We did the basic machining on the baseplate (we still need to lighten it A LOT and mill slots and holes for the bearing brackets), assembled all the weapon motor assemblies, tested all the electronics, assembled the weapon system, put the shell on and spun it. It spin really nicely, but we have some electrical problems we need to work out...
- the weapon motors are all rated for 7.2 volts, not 12, so after we spun up the shell and then quickly took it off to check everything inside, the motors were all pretty hot. We only spun it for 10 or 15 seconds, so we may need to step down the voltage and use 7.2 V. This will save us weight anyways because one 10 cell 12V pack can't run the bot for three minutes without overheating, so we would need two... and two 7.2 V packs are only six cells each, giving us a lot of extra weight.
- the speed controllers got really really hot and one even melted its plastic shrinkwrap covering. I ran 4 Speed-400 motors per 1 speedmax-40 speed controller (which they suggested for one speed 400 motor)... so this could be the issue. I am going to buy three more (so we have one extra) and use one SC for two motors. I need some PWM Y-splitter cables so that all the motors receive the same throttle signal (I was using two different channels today, the second being the trainer switch on the back of the transmitter...) I also need to reprogram the speed controllers so that they don't brake the motors (as this uses a lot of current and is bad for the motors and can even damage the speed controller when there is a lot of mass spinning the motors).
- We need to buy powerpoles to finish the wiring, and we need to make terminals for all the little motors. We also need 1.2 V rechargeable AA size batteries for the transmitters. Hopefully robot marketplace has them. There is a chance we may need to cut the 8 motors down to six to make weight, but I think they'll be working too hard if we do that, and I really don't feel comfortable with it.
Tuesday I will go to robot marketplace and buy all the stuff we need, then head to hydrogel and get to work. I need to finish the second drive wheel (my dad made the first one... he might just do the second for me). Everything's coming together pretty well. We're going to take the shaft and the stop piece to Rick to get welded on Monday so we'll have that done by Tuesday.
I'm excited. :]
Rick Wilson - our awesome machinst
Rick Wilson - our awesome machinst
7 comments:
we can call it turtle because the entire bot is inside a shell
You can buy standard rechargeable AA batteries at places like Walmart. They are only like $10 for 4 high capacity Ni-MH batteries. I used to buy the Energizer years ago. Last ones I bought in '05 were rated for 2500 mAH. The first pack I ever bought a few years before that was only rated for 1700 mAH.
but justin, are they 1.2 V or 1.5? the transmitter came with 1.2V... i have to double check to see if it can take 6V instead of 4.8V...
All rechargeable batteries are 1.2V. If in doubt, you could always just have 5 batteries for 6V. ;) But everything should run on 4.8V just fine.
well in that case, i have energizer rechargeables at home... :]
thanks justin
Hey Dan, I got a stainless steel washer we can cash in at the scrapyard... problem is i need a truck to haul it over there
rob, i think justin's dad has a truck... ummm ask around. We can definitely scrap it.
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