Re: [CAD_CAM_EDM_DRO] Re: machine inaccuracies fixed by software compensation

vrsculptor@... wrote:

> The original post made a good point. There are a lot of possible
> sources of errors in a CNC milling machine. The lead screw could be
> off, tables not square, slides worn... What is need is a way to enter
> a machine compensation table into EMC (sort of like cutter
> compensation) and have it compensate for the inaccuracies based on
> the current X-Y-Z coordinates.

EMC has "machine error compensation" already built in. This is a fairly
recent addition, late 2000 or early 2001, and it isn't well documented, yet.

This will not fix interactions between axes, so it won't handle
non-orthogonality
(out of square) but it will fix leadscrew pitch variations and similar
errors
that affect the relationship between encoder counts and position.

> I read about this in an article in American Machinest. Some high end
> controllers are already doing this.

My Allen-Bradley 7320 control from about 1978 had this as an option,
so it is most definitely not new!

Jon