Re: [CAD_CAM_EDM_DRO] Trav-Dial type rotary encoders

Joe Burns wrote:

> I found an interesting item on ebay...are these things any good?
>
> http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1605990453
>
> I've also got a couple of them, but haven't made the time to get it
> working. Is it worth my time? I have no idea how to set them up or what
> the resolution is.

I think they work pretty well on a lathe. On other machines, you need to have a
very clean place, like a bedway, for the roller to roll against and measure
movement. Just bolting it on the saddle and having it read the front edge of the
table as it moves past will not work well. Chips will make it work even worse.
I suspect you might be able to put a ground bar on the front of the table in the stop
block track and have an aluminum cover that keeps chips off the works. Then
it would probably work fine. I suspect the resolution is .0005 or .0002", which
is good enough for a DRO. If the measuring wheel and track are clean and
smooth, then it is probably accurate. The Trav-a-Dial looks a bit hokey, but
if you keep them reasonably clean, people who use them say they work VERY well.

Jon