I got tired of using my cheap Chinese mill without a DRO.
Linear scales are $400 and up per axis. Complete DRO's run about $1000
and up.

An Omron rotary encoder is $25 with 2000 pulses per rev.
You can't gear it to the ball screw as that has backlash.
So I came up with this scheme.

I am using a $50 Maximite to display the numbers on a PC VGA monitor.
An old  PC keyboard to zero the numbers. I have half a dozen.
A simple BASIC program will get the job done. I will upload the source
code shortly.

First step to a cheap NC mill.
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"Wait a minute. Suppose the cable slips on the drum?" you might say
Well here is the answer for that. Use a MXL cog belt.
The proper pulley for .001" resolution is .611" pitch diameter 1/4 inch
wide.
The Maximite floating point math can correct that to exactly .001"
resolution.

Utilizing the Maximite storage capabilities  on 64 Gig SD card, it can
do things no expensive
DRO on the market can match. How about a complete history of what you
made, how you made
it and the time and date you made it?

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Really cheap DRO. These 2 inch travel dial indicators are about $20 each.


Paul Lamar

Paul,
 Where did you source these dial indicators ??
Kelly Troyer

Shars.com
http://www.mcmaster.com/
http://www.mscdirect.com/

Paul Lamar

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