First time experience with Path workbench

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djm
Posts: 1
Joined: Sat May 28, 2022 9:06 am

First time experience with Path workbench

Post by djm »

Hi,

I just completed a CNC milling project using the Path workbench for the first time and thought I might share some observations. The part was a simple mounting bracket with a central bore, a few counterbored holes and filleted perimeter. It used two Path objects - the front side with most of the features, but a couple a counterbores on the back. I'm using FreeCAD 0.19.4 on Windows with the centroid post.

mounting_plate.png
mounting_plate.png (132.4 KiB) Viewed 2231 times
Screenshot 2022-05-28 234110.png
Screenshot 2022-05-28 234110.png (169.69 KiB) Viewed 2231 times

A few things either didn't work right or were surprising:

1) Using an adaptive path with the default settings for the central bore and surrounding countersinks yielded a bad path. AFAIK this is issue 6217. The workaround provided there of setting some stock to leave gave me a good toolpath.

badpath.jpg
badpath.jpg (886.54 KiB) Viewed 2231 times

2) For the second path object for the rear of the path, the counterbores were made using adaptive operations. However, if I included all four counterbores in the Base geometry then the resultant path was quite suboptimal: it process each bore sequentially at each depth before going deeper. This resulted in a lot of retraction, re-entry and jumping between holes. It would have been better if it could identify each bore as disjoint geometry and process it to full depth before moving on to the next. This was pretty easily avoided by using separate operations for each bore.

2) The generated path used only linear G1 and not circular G2/G3 moves. It worked fine but the file was many times larger than it needed to be and less hand-editable.

3) The options to use mist coolant in the operation or path object default page didn't seem to work. No M7/M9 codes were generated

4) Tool changes generated M6 codes, but no G43 height compensation. I can't think of a situation where I'd not want to use this.

5) Having to re-import tools and re-specify all the feeds/speeds for each Path object was a bit of a hassle and quite error-prone. Even being able to clone a Path object's settings would have helped.

Anyway, the part came out fine. I'm really impressed and grateful that I can do CAM with open-source tools, even if it needs a little babysitting.
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