UCCNC does not move the spindle smoothly

[RJS]

I have been having an issue using UCCNC with the UC100 where the motion of the spindle slows and speeds up between lines and arcs in the nc file. With the laser this causes the laser to make deeper and wider burns where the software is slowing down the motion of the laser. When cutting with the spindle the changes in speed cause the bit to cut further into the work piece in the areas where is slows down. This requires substantial sanding to remove these. I was not having this issue with the other software program I was using before I purchased UCCNC. I had this posted in a different forum but I was concerned it was posted in the wrong section of the forum so i am starting a new thread here.

To show what is happening I posted 2 videos on YouTube

This video is using another software program to control the CNC and you can see the spindle smoothly moves around the path
https://youtu.be/ok0UQ0SdYk4

This video is using UCCNC and can see the issue i am talking about.
https://youtu.be/O_-9CvHlXvA

I have also included the profile and the NC file used for both software programs.

I have tried changing the acceleration, the stop and angle degrees and the corner error max with no really improvement. Please let me know if I am doing something wrong or if not please consider correct this. Please let me know if you have any questions or need additional information.

Thanks

RJS

[cncdrive]

The motion of the spindle is a simple PWM whose duty cycle depends on the programmed S value, e.g. S15000 in the code you posted. It is just a continous pulse with defined duty cycle.
So, the spindle speed does not depends on the motion executed. The PWM is set once when the S is programmed and it keeps the value, there is no spindle speed calculation based on the motion.
This means that no CV settings will change the spindle speed.

We will verify the issue with measuring out the PWM using your profile file and running your code,
but there is one question, which version of the UCCNC are you running?

[RJS]

I am not referring to how fast the spindle is spinning but how the spindle motor itself is being moved around on the X and Y axis. The spindle speed is fine. If you can review the videos you will be able see what I mean.

Thanks,

RJS

[cncdrive]

I gave your files to my collegue, he will hopefully manage to run it tomorrow and give me the results, so then I can advice you...

[ger21]

If you watch his videos, you'll see that the issue appears to be with his CV settings.

[RJS]

ger21,

It does look at way but I have double checked and best I can tell it is set to constant velocity in the nc file (G21 G90 G91.1 G64 G40) and in the general settings for UCCNC.

Thanks,

RJS

[ger21]

Yes, but you need to adjust your CV settings. There are 5-6 settings that can be adjusted.

[Robertspark]

as attached

[cncdrive]

My collegue said that for first sight the issue seems to be that you have arcs with 0.001 units size which seems to cause the problem.
He will further study the issue, but the question for now is why is it nessessary to have this small size of circles in the code when it is about 3 times smaller than your axes step size (based on your profile file datas)?

[RJS]

I did not realize it had such tiny movements, which now make perfect sense as to what was happening. I have been using ViaCAD Pro and apparently it outputs dozens of tiny lines and arcs. I used CAMBam's ArcFit and it substantially reduced the number of elements and thus increasing the distance between the lines and arcs. Now UCCNC run smoothly.

Thank you so much for helping with this, you all are the best!

Randy