Re: [CAD_CAM_EDM_DRO] BP variable speed questions

If the damage isn't too severe, you could simply clean up the existing
keyways in the shaft and sheave and make a custom fitted key. The slightly
oversized key would add a bit of strength as well.

For the Pulleys, you could use multiple step pulleys. This would give you an
even wider range of options for the speed control. If your taking the head
apart anyway...why not count the teeth on all the gears, make yourself a
sketch and calculate what all the existing ratios are?
That would be a good FIRST step.

Smoke

> I am in the process of rebuilding the variable speed drive in my
> Bridgport Series I CNC, and am trying to make a decision in regard to
> the worn front pulley parts. The keyways are worn in the pulleys and
> hub. I'm thinking the easiest (and cheapest) way to repair the hub
> and shives are to press the hub out and cut new keyways on the
> opposite sides of the hub and the shieves. The Bridgeport parts guy
> I deal with was very adament about not doing that, saying the balance
> would be upset, and the old keyway would quickly damage the delrin
> bushings as the shives slide up and down the hub. I'm not sure if I
> buy that one, especially since he's the one trying to sell me new
> parts. Can anyone see anything wrong with cutting new keyways? Is
> there a special procedure to press the hub out of the bottom shieve
> without galling it?
>
> The other thing I thought of was since I am going to be using a VFD
> to drive the motor, maybe it wouldn't be a bad idea to eliminate the
> top variable speed components altogether with fixed-size pulleys.
> That would seem simpler and quieter. However, I haven't any idea
> what would be a good ratio to choose for the pulleys to be able to
> get high and low speeds. I don't have a manual for the machine, so I
> don't know what the reduction is for the back gear (low speed). Its
> also my understanding that torque shouldn't be affected by using the
> Mitsubushi VFD's at low speeds--is this true?
>
> Appreciate any help.
>
> Bob
>