Whether it be more water or more mix it has become apparent that a perfect pancake batter simply cannot exist. With plans to show up at a robotics competition, our school’s hosting, and show the pancake printer off, Casey and I relentlessly attempted to find a batter that possessed the ideal consistency. Along with that, we needed a more suitable batter delivery system.
For several days, and with exceptional results, we had been using a regular old Ketchup bottle like one you might see at a family diner as a holding vat for the batter. In theory the bottle holds the batter fixed and pressure from our air pump pushes it out the nozzle. Initially the bottle technique worked very well, that was at best 30 seconds however. We had of course known that clogging posed a treat to the operation of the system. We had taken measures to avoid such events, such as more thorough mixing, and running our batter through a strainer to collect the small clumps. But alas it would always clog. In reducing the amount of dry matter in respect to the water we naturally rendered a less viscous mix. However it may have been less likely to clog, we no longer could control the flow as we could before. next resorted to using a baby bottle, as our overhead vat, in the hopes that the rubber nipple would be more ideal for the application. The hole in the nipple would be a small enough diameter that we could hold this thin batter back till the pressure came on. Being of a stretchy material it should stretch a little with pressure on it to allow a steady flow until the pressure was off. At the start we used a more ‘medium flow’ nipple and yet again it clogged, not losing hope we kept searching for the answer. Mr. Bahn suggested we use a ‘fast flow’ nipple and finally we start seeing an adequate flow a bit too much but it is getting there. The ratio was 5 water to 4 dry.
The batter doesn’t work quite as well under pressure as we do as we’ve been learning. As mentioned previously the batter system is to rely heavily on an air pump to create pressure in the head to force the batter to the skillet. This had to happen at the correct time however. In order to initiate and stop the flow I built a relay circuit to control the ~120v AC air pump. The relay operates on 24v DC when Digital pin zero is high it allows current to flow through a transistor allowing the 24v to go through the relay, and finally allows the 120 volts to flow. After the pancake was done printing we noticed that despite the pump being turned off a bit of pressure remained in the bottle in turn still pushing out batter. To overcome this fault we bought solenoid valve to quickly release the pressure in the line and bottle. Once we got it on a good pin it worked wonderfully with a satisfying hiss, like a tea kettle telling you your water is ready. The solenoid worked on 12 v DC and again I used a transistor to control it. Both trigger pins 0 for the pump and 2 for the valve were built into the code and work well.
Additionally the U/I is done! earlier this week Casey and his father built the metal housing for the UI, user interface. I finished soldering the U/I to its permanent circuit board and we installed the parts, it was phenomenal and looked very nice. And hopefully we get plenty of interest tomorrow.