Cause of slow X/Y travel when cutting curves?

[Chris Neal]

Just wondering if anyone can point me in the right direction for speeding up the vector cut movements on my machine. If I import a DXF into LaserCut 5.3 and start cutting, simple boxes cut at the speed specified, but during curve cuts the movements slow down to what seems like 1/3 speed.

My first thought is the controller board may have too much info to process. Would an upgrade from the mpc6515 that came with my G.Weike be the fix?

My second thought was the DXF files I'm importing could be the issue, maybe I'm not preparing them efficiently? I'm drawing them in Onshape, exporting to DXF format, and then just importing directly to LaserCut 5.3. A sample DXF sampleDXF.zipfile is attached

TIA,
Chris

[Tony Lenkic]

Chres,

Reduce nodes on curved parts.

Try this sample

[Chris Neal]

Thanks for the quick reply. I will try that out!

[Kev Williams]

The slowdown is on purpose, and if you speed it up much, you'll find out why in the form of ratty edged arcs. Some speedup is likely okay but it will depend on your machine...
This is the results I got after slowing my Triumph down on curves, which I did with machine settings rather than node editing-
The shapes are doubled up, top shape was original speed, bottom shape after the slowdown. Very noticeable difference...
fcv2.jpgfcv.jpg
so if you successfully speed up like you want, be sure to check the results

[Chris Neal]

I've seen similar results on some arcs in my projects: To me it looks like steps are getting skipped because the controller brain can't keep up with processing the planned movements while executing them at such speeds.

I've seen FDM 3D printers having the same issue when speeds are set too high. The way I understand it, in Gcode curves aren't actually curves, they're just really short straight lines strung together. Some of the segments get skipped and what once looked like curved areas turn into jagged ones. In the 3d printers it's been caused by limited processing power. That's why I was wondering if upgrading my 6515 controller could be a quick fix. But I don't see any brand new HP controllers on the market. The offerings seem to be 2014-ish designs.

[Chris Neal]

Tony,

I tried importing that file, setting the speed to 200 mm/s and ran a test. It looked to be travelling at 10-15. Then I added a box next to the original design. My curved design gets cut very slow, then the box is run at what seems like 200 mm/s.

Thanks for sending the file, getting me thinking more on this. Maybe I need to find a limitation in my machine like Kev was saying.

It's frustrating because these are textiles I'm cutting, and at 15 mm/s it takes forever and a day!

[Chris Neal]

Solution was found in LaserCut's Machine Settings. Thanks for pointing me in the right direction!
File --> Machine-Options --> Work Mode --> Cut --> Curve Disperse (was set to .02. I ended up at .25 and the machine head is flying through curves now)

Other changes that also affected the curve speed:
File --> Machine-Options --> Worktable --> Start Speed (was 5, changed to 50)
File --> Machine-Options --> Worktable --> Const Speed (was 5, changed to 100)

Chris