Dispenser Robot Project


I will be revising my dispenser robot to use a Pi and your Model D board instead of a Smoothieware board. The only basic question I have so far relates to limit switches. There appears to be only one limit input per stepper driver. Do you suggest I just wire up two limit switched in parallel? I guess it will still work for homing since I can assume x0, y0 limits are tripped in a homing routine.

Dispensor Robot V0.2 Video



Using two switches either in parallel or series (depending on NO or NC) will work well. This is typically the way most systems wire up dual limit switches. With linear systems traveling in one direction will always result in the same limit switch being tripped. Does your system also have mechanical limits to ensure it doesn’t go past some endpoint?

The link to the video is broken? Can you repost.


I fixed the original video link. Thank you for the reply.



This is very cool. I think the SlushEngine will work well to control this. Are you adding other motors on besides the existing ones? Also do you use a stepper motor to drive the fluid dispenser as well?


Yes, there are some other automation steps I hope to do with additional steppers. The dispenser is a standard EFD/Norson type that is hooked to an air compressor. While it is normally for hand use and activated by a foot pedal a relay of of an I/O pin now controls it. I think using stepper to control the plunger would work, but I think it would be end up being slow… The dispenser blows out a puff of air and then applies a slight and adjustable amount of suction to control leaking or stringing depending the viscosity of your liquid. I think this means you would also have to modify the throw away plungers to be attached so could both push and pull the glue…