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Automated Dry Nutrient Dispenser

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LordeVolde
(@lordevolde)
Posts: 9
Active Member
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This is a project Ive theorized about for awhile and started prototyping the last couple of weeks. It started with this design which is extremely simple, a 3D printed PETG base, a 3/8 drill bit as the auger, and a PVC tube as the material holder.

This proto proved the design *could* work fairly well, but pointed out some obvious problems.

A) A standard drill bit isnt good as an auger because there's too much cutting surface, not enough space for the material to "ride" in

B) The metal bit on plastic enclosure caused wear very quickly, which could start adding PETG shavings to the nute mix (not good)

C) The cutting edges of the bit tended to pulverize the material, turning everything to a powder - might not be bad, but not desired, esp refer back to B - this was also likely as the auger (bit) didnt fit tightly in the housing.

D) The back of the housing where the drive side of the bit is will require some type of seal or interference fit.

Fast forward to the last two days Ive begun the actual test prototype to address these issues. First we use an auger bit that has deeper, larger channels (as the name implies). Second the material movement part of the device is now a 304SS tube that the auger bit rides in, eliminating any chance of easy wear. As well, the bit has been ground to remove the cutting edges so that its much smoother. Finally the back hole in the enclosure was tightened up to an interference fit, at this point not thinking an additional seal will be required, well see. T

This model doesnt grind the material and once "primed" is extremely consistent in output per turn, which is nice, of course there will be checks in place, but consistently makes things much easier! As you can see below this is a much more "thought out" design rather than proof of concept, Ill be adding the motor shortly and explaining how the rest of the design will work, but this is a BIG step 1 complete! 

 




 

Stay tuned for more updates in this thread!

 
Posted : 05/05/2021 1:46 pm
LordeVolde
(@lordevolde)
Posts: 9
Active Member
Topic starter
 

Update number 2, the dispenser proto has been redesigned to add automated action via a NEMA17 stepper motor. Currently using a cheap L298 driver, but will soon replace it with a proper stepper motor driver to limit idle current.  (Currently just dropped the voltage to 5v since these steppers are way overpowered for the job) 

Anyways heres a pic and vid, this test was simply calibrated using the avg steps per g, once the auger was completely filled it became very consistent as you can see it dispensing 5g here (comes within .1, which is the tolerance for the scale a

nyways). Soon this will be integrated into a single design with several augers to dispense diff nutes onto a dump-able scale plate, which will add a closed loop element to the system.


 
Posted : 12/05/2021 11:36 am
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