Parallel Finish [to edge] not recognizing surface edge

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MS1640987267
Posts: 4
Joined: Sat Jan 01, 2022 1:00 am

Parallel Finish [to edge] not recognizing surface edge

Post by MS1640987267 »

I'm having trouble with a parallel finishing operation.

I am trying to parallel finish a surface that has a vertical feature. I always use "Surface Extent Condition" = TO, because otherwise the tool path always gouges into the vertical feature. The gouge in the part is mirrored in the simulation, so there is a problem in the parallel tool path. Using surface extent condition solves the problem.

Today I have a file that won't cooperate. The part is a scaled version of parts I have programmed like this in the past. What is happening is that when I select just the perimeter serface and select condition "to", it ignores the inner boundary and machines over the entire vertical feature and raised surface.
The bad tool path I am getting.
The bad tool path I am getting.
2024-03-31 15_07_44-2024-03-31 (Medium) Silicone Bottom Mold.3dm (45 MB) - Rhino 7 Commercial - [Per.jpg (221.91 KiB) Viewed 9097 times
It should look like this:
How the parallel finish tool path should look.
How the parallel finish tool path should look.
2024-03-31 15_06_13-test 2023-11-16 (Small) Silicone Top Mold CAM.3dm (7 MB) - Rhino 7 Commercial - .jpg (116.47 KiB) Viewed 9097 times
I've done a few experiments while troubleshooting. I deleted the vertical feature leaving a single surface with a hole in the middle. It went past the inner edge. Then I started over, creating a new file, re-importing the part. No change. I analyzed the surface, but I didn't find any issues. I duplicated edges and analyzed with curvegraph, and no self-intersecting edges or other oddities detected.

I have re-installed Rhino and RhinoCAM (v2021). No change. I opened another version of the exact same part to test, and it behaved normally (screen shot).

Here I used a larger step-over to show a simulation of what is happening. The parallel pass is running over the entire part, and then it makes a second pass over the raised feature.
It runs a parallel pass over the entire part, then comes back and does another parallel pass over the vertical feature
It runs a parallel pass over the entire part, then comes back and does another parallel pass over the vertical feature
2024-03-31 15_41_37-Rhino 7 Commercial - [Perspective].jpg (225.28 KiB) Viewed 9097 times
Last edited by MS1640987267 on Sun Mar 31, 2024 2:38 pm, edited 1 time in total.
MS1640987267
Posts: 4
Joined: Sat Jan 01, 2022 1:00 am

Re: Parallel Finish [to edge] not recognizing surface edge

Post by MS1640987267 »

Here's a screen shot of the control geometry selection.
2024-03-31 15_46_02-Rhino 7 Commercial - [Perspective].jpg
2024-03-31 15_46_02-Rhino 7 Commercial - [Perspective].jpg (308.66 KiB) Viewed 9096 times
Example of eliminating the raised feature:
2024-03-31 15_23_29-2024-03-31 (Medium) Silicone Bottom Mold.3dm (45 MB) - Rhino 7 Commercial - [Per.jpg
2024-03-31 15_23_29-2024-03-31 (Medium) Silicone Bottom Mold.3dm (45 MB) - Rhino 7 Commercial - [Per.jpg (138.3 KiB) Viewed 9095 times
MS1640987267
Posts: 4
Joined: Sat Jan 01, 2022 1:00 am

Re: Parallel Finish [to edge] not recognizing surface edge

Post by MS1640987267 »

Problem avoided, not solved!

I offset the surface edge by 1/2 the cutter diameter, creating a curve that I could use as a boundary. Then I selected the region between the edges and the new curve.

I'd still like to know what went off the rails on this one!
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