Poor quality v-carve

[jtb223]

Has anyone ever seen this problem? The file is the Paradise Box top sample from Vectric. the G-code file was exported as Mach2/3 Arcs (inch) (*.txt) and run on my home made CNC machine with UCCNC. The material is MDF.

[jtb223]

It should look more like this...

...it should look more like this...

[mphel]

My first thought is maybe a cutter geometry issue, calculated with a 45 degree cutter and cut with a 60 possibly...or vice versa..
Or calculated with with a larger diameter cutter than actually used.

I assume you normally get good results with your setup?

Mark

[cncdrive]

Or trajectory settings problem.
Remember that in G64 (constant velocity mode) the software will optimise out the path for fastest possible execution
with taking the trajectory parameters into account with not creating larger error than the values you setup.
So, check your CV trajectory settings and lower them if they higher than what error size you want to see on the workpiece.
For more informations on the mentioned parameters please see the UCCNC manual, the parameters are described there in details.

[jtb223]

Wow, what a difference. These are the lid decor v-carve of the Vectric candy duet. The right was done in constant velocity mode and the left was done in exact stop mode. It took a little longer but really made a difference. Thanks cncdrive.

[ger21]

You really don't want to run in Exact Stop mode. You should adjust your CV settings so that the results are the same, but it will cut much faster in CV mode.

[jtb223]

Gerry,

I'm willing to learn. What changes would you recommend that will result in biggest bang for the buck?

thanks,

Jim

[ger21]

I've actually never used UCCNC yet, as I'm a long time Mach3 user.

I think the default settings that you're using are meant to be used with a metric setup, and the 4 values should be much smaller.
I'd basically start by dividing the numbers by 25, and start there.
Change the .03 to about .001-.002
Change the 1 to .04
Change the 2 to .08
And see how it works.

[jtb223]

Gerry,

That did work. I've still got a lot to learn.

Thanks for your time.

Jim

[jtb223]

I'm back. Thanks to Gerry the v-carve has improved but it's still not quite what I had hoped for. The attached photo shows the latest attempt. Not bad but the circles around the center floral and at the middle are still not quite round and the outside edges are okay in a few places but still scalloped in others.
I calibrated all three axis prior to the cut and when done the cutter came back to 0,0,0 quite well so if I'm missing steps somewhere in the middle of the cut it doesn't show up at the end.
The machine is a home built version of the X-Carve with four Wantai DQ542MA controllers running four LIN Engineering 5718M 2.8A steppers (two on the Y-axis, one slaved to the other) through a Chinese Savebase 5 axis breakout board.
I output the Vectric file using mach2/3 Arcs (inch) and controlled the machine with UCCNC software and the UC400ETH controller.

Is this the best that I can expect from this machine?

Thanks,

Jim