QCAD.org Forum

Hi,

I'm a registered user of QCAD-Pro, primarily because it was recommended to me by the UCCNC control software developers, cncdrive.

With UCCNC, which I use with my Stepcraft CNC machine to cut foam, cardboard and leather, etc., the CAM facility is quite dated, and only supports (at a push) the older Autodesk standard (.

For some reason, the exported file shows the circles as squares (see below), although they're definitely circles in the imported file, and nothing is changed in the file before it's exported.
Does anyone know why this would be, please?

Thank you.

Hi,

One can export to a DXF based on dxflib: R15 [2000/LT2000] DXF Drawing [dxflib]
And also based on OpenDesign libraries: R15 [2000/LT2000] DXF Drawing [OpenDesign] or as DWG.
Most likely also supported ...


I suspect that all are Polylines.
Especially when the the inner and the outer contour are intended to be rounded.

Probably the bulge factors are not accounted for and what remains is the chord of the intended Arc.
Then the 'holes' may be considered as a chain of 90°Arcs but only displayed as the 4 straight chords.

That may be simply a visualization limitation when dealing with Polylines.
Are there any G2/3 moves in the generated G-Code when displaying squares?
If yes, Arc-like Polyline segments are not rendered on screen.
Otherwise they are not supported.

You could try to explode (XP) all the Polylines to Line and Arc-segments before saving to DXF.

Other issues can be: Not 2D or Z coordinates different from zero, Global or Local Widths different from zero, Polyline Pattern Yes/No.
Not common but CW vs CCW may also be an issue for very old systems because DXF Arcs are basically all CCW.

Regards,
CVH

Thanks.

The software only supports dxf files. I tried dwg but got the following error:
Both the OpenDesign and dxflib present the tilted squares, but I understand what they are now, thank you. The outer chamfers are not rounded, by the way.

There are no G2/G3 moves. They're all G0/G1.

I'll try the exploding bit, and see how it goes.

Thank you

Update: I edited one of the circles by exploding it and that vector is now round, so this looks promising!

Further Update: So, I selected all the vectors, XP'd them and exported the file - but forgot to change it from an r@& format, and the file loaded properly and I was able to generate a toolpath, so maybe the XP is the solution!

Hi,

Didn't advice to export to DWG.

CNCnStuff wrote: ↑

Mon Mar 31, 2025 3:20 pm

There are no G2/G3 moves. They're all G0/G1.

Then it is more than a display rendering issue.

I would also try Polyline Pattern Yes/No in combination with 'curved' Polylines.

Regards,
CVH

CVH wrote: ↑

Mon Mar 31, 2025 3:48 pm

Hi,

Didn't advice to export to DWG.

CNCnStuff wrote: ↑

Mon Mar 31, 2025 3:20 pm

There are no G2/G3 moves. They're all G0/G1.

Then it is more than a display rendering issue.

I would also try Polyline Pattern Yes/No in combination with 'curved' Polylines.

Regards,
CVH

Did you see my Further Update?

CNCnStuff wrote: ↑

Mon Mar 31, 2025 3:57 pm

Did you see my Further Update?

Yes, but I also know that with 'sister' CNC driver applications there is an issue with the Polyline Pattern flag.
All use the same libraries to load a DXF file and also share the same basic CAM functionality.

Regards,
CVH