Difference between a stock lathe and Mod lathe

[24601]

Can someone explain to me why you need a different lathe for a stock motor than for a mod motor?
I was looking on tower and noticed they are different, and the conversion between the two is almost as expensive as one of each. I am confused.

[TCorzett]

From what I understand, and someone please correct me if I'm wrong, but a "Stock" lathe is for use with closed-endbell (non-rebuildable) motors. There is some sort of bit that does inside the endbell and cuts the comm (I'd guess that's what it does). This was used before rebuildable stock motors. A "Mod" lathe is for rebuildable motors stock (24deg,27 turn) or mod (less than 24deg, less than 27 turn). With these lathes the armature is removed from the can and placed on the lathe where the comm is cut. If you are trying to cut the comm on a rebuildable motor (one where you can remove the endbell and the armature) then you want a "Mod" lathe.

-Todd...

[24601]

That was my first thought. I really didn't think there was a way to cut the com on a closed endbell, maybe I was wrong. I doubt i would be in the market any time soon, but if I am going to be paying $5 or so to have it done, it might be cheaper in the long run to buy one. Any more thoughts?

[Moo-Shoe]

Some of the older stock motors have the ability to take all the parts of the endbell (brush hoods, heatsinks, etc) off, without actually removing the endbell. What this does is gives you a hole through which you can cut the comm. A stock lathe is one where you mount the entire can of the motor to be cut and cut through this hole in the endbell.

Most, if not all, motors you buy today are rebuildable so you can take the armature out of the can. These are more easily cut on a "Mod" lathe. I would not spend money on a stock lathe personally since it is easier to cut comms with a mod lathe.

[Grizzbob]

Yup, y'all got it right, before the first rebuildable stock motor(the Paradox), the only way to legally cut the comm in a stock was to remove the brush hoods & use a stock lathe, which has a much narrower bit. Nowadays they aren't neccessary, since pretty much all stocks today are rebuildable. Incidentally, it is possible to use a stock lathe's bit on a mod lathe( I've been using one on mine for almost 2 years, works fine) if you're in a pinch & can't find a normal one. And if you end up needing to cut your comms as often as I do(at least one motor's comm per week, sometimes more), then it would save you money in the long run to buy your own.....:)