Beginner's problems with step files

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Siltti
Posts: 39
Joined: Tue Apr 19, 2016 6:27 am

Beginner's problems with step files

Post by Siltti »

Hello. First I must say humbe thanks to Path developers, you have done tremendous work! Then as usual with beginners, I have been banging my head against a wall with some newby problems. Using FC 20.20 I import quite complicated Step files, which are too labourious to be remodel with Freecad. However I like to use FC to finalise some details and define necessary helping features. There I come to a dead ends:

1. Step model was imported to a new body and base feature created from it. I can add pads to it and cut holes to it, so conversion to solid seems ot be Ok. Then I would like to define face milling limits locally outside of surfaces, because I need to expand the milling area in sharp corners. Otherways a small concave column will be left there when milling tool cuts along the edges. I didn't find any build in function in FC/Path for this. If there is, please tell where to find it and how it works.

I tried several approaches with sketches, without adding material to the model. A sketch under body is not shown at all when defining operation to a job. Body and job using it seem to be totally independent data structures. I didn't even succeed to create a sketch directly to job, but was able to drag and drop one from body to it. Then it was visible when defining MillFace, but the sketch lines and circles were not pickable to BaseGeometry, whatever I tried. The only way I can imagine, is to add dummy material to corners, but that will make problems in other Path Operations and head ache in consequent milling/drilling steps' operations. So how to use sketch lines and circles in Base Geometry?

2. Since my part is going to be milled and drilled from several sides, I have added multiple bodies with their base feature into my document, one for each orientation. First body is in it's original orientation good for first job (step was greated that way), others have been rotated and shifted according to removed material to have constant bottom height and origin on the table. The common imported Step model for all bodies is crayed out at the top of the document feature tree.

This approach does not work in expected way, because the sketches, although dragged to the mentioned bodies jobs, seem to refer to the original grayed Step body (blue symbol means body?) orientation. When dragging them to the other bodies, they turn to surpricing orientations and external sketch references stick to original details, which are not present in the curent body. Again my best effort didn't work, but I assume somebody has solved this already ages ago. Due to limited knowledge of correct wording used in this context, I couldn'd find any references in Forum, so please give correct search terms or links to begin with.

Best regards,

Timo
GeneFC
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Re: Beginner's problems with step files

Post by GeneFC »

Siltti wrote: Mon Jan 23, 2023 11:29 am
It sounds like what you are attempting should be readily possible, but I cannot fully picture the needed actions from your description.

Can you include an example FCStd file and perhaps an image that shows what you are trying to do?

The sketches are Likely attached incorrectly, and they may not be positioned in the right places, but it is unclear to me.

Gene
Siltti
Posts: 39
Joined: Tue Apr 19, 2016 6:27 am

Re: Beginner's problems with step files

Post by Siltti »

Dear Sir,

please find enclosed my model showing some of the problems. In the -Y end there is lot of material which I can't remove, milling leaves some corners outside and stops prematurely inside. I should be able to somehow continue milling further, over the surface edge to prevent manual programming. As explained in my previous message, my sketch does not show up when I define the Base Geometry.

There may be other approaches like copying and extending surfaces or something alike, but not knowing how to do that in FC, I am a bit stuck. Any tips are most wellcome!

A tiny wish would be different colouring for different operations, it would make checking much more comprehensive. I understand that then the stock color should be changed somehow, sounds to be doable.

I also tried to use the stock remainder from job_out for job_in, but it took overnight to get is processed and process just jammed. Might be tolerance problem or something, but the resulting file was really huge and action impractical slow. Also tried sewing it, but with less success.

Best regards,

Timo
Attachments
Test_run.7z
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Siltti
Posts: 39
Joined: Tue Apr 19, 2016 6:27 am

Re: Beginner's problems with step files

Post by Siltti »

Dear Sir,

please find attached pictures showing where I managed to get. Target part is in the previous message's attachment file.

Best regards,

Timo
Attachments
Outside.PNG
Outside.PNG (89.75 KiB) Viewed 1178 times
Inside.PNG
Inside.PNG (39.04 KiB) Viewed 1178 times
GeneFC
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Re: Beginner's problems with step files

Post by GeneFC »

Siltti wrote: Mon Jan 23, 2023 5:51 pm
1. The adaptive operation will not move the cutter outside the surface being processed. Adaptive also requires more that just the tool width, because by its nature the adaptive operation works in circles and other shapes. It is not just a straight line pattern.

If you switch to the Pocket Shape operation you can reach all the locations in the -Y direction.

Sometimes it is possible to use "Extensions" to go beyond the borders of the model, but I did not make that work for adaptive.

