Re: [CAD_CAM_EDM_DRO] Re: DRO encoders- Rotary or Linear?

John A. McFadden wrote:

>Instead of using a rack and pinion, would it be possible to use a rigid bar
>(like 1" or 1.5" drill rod) and a rubber roller mounted to a rotary encoder?
>With a solid bar, wipes could be used to clear the surface before the roller
>passed over it, unlike the rack and pinion where clearing it would be a
>difficult measure at best if something were to get in the teeth.
>
>

Yup, this is basically a trav-a-dial. I think they use a brass or
bronze roller under a fair amount
of pressure. They just use the mill table or lathe ways as the 'track'.

A rubber roller won't work, unless it is extremely hard, as the pressure
will cause a flat spot
to develop as it rolls, and you won't get a consistant turns/inch.
Also, when sitting for a while
it would get a more permanent flat spot.

Jon