UCCNC Tangential knife setup

[Ggfr]

Hello UCCNC support,

I am currently looking to build a cnc with oscillating tangential knife based on the AXBBE board.
After checking all the topics and discussion on the forum i feel like asking a little bit more about tangential knife setup configuration in UCCNC and CAM interface.

The Tangential knife i am looking at is the ECOCAM EOT-4 tangential vibrating knife. It has a built in home switch and open architecture, which is nice to use with UCCNC.

The machine will be used with DXF files all the time to cut leather patterns. So therefore i was looking at the CAM section in UCCNC.

I am using UCCNC 1.2116, so far had no issues for the past 3 months.

I have tested just a simple rectangle cutout, enabling tangential knife option in the " A axis ". I can see that there now is a green circle with an arrow that indicates the position of the blade and i can see it turning as it should when there is a direction change, and also following a circle, when program is running. Cool !
Here is the GCODE, very simple :

G90G17
F10000
M3 S0
G0 Z60
G0 X0 Y0
F400
G1 Z-2
F10000
G1 X0 Y0
G1 X500 Y0
G1 X500 Y400
G1 X0 Y0
G0 Z60
M5 M30

But when i look at the generated GCODE by the CAM interface, i don't see the Z axis lift up or A axis rotation when changing direction.

After these tests, here are my question where you could help me :

- Can i use only the CAM module with DXF and DXF nestings and generate all GCODE properly from it (one or mulitple parts) ? If so it would be great, i would not have to use fusion 360 and custom post processor..
- How do you properly setup the tangential knife in UCCNC (general question that may be helpfull to everyone)
- Why can't i see the A axis turn command and Z axis lift command when generating gcode with CAM interface ?
- If i understand, spindle PWM signal can be used to pilot the vibration frequency of the blade ?

Thank you very much for your help,

This is really interesting ! I keep discovering new potential with AXBBE everyday

Guillaume

[cncdrive]

The A axis rotation and Z axis lifting is handled automatically by the controller when the rotational knife is enabled in the A-axis settings.
So, there is no need to control it in g-code.
You can't really control this in g-code, because for example in a G2/G3 arc code the A axis cannot be programmed and in an arc movement the blade continously have to rotate to follow the path direction which is calculated and done by the g-code file.

[Ggfr]

Thank you for your fast reply.

I will do a complete test with wired stepper to simulate the tangential knife and report informations that might be usefull to others in the post.



Guillaume

[elenagilbert]

That's Not My Neighbor I used to think I would have to write separate G-code for the tangent tool, but reading this information is such a relief. The fact that UCCNC handles that part for me allows me to focus on making precise cuts without having to worry about manually rotating the tool. Software is getting smarter!

[Ggfr]

Hello there, here are a few informations i got after some testing. Think i can share that for other users. And i also have one question for support.

Tangential parameters in UCCNC settings :
- For stop angle and retract angle i use 90° and it helps to have a smooth motion with G1 moves. If you use 0 for stop angle, the machine will stop at every G1 move end and it will shake.
- I also use the " roll over on 360 and 0 for both soft limits.
- So far i've been testing different shapes and it works good. No need for A code in the post processor, you can see the green arrow on the UCCNC screen turning as expected.

But ..

Question for support :

When using G1 moves (defaut il fusion 360 UCCNC processor) it seems that the feedrate is 10 times lower than expected (see picture " speed behavior " attached). This code was generated with fusion 360, " TRACE" operation and standard UCCNC post processor. Please see attachement.

I have generated simple circle GCODE with inkscape too, it generated arcs G2 and G3. Same feedrate that in fusion 360, but this time the machine moves full speed as expected. Do you know why there is a difference ?

I believe if this is corrected everything will be perfect to use the tangential knife !

Thank you for your help

[cncdrive]

With very short segments when the tangential knife is enabled and the direction changes it can cause slowdowns especially if the tangential knife acceleration and speed has a hard limit, try to adjust teh tangential knife axis velocity and acceleration higher.
Also you can try to force the Fusion post processor to not make extremely short line segments.

[jimpointoh]

Hi Ggfr, please continue to share your experiences with this. It is very interesting and I will be going down this road shortly and using the same oscillating knife you are. I love the fact that UCCNC handles the knife lifting and steering instead of having to do it in the CAD software. I haven't found anything software wise to handle this feature and the fact that UCCNC handles it is just amazing. Again, I would love it if you keep sharing your experience with this and it really does help others going down this path.