RE: [CAD_CAM_EDM_DRO] 3D Contouring - Loss of Accuracy

Ok, I'm no expert here but I'll stick my neck out ...

As I understand it you're using the parallel port in all cases. Could it be
that the error is occurring during direction reversals only one step at a
time?

Possibly the edge of the 'direction' line is not correctly oriented with
respect to the 'step' line.

While watching the step and direction lines with your scope (dual trace I
hope) you might try configuring a test case such as:

-----
|
A |
X ----- |
I | | |
S | | |
----- | -----
A | | |
| | |
| -----
|
|

AXIS B

using different combinations of axis with and without motion in the third
axis to see if the error shows up.

You might also try purchasing a parallel port card and trying that.

Cheers,

Chuck Hackett
"Good judgment comes from experience, experience comes from bad judgment"
7.5" gauge Union Pacific Northern (4-8-4) 844
Railroad: Camp Creek Railroaders, Waverly, Nebraska, USA (3000', 7.5")
Home: Elkhorn, Nebraska (just west of Omaha)

> From: Peter [mailto:prenolds@...]
>
> Hi all,
>
> I'm stumped! ....
> I find is that running a large 3D file I gradually accumulate a small
> error typically in one of the most active axes which often exceeds 0.3mm
> or .012" after half an hour to an hour of running time. It is usually
> in the same direction, but not always.
> ....
>
> Cheers, Peter