Trucut Armature Mica Undercutter

[ndnchf]

Its not a tool I use very often. But yesterday I pulled it out to undercut the mica on a Willys jeep starter armature. I snapped a photo as I was doing it. In todays modern, throwaway world, its not something you see very often. I thought maybe you guys would appreciate it.

 

[bonneyman]

Cool!

 

[wrenchguy]

Nice!
I found a low bar (.004) on my big lincoln welding machine commutator. Trying to decide what 2do.

 

[Oldtuleguy]

Nice. I have an old snap on version thats been gathering dust. Just don't rebuild that stuff these days.

 

[woody 73]

Very nice and super cool.

 

[The Cobbler]

brings back memories of when I worked in an automotive electrical rebuild shop

 

[gben]

Back in the 1950s, my father worked maintenance at a paper mill working on electric motors. He took a hacksaw blade, broke it to about 4" long, and made a nice wood handle for it that backed the entire blade up. This he used to cut and clean on motor commutators and armatures. He gave me the tool one day and I have it somewhere.

 

[joecon]

I have a manual version of that that was my fathers. I haven't used it in years. I also have a tool to turn the commutator that you clamp in a vice.

 

[ndnchf]

I have used a modified hacksaw blade in the past. But when the mica is flush with the commutator bars like this, it is very difficult to keep the hand held saw blade from slipping over and gouging the copper. This tool is far more precise.

 

[JZiggy]

So this is necessary to keep an air gap between the commutators? I guess the commutator bars get worn down by the brushes over a long period of time?

Cool stuff!!!

 

[ndnchf]

The mica is much harder than the copper bars. It needs to be below the copper to prevent the brushes from being worn down quickly.

 

[engineer2]

I could use one of those once in a while. It tried doing one with a Dremel and a small abrasive wheel. Holding it by hand doesn't work too well.

 

[ndnchf]

They turn up on ebay regularly. This is another one I have. It attaches the the cross slide of my lathe.