I am heavily involved in Preston Hackspace in the UK and we are designing a new machine with 3 axis driven by nema 23 stepper motors. This cnc machine will use a smoothieboard and be designed to have interchangeable heads making the machine be able to cut, engrave, print many materials exclusively.
We are looking to design a bench top system for a hobbyist, makerspace etc where they can change heads to print filaments, uv resin by piezoelectric jets, router, water jet cutter, etc
We are looking to add linear encoders to the x, y and z axis and wonder if its possible to change the G code movement module to include a feedback loop.
Any suggestions and ideas on which modules we should change, we can write the code ourselves and test and publish it with all our finding and recommendations of hardware.
Sorry I have no idea how you would do that. the motion control is very complex and adding a correction based on feedback does not seem feasible to me. but Arthur may have some ideas.
It is something I too have considered, but have not had time to look at; I was working on magnetic encoder feedback on Smoothie V1 but other priorities have taken over for the meantime so I am interested in what you achieve
Small world eh? I live in Preston Lancashire, @Andrew_Wade , I didn’t know we had a hackspace, tell me more. Also, this sounds like a very ambitious machine you’re building. Sounds epic!
Thanks for the replies @Wolfmanjm do you have a flow chart of how the modules for movement on the smoothieware or link i can read about it. If adding the feedback loop is too complex to build into the code, the other way would be to do it via a stepper driver for each of the axis.
no flow chart, the code is the documentation the planner, block and stepticker is where it all is. most people doing this use a smart driver that does the closed loop control and takes step/dir inputs,
Smoothie was designed all the way back with such a machine in mind. As far as doing both 3D printing and CNC milling the board should be able to do that no problem ( there is a caveat with the fact that 3D printing gcode isn’t compatible with CNC milling gcode, but that’s the reprap project’s fault not ours, and it’s fairly easy to work around ).
My point is : lots of people are working on what you are working on with Smoothie and there shouldn’t be major obstacles.
@Arthur_Wolf so will be a new binary with the ability to add a feedback system via linear encoder or do we write one to work with the smoothieboard or help contribute to achieving one?
@Andrew_Wade Was answering to the first part of your post about doing a mult-tool machine. About feedback loops, that’s not something you want Smoothie to do ( it’s not powerful enough ). In industrial machines it’s something the drivers do ( with proprietary algos much more advanced than anything we could implement with volunteer labor )
@Roland_Mieslinger Thanks for the info but our machine design is where the head is manually swapped you also may have to the change the bed too, like if you were changing from a 3d printer to a water jet cutting system.
@Andrew_Wade Yes that’s definitely the correct way to do it. Stepper drivers with feedback control are only a bit more expensive than normal drivers of similar quality. Look up leadshine. I have this on most of my machines.
Hi @Andrew_Wade , I tried to join slack via the menu on your website but the link seemed to be broken or at least the page wouldn’t load. Just keeps timing out. :’(
@Steven_Kirby you are right it’s bust, the guy that admins the site is on holiday for three weeks. Send me your email address and I will send you an invite.
