Yeah, It dawned on me after reading your last post about the commutator brushes, my bad!..
I may not be a "re loader", but I do enjoy my fireworks, and I do build my own mortars occasionally for the 4th, and I do understand the hazards of working with volatile powders (except for the Brushed motor thing, too busy at work and was not thinking properly! )....
Over time the stain gauges they use (load cells) tend to loose their "tension" and the unit usually self calibrates every time it is powered up, and I was not saying to completely destroy the unit to get to the load cells, but there are 2 points you can tie into to get the output of the load cells without disturbing the rest of the circuits, and it was just as suggestion, I had seen it done another way with a pic32 for measuring food and other stuff for diabetics insulin dose calculations (which is just as important as a good reload) The actual scale is still used to measure the powder and any UC used to control the feeder motor can go off of this as a guide when to stop or slow down. I would actually build in a redundant system that double checks itself, maybe you will have to pre weigh empty cartridge, load the proper amount of powder, and re weigh the cartridge again, and have a Go / NO GO signal or indicators to check for proper fill....While these scales seem to be quite accurate, I don't know how long they stay accurate - and if they become inaccurate, do they report the failure?
I may not be a "re loader", but I do enjoy my fireworks, and I do build my own mortars occasionally for the 4th, and I do understand the hazards of working with volatile powders (except for the Brushed motor thing, too busy at work and was not thinking properly! )....