Hi!
The "Face milling" strategy under "Curve Machining" is yielding weird results for me. Specifically, it seems to be violating the stepover in the last pass in every XY slice (i.e. just before lead out).
As shown in the photo, my stepover is set to 6mm. However in the last pass in every XY slice, it is doubling the stepover to 12mm. I have tried it in both, 2019 and 2018.
Hi,
This is by design, and as requested to us by the customers we consulted when designing the strategy. You're not the first one to find it surprising, though.
On the final pass, the tool attacks the material from the other side of the block. If we kept using the stepover instead, you would end up with a final pass to remove just a thin sliver of material on the edge of the block and we have been advised that it's not a good use of facing tools.
If you compare the spacing between your two final passes to the tool diameter, you should find that it clears all material.
@precicam wrote:
Hi!
Thanks for the reply. I would love to know more about the theory behind this.
I had marked this as the solution after I saw that there was sufficient overlap between the last & second last passes. For this I had generated the toolpath with a dia 12mm endmill. I also tried the same with a dia 12 R 1.0 corner radius cutter. This also worked.
However, as in my original question, when tried with a dia 12 R 0.5 corner radius cutter, the overlap is very very small (on the order of the tolerance). I don't know why the results are different with different tools.
Kindly see the attached project so you may recreate the problem.
Hi @precicam,
Thanks for the feedback.
I had a look at the supplied PowerMill project and found that for both the toolpaths (12E and 12R0.5 <-- problem) created with EndMill 12 and Tip radius 12 R0.5 respectively has similar passes (Even the last pass).
Here it seems that PowerMill takes into consideration the Stepover, tool Diameter as well as Block width to machine. Having said this, if I slightly change the stepover for toolpath 12R0.5 <-- problem to 6.01 then I am getting a better result as can be seen from the image,
So I will suggest to try changing the required stepover slightly and see if you get the desired result.
This behavior of last pass (not similar as stepover) only happen when the stepover used is less than half of the cutter diameter. If you use the stepover greater than half of the cutter diameter we don't encounter this behavior. The reason behind it is already mentioned by @emilie.a.
I hope this helps.
Regards,
