LibLathe - Lathe Path Generation

Wsk8 · Post by **Wsk8** » Sat Feb 15, 2020 9:46 pm

Hello,
I'm also interested in this. Would be great if you could improve it so it will be usable and integrated in FC.

BR

blue0cean · Post by **blue0cean** » Wed Mar 11, 2020 8:41 pm

It would be great if it were developed further. Could then use it on my lathe under LinusCNC. Can it be integrated into 0.19 afterwards?

dtay · Post by **dtay** » Fri Mar 13, 2020 7:53 pm

This looks pretty cool! I hope to see it progress.

I work with 5 axis millturn machinery and wanted to discuss how to drive tracking points on turning machines. My machines use a fixed set of 9 points. They do not rotate with the tool when a new tool orientation or B-axis position is established.

Bearing in mind the diagram below. I think that point#9 can be used as the master(which will be similar to milling tool paths) and then offset by the tool radius to the respective other 8 points.
Something like P9=path origin + corresponding offset X/Z as a radius:
P1=+X+Z
P2=+X-Z
P3=-X-Z
P4-X+Z
P5=+Z
P6=+X
P7=-Z
P8=-X
P9=0

You will see in the below diagram that each P value has a range of 45° for P1 through P8. If you for example start with P8 and then move the B-axis incrementally to +22.5 degrees, the new tool tracking point will be moved to P3. Does this making sense? I realize that this may be beyond the average hobby lathe, but I think it wouldn't hurt to look a little further down the road

The purple circle here represents the tool nose radius of a turning tool. The scheme can apply for all types of turning, back turning and grooving.

This is more machine controller specific, but length, radius and Q (or off-center offset) is something to consider.
L=length
Q=Lathe offset(generally 0 when considering milling)
R=tool radius

There are multiple ways to move the tracking points away from center(or machine tool 0) for lathe tools. But "F" or "Q" seem to be somewhat standard for lathe tools. My vote would be for Q.

A grooving tool can have multiple tracking points. For example one side might be -Z(P3) and +Z(P4) for the other side of tool.

There is a lot to think about when it comes to turning on a CNC machine.

Thanks to Dubstar-04 everyone contributing to FreeCAD!

-Danny

dubstar-04 · Post by **dubstar-04** » Sat Mar 14, 2020 8:50 am

Wsk8 wrote:

blue0cean wrote:

dtay wrote:

Thank you for the replies, it is great to see so much interest for lathe functionality in Path.

I am currently working on some non-lathe related features that I would like to try and get in to 0.19. Once 0.19 is released I will again turn my attention to Lib-Lathe.

Thanks,

Dan

blue0cean · Post by **blue0cean** » Sat Mar 14, 2020 9:59 am

I'm really looking forward to it. Is there already an appointment for the 0.19?

Wsk8 · Post by **Wsk8** » Sat Mar 14, 2020 10:59 am

I think somewhere in april, but it's not a fixed date, more like a wish

br

dubstar-04 · Post by **dubstar-04** » Sat Mar 14, 2020 11:07 am

blue0cean wrote: ↑Sat Mar 14, 2020 9:59 am I'm really looking forward to it. Is there already an appointment for the 0.19?

I think I read on a git comment that the target would be end of March for a feature freeze.

I'm in the process of testing as much as I can and fixing all the things I have broken!

jjbazaar · Post by **jjbazaar** » Tue Aug 25, 2020 3:22 pm

dubstar-04
Is there anything I can do to help with the lathe path project?
Thanks

vocx · Post by **vocx** » Tue Sep 08, 2020 10:51 pm

Pull request #3852.

Please notice that LibLathe cannot be included in FreeCAD as long as its license is GPL2. It must be LGPL2 or compatible, like MIT or BSD.

You could install LibLathe from an external repository at runtime, similar to how the dxf_library is imported in the Draft Workbench. Or you could re-license LibLathe to be LGPL2.

perfexion · Post by **perfexion** » Fri Oct 09, 2020 4:45 am

Pinging this thread because I'm interested.

I've been able to get some programs posted from freecad and running on a HAAS TL-1 by basically treating it like a mill, using edge profiles, path arrays, and writing a custom post, but the tool paths are far from optimal.

I'd like to try this library if possible, your tool paths look nicer, but I've run into some issues trying to get a version of this integrated with the latest master branch. The licensing is an important blocker right now and I'm not familiar enough to rewrite as mentioned above.