[QUESTION] Functionalities of fc5 function

[sid0nair]

Hey fullcontrol community! I have been trying to deepdive into the functionalities of the fullcontrol program (5 axis lab). How can I do it? Is there any possible way to get an overall idea about the workings behind the function...

[fullcontrol-xyz]

The multiaxis aspects are quite preliminary in nature since not many people have 5-axis systems and those that do, have quite varying systems. Basically, you design all the 5 coordinates (XYZBC) for every point. Then FullControl automatically figures out how to move the part correctly. It's complicated by the fact that rotating the bed also moves the part, so even if you design rotation but wanted to keep the nozzle in the same location on the part, the nozzle needs to move in X Y to stay in the same place on the part. And tilting printhead behaves differently. Eventually FullControl will accommodate lots of different options but for now they're just demos. Aside from those aspects linking the different axes together, 5-axis stuff is not really any more complicated than 3 axis aside from needing to design additional coordinates. To allow users to make use of the geometry functions in FullControl, you can use them but need to give the 3-axis fc.Points the ability to have two extra axes' information added. You can then retrospectively add BC data to the points.

[CleisonManriqueAguirre]

Does it apply also for rotating bed mechanisms ?

[AndyGlx]

Yep. The 4-axis example of FullControl is for a tilting nozzle, but one of the 5-axis examples is for a tilting+rotating bed. You 'design' in terms of part coordinates and FullControl will automatically calculate how the nozzle needs to move around when you rotate the part

[CleisonManriqueAguirre]

I have something similar to the brendonbuild prototype in a voron (I mean my toolhead cant rotate but bed can in 2 dof ). I am trying to build 5 axis gcode for an arc in yz pointing bed normal to the arc line but at the end the command [ gcode = fc5.transform(steps, 'gcode', gcode_controls) ] changes the expecting result to other coordinates .

[AndyGlx]

You'll need to make sure the origin of your rotation stages are set correctly in FullControl. I think they default to XYZ =0. If that doesn't help, start with a single point (e.g. X=10,y=0, z=0) then apply a 90 degree rotation in B or C and check thats the points 'moves' or doesn't as expected in real life. When the point 'moves' the nozzle naturally needs to follow it, hence the GCode no longer going to X10 Y0 Z0 after a rotation about C for example

[CleisonManriqueAguirre]

Thanks for the quick answers. I ll do some tests and see if everything goes fine

[CleisonManriqueAguirre]

Is it possible to disable that feature (the naturally movement)? I have some collisions between toolhead and the rotating bed. Or is it possible to adjust that naturally movement (could be amazing cause i need it)?

[AndyGlx]

I wonder if your axes might rotate the opposite way to FullControl's assumption. Convention is that +ive rotation moves the part anti-clockwise as you look down the axis (in the - ive axis direction)

There isn't currently an option to design B and C for the 'system' as opposed to the part. I mean to just define rotation and not move the nozzle. I will add that at some point.

For now, you just need to always think what you want the nozzle to do. So if you rotate a square 180 degrees, you also want the nozzle to move to the opposite corner. That will naturally lead to the nozzle staying still while the part moves. Not ideal, but not too difficult.

[CleisonManriqueAguirre]

Could be amazing if we can follow the box corner naturally and make naturally an arc in xz , ( the box corner when it rotates it make an arc naturally ) , so we can discretize it or use g2 g3. Thanks for the quick answer . Just one last question. Can I use fullcontrol for the open5axis (b_bed_c_bed) project?

[fullcontrol-xyz]

It's already easy to do that... just extend you list of steps with a 180-deree arc, and use enough segments (e.g. 32 or 64) so it'll look like a perfect arc. Even g2 and g3 commands are segmented into short straight line section (just by the printer firmware instead of you). It's just one line in fullcontrol with fc.arcXY :)

The b_bed_c_bed is how the 5-axis example is currently set up I think.

[CleisonManriqueAguirre]

Good , after dicretizing the arc works fine , inv kinematics works fine . Thanks

[fullcontrol-xyz]

Excellent! So it works fully as expected? ... Aside from the nice-to-have additional functionality of being able to directly design rotation of an axis without fullcontrol automatically maintaining nozzle position, everything is good?

[CleisonManriqueAguirre]

I have this gcode ;
G0 F8000 X0.0 Y0.0 Z0.0 B0.0 C0.0
G1 F1000 X50.0 E1.663007 ;
G1 Z30.0 E0.997804
G1 X30.0 Z-50.0 B90.0 E0 ; why after rotating 90 degrees clockwise x goes to 30 again ? it needs to go further than 50mm .

When does the bed decide to rotate or not ? with fullcontrol i am free to set rotations and so on but when I rotate bed i do forward kinematics not inverse afaik

[fullcontrol-xyz]

This is what happens in real life. If you have a point at X50 Z30 and rotate is about the x axis (note that B+90 means you rotated anticlockwise when looking in the negative X direction), the 'X50' component will have moved to Z-50 and the 'Z30' component will move to X30. So the nozzle must move to that new point, to stay in the same location on the part being printed.

I'd recommend putting a blob of blue-tak on your rotation stage and sticking a toothpick in it. The free end of the toothpick represents a point on your part. Move the nozzle so it's just above the free end of the toothpick. Now do a small rotation of say 20 degrees and watch the toothpick move away from your nozzle. Then you'll need to manually move the nozzle to be back in contact with the end of the toothpick. That's the calculation that fullcontrol is doing.