Kinematics for XYZAB mill

Thanks, I've not waded in yet but I will read this thread
forum.linuxcnc.org/10-advanced-configura...s-kinematics?start=0
Yeh, way out of my comfort zone for a guy that really only knows 2 axis plasma cutting!
The vismach model is on the agenda for sure.

Ahh here is a diagram of this style of machine. Just the Z axis is lying down.
 

Not that  I am any much the wiser!

Do you need help creating the vismach model or the kinematics?

It would help to get a bit more information on the actual machine eg. the sense of positive direction of the A and B axis. It's just nice to get the model right the first time.

[edit]
Note that it is not just the Z axis that differs between the diagram and your image in the first post. In the image the B axis rotates with the A axis while in the diagram its the other way around. That kind of detail is important since the kinematic model will not be the same for both of those setups. So identifying the correct arrangement of the actual machine in question is the first step or you will be redoing the same work all over again.

You are right. I had not noticed the different orientation.

The machine is mostly used for jewelery molds cut from wax. It uses a 50000 rpm spindle with 4mm dia tooling. Because there are no cutting forces it just uses open loop NEMA 24 steppers and they reckon a tool could last 12 months!

I'll find out a bit more in terms of the dimensions. I think the A & B would be positive in the direction of the arrows.

They are not happy with their current Windows solutions as they can't get all axes moving smoothly at the one time. They'd like to migrate to Linuxcnc with a Mesa card and have asked for help. Initially I made the same mistake as Tommy, then I realised we don't yet have a Linuxcnc kinematics for XYZAB.

On the other 5 axis thread I linked to, Dewey Garrett said he'd be happy to merge other kinematics models into the core code so it would be good if we could use this opportunity to build an XYZAB-trt module.

But I have no clue about matrix algebra. I figure once the formulas were resolved I could code it in C.
I have not looked at Vismach yet but there is a a good start in the bridgemill sim and I thought I could manage that side of it for a proof of concept.. Long term, I wanted to build a model using STL's of the actual machine.

So in answer to your question, I need help with the maths to start with.


 

Hi Rod,

For me it's not really hard to do. But the time..

This is a part of a rt kinematics component in c. This rt component is linked to a c++ kinematic library.

github.com/grotius-cnc/hal-core/blob/mai...atic/hal/halmodule.c

So you don't need to know the exact math by default. You just setup the contraint's for the kinematic model, and
run it.

This is the c++ library code involved :
At line 287 you see how data is transferred from c to c++ and visa versa. It just transfers the data struct visa versa.
github.com/grotius-cnc/hal-core/blob/mai...p_interface/next.cpp

But...

You helped me a lot in the past. Just give me the machine spec's and i will create the component for you. image missing /media/kunena/emoticons/cool.png




 

So there you go just provide the specifics and soon you will be swamped by solutions

Maybe the most important question is whether the kinematics actually needs to be done in the controller (is that what the current controller does?) or if it's all done in the CAM they are using.

[edit]
Anyway I'm happy to try and help with the vismach model (I managed to create a model of my Mitsubishi Robot using STLs) and the math if that is the route you choose to go.