Re: [CAD_CAM_EDM_DRO] Subject: Re: big stepper on ebay

Agreed... I think he would be better with one of the 90v DCR motors
that can be driven with an SCR speed control, or perhaps the treadmill
motor from surplus center. The only advantge I'd see in using a
stepper as opposed to a DC or even AC motor with appropriate drive for
the spindle is if he wants to use it for indexed operations.

Anyone figured out how to hack the sherline spindle drive to take an
external control voltage?

Chris

> I don't think it would be a great modification. It would probably work, but
> I would be concerned about 2 primary things:
> 1 - Large steppers tend to have relatively low maximum rpm. Small lathes
> tend to like high rpm. If you use a belt drive to gear it up you will have
> little torque. Also, just by the nature of steppers your torque will drop
> rapidly with rpm so your top spindle speed regardless of how you achieve it
> will not have a lot of power.
> 2 - At slower speed the motion of a stepper may tend to aggravate chatter. A
> stepper does not have a smooth rotation at a fixed speed, but moves in a
> series of steps. At lower rpm this would be most pronounced and is
> effectively full speed to the next step and then a pause followed by a full
> speed move again.
>
> Only way to tell for sure is to get a motor and try it.
>
> Tim
> [Denver, CO]
>
> > -----Original Message-----
> > I am in the process of converting a taig lathe to cnc. My
> > question is can a
> > stepper motor of sufficient power be substituted for the AC spindle drive
> > motor? That way with the proper DC power source the spindle forward and
> > reverse and variable speed could be controlled by the computer.
> > Any and all
> > suggestions appriciated.
> > Thanks in advance. BILL.
> >
> > FAQ: http://www.ktmarketing.com/faq.html
>
>
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--
Christopher C. Stratton, stratton@...
Instrument Maker, Horn Player & Engineer
22 Adrian Street, Somerville, MA 02143
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