[V1 - 70] TOOLPATH FAILS TO FOLLOW SURFACE WITH LARGER STEP OVER VALUES

[Bob La Londe]

I have fought with this for years. 

How can I get the finish operation to ACTUALLY FOLLOW THE FINISH SURFACE. 

[lloydsp]

I'm sorry.  I don't understand.

Perhaps I don't need to finish to the degree you do, but I've never had a problem.  Is this only on '3D' surfaces, or on geometric designs, also?

I get finishes on geometric designs fine-enough for casting resins with decent release properties.

Lloyd

[Bob La Londe]

You can't see in the attached picture that the roughing operation clearing follows the surface (less roughing clearance), but the finish operation does not even come close at the end of the surface? 

You can't see in the CamBam view that the tool paths shown clearly do not follow the surface either? 

This is NOT a fine finish.  Its a very coarse finish with a step over of 50%. 

When doing a fine finish the problem is much less pronounced, but it is still there.  Often it is small enough that you can ignore it, but the problem still is there. 

[Bob La Londe]

Maybe this image with just the finish operation will show what its NOT doing. 

It is not a resolution issue.  Even with the resolution set at 0.005 it still occurs. 

.0625 (tool diamter) x .005 gives a calculation distance of .0003125.  Its NOT a resolution setting issue. 

[Bubba]

Shooting in the dark here Bob. Did you considered step down on tool diameter? Just an idea.. Good luck.

[Bob La Londe]

Shooting in the dark here Bob. Did you considered step down on tool diameter? Just an idea.. Good luck.

If I reduce from a .0625 to a .060 tool the problem is reduced slightly but not eliminated.  Its almost like the result of the step over calculation is affecting the resolution calculation in some places.

[Bob La Londe]

I did a quick simulation with DeskProto and with VisualMill.  I don't know how to use those, but the basic scanline operation did not reveal some invisible problem with the surface.  They both appear to roughly follow the surface properly. 

[dh42]

Hello

I do a lot of test, and IHMO the problem is not with the finish but with the roughing ; the WL rough cut too much material.

on the picture, the yellow cut is done with WL rough and the brown with the same mop (a copy) but with scanline mode (both with rough clearance =0.08) ; as you can see there is too much material removed with the WL mop.

Also, sometimes I got strange toolpath with the WL ...

++
David

[Bob La Londe]

Hello

I do a lot of test, and IHMO the problem is not with the finish but with the roughing ; the WL rough cut too much material.

on the picture, the yellow cut is done with WL rough and the brown with the same mop (a copy) but with scanline mode (both with rough clearance =0.08) ; as you can see there is too much material removed with the WL mop.

Also, sometimes I got strange toolpath with the WL ...

++
David

If you look at the image I posted with JUST AND ONLY AND NOTHING BUT the finish operation you can clearly see that the finish operation does NOT finish. 

Even if the roughing operation was perfect the finish operation is still broken. 

[Bob La Londe]

If I change the STEPOVER from 0.5 (desired) to 0.05 (not desired) it comes very close to a proper finish. 

The very crappy and tedious work around is to convert the tool paths to geometry and remove 9 out of 10 of the resulting polylines leaving every tenth line behind.  This slow and onerous and I can not justify in good conscience charging the customer for that time. 

[Bob La Londe]

See image. 

Clearly CamBam could produce better tool paths.  It just REFUSES to do so. 

The image shows a simulation using the tedious obnoxious ridiculous work around and the original UNCHANGED roughing operation.  It sure doesn't look like the roughing operation was the problem. 

[dh42]

what I do for ends is to use a crossed cut (vertical/horizontal) only for finishing the ends. (and with a smaller steep over just for that)

also, use a positive " Boundary Margin " = 1/2 of the tool radius so the center of the tool go exactly to the boundary line, it can help sometimes.

++
David

[Bob La Londe]

what I do for ends is to use a crossed cut (vertical/horizontal) only for finishing the ends. (and with a smaller steep over just for that)

also, use a positive " Boundary Margin " = 1/2 of the tool radius so the center of the tool go exactly to the boundary line, it can help sometimes.

++
David

CB generates better tool paths if the stepover is smaller.  My image in my previous post shows the results. 

[Bob La Londe]

Please move this to bug reports.  While I have managed a workaround, clearly this is a flaw in the toolpath generation.

[Garyhlucas]

I replied to this thread earlier but it appears it got lost. As I understand it CB assumes a square end tool for roughing. So using a ball mill would leave more material behind. So to me the question would be is finish function also using a square end tool thus leaving a lot of material behind when using a ball mill.  I suggest trying a very small diameter tool with a fairly large stepover to see what that looks like.