the rows and attach to finish

Sent from my SM-G781V using Tapatalk

 

[markba633csi]

Doesn't look burned out to me- are you sure it's faulty? Is there a short?
-Mark

 

[Flynth]

Can only suggest using a PAINT PEN to mark up the slots, does not matter how, but suggest finding whatever wire is on top and wherever it goes is number 1.

Make a map of commutator and maybe mark some.

Use a spreadsheet and camera.

Label first column 1 to how many steps you do.

Add next to record the task

Next is commutator pin START wire cut from.

Next 2 are the slots the wires go through
Start
Finish

Last is commutator other end FINISH cut from.

One line for each coil.

Unwind one at a time.

Save after each coil.

After done, copy tab as "reverse"

Click on first column and do reverse sort.

Next, reverse the labels in start and finish columns.

Now attach the wire to start, wind through the rows and attach to finish

Sent from my SM-G781V using Tapatalk

Unfortunately this wasn't possible. I did try for a couple of hours, but the windings below the very top consisted of a stone hard mass of epoxy. It was impossible to pull one wire and unwind it. Furthermore, cutting multiple wires, they could be pulled out as a chunk, but underneath the very first layer, shattered glue and wires were such a mess it wasn't possible to trace them (even when wet in hope of improving visibility).

I've removed both sides of windings by now and next I'll be removing wires from the slots. I counted 80 wires in each slot(from the ends, after cutting) and that the wire is 0.35mm single enamelled wire.

It is just a universal motor, there are only so many ways it can be wound. I was hoping someone who rewound such motors in the past would take one look and say: yes, that's a "simplex lap wound" or something...

One additional bit of info is that I measured the resistance precisely before I started cutting. There was on average 0.710 ohm between the commutator poles (except the short and break). The resistance varied from 0.730 mOhm to 0.690ohm.

If no one advises otherwise I'll be winding it with winding pitch of 9 if I manage to work it out fine on a piece of paper, or if not I'll use a winding pattern described online for a similar motor (double flier lap winding with a pitch of 8 - spanning 7 teeth). What is the worst that can happen? It will run slightly differently?

One thing I'm still unclear on after reading some book excerpts is why there are different winding patterns used in motors that have same number of poles, slots and commutator connections. For example in my 16 slot, 32 connection commutator motor, there are two brushes located right in a center of stationary windings.

Doesn't look burned out to me- are you sure it's faulty? Is there a short?
-Mark

There is one short and one open. Also there was discoloration in a little cavity formed by wires as they go into a slot. It is not visible on a photo for some reason (I reviewed all the photos, but I couldn't find it). When I looked at it under a microscope I saw a copper ball (melted wire) on one coil and 3 wires on top with burned off isolation... So in short, yes it was burned up, but as you said it looks surprisingly good. So I'm suspecting the wire must have been scuffed in the factory and over time one coil was overheating more and more resulting in failure.

Also I managed to touch that ball of copper and naked wires with a multimeter prove and it had continuity to broken (ball) and shorted (wires) coils.

I came later to this thread and I noticed I forgot to hit send. So I'll add this too. I'm in the process of removing the windings from the slots and I found one where flexible isolator is discolored black (while others are white). Also I could smell the burnt smell once I cut it open.

 

[tq60]

Different spacing patterns may be to control torque or speed

Sent from my SM-G781V using Tapatalk

 

[Flynth]

Different spacing patterns may be to control torque or speed

Sent from my SM-G781V using Tapatalk

Best I can come up with is this: commutator connectors on the bottom, armature slots on top. Where no connection is present on the commutator it means the middle of the coil connected on both sides goes there. I didn't draw those connections for clarity.

Then I tried to draw it in a circular form to imagine how it will look like: (I hope it is clear roughly what I meant - connections to commutator are signified with a dot on it, different colors were used for clarity, inner circle is the commutator, outer circle are armature slots).

And here is the rotor with windings (and some isolators) removed.



Edit:One more thing. I noticed the brushes are rotated by 90 degrees compared with typical "angle grinder/drill" motors. I wonder if I need to rotate commutator connections likewise (in relation to my drawing).

 

[Flynth]

I'm done rewinding. I've tested the motor with low voltage and it seems to run fine. This will be the epoxy gluing setup:

 

[Flynth]

Ok, I've glued the motor, I've balanced it. I reassembled it and I started driving it faster (about 6k rpm) when I heard that bearings don't sound too good. I took them out. I cleaned and oiled them which helped for entire 2 minutes...

Now I can actually feel a spot with higher resistance when turning. Interestingly it becomes apparent only when everything is put together and springs press the bearings axially slightly.

Now I wonder if this is the original cause of the failure, or did I manage to mess the bearings up somehow by washing them and relubing? They didn't feel any differently on first and last disassembly. They are steel shielded bearings and they were washed with brake cleaner and lubed with lithium grease, (then oil later). I hope replacing them will be the last thing I have to swap

 

[Eddyde]

You have to be carful with brake cleaner, it can damage plastic parts. Some bearings have plastic seals and or spacers inside.

 

[Winegrower]

That's pretty impressive, @Flynth. Congratulations!