Re: Interesting problem

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dan Mauch" <dmauch@s...>
wrote:

>
> I couldn't figure out why I should be
> getting these circles as the dxf file was perfect. It was also too

early

> in the year for mysterious crop circles to appear in my G code.
> Knowing that there wasn't a bug in Mach1 I returned to bobcad. I
> reloaded the G code and in the CAM program Selected All. Then I

selected

> Geometry from code.
> To my shock the mysterious circles appeared on my drawing.

Dan, this is the infamous "looping". It is caused by creating CNC
code from geometry with arcs smaller than the least increment in your
G-code. If you set your number of decimals to 6, 99.9% of your loops
will be eliminated. What happens is the first arc cuts correctly,
but the second one is extremely small, and results in the exact same
G code line, which makes a full circle!

There have been "extensive" discussions of this problem in past
threads of the Vector user forum. A sympathetic programmer donated a
small program that flags the duplicated arcs in a text editor. It
can be downloaded at no charge (Freeware) and used for checking.

http://www.imsrv.com/discus

Enter the General Vector Cad and Cam topics, about the 4th thread
down. "NC code generating loops and circles"

In Vector 9.4 filtering was added to eliminate the duplication, based
on the number of decimals in the output.

Best Regards, Fred Smith- IMService

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