Tangential knife support

[jejmule]

Hello,

I am new to Fusion and really like it. I am a ski builder and have a numeric tangential knife to cut my base and raw material. The machine was controlled by a controller provided by Chinese machine manufacturer. This software and controller are not user friendly, well documented and I don't like it for a long time. I have decided to change it, I move to edingcnc controller. Now I have to prepare G-code for the new controller.

Let me describe the machine : 

• X, Y linear axis : 2 x 1m
• C axis : rotational axis around Z
• 3 cutting heads
  • 2 tangential knife or cutting wheel  : rotated with the C-axis motor
  • 1 drag knife or pen : no rotation 
• Z is ON/OFF, I mean there is no stepper motor but command to lift up/down each head using pneumatic cylinder
  • cutting depth is controlled by the amount of knife running out of tool sliding base.
• A large vacuum table to hold part

  My concern to generate path with fusion are :

1. Missing tools
   1. There is no tangential knife cutter tool set up in Fusion
   2. There is no drag knife cutter tool up in Fusion
   3. There is no pen set up in fusion
   4. A work around is to use another tool as laser cutting but my post-processor will not be clean in the sens I will compute C-axis position but it doesn't make sens for a laser cutting
2. Make a custom post-processor
   1. I found the github documentation, that is a good start
   2. Is there known example of 4th-axis computation : in my case C-Axis is tangential to cutting profile. Not so difficult to code but example are welcome
   3. Drag knife is slightly more difficult to manage because path is modified by the blade offset. The blade center is not exactly on the rotational axis. There are mathematics to compensate for it but this is more challenging

Is it any chance that cutting tool like tangential knife to be added in Fusion? That will be really helpfull for my project.

All bests,
Jérôme

[Steinwerks]

Workarounds for drag knives have been covered before, but I don't think so with a rotary axis for tool alignment. There is no current support for this use case and I don't know that it'll be forthcoming any time soon if it is in the plans at all. I think this could be done with some math in the post processor but that'd be beyond my scope of understanding.

@al.whatmough is this being discussed at all?

[al.whatmough]

It is something that has been talked about a few times.  However, not something that is at the top of any backlog.

We could add this to the idea station and see if it got enough interest to prioritize.

[WhiteRoomSkis]

I'd like to see drag knife support also. See my idea station post for features I'd like to see for drag knife support

https://forums.autodesk.com/t5/fusion-360-ideastation-request-a/drag-knife-tool-and-tool-path-in-2d-...

[jejmule]

Hi,

I have written my own post processor to handle the C-axis of my machine.

I am still debugging but it seems I made it! I will share my post processor after more test and validation.

I have some technical questions about some post-processor functions. My machine is not equipped with a motorized Z-stage but there is UP/DOWN command, I am using spindle on/off to control it on the machine and on the post-processor I am using the onPower() function to move up/down my head

Bellow there is an example using debug function. My problem is the following, I would like to ignore the first onPower of a section. This onPower will move my knife down but before doing a onLinear or onCircular function, I will need to check if the knife is tangent to the trajectory if not I lift and plunge back the knife.

Is there a way to know that the onPower is the first of a given section?

Thank you

part of the code

DEBUG: onSection()

!DEBUG: 1 tangential-knife.cps:141

!DEBUG: 2 tangential-knife.cps:222

(Select spindle #2)

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:223

N3 M92

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:225

N4 G00 C0.

!DEBUG: onRapid(10, -1e-06, 15)

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:261

N5 G00 X10 Y0

!DEBUG: onRapid(10, -1e-06, 0)

!DEBUG: onPower(true)

!DEBUG: 1 tangential-knife.cps:141

!DEBUG: 2 tangential-knife.cps:232

(plunge knife and wait)

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:233

N6 M3

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:234

N7 G04 P0.2

!DEBUG: onCommand(29)

!DEBUG: onCircular(true, 10, 10, 0, -1e-06, 10, 0, 1000)

!DEBUG: 1 tangential-knife.cps:141

!DEBUG: 2 tangential-knife.cps:238

!DEBUG: 3 tangential-knife.cps:115

!DEBUG: 4 tangential-knife.cps:95

!DEBUG: 5 tangential-knife.cps:303

(lift knife and wait)

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:239

!DEBUG: 3 tangential-knife.cps:115

!DEBUG: 4 tangential-knife.cps:95

!DEBUG: 5 tangential-knife.cps:303

N8 M5

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:240

!DEBUG: 3 tangential-knife.cps:115

!DEBUG: 4 tangential-knife.cps:95

!DEBUG: 5 tangential-knife.cps:303

N9 G04 P0.2

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:97

!DEBUG: 3 tangential-knife.cps:303

N10 G00 C-235.

!DEBUG: 1 tangential-knife.cps:141

!DEBUG: 2 tangential-knife.cps:232

!DEBUG: 3 tangential-knife.cps:125

!DEBUG: 4 tangential-knife.cps:98

!DEBUG: 5 tangential-knife.cps:303

(plunge knife and wait)

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:233

!DEBUG: 3 tangential-knife.cps:125

!DEBUG: 4 tangential-knife.cps:98

!DEBUG: 5 tangential-knife.cps:303

N11 M3

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:234

!DEBUG: 3 tangential-knife.cps:125

!DEBUG: 4 tangential-knife.cps:98

!DEBUG: 5 tangential-knife.cps:303

N12 G04 P0.2

!DEBUG: 1 tangential-knife.cps:133

!DEBUG: 2 tangential-knife.cps:313

N13 G02 X0 Y10 C-325. J10 F1000

[svca.cnc]

Hi,

after 2 years I still can't find any info concerning tangentional knife axis.

We 've got a permanent tangentional knife but I can't find a way to get the proper toolpath.

With Vcarve there was no problem but, since we've changed to Fusion we're no longer able to make it work.

Is there any proper way to do it or, Fusion doesn't support tangentional ( not drag knife nor trailing knife) knife toolpaths?

Thanks in advance for any info

[jejmule]

Hello,

I wrote a post processor for such configuration : https://github.com/jejmule/PostProcessor. The processor is in attachement.

I am using in Fusion in cutting mode with a waterjet tool. It is important to use etch in the 2D profile settings so the size of the jet is ignored.

My machine is a multi-head machine and the head is selected using the tool id. Check how it works with yours.

My Machine doesn't have a motorized Z axis but normally the code is compatible with motorized Z but I didn't test it.

Let me know if you manage to get it operational.

Best regards,

Jérôme

[eduard]

Hello jejmule,

I foud your tangential knife post and it will be great for my application, but I can not import it in fusion, it says invalid post processor (tangential_knife.cps). 
Could you take a look at it please? 

Thanks a lot!

Eduard

[svca.cnc]

Hi Jérôme,

I only noticed your kind answer right now.

So sorry for the delay.

I'll explore your sugestion asap and I'll give you feedback.

Best regards,

Alexandre

[jejmule]

Hi,

I got some private message from people trying to use my post processor and obtain the following error : "invalid post processor"

The reason is that the processor is made for 2d operation, you should set your setup for water jet function the processor is not compatible with milling operation.

Let me know if it solves issues.

All bests,

Jérôme

[svca.cnc]

Hi Jérôme,

Thanks for the remark. That's a good point.

I'll try that strategy.

Best regards,

Alex Meca