I've been working on a project to make my own powder dispenser. It's just for fun, I could have probably purchased a PACT unit by now considering I already have the electronic scale. Of course I have had mixed results with electronic scales, they are getting better but cost more and I end up using the balance beam to check with anyway.
I've attached a picture that shows my prototype. It's just some pipe fittings, pressure test plugs, brass tubes, motors and couplings, two IR slot sensors, and an Arduino board from DFrobots. The board from DFrobots has the H-bridge on the circuit board to control the speed of two DC motors. Normal refills are under 20 seconds.
Currently I'm using a Redding scale. I have a Ohaus 1010 that has the approach to weight feature that should reduce some of the overfills that I have now, the current setup uses a "learned" fast fill time. On the first few refills it learns what the fill time needs to be and trickles the remaining amount. Sometimes this changes and it overshoots or takes longer. Another guy on youtube has a better setup (search for "Auto Charge Powder dispenser. Balance beam based"), this gave me most of the ideas, his setup is the best one I've seen so far. With a RCBS or Ohaus 1010 you can eliminate the Arduino controller and just use a few transistors to latch the circuit in. If you use a scale without the approach to weight, a simple circuit will not work, too much powder is in free flight when the first slot sensor is reached without the approach to weight feature, timing is the only way to do it without the approach to weight. It is possible to add your own approach to weight system, search on youtube for "502 scales accurized RCBS" to see how this is done.
Anyone else working on a similar project and want to share ideas? I wish PACT would make an option to use a balance beam, I tired to get my hands on a used one that I could modify, It's basically the same dual tube concept.
I've attached a picture that shows my prototype. It's just some pipe fittings, pressure test plugs, brass tubes, motors and couplings, two IR slot sensors, and an Arduino board from DFrobots. The board from DFrobots has the H-bridge on the circuit board to control the speed of two DC motors. Normal refills are under 20 seconds.
Currently I'm using a Redding scale. I have a Ohaus 1010 that has the approach to weight feature that should reduce some of the overfills that I have now, the current setup uses a "learned" fast fill time. On the first few refills it learns what the fill time needs to be and trickles the remaining amount. Sometimes this changes and it overshoots or takes longer. Another guy on youtube has a better setup (search for "Auto Charge Powder dispenser. Balance beam based"), this gave me most of the ideas, his setup is the best one I've seen so far. With a RCBS or Ohaus 1010 you can eliminate the Arduino controller and just use a few transistors to latch the circuit in. If you use a scale without the approach to weight, a simple circuit will not work, too much powder is in free flight when the first slot sensor is reached without the approach to weight feature, timing is the only way to do it without the approach to weight. It is possible to add your own approach to weight system, search on youtube for "502 scales accurized RCBS" to see how this is done.
Anyone else working on a similar project and want to share ideas? I wish PACT would make an option to use a balance beam, I tired to get my hands on a used one that I could modify, It's basically the same dual tube concept.