QcadCAM ignores path direction

Discussions around the CAM Add-On of QCAD.

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frantheman
Newbie Member
Posts: 3
Joined: Wed Aug 07, 2019 10:22 am

QcadCAM ignores path direction

Post by frantheman » Wed Aug 07, 2019 10:33 am

Good day,

I have been using QcadCAM for 3 years now - recently noticed an issue with circles and direction of cutting. I don't know if the issue has always been there, but I only noticed it recently. It seems that the CAM processor ignores which direction you specify on the toolpath, and uses the codes G2 / G3 randomly. Attached DXF with multiple toolpaths all specified as direction-Conventional/Right.

When I export the G-code (using G-code offset (mm) as required by my machine) I notice the following:

N1860 G2 X-140.5 I-140.5 J0 F800
N1870 G2 X140.5 I140.5 J0
N1880 G1 Z5
N1890 G0 X100.7627 Y-100.7627
N1900 G1 Z-2 F200
N1910 G3 X-100.7627 Y100.7627 I-100.7627 J100.7627 F800
N1920 G3 X100.7627 Y-100.7627 I100.7627 J-100.7627
N1930 G1 Z5
N1940 G0 X90.1561 Y-90.1561
N1950 G1 Z-3 F200
N1960 G3 X-90.1561 Y90.1561 I-90.1561 J90.1561 F800
N1970 G3 X90.1561 Y-90.1561 I90.1561 J-90.1561
N1980 G1 Z5
N1990 G0 X128.5 Y0
N2000 G1 Z-3 F200
N2010 G2 X-128.5 I-128.5 J0 F800

G-code also attached.

Why would it create toolpaths for both clockwise and counterclockwise - when only clockwise paths has been specified? At this point I need to manually edit my NC files and replace all G3 with G2. And if I don't - I break router bits.

Please assist

Qcad/CAM details:
Version:
3.23.0.0 (3.23.0)
Internet:
QCAD.org
Build Date:
Jul 18 2019
Revision:
42e52bf
Qt Version:
5.5.1
Architecture:
x86_64
Compiler:
MSVC++ 12.0 (2013)

OS: Windows 10
Attachments
pottery wheel cast mould.dxf
(682.41 KiB) Downloaded 92 times
big disk casting.nc
(18.58 KiB) Downloaded 82 times

CVH
Premier Member
Posts: 423
Joined: Wed Sep 27, 2017 4:17 pm
Location: Belgium; Antwerp

Re: QcadCAM ignores path direction

Post by CVH » Thu Aug 08, 2019 12:06 am

First CW and CCW are more convetionally.

The polys are CCW
The two outer ones and the inner one are CW
Two are Circle Entity so CCW

Regards

frantheman
Newbie Member
Posts: 3
Joined: Wed Aug 07, 2019 10:22 am

Re: QcadCAM ignores path direction

Post by frantheman » Thu Aug 08, 2019 8:39 am

Thank you for the reply. I agree CW and CCW are more correct - however when you specify the path direction on the CAM profile QcadCAM uses "Conventional/Right" and "Climb/Left". Maybe this should be addressed then?

I did some more investigation:

Procedure as follows:
1. Create a circle with the draw tool.
2. Create an offset of the circle using the "Modify - Offset with distance" tool

Create a CAM profile for both these entities.

What happens is that Qcad now decided the offset that I created by using the offset tool is an actual polyline, and not a circle anymore. The polyline now has a direction field associated with it - which overrides any CW or CCW CAM profile settings. Setting the CAM profile to "Conventional/Right" or "Climb/Left" has zero effect on a polyline. Weird. These settings do however change the direction that the CAM processor uses on a circle - which is the way it should be (according to me).

Is this correct? My guess would be that the CAM profiling is independent of the actual polyline direction?

CVH
Premier Member
Posts: 423
Joined: Wed Sep 27, 2017 4:17 pm
Location: Belgium; Antwerp

Re: QcadCAM ignores path direction

Post by CVH » Thu Aug 08, 2019 11:34 am

CW / CWW are well defined.
Depending on the motion and the spindle direction and the side of the cutter in action we can speak of Conv./Climb cutting.

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