Unusual 3D waterline toolpath

[billo]

I'm trying to create a waterline toolpath for a series of parts I have. I'm testing with a simple disk shape with sides of varying steepness. I think I have the rough path working (using "Region Fill Style: Outside Offsets" instead of the default).

It seems like this should be pretty simple, but I can't get a finish toolpath that works. Here is what I have.

Attached is a 3D view of part, and the top and side views of the toolpath.

I would expect for a waterline to see "concentric" ovals, but instead I get crossing (or connecting) paths.

Is there some obvious option I'm missing?

Thanks,
Bill

[dave benson]

Hi Bill

Often with 3d shapes, especially with even more complex shapes than this, you can use
the boundary method to get consistent symmetrical toolpaths.
It the pics I’ve used a 3d shape and a polyline made from a detect edges command that is offset
one and a half tool diameters.

If at all possible, convert some of your 50 shapes to 2.5 d operations, as they can (depending on the shape)
give you an order of magnitude speed up in cutting time.

Dave

EDIT to add for most cases it's ok to use the 0.98 optimisations not the 0.97 legacy ones (there are valid reasons) to use the legacy
optimisations but not in this case.

[billo]

I tried various boundary shapes (detected edge with offsets) as you suggested. I didn't see much difference. The paths are still not concentric in seemingly random ways.

I thought my rough cut was good. However, even though the paths are concentric, they are shifted towards one side of the symmetric 3D object.

I applied a horizontal-method finish pass to the rough (which has a 2mm clearance), and the rough shows through the finish.

Given our different results it seems like it must be due to the characteristics of my particular .stl?

Attached are the nice-looking rough toolpath (but notice how the start/end points are not symmetric with the slope around the island), and the Camotic of rough and finish (with the rough peeking through).

[EddyCurrent]

As always, please attach the cb file otherwise everyone else just has to guess.

[billo]

My toolpaths make extensive use of styles. I've searched and I do not see a way to detach a toolpath from it's style and bring all of those style properties forward into the document.

That would seem to be the only way to make my .cb useful. Or, would it be useful anyway?

Bill

[billo]

To detach from the style: I copied from the Style to clipboard, then "paste format" onto my toolpath. That seemed to capture most of the appropriate properties from the style to the document.

I exported a new .3ds from Rhino with minimal triangles. This version has only 60 triangles. That is now in the .cb.

Waterline still produces a funky toolpath.

[dave benson]

Bill
The cb file as posted works fine, see pics.
You are having issues with the one of the previous mops,  the cb file doesn’t have them included
so it’s not possible to determine the issue.

In your posted file camotics info window there are  warnings about ARC issues
this can be a Style setting and also be a post processor issue.

You could try running the file with the default style settings and if the warnings go away in
camotics then it’s a style issue, if they don’t it’s likely to be a PP setting.

Dave

[billo]

Thank you very much Dave.

Your effort made me realize the problem must be in my Standard style.

There I found I had a non-default value for "Arc Fit Tolerance". Setting that back to the default of 0 fixed all of my problems.

(Although still working on the minor warnings in Camotics.)

Pics show the low-triangle and high-triangle simulations.

Bill

[lloydsp]

Hey!  Hooray!  Sure, it took a bit of insight from others to help, but YOU found the problem.

Congratulations.

Lloyd

[billo]

This forum has been a wonderful resource for me. Thanks to all who participate.

p.s. The Camotics "arc warnings" are because I had set my PP number format to 0.0# (which is plenty precise for us and makes the gcode easier to read).  I added another digit with 0.0## and Camotics is now happy.

Bill

[dave benson]

Glad you got it sorted Bill.