Jerky Tool Movement

[richardsalzman]

I am new to CAM and machining.  I just finished converting a 2HP benchtop mill to CNC and have run 5 parts to date.  I am making these parts by watching an online CAM tutorial.  I was doing a dry run with part #6 (attached below) and noticed that during the 3D Adaptive tool path there was some jerking motion.  I reduced the no engagement feed rate from 90 ipm to 60 ipm and the jerking motion was reduced dramatically.  I could probably run the part with either the 90 or 60 imp no engagement feed rate however the jerking motion appears to make the mill shake a bit and I think I should try to avoid this.  At 60 imp, the jerking was quite minimal and may be just fine.

Are there other options within Fusion to smooth out these movements action?  I could probably adjust some of the acceleration parameters on my mill, but I thought I would see if it can be controlled via Fusion settings.

Thanks... Richard

[Laurens-3DTechDraw]

Hi Man,

If the whole mill is shaking it will have an effect on a lot of things, so if can be avoided I would do it.
I turned on the points in toolpath visibility and saw your adaptive had a lot of points which I think are causing your problems;

If this is causing problems is highly control and acceleration settings dependent. But it's a good place to start checking. To create less points there is the smoothing option in the passes tab;

Generally, it is set to 0.1*tolerance which I think it kind of useless, so I would go for the same as your tolerance.

So same toolpath with a lot fewer points. Try that and see if it's better.

[richardsalzman]

Thanks for the rapid reply.  I will try changing the smoothing to .004 and see how it works.  Just curious, how do you turn on points in the toolpath?

I will also check with the Centroid CNC (the controller dudes) to see how I can adjust the acceleration parameters of the mill.

Thanks for you help!

[richardsalzman]

Hello again.  I did some further investigating.  I changed the mills acceleration parameter and it had no effect at all.  I reduced the no engagement feed rate to 45 ipm and it too had very little effect.  If I try increase the feed rate on the mill while running the gcode, the problem gets much worse.  

I highlighted the sections of the toolpath on the attached image where the jerking is the worst.  Would it be a good idea for me to change the "High Feedrate Mode"?

Thanks... Richard

[richardsalzman]

Quick thought.  Here is a video of the toolpath.  Perhaps I am must being overly cautious.

Here is a video of this toolpath running at 100% federate (18 imp).

https://www.dropbox.com/s/pmyhbwsy8ql9lsz/20230217_111005.mp4?dl=0

If you think it looks good... I will run with it!

Thanks... Richard

[richardsalzman · Accepted solution]

Thanks for all your help.  I ran the part and it ran quite well.  I had another problem but thanks for all your help with this issue.

All the best... Richard