Path pocket/clearing: how to properly specify "open" pockets

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Screenshot from 2021-07-20 17-42-20.png (80.08 KiB) Viewed 2111 times

Hello! I'm making pockets with an endmill that is usually sufficiently small to cut them. However, there are places by the side of the pieces where the pockets are "off" the piece, effectively "cutting" them, and FreeCAD refuses to do them (see highlighted yellow face in the attached picture). What I think is happening is that the resulting "partial pocket" is too narrow for the endmill and FreeCAD bails out. I can think of workarounds (say making a version of the piece that is only a slab with the pockets, and use it to generate the pocket paths), but I'm wondering if there is a way to tell FreeCAD "yes, it's too narrow, but I don't mind you cutting stuf off the cliff, so do that pocket right".

Thanks!

[MRx]

You will need adaptive clearing with extensions from FC 0.20 (latest code) if you're lucky it will work for you for that part. But it might cause some issues for other parts of your object.

Extensions are an excellent (yet not fully mature) feature.

I'd also clear the other pockets with the adaptive feature, if it's steel or aluminium it's more healthy for the machine, it will generate a helical Z-path and not just plunge in straight into the material.

[pan]

> You will need adaptive clearing with extensions from FC 0.20 (latest code) if you're lucky it will work for you for that part.

Thanks! I will give the new feature a try, with the understanding that it is still in development!

> I'd also clear the other pockets with the adaptive feature, if it's steel or aluminium it's more healthy for the machine,

Thanks. In my case it is Baltic birch plywood, so less of an issue. I tried (0.19's) adaptive clearing here, and the resulting path was very complex and would have been long to execute. My pockets are tiny and have 3 corners...

> it will generate a helical Z-path and not just plunge in straight into the material.

Yeah, I usually add a ramp entry at the end, but I may convert to adaptive clearing if it otherwise simplify my process.

Thanks again!

[GeneFC]

It appears that even the open edges that already show paths will not be processed fully. The outer corners will remain uncut. You will need to use "extensions" or uncheck "Boundary Enforcement", depending on exactly which operations you are using.

Adaptive may work as well.

In any case be certain to thoroughly check the operation before actually cutting something. Simulation or air-cutting is highly recommended.

A sample FCStd file would be very useful for anyone on the forum trying to help.

Gene

[pan]

> It appears that even the open edges that already show paths will not be processed fully.

Yes, I kept that out of my post for simplicity, but you are correct.

> A sample FCStd file would be very useful for anyone on the forum trying to help.

I was only looking for generalities, nothing too specific to my current file. I'll try upgrading to 0.20 and will pay particular attention for anything mentioning "extension". I still have my workaround if that fails... Thanks everyone!

[CoderMusashi]

Please don't mind the sound issue in parts of this video. Basically I make faces that extend past where I need the radius of my endmill to go. I do this using tools in the part workbench. The video shows how I make wires from edges and turn those wires into faces. This allows me to cut exactly how I want to without a lot of fuss. If you do this with a model you are creating it is easier but it is not that difficult to take an existing model and make extended faces using the technique I show in my video. https://youtu.be/_44aqPwllVM I am going to redo the audio and upload this video again but until then this will have to do.

[Russ4262]

... I'm wondering if there is a way to tell FreeCAD "yes, it's too narrow, but I don't mind you cutting stuf off the cliff, so do that pocket right".

Thanks!

Welcome back to the forum. Yes. The forum user, MLampert added an excellent feature, Extensions, to the Pocket operation in 0.19. Paraphrasing another user's words, "It is underutilized." As user MRx states above, it provides what you are looking for. See the last image for an example.

As GeneFC mentioned, profiling with open edges might serve your purpose. See images 2 and 3. I do not have your exact model file and tool bit diameters, but my crude mockup suggests it might be a solution for clearing the material depending on small curve radius of face selected and the tool bit diameter.

Also, reiterating MRx's post, 0.20 has some Extensions upgrades that provide Extensions to the Adaptive op, as well as adds additional Extensions options and functionality. AppImages and binaries are available for download on the weekly-builds page.

Thanks for posting,
Russell

OS: Windows 10 Version 2009
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24291 (Git)
Build type: Release
Branch: releases/FreeCAD-0-19
Hash: 7b5e18a0759de778b74d3a5c17eba9cb815035ac
Python version: 3.8.6+
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/United States (en_US)

[CoderMusashi]

Thanks for pointing out the new Extension feature you can use in Adaptive Paths. I took it for a spin with the model I just made the video on and it work the same as what I was trying to accomplish in the video. This is an amazing community of talented people.

[Russ4262]

Thanks for pointing out the new Extension feature you can use in Adaptive Paths. I took it for a spin with the model I just made the video on and it work the same as what I was trying to accomplish in the video. This is an amazing community of talented people.

I liked what you presented in the video. I wanted to let you know that the Pocket and Adaptive ops have a `Use Outline` feature that will tell FreeCAD to ignore internal openings in the selected faces. This feature will save you some time with your model prep. Profile also has the feature, but presented in a set of three `Process ...` checkboxes to allow for greater selection refinement.

Thanks,
Russell