[solved] cutter jumps at multipoint objects

Discussions around the CAM Add-On of QCAD.

Moderator: andrew

Post Reply
cki61
Junior Member
Posts: 18
Joined: Fri Jan 19, 2018 5:43 pm

[solved] cutter jumps at multipoint objects

Post by cki61 » Sun Feb 11, 2018 12:09 am

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
Attachments
Screenshot_20180210_235714.png
the test object
Screenshot_20180210_235714.png (46.97 KiB) Viewed 1219 times
Screenshot_20180210_235330.png
cutter jumps at rectangle
Screenshot_20180210_235330.png (3.75 KiB) Viewed 1219 times
Screenshot_20180210_234337.png
cutter jumps at multipoint circle
Screenshot_20180210_234337.png (7.82 KiB) Viewed 1219 times
ProfilTest01.dxf
test object
(127.29 KiB) Downloaded 47 times
Last edited by cki61 on Thu May 17, 2018 4:32 pm, edited 1 time in total.

cki61
Junior Member
Posts: 18
Joined: Fri Jan 19, 2018 5:43 pm

Re: cutter jumps at multipoint objects

Post by cki61 » Sun Feb 18, 2018 10:58 am

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:
Screenshot_20180218_103230.png
Screenshot_20180218_103230.png (175.04 KiB) Viewed 1131 times
here I selected cutting outside:
Screenshot_20180218_103531.png
Screenshot_20180218_103531.png (173.05 KiB) Viewed 1131 times
Hope it's helpfull finding a solution.

Best Regards,
Christof
Attachments
MultipointCircleTest.dxf
(108.37 KiB) Downloaded 40 times

User avatar
andrew
Site Admin
Posts: 5552
Joined: Fri Mar 30, 2007 6:07 am

Re: cutter jumps at multipoint objects

Post by andrew » Mon Feb 19, 2018 2:56 pm

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"

cki61
Junior Member
Posts: 18
Joined: Fri Jan 19, 2018 5:43 pm

Re: cutter jumps at multipoint objects

Post by cki61 » Tue Feb 20, 2018 8:36 pm

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

User avatar
Husky
Moderator/Drawing Help/Testing
Posts: 2097
Joined: Wed May 11, 2011 9:25 am
Location: USA

Re: cutter jumps at multipoint objects

Post by Husky » Tue Feb 20, 2018 10:23 pm

Hi Christof,
cki61 wrote:Now I know that data quality is not always the best.
I need to underline this finding! :wink:
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 ...
ProfilTest01_Husky.dxf
(116.81 KiB) Downloaded 41 times
Work smart, not hard: QCad Pro

cki61
Junior Member
Posts: 18
Joined: Fri Jan 19, 2018 5:43 pm

Re: cutter jumps at multipoint objects

Post by cki61 » Tue Feb 20, 2018 11:14 pm

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

User avatar
andrew
Site Admin
Posts: 5552
Joined: Fri Mar 30, 2007 6:07 am

Re: cutter jumps at multipoint objects

Post by andrew » Wed Feb 21, 2018 10:12 am

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

cki61
Junior Member
Posts: 18
Joined: Fri Jan 19, 2018 5:43 pm

Re: cutter jumps at multipoint objects

Post by cki61 » Wed Feb 21, 2018 4:10 pm

Thanks a lot for your help!

Regards,
Christof

Post Reply

Return to “QCAD/CAM”