CAM: Ability to have Multi-pass profile operations

[davidgilkaufman]

Is there an existing issue for this?

• [X] I have searched the existing issues

Problem description

I want to profile a contour, but there is too much material left to remove in all in one pass, so I need to do multiple profile passes. Other software makes this easy; FreeCAD should also have an easy way to generate these successive offset profile passes. I propose adding "number of passes" (integer) and "pass step over" (formula) parameters to the profile operation UI to control generation of multiple successive profile passes. By default, "number of passes" will be 1, and "pass step over" will be disabled (auto enables for larger "number of passes"; default value OpToolDiameter)

Full version info

Version 0.21.2-24
Revision number 33771 (git)
Release date 2023/11/14 02:33:39
Operating system Arch Linux
Word size 64-bit
Branch makepkg
Hash b9bfa5c

Subproject(s) affected?

CAM

Anything else?

I intend to implement this feature myself.

I started a forum thread with a detailed description of the problem and a screenshot of the desired paths (and the workaround I used to generate them).

@spanner888 found an older thread about a prior attempt to implement a version of this feature, and disagreement over when and how it should be done. As best I can tell, this ultimately resulted in a macro, but nothing integrated into the profile operation.

The "when" part of this disagreement I believe is now deprecated, since much time has passed, but I'd like to address some comments from a post by @mlampert in that thread. @mlampert objected to the feature saying that a profile operation is a line-following operation, and that the proposed feature changed it to an area-clearing operation, and that this is the domain of a pocket operation and not a profile operation.

I'm not intimately familiar with the prior attempt to implement this feature, but in my opinion, the version I am proposing here should not be subject to this objection. The intended use case of this feature is to generate a small number of profile passes -- each one a line-following operation -- with the goal of profiling a surface without cutting too much material in a single pass. This use case is important and not well served by FreeCAD's current features, and imo even with multiple passes it is still correct to think of it as a line-following profile operation. I would agree that a user could pick a very large number of passes to use this feature to cut an area, but I would call this an abuse/misuse of the feature, not an overreach of the profile operation into the land of pocketing.

For additional context, I want to refer to Fusion 360's Contour 2D operation, which has a "passes" tab, with controls for the number of passes and the step over. I believe it is standard to include these features in a contour-following operation.

I will post the contents of this issue at the end of my forum thread for further discussion -- please discuss it there.

Code of Conduct

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[GeneGH]

This would be a very useful expansion of the profile operation. I have the same concern about chewing too much metal at one time or creating "slotting" action in stock corners, for example.

The model reference remains a single edge, similar to profile, not an area which is similar to pocket.

The distinction between the names "profile" and "area-clearing" is only semantics. Call it whatever gets the most votes.

[AdrianCM95]

This issue deserves attention. The path generated is limited to the boundary of the stock or the surface to machine. If there is no material around it, the path generator should be able to take advantage of this condition and generate a path similar to this picture.

In addition, being able to setup a start point outside of the stock boundaries would be helpful to avoid that the mill is "drilling" at the start of each operation.

I hope this suggestion is useful.

[luvtofish]

I concur with the need for a multi pass profiling step over capability. Many times the stock in use is larger than the finished part which forces an undesirable slot milling operation during the profile op.