Beginner's problems with step files

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chrisb
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Re: Beginner's problems with step files

Post by chrisb »

They are no separate items, PartDesign glues automatically. In certain cases (flat or cylindrical faces) Refine=true removes these seam lines.
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GeneFC
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Re: Beginner's problems with step files

Post by GeneFC »

Siltti wrote: Tue Jan 24, 2023 11:22 am I recognize that this is a bit off topic question, but there is high probability some Path workbench users have been facing this before, since Step has been the most popular geometry exchange format to CAM.
I am sure that is possible, but there has been almost no forum discussion.

I work 100% with models I have created from a blank computer screen, and I suspect most other users work with (mostly) self-created models.

There has been a growing interest in working on downloaded STL files for 3D printing but those do not use the Path WB for output.

In any case I already tried to explain what you need to do. The model you have, whether new or imported, needs to be made ready for CAM before you try to create G-code for output. That could include adding extra area for the cutter to overlap the edges, filling holes, removing protrusions, etc.

I sometimes create several clones of the model to add (or subtract) those helper elements. That sort of modification can usually be performed quite rapidly.

Yes, ideally FreeCAD or any software would know exactly what you want, but that feature is not quite ready. 8-)

Gene
Siltti
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Re: Beginner's problems with step files

Post by Siltti »

Dea Sirs,

many thanks chrisb! I found the same switch. It is quite confusing since by the book a body should be continuous united solid, so what's the point of showing non-existing surfaces. Well anyway that solved my problem and now I can continue with original questions.

Only adative operation seem to be able to handle a surface having internal island. I tried with MillFace and Pocket, but they ignored the large hole and cut it's frame flat. Neither accept island edges as Base Geometry input, so they are not aware of it. Which is pity, because they have extension possibility. With adptive I have still the remining corner material problem.

There are two possibilities: eiher make extension the hard way, e.g. fill in extra material to ensure entire surface gets cut, or split the surface through the island thus removing it's isolation. Former one is possible, but I am a bit reluctant to use it due to some problems in consequent Path operations. Latter one requires splitting surface, which I assume is possible in FC as it is a basic function in other CAD:s. Before trying it, can you straigh see a reason why MillFace wouldn't work with splitted halves? Splitting line can have soft extensions to avoid remainders.

Best regards,

Timo
jescombe
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Re: Beginner's problems with step files

Post by jescombe »

I had a little play with your file. For simplicity I removed everything except the first model, which I then copied and transformed (rotated 180 degrees to get to the lower faces).

A couple of observations;

Using adaptive for the larger faces, I was able to extend the necessary edges to clear them - as long as I selected the 'face' for the base geometry and not the edges. However, when using the face as the geometry like this, the adaptive path steers around all the holes.

If I select all the relevant edges as the base geometry for an adaptive path, then the generated path machines right over the holes. However, am then unable to select any edges as extensions, so left with the issue of not clearing the external corners correctly.

Bit of a catch 22! Not sure how to get around that with adaptive, other than perhaps creating a defeatured version of the model?
jescombe
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Re: Beginner's problems with step files

Post by jescombe »

I had a look at a more basic model, containing a pocket that reaches the edge of the part, and a through hole. For this test part, it could be machined correctly using an adaptive on the face of the pocket, with 'use outline' and the two external wires selected as extensions..

Taking another look at the OP's original model, 'use outline' doesn't generate a path for the large flat faces at all (using either adaptive or pocket). The problem appears to be the holes in the face. Once they are removed, the adaptive path is generated as expected, and can be extended to clear the 'open' edges of the face.

Looking at the Adaptive code, can see it is expecting face.Wires[0] to form the outline, so was suspicious that wasn't the case for this particular model. Changing the code to use face.OuterWire appears to resolve the issue for me.

Pinging @sliptonic for awareness, I've no idea whether this change seems sensible or not..

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Siltti
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Re: Beginner's problems with step files

Post by Siltti »

Dear Sirs,

there are problems with the Job_in (Body_in) side of tasks. Job_out can be solved successfully because a frame is left to the surface.

You can see that by running simulations. In Job_in there will always be some remaining material on the edges because mill does not want to go over and out from surface edges. At the bottom I solved this by adding non-existing pads to the legs, but at the top there will always be corner and some side remainders. I tried both using the surface edges (Adaptive 003) and surface (Adaptive004). Cutting route indicates that edges will not be completely cleaned. Using the surface for geometry does not even reach the bottom, but turns back about 10mm too high (Adaptive004). This was the reason for my initial trial using some sketch lines for surface definition to extend the area in critical position.

I filled the holes to enable milling over them. Something that should rather be handled by ordering the milling operation ignore them, because checking the result leaves possibility to mistakes when the holes aren't visible but are drilled in the job. I think I have now tried all possible combination of switches (outline etc), but not getting the surface properly cleaned without additional manual programming.

I couldn't quite understand the change you made, should I learn coding and recompile the code or is it going to be published somewhere?

Best regards,

Timo
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jescombe
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Re: Beginner's problems with step files

Post by jescombe »

Siltti wrote: Thu Jan 26, 2023 2:40 pm I couldn't quite understand the change you made, should I learn coding and recompile the code or is it going to be published somewhere?
No, I was just curious why 'use outline' was failing when the holes were present. Was more of an observation for the developers..

Regarding clearing the edges, I think you just need add extensions where necessary? Attaching my attempt at the top(?) side - with holes removed for simplicity. This has three adaptive operations to clear the main surface at the different levels, and then profiles the outside edge (with holding tags)..
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Test_run_top_only.FCStd
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chrisb
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Re: Beginner's problems with step files

Post by chrisb »

You can use a path pocket to clear just the ends. It would need some extra rapid moves, but it would fully automate the milling paths.

Beyond that I removed in the attached file the (to me) unnecessary two bodies.
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jescombe
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Re: Beginner's problems with step files

Post by jescombe »

Just for completeness, I also had a go at the other side. Created from the same defeatured model, just rotated 180 degrees around Y axis within the Job model properties..

An adaptive for the clearing, plus a profiling pass. Please note the profiling gives no thought to the work holding, and will cut straight through the holding tags from the first operation! ;)

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Test_run_bottom_only.FCStd
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Siltti
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Re: Beginner's problems with step files

Post by Siltti »

Dear Sirs,

how could I use extension as they are not currently available with Adaptive (FC 20.02) as GeneFC also confirmed in his previous message? Having that available would solve most of the problems I am strugling with now.

Best regards,

Timo
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