Saw blade sharpener?

[superzstuff]

This machine is for sale at Friday night auction here. They only posted this one picture and called it a lathe. It looks more like a saw blade sharpener? maybe. I won't get to see it in person until Thursday. Does anyone know for sure? Name cast in is in photo, but I can't make it out. ?????

[john k]

I have seen one, some time in the distant foggy past, but, of course they post a picture of the backside of it!   Now what did it do?   I see a round bar on the other side, with a sliding center, but where is the other center?  What does the motor turn?  It is sitting there like an undercutter for rebuilding generators. 

[Aunt Phil]

Commutator saw.
I know where a similar one sits

[john k]

After carefully studying the picture, I do believe its an armature lathe, for rebuilding starters and generators.   

[superzstuff]

Thanks. Maybe they know more about it than they described since they listed it as a lathe. I will go see it tomorrow and get a name.

[Aunt Phil]

If it's a lathe, WHERE is the cutter to bring the commutator back to round?

[john k]

To me the cutter should be on the top most, center piece pointing away from us.  There should be a belt from the backside of the motor to the round pulley on this top most piece.  Why it should be spinning, or appear to be, can't tell til I see the other side.   Seems like every one of the armature tools I had used was painted red as well.   I could be wrong on all counts, we'll soon find out.  Part of what makes this board interesting. 

[superzstuff]

Went and looked at lathe today. It is a Weidenhoff brand with a Dumore motor that works. The belt is missing but there is a cutter in the belt driven spindle. Armature lathe for sure. Thanks guys.

[Aunt Phil]

NO, it is NOT an armature lathe.  This is a mica undercutter.

An armature lathe has the capacity to rotate the armature & bring the copper to true round.  Some lathes have attached mica undercutters attached.  There are even field lathes that a man attaches to the armature in place, such as in the situation of a large generator.

ALL armature lathes bring the commutator to true round.

The device pictured is ONLY capable of cutting the mica between commutator bars down, it locks the rotor to prevent rotation, indexes the saw and controls depth of the cut as a secondary operation to the lathe turning the commutator, therefore it is not a lathe.  By definition it is a horizontal mill!

[superzstuff]

I see, you turn the armature in a lathe, then cut or clean out the slots where the brushes run with this. I found some like this on line under the Weidenhoff name but didn't take time to read about them. It will probably sell to someone who is buying it for art rather than use anyway.

[Aunt Phil]

Turns out I remembered where this landed after it was thrown because the saw blade hogged into the copper due to the wrong blade being on the saw, and an operator not knowing WTF he was doing with the saw.

First pic shows the commutator as turned down.  This rotor was in an IF it flys we'll see how long it lasts condition before turning and was cut about .060 to get it round.  Chances of the rotor lasting long were pretty damn small.

Second pic shows what happened, not what was supposed to happen. 
Normally the mica would be sawn out .005 to .010 below the copper circumference on a small commutator. 
The mica is there to prevent arcing between segments as the brush leaves one segment for the next.

[john k]

I believe this is an armature turning, lathe attachment.  Can't undercut, but has the cutter for making the rotor round again.

[Papaw]

Here are some pictures of a commutator undercutter. I bought this one after seeing one at a bar in Arcola, Texas that the owner thought was a wrench. I didn't figure it out myself, even after buying this one. It was one of our earliest What's-Its on Tool Talk some years ago.
After posting it, several members recognized it and soon gave us an ID. I now have three of them for some reason, two of them on rails. I'll have to dig for pictures of those.

[Papaw]

Here is one of the ones on rails. I think this one was Lynn Dowd's. The one shown on a shelf is one of mine.

[Aunt Phil]

As I said, it's a mica saw for cutting the mica on commutators.
They are still made & sold.
http://www.graytec.nl/mm/cutting/page.html

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