Thread: Start motor reco

Turning the commutator leading to loosening segments sounds like an old internet tale to me..

I skimmed the comm on the Lucas starter I'm my dozer and didn't have a problem. Also done a few bigger ones for trucks and diggers at work and never had a problem.

Hi Stuart,

Turning commutators on the lathe is standard practice, if you get down to the insulation ( mica?) you need to undercut the mica so that it is below the commutator bars. You can do the undercut with a slitting saw, if you have one of the right width. I looked up Rosenberg, and he recommends 1/32" undercut, and square sides.... that is no mica at all near the top of the bars.

The rotor will try to center itself magnetically to the stator.. you could power it up with lots of end float and see where it likes to run.


Ray

Thanks guys, I thought the grinding might have been a little over the top.

It's already down to the mica in many places. I don't have a slitting saw small enough, it needs to be less than 14mm Dia. I'm thinking single tooth form tool on the mill. Be easier to make the tool for the shaper but I doubt it will fit.

Stuart

Originally Posted by Stustoys

Thanks guys, I thought the grinding might have been a little over the top.

It's already down to the mica in many places. I don't have a slitting saw small enough, it needs to be less than 14mm Dia. I'm thinking single tooth form tool on the mill. Be easier to make the tool for the shaper but I doubt it will fit.

Stuart

Undercutting can be done with a piece of hacksaw blade, grind off the "set" on the teeth though (sort of like a safe edge on a file)

Also don't use emery to polish the commutator, use sandpaper. it's non-conductive

Originally Posted by johntopp

Undercutting can be done with a piece of hacksaw blade, grind off the "set" on the teeth though (sort of like a safe edge on a file)

Also don't use emery to polish the commutator, use sandpaper. it's non-conductive

Exactly right, I've used the ground off hacksaw on several occasions.
Something is definitely wrong with the alignment of the armature and the way the brushes are hanging over the end of the commutator.
Is the Lucas M45 the one with the internal solenoid? If so, they are exceptionally touchy to rebuild and set up correctly.
I think I may have an exploded diagram and repair and setup instructions if you should need it.
You mention these motors are running for long periods at low load. What are they running?

Hi Stuart,

I've turned down a few commutators, mostly for domestic product motors. One of the issues with undercutting the mica, is that it is very easy to slip and scratch the copper bars. A dodge that I use is to turn a collar that is a good fit over the commutator and then slit it lengthwise, using a hose clamp to secure it. I use a hacksaw blade ground to suit the width of the mica, but put a hook in it and in use pull it towards you away from the windings. I put a wood handle on mine.

dscn0032.jpgdscn0033.jpg

It took a while to find the tool, not used it for a few years. Seems that I've broken the tip off at some time. I can't find any of the wooden collars that I made, they have probably got lost or broken over the years. My favorite trick was knocking them on the floor, forgetting and then treading on them.

Hi

Originally Posted by johntopp

Also don't use emery to polish the commutator, use sandpaper. it's non-conductive

That was part of my thoughts about grinding, I wouldn't need to polish. But I'll keep that in mind.

Originally Posted by Karl Robbers

Something is definitely wrong with the alignment of the armature and the way the brushes are hanging over the end of the commutator.

I have some ideas what might be wrong but until I get the new parts I wont know(might not know even then). The machine has been like this for over 15 years(at a WIG averaging 2 hours a month)

Originally Posted by Karl Robbers

Is the Lucas M45 the one with the internal solenoid?

Now thats in interesting question in itself(well for me anyway lol)
No they dont have the built solenoid.
They have M45G bodies, but the brushes are listed for M45.
The brush spring are "about the right size" for an M45/45G but only half the width.(that maybe one reason for the tapered wear)

Originally Posted by Karl Robbers

I think I may have an exploded diagram and repair and setup instructions if you should need it.

It sure couldn't hurt if you have it handy.

Originally Posted by Karl Robbers

You mention these motors are running for long periods at low load. What are they running?

Its a lure coursing.(dogs chasing a plastic bag tied to fishing line)

Originally Posted by BaronJ

It took a while to find the tool, not used it for a few years. Seems that I've broken the tip off at some time. I can't find any of the wooden collars that I made, they have probably got lost or broken over the years. My favorite trick was knocking them on the floor, forgetting and then treading on them.

I'd heard about the hacksaw idea but the collar would help. I'm more worried about depth control because as an estimator I suck. Besides I can say to SWMBO "see I do need all that crap in the garage" . So best we keep the hacksaw idea to ourselves.

Thanks all

Stuart

Hey there Stuart,
Mr Pete on YouTube has a video or two on turning comms etc;
Well worth a watch if your unsure..

All the best with it..

Matt

Originally Posted by BaronJ

Hi Stuart,

dscn0032.jpgdscn0033.jpg

It took a while to find the tool, not used it for a few years. Seems that I've broken the tip off at some time. I can't find any of the wooden collars that I made, they have probably got lost or broken over the years. My favorite trick was knocking them on the floor, forgetting and then treading on them.

From the pictures you can see that the tool looks quite worn and abused
I've just discovered that my good wife has been using it to clear the weeds that grow in between the blocks on our drive ! Hence the rather worn end bit. Grrrr.

I knew that I couldn't remember breaking the tip off. Anyway that is a new use for an old tool.

Here is the literature I have for your starter motor.
The starter motors I mentioned earlier as having internal solenoids are more correctly termed coaxial solenoid motors and are touchy little dears to rebuild.
Hope this helps.

Originally Posted by matthew_g

Hey there Stuart,
Mr Pete on YouTube has a video or two on turning comms etc;
Well worth a watch if your unsure..

All the best with it..

Matt

https://www.youtube.com/watch?annota...&v=_qZvUD48cZY
G'Day Stuart, Matt and all,
I'm not sure if this is the YT vid you were referring to Matt, but it is worth a look anyway, if you want a fine finish on copper. The worst bit is, that you can't machine right up to a shoulder, although by manipulating tool angles and height, you could get close enough I would think.He is experimenting with vertical shear tools, and at about the 3minute 40 sec mark he shows the machining of copper. This is the second part of this topic, and you will have to go back to the first part to get the grind angles for the tool he is using.
If you roughed the commutator down and then undercut the mica insulation with a ground hacksaw blade, you could take the last couple of thou off with a vertical shear tool for a nice clean final finish, (or not). I hope that it works out well in the end,
Rob

Depending on how bad the wear is, I usually cleaned and cut the mica first. It also makes it easier to align the slot in the collar with the mica. It doesn't take much, just a couple or three strokes to take half millimeter off. The other thing that I used to do was to "Com Stone" the armature under power. The com stone was simply a stick of abrasive bonded material about 5/8" cross section and around 5" inches long. It helped the brushes to bed in and polished the com.

Should have paid more attention to the elec fitters when I used to work with em. not unusual to see the boys fixing a motor by putting bits in the lathe.

Lucas........brings back bad memories.

My actions on finding a defective Lucas in a car was to replace with Bosch.

Interesting to watch the fix.