Small nearly air cuts on 3D adaptive

[dallasjcutler]

Doing 3D adaptive on all of my parts I get a lot of these little basically meaningless cuts. When cutting their is a small bit of sound so it is technically cutting something but its in the thousandths of thickness. To decrease on the first op it seems like dropping tolerance real small helps a fair bit but makes for a real heavy file. On the Rest machining second op (2nd pic) I can reduce them increasing Radial stock to leave but that's not quite what I want.

Any other tricks to getting rid of these wasted moves without creating a huge file?

[LibertyMachine]

I assume the wasted moves we are supposed to be looking at are present in the top photo, in the form of very small Z moves for each roughing pass?

Tolerance and Smoothing (to my understanding) in Adaptive only effect the toolpath in the XY motion. ie; the contour cutting.

I think what you really want to be looking at is your Maximum Roughing Stepdown and Fine Stepdown. This is what controls the depth of each pass. Increase the value if the Fine Stepdown to what you want to see for a cut and that should do the trick, I would think

[dallasjcutler]

Sorry, probably could have been more clear. The cuts I'm referring to are the short cuts between the major step downs (blue lines cutting in X-Y), the stepping back up portion. Obviously I can get rid of them by removing those or reducing those steps but I have 3D tool paths that those are also clearing.

I took the second screen shot to show how many of these small cuts are coming up. Played with it some more last night, though Ive been trying to find a solution for months, and smoothing seems to make it worse and high tolerance doesn't actually help that much either.

[LibertyMachine]

Is this a model you can share? I'd like to fully understand your geometry selections as well as your cutting parameters

[Steinwerks]

What do you have set for your Minimum Axial Engagement value? This is the best way to help reduce the small cuts you're talking about.

[Steinwerks]

Here's a quick example using a random part from GrabCAD:

Minimum Axial Engagement set to 0:

Minimum Axial Engagement set to .25":

Note the 97k difference in toolpath size, although the majority of the path hasn't changed much (Smoothing is off as well). The only difference in this path is the Minimum Axial Engagement setting. It usually won't eliminate ALL of those moves but it can certainly help drastically.

Edit: I have Accuracy set to .0001" also. Turning on .001" smoothing made the first toolpath 129.3k and the second 101.8k respectively.

[dallasjcutler]

Alright Gents, Im not sure why Axial engagement works since its seems like a radial cut issues, but that seems to be the hot ticket here. Setting Axial engagement to the same as my Step up increment seems to get rid of 95% of those small cuts.

Thanks a ton guys!

[LibertyMachine]

Axial cut is up and down step-overs (Z), radial is left and right (XY)

[Steinwerks]

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@dallasjcutler wrote:

Alright Gents, Im not sure why Axial engagement works since its seems like a radial cut issues, but that seems to be the hot ticket here. Setting Axial engagement to the same as my Step up increment seems to get rid of 95% of those small cuts.

Thanks a ton guys!

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I'm not the best at explaining why I see things work but I'll give it a shot here:

Minimum Axial Engagement forces the toolpath to adhere to depth limits. While the STL generated by the CAM in the background may be leaving stock in some places due to tolerance setting for the Adaptive operation (we're talking tenths here in some cases) there is still stock to be removed, so the toolpath comes back and removes these. The Axial Engagement setting overrides these small remainders and forces the toolpath to skip small axial areas, potentially leaving stock (see the tooltip). I have not found these to be of any significant issue, though.

(@al.whatmough @jeff.walters Does this approximate what's happening? Makes sense to me, so hoping I'm correct here.)

If the previous answer on the Minimum Axial Engagement setting solved your problem, please mark it as such so others are able to find it.

[dallasjcutler]

After working on it more, it doesn't seem this is the fix but for some particular instances it helps.

I'm seeing these small cuts as a radial issue where it seems to be cutting extra material in X/Y but like .000X" depth left from earlier tool paths. What I don't get is why it steps up the small X/Y cuts in Z at the same X/Y location. I've tried turning all the knobs I can think of that logically make sense to me but maybe haven't gone far enough on Axial depth or tolerance. Will keep playing with it and report back if I find the right parameter to adjust.

I can certainly share my model for another to try if there is a simple way to do it.

[Steinwerks]

If you share it I'd be glad to take a look when I've got a moment. Others likely would as well.