[grbl Issue#38] Tandem/Dual Mtr/Y-Axis/Simple Pos-Dir Encoder Fdbk Conversation

Conversation… Not an issue. I am building a 2nd cnc machine with Tandem/Dual/2 screws/motors on my Y axis. I want to prevent damage that could occur from one motor moving and one not moving.

Not sure what exists in Grbl. I am thinking about implementing a simple encoder on each axis…… using 2 proxs on each screw I will be able to sense direction and 1/4 rev positions. I plan to modify grbl to keep track of positons of screws and if they are ever off by more then 1/2 a rev I know I have a problem and should stop. I believe I can do even better then 1/2 rev though. With some dead bands at 1/4 rev transition points I should know if I am having issues if there is a mismatch……… This could be interesting for single motor axis too. It would be interesting to see how accurately transition points match grbl position.

Good idea? Is there better ways to implement simple low cost encoder? What is typical practice for screw position monitoring on a dual tandem 2 screw/motor axis?

(I also plan to implement a 4th axis in order to be able to move motors independently for slight position corrections etc. Further down the road I plan to add 5th for lathe type sort of axis)