G320 receiving feedback from linear scale

[Paraprop]

Instead of using the conventional encoder mounted onto the servo motor shaft, I am thinking of connecting a linear scale with a compatible signal onto the feedback inputs of the G320's.
This will allow to compensate for all the issues coming from reduction pulley system, ballscrew acuracy, backlash, etc.. Therefore it would just be one step short of telling to the CNC controller where we are exactly.
Given that this is not comon practice, am I missing something out which jeopardizes this approach or is it just a price issue ? Many do already have linear scales fit for DRO so the signal could be fed easily to the drives.

[CJL5585]

Linear scales are used on many high quality CNC machines which require extreme accuracy.

The main reason they are not so common is price, oils and coolants and trash getting into the unit electronics. Most linear scales are made of etched glass.

Congratulations.

[Al_The_Man]

This recent post explains some of the problems.
http://cnczone.com/forums/showthread.php?t=24817
Al.

[Paraprop]

Al thanks a lot for putting me onto this thread. Spot On !!

reading this I think it is the way to go.

rotary encoder on the servo or stepper
linear scale on the table
cheap rolled ballscrews
proper table guideways
proper ballscrew bearing

hardware able to collect the 2 feedbacks

Mach 3 plug in to sort it all out.

I am looking forard to this day to come

Daniel.