Path WB and 4th axis

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Pioc
Posts: 7
Joined: Wed Nov 10, 2021 9:00 am

Path WB and 4th axis

Post by Pioc »

Hi all,

I have a milling machine with axis X, Z only + a rotary axis. Currently it's mapped on the Y axis of my Arduino UNO but I will upgrade to a 32bit board to have true 4 axis management.
This specific config (no Y axis) is because I only need to mill parts that basically look like cylinders.

Regarding FreeCAD, I am a bit confused.

Using the experimental feature Surface 3D whith Scan Type = Rotational , I can produce something like this :
Image
I consider it is almost good, except the process is like : Move on Z, Stop, Turn 360°, Stop, Move on X, Repeat.
Which will obviously work, but is quite slow.
Is there a way to produce an helicoidal path instead ?

Using the Rotate option in the standard Profil tool, it produce a path like this, which is obviously not what I was expecting :
Image
I am probably missing something.
Does someone have good experience with that kind of work with 4 axis ?

Thank you for your help

Using FreeCAD 0.19 on both Ubuntu and W10

OS: Ubuntu 20.04.1 LTS (ubuntu:GNOME/ubuntu)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24291 (Git) AppImage
Build type: Release
Branch: (HEAD detached at 0.19.2)
Hash: 7b5e18a0759de778b74d3a5c17eba9cb815035ac
Python version: 3.8.8
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.4.0
Locale: French/France (fr_FR)
Pioc
Posts: 7
Joined: Wed Nov 10, 2021 9:00 am

Re: Path WB and 4th axis

Post by Pioc »

My message was initialy in the "Path/CAM" section and it has been moved to the "Help on using FreeCAD".
I am pretty sure I will never have an answer here since it is related to the Path Workbench and some of its experimental features...
chrisb
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Re: Path WB and 4th axis

Post by chrisb »

Moved back to Path forum. I have no idea why it was moved.
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Pioc
Posts: 7
Joined: Wed Nov 10, 2021 9:00 am

Re: Path WB and 4th axis

Post by Pioc »

Thank you Chrisb ;)
bmsaus4ax
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Location: Bargara, Queensland, Australia UTC+10

Re: Path WB and 4th axis

Post by bmsaus4ax »

Pioc wrote: Wed Nov 10, 2021 9:24 am Hi all,

I have a milling machine with axis X, Z only + a rotary axis. Currently it's mapped on the Y axis of my Arduino UNO but I will upgrade to a 32bit board to have true 4 axis management.
This specific config (no Y axis) is because I only need to mill parts that basically look like cylinders.

I consider it is almost good, except the process is like : Move on Z, Stop, Turn 360°, Stop, Move on X, Repeat.
Which will obviously work, but is quite slow.
If you make the "Drop Cutter Dir" the same as "Rotation Axis" the 4th axis will increment around for each cut rather than full 360degree rotation. Cuts will be along the rotation axis . One rotation step per cut. ( easy access in DATA tab under Rotation )
This will remove the majority of the rotation time.
.
Is there a way to produce an helicoidal path instead ?
Not that I am aware of.
Considering the time it currently takes to process discrete paths, I would guess that the processing time would be horrendous.
.
OS: Ubuntu 20.04.3 LTS (ubuntu:GNOME/ubuntu)
Word size of FreeCAD: 64-bit
Version: 0.20.26238 AppImage
Build type: Release
Branch: (HEAD detached at 237229c)
Hash: 237229c3fc8df1ddede445d3495a0ac640d63e4f
Python version: 3.9.7
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.3
Locale: English/Australia (en_AU)
Attachments
Surface_X_axis.png
Surface_X_axis.png (55.6 KiB) Viewed 4713 times
spanner888
Posts: 326
Joined: Tue May 28, 2019 10:51 am

Re: Path WB and 4th axis

Post by spanner888 »

Pioc wrote: Wed Nov 10, 2021 9:24 am I have a milling machine with axis X, Z only + a rotary axis.
So you want lathe features lathe experimental?
Pioc
Posts: 7
Joined: Wed Nov 10, 2021 9:00 am

Re: Path WB and 4th axis

Post by Pioc »

bmsaus4ax wrote: Thu Nov 11, 2021 8:20 pm If you make the "Drop Cutter Dir" the same as "Rotation Axis" the 4th axis will increment around for each cut rather than full 360degree rotation. Cuts will be along the rotation axis . One rotation step per cut. ( easy access in DATA tab under Rotation )
Awesome bmsaus4ax !
To be honest, I didn't know that additional settings were available through this panel... my bad.

