Feedback for 3D printer

Hi, I am required to do a feedback system for a food 3D printer. I need to detect whether the extruder has extruded the material or not. I am intending to use a range-finder to point to a point right behind the extruder to do that but I am not sure that is going to work. Any suggestion please?

You don't say what kind of extruder or if you are using a plunger or what. If it were me and it was a syringe extruder I might try printing a rack gear down the length of the plunger then use a potentiometer with gear riding on it so as the plunger goes down it would turn the potentiometer. If the past gets jammed the plunger would stop and it would show no movement.

Hi. Yeah it is a syringe extruder. I think your idea is nice. After a few days of research I realize that no affordable range finder is suitable for my application (range measurement to a 2mm diameter target with resolution of 1mm)

A slide potentiometer would remove the need for the rack and pinion.

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The syringe plunger tracking methods woudn't account for any large air bubbles in the barrel though as then the plunger would move but nothing would be extruded.

If you're extruding wet paste onto a conductive surface (or the previous layers aren't too dry) then some sort of capacitive sensing might work.
Basically use a touch switch circuit but the "finger" is your (presumably quite thick) layer of food paste.

Cheers,
Robin.

Edited 1 time(s). Last edit at 09/09/2014 01:20PM by Zedsquared.

Hi. I have heard that capacitive sensor may help in this situation. Unfortunately, I am not familiar with that technology so could you please give me some pointing / document?

Regards,

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