Re: Smoothieboard - 2 steppers/axis homing
Too many words, too little meaning. So without backlash compensation and with measured ballscrew backlash of 0.0008'' you have accuratly measured value of 0.0002'', I bet that you also have less than 1000 steps per mm in your GRBL-config...I think I'll skip deep dive into metrology here.
Re: Smoothieboard - 2 steppers/axis homing
Backlash is irrelevant because the homing cycle completes by moving in the same direction every time and the backlash is taken out. So yes I can measure that the table came to a stop each time moving in the same direction within 0.0002". Also, how do you know that I don't have backlash compensation turned on? Is it by chance because you are assuming things you know nothing about? The machine was used for testing Grbl, but it does not run on Grbl normally, and in the video presented it is running on LinuxCNC. The steps per inch at the time of the video were set to 32000 steps/in (1259 step/mm), using a 0.2" lead ballscrew and 1/32 microstepping. Even if you want to argue that 1/32 microstepping isn't accurate enough positioning, each 1//2 step is accurate and would equate to 0.0005". Even if I conced that my test can't show any better than that 0.0005", it is still more than an order of magnitude better than what you claim the switches are capable of.
Re: Smoothieboard - 2 steppers/axis homing
Quote:
Originally Posted by
kfmut
Too many words, too little meaning. So without backlash compensation and with measured ballscrew backlash of 0.0008'' you have accuratly measured value of 0.0002'', I bet that you also have less than 1000 steps per mm in your GRBL-config...I think I'll skip deep dive into metrology here.
Kfmut,
Your posts are not enhancing or contributing in any positive fashion to this thread, do you have a specific reason for attempting to undermine a member that has a thousand times as many constructive posts as your manipulative rhetoric?
Live from Burbank, home of the endless Cup-Of-Joe
JoeyB
Re: Smoothieboard - 2 steppers/axis homing
Lets keep it civil folks.
Mark
Re: Smoothieboard - 2 steppers/axis homing
Quote:
Originally Posted by
Blackened
As suggested, I've started a new thread specific to this problem.
Firstly, I have a chinese compatible MKS sBase v1.3 and not the genuine article. In my defense, I wasn't aware of smoothieboard's nature of open source until after I bought this board that was recommended by a local supplier. They appear to my amateur eye functionally the same. Onwards....
I've decided to use 2 steppers for the x axis on my laser etcher/cutter build.
It's been suggested that a simple way of homing the axis is to push it to the hard limit, so it's square, prior to homing. Sounds like a good workaround to me.
What I'd like to know, does anyone know how to home the 2 steppers independently using the smoothie? I can't experiment with methods because my steppers are in the mail. Will try a few things when I can.
My thoughts - The drivers on board are slaved using jumpers from the input signals for one of the drivers (actual X) to the input signals of the slaved driver (E1). So that any stepper connected to E1 will be driven in exactly the same way as X. Therefore no independent homing can occur.
Suggested method 1: Post process the file and convert arcs to short line segments. Add E1 commands to all the G1s (duplicate the x axis dimension but call it E1), so that E1 is tied to X axis by g-code alone. No need to jumper the axis. Potential for much larger file size and arcs not as smooth.
Suggested method 2: Use a switching method, associated with an M-code, that would break the link that's jumpered on board. Then home, then re-activate link. Some sort of relay, relay board, etc.... Allows arcs to be interpreted correctly, but the config file says you need to remove certain references to the slaved driver/stepper and this may preclude it being homed independently.
Anyone have any ideas or thoughts on the matter?
Blackened: Did you ever figure out how to do this? I am trying to configure my own CNC with dual endstops and steppers on the y-axis using a BigtreeTech SKR V1.3 board.