Re: [CAD_CAM_EDM_DRO] Which to trust, home-built DROs or hash marks?

I've noticed the 0.001" error per 1" of travel, over the full range of
motion of the table (~7") the DROs said the table moved 7.007xxx", so I've
probably got the same set of lead screws you had.

John

----- Original Message -----
From: "Dan Mauch" <dmauch@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, August 04, 2003 10:41 PM
Subject: RE: [CAD_CAM_EDM_DRO] Which to trust, home-built DROs or hash
marks?


> Don't trust the leadscrews in the mill/drill. When I first gotmoni I
> took it apart because there was a bind in one spot on the X axis. After
> I reassembled it I started checking it with my dro and was coming up
> with a difference but I was using usdigital linear encoders. So after
> messing with both of them for a while I went back and got out my long
> drift dial indicator with a 2" travel. I removed the backlash and then
> was shocked to see that the dial indicator matched the dro so that
> verified that the acme leadscrew pitch was off. It was a consistent .001
> per inch. Using various methods I verified that in 10" it was .010 off.
> So I quit fooling around with it and retrofitted it to ballscrews and
> cnc and am glad that I did.
> Dan
>
>