QCAD.org Forum

Hi Andrew,

no problems to cut circles from QCAD. Trying to create gcode from the example appended brings many problems. The cutter jumps cutting cirles, see pictures. You can test it easyly with my appended dxf file.
I tested if countour is closed using hashures, no problem, no open forms found.
Could you support please?

Best Regards,
Christof

Hi Andrew,

maybe I found a possible hint: the suchcalled entry point is calculated independent (I respect only my examples) of choosing cutting inside or cutting outside the contour. In every case its the same coordinate.

here I selected cutting inside: here I selected cutting outside: Hope it's helpfull finding a solution.

Best Regards,
Christof

The circle shaped polyline has some duplicate nodes (to be precise, very small or zero sized arc segments).

To get rid of these tiny segments, proceed as follows:
- Select polyline
- Modify > Explode
- Modify > Detect Zero-Length Entities
- Click Delete button in options toolbar at the top
- Right-Click a segment and choose "Auto Create Polyline"

Hi Andrew,

I have to admit: QCAD is a great tool, I know no competitor at the moment.
Thanks for your excellent support.
Now I know that data quality is not always the best.

A question: exploding - detecting zero length entities - deleting them - auto-create-polyline
has to be done polyline by polyline?
Is it perhaps scriptable?

Best Regards,
Christof

Hi Christof,

cki61 wrote:Now I know that data quality is not always the best.

I need to underline this finding!
The goal should always bee to make it as easy as possible for all involved participants. I'm talking about the Human, CAD, CAM and CNC part.
To break it down. If possible a circle should be a circle and not a polyline. Sure, a polyline with many segments looks like a circle but it isn't. Think about how many extra calculation, data and movements are required to produce a polyline / workpiece which has to look like a circle. Every extra step could be a source for a mistake. Don't make it more complicated than necessary and you will win in the long run.

In this particular case I would replace the polyline "circle" with a real circle. If you know the x/y position and the diameter then it is easy to do. If you don't have such information approach the circle with one of the multiple QCAD tools like "Circle three Points"or "Circle two Points and Radius". It is easy to do and prevents further headache ....

Belief it or not - it is also much better for your CNC machine. Clean drawing / code will put much less stress on it and it will thank you with longer tool life and less maintenance and a all over all better result.

That's the idea ...

Hi Husky,

thanks for your hints. With regrets I have to admit that there is no chance to change that dxf code. It comes from an older app named wingdesigner which is no more maintained. Thanks god QCAD can handle the errors verry well. In that way I can still use that app.

Best Regards,
Christof

cki61 wrote:A question: exploding - detecting zero length entities - deleting them - auto-create-polyline
has to be done polyline by polyline?

For multiple polylines, you could do all at once:
- Select all polylines
- Modify > Explode
- Modify > Detect Zero-Length Entities
- Click Delete button in options toolbar at the top
- Select all loose segments (rectangle select, layer select, double click on contour, etc)
- Draw > Polyline > Create from Selected Entities

Thanks a lot for your help!

Regards,
Christof