Subject: Re: DRO on PC

From: [email-masked] (Steve Lindsay)
Date: 10 Jan 1995 09:32:38 -0700

>This sound great, Steve.

>One potential problem, though, the rotary encoder.  Do you plan to
>attach it to the lead screw or somehow attach it to the table to read
>motion directly?  If you read lead screw position, you don't read any
>inacuracies in the lead screw and nut.  A commercial DRO does because it
>measures table motion directly.

>Strange thing is the CNC manufacturers use lead screw motion (ground
>ball screws, actually) to move the table in their open loop systems.
>Funny they do that when a linear encoder would allow them to close the
>loop!

>Best,

>Mike

Yes, I was thinking of hooking to the table with rotary encoder.  I realize
the linear motion will have to be converted to rotary but hopefully that
won't be complex.  I can think of several ideas how to do it but I'm unsure
at this point as to just how accurately it can be done and that by the
time it is
all set up maybe it would of been easier to spend the $ for some linear
encoders.