2. There is no sketch in your sample file, so I cannot comment further.

3. The "out-in" option to process only the remaining material after some operations are already done is a requested improvement to the Path WB, but it does not yet exist.

Gene
Siltti
Posts: 39
Joined: Tue Apr 19, 2016 6:27 am

Re: Beginner's problems with step files

Post by Siltti »

Dear Sir,

1. A non-linear cutting pattern is fine, if it would be entendable to the edges. It might be even better because it begins from centre and thick material around makes the area stiffer than with linear operation. Thanks for tip anyway, I will try the pocket insted. Yes, I noticed that extension is not available for adaptive, that was the reason for tryong a sketch to extend some edges. Just a plain guess that something like that could work.

2. There is a sketch in model as shown in attached picture. It shows up before zipping the file, could it be dropped out somehow... I can send the model unzipped if it is missing. In this version it is in the Body structure, dragging and dropping it to job creates error messages, which meaning I don't yet understand.

3. The mesh of remaining material become very dense in my trial. In OpenFlow there is a mesh generator called SnappyHexMesh. It has pretty good algorithms for joining dense mesh to few cells only in unimportant areas. Might be worth taking a look for this application.

Best regards,

Timo
Attachments
Sketch.PNG
Sketch.PNG (60.51 KiB) Viewed 1111 times
Model.PNG
Model.PNG (63.11 KiB) Viewed 1111 times
Siltti
Posts: 39
Joined: Tue Apr 19, 2016 6:27 am

Re: Beginner's problems with step files

Post by Siltti »

Dear Sir,

I found a pocket version I tried already before. There is a problem caused by the holes in the surface. Pocket wants to leave them intact like it does for the extruded hole frame. Watching lots of tutorial, I saw in some note about ignoring holes, but I am not sure whether it applied to this version and pocket operation. Couldn't find anything like that any more.

Because of these holes I assumed that using a sketch having preferred outline and inner objects to be left intact, would probably solve the problem. However I can't still use the sketch wit a pocket either. Is it in wrong place in the body?

Best reagrds,

Timo
Attachments
Pocket.PNG
Pocket.PNG (92.85 KiB) Viewed 1093 times
GeneFC
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Re: Beginner's problems with step files

Post by GeneFC »

OK, I found the sketch, and it can be made visible with the right selection of the space bar.

What do you plan to do with the sketch in the Job?

I suspect you are trying to use the sketch to somehow control the Path operations. I do not know any way to do that. You can use the sketch to actually add some real 3D structure to the BaseFeature. Then the Path WB can use it.

Gene
Siltti
Posts: 39
Joined: Tue Apr 19, 2016 6:27 am

Re: Beginner's problems with step files

Post by Siltti »

Dear Sir,

Yes, sketch can be made visible, but it's contents disappear when one makes new operation into a job and tries to use it. As mentioned, I tried to drag a sketch to job, it remained visible, but even then the lines and circles from sketch were not pickable to Base Geometry.

My intention was to use the sketch for adding some outline for milled area instead of solid's edges which don't clear the area completely in sharp corners, and use sketch instead of surfaces with holes because ot he remaining studs in the holes. Did you also notice that there is remainder material between a hole and edge when tool does not fit there. So even drilling the holes before milling does not solve the problem. It would have been a method to get rid of remaining leftovers in the holes, tight areas and corners. Island edges can be picked from geometry, no need to copy them to sketch.

It was unclear if a sketch approach could have been working. Now we know that sketch geometry can't be used but some other tricks are definitely needed. One is making multiple temporary Step models with expanded corners. Works but requires lot of effort, multiple bodies and multiple jobs. I tried before with assembly Steps including copied additional surfaces without holes, but they created other types of problems. It seems there is currently no easy solution, but I will try to find a workaround.

Best regards,

Timo
Siltti
Posts: 39
Joined: Tue Apr 19, 2016 6:27 am

Re: Beginner's problems with step files

Post by Siltti »

Dear Sir,

Another problem popping to daylight: I import my Step file, create a new body into my document in Part Design, get a BaseFeature linked to imported Step model just as explained in Wiki and Forum.

I can sketch to it's surface and cut a pocket through it, BaseFeature is obviously a solid because hole has internal surface. Works as expected.

Then I would like to get rid of the problematic holes, in order to enable Path operation with clean surface. But I can't get a pad becoming united with my BaseFeature. They always remain separate items, there is an overlapping surface coming from the pad (please see attached picture).

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. Therefore I ask, if there is a prevention switch somewhere or another trick to get them united in FC? I understood from many documents that it should happen automatically, but no. Even boolean does not unite them. If this sounds to be a bug, has it been working in a particular previous versions of FC?

Best regards,

Timo
Attachments
Hole.PNG
Hole.PNG (10.4 KiB) Viewed 902 times
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