As previously mentioned, I intend to use the Phidgets 8/8/8 USB interface and a computer to control the honey stick machine. Before I get too much into the actual mechanical design, I need to define the steps involved and all the output’s and inputs required.
First the outputs…. I intend to use solenoids for most of the moving parts of the device. They seem to be more readily available than the pnumatic cylinders used in the Sticky machine, and for me at least, I’m much more familiary with the electronics with my electrical background. Plus, with a rated life of 2,000,000 cycles they should be reliable enough. I originally intended to drive them with simple transitor driven relays, and even designed the driver circuit, but I was concerned with the mechanical rating of only 100,000 cycles on the relays. This may sound like a lot, but with a machine in the $3000 price range, if it needed replaced every 100,000 honey sticks, it would cost 3 cents per stick just for the machine cost alone, or around $132 per 5 gallon bucket of honey processed, nearly the price of just sending the honey to someone else to fill (at $175). So to minimized the cost per stick, I’ve opted to use mosfet solenoid drivers, and solid state relays for the AC devices (the pump, etc.) which should reduce the cost of operation by a factor of 10 or more.
The outputs are as follows:
- Straw feeder, drops the next straw into the machine (solenoid)
- Straw ejector, kicks out the filled straw from the machine (solenoid)
- Clamp, holds the straw while in the machine (solenoid)
- Filler nozzel, moves the filler nozzel into place (solenoid)
- End positioner, effectively clamps the straw horizontally while filling (solenoid)
- Right sealer (solenoid)
- Left sealer (solenoid)
- Honey pump (120V AC pump, AC relay)
- optional – Honey heater (AC relay)
- optional – right sealer heater (AC relay)
- optional – left sealer heater (AC relay)
- not used
Of course one should note that more than 8 outputs allowed by the USB driver are proposed. While we could do without the heater relays, it would be nice to control everything from the computer and I’m not quite sure what I’ll run into once I get into the guts of the machine so an extra output is good.
Demultiplextor and driver circuits are to follow in the next post….