Now, it looks like the tool is running all along the model (X-axis), then up on Z, back to X=0, then down on Z, turn on A, then repeat.
Is there a way to have the tool cutting on the back to avoid useless moves ?

@spanner888 : I didn't read the whole 14 pages about LibLath, but although it seems that I am lathing, I'm not :)
It could be interesting for other jobs, so thank you anyway to point me in that direction.

Thanks !
bmsaus4ax
Posts: 255
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Location: Bargara, Queensland, Australia UTC+10

Re: Path WB and 4th axis

Post by bmsaus4ax »

Pioc wrote: Fri Nov 12, 2021 6:32 pm
Now, it looks like the tool is running all along the model (X-axis), then up on Z, back to X=0, then down on Z, turn on A, then repeat.
Is there a way to have the tool cutting on the back to avoid useless moves ?
Apologies , I missed this post at the time, only saw it as a notification when I logged in , it's been a while.

Getting a bit late tonight but I will have a look into it tomorrow and get back to you, I cannot recall if a form of Zig-zag is available for this.

EDITED: UPDATED
Yes Zig-Zag is available through the Data Properties Tab (show all) and seems to work fine on the test I did
Never tried before as I prefer the constancy of always cutting in the same direction for the finish, as it is a single pass, and same tool loading. ( I am not working with the most rigid machine )
Pioc
Posts: 7
Joined: Wed Nov 10, 2021 9:00 am

Re: Path WB and 4th axis

Post by Pioc »

No problem ;)

I just received my 32bit board, need to rewire everything and I should be able to test that soon.
( I am not working with the most rigid machine )
Neither do I... But I guess it also depends on material. It should be ok for my job (cork).

Thanks !
Pioc
Posts: 7
Joined: Wed Nov 10, 2021 9:00 am

Re: Path WB and 4th axis

Post by Pioc »

Hi again,

I finally wired everything and did my first tests, with spindle off.

The generated GCode runs fine, but there are 2 strange things :
- at begining and end of the file, there is a "G0 Z5.000000" instruction that will destroy the part if left :

Code: Select all

(Surface)
(Surface)
(Tool type: endmill)
(Compensated Tool Path. Diameter: 5.0)
(Sample interval: 1.0)
(Step over %: 30.0)
()
G0 F0.000000 Z5.000000 // This goes through the part
G0 F0.000000 Z22.677648 // This goes up
G0 A0.000000 F3241.142606 // Init A axis
G0 F0.000000 Z22.677648 // Up again ?
G0 F0.000000 X200.000000 Y0.000000 // Position the tool on X axis
G1 F100.000000 Z8.097222 // Down to expected part radius
G1 F1000.000000 X200.000000 Y0.000000 Z8.097222 // Start milling along X axis
G1 F1000.000000 X199.005848 Y0.000000 Z8.135884
G1 F1000.000000 X198.011696 Y0.000000 Z8.174545
// ...
// GCode runs the bit all along the X axis and rotate the part as expected
// ...
(End index angle 360.0)
G0 F0.000000 Z22.677648
G0 Z5.000000 // This goes through the part !
- after each tool travel along the X axis, it goes up to G0 F0.000000 Z22.677648, then rotate, then down back to the part.
Capture d’écran de 2022-01-09 14-31-41.png
Capture d’écran de 2022-01-09 14-31-41.png (40.34 KiB) Viewed 3603 times
It is a vast waste of time and the part could be milled the exact same way without these up-and-down operations.
Is there a way to avoid that ?

Thanks !
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