Our tote and container stacker is primarily pneumatic and to that end we needed to store lots of air. 5 gallons worth to be safe. So we invested in a VIAR 250C and a 5 Gal air tank from Harbor Frieght.
What’s the weight?
How long does it take to charge that thing?
… and for that matter, how long does it take to dump after the match?
Harbor Freight has the tank listed at 15 pounds. About the same weight and capacity of 30 clippard tanks.
I’m smiling looking at this photo. We had similar air use issues with our pneumatic elevator in Week 4 because of the way we (mis)read the compressor specs. Our choice was either mount 30 tanks, or retrofit a motorized winch. We went with the winch, but the switch ate up most of Week 5 (and a good chunk of our budget). I hope the “more tanks” choice works well for you!
it takes our little Viair compressor just over half a minute to fill our one long skinny (2012 KOP) metal storage tank. I’m guessing it will take that compressor at least 5 minutes to fill the big tank. Hopefully you can get it done before each match…
We are using that same compressor, and a metal Viair tank. However, we are thinking that half a gallon of air should be enough.
Five gallons is a lot of air. Based on measurements my team reported earlier, I would estimate this compressor would require about four minutes to recharge a five gallon tank from ~100 PSI back to ~120 PSI. So with a tank that large, it is unlikely you would see a benefit from have the compressor on board.
…without burning up that compressor that I’m guessing wasn’t designed for continuous duty.
Last year, I saw a team from Mexico do something similar. It took them about 5 minutes to recharge. If they made it to the finals, I have no idea what they would do to reset for the back to back matches.
Actually, the VAIR 250c is rated for a 100% duty cycle.
The compressor they are using, the viair 250C, is rated for continuous duty.
Why would they dump their stored air after the match?
Without seeing the rest of the robot design, we can only guess.
I believe that this was explicitly required in previous years - that all stored air must be dumped at the end of the match. I couldn’t find anything stating or implying so in the 2015 game manual.
If you find yourself close on weight, go for the 7gal aluminum one at HF. Saves a little bit and then you’ll really have to try to run out of air.
We did a lot of math on the volume of air our Cylinders use per stroke and we found that an air tank with volume like this is almost a necessity.
The tank is 15 LBS. (I am aware of the light weight version at harbor freight and we’ll keep that in mind if weight is problem, which at the moment our robot is about 30 pounds under weight without the tank on.
Our plan was to use the compressor off-board. If we needed extra weight…on it would go. The compressor is also roughly 15 pounds.
100% Duty cycle at 100 PSI. Charge time is 5 minutes from empty to full. We don’t need to empty the system after every match. We would only do so in the times where we needed to. I also checked the rules for that.
Well I guess we aren’t the only team going with a lot of air this year, although we do have you beat by one gallon 
Finals Could Be a problem if you have to fix something during that time.
Having been through elims at orlando last year, I think we should be fine. We wouldn’t need a full charge to be effective either. The number of actuations we get from a half charge is at the minimum of what we’d need to score around 100+ points by ourselves.
Our goal with this design was extreme simplicity and speed. Come reveal night you should see that we’ve achieved just that.
Cool - when I looked for Ultimate Ascent (our primary climber actuators were pneumatic, as well as the “trigger” for the frisbee thrower), the only 100% duty cycle compressors I found were significantly larger.
I did a search on compressors on CD and found this thread http://www.chiefdelphi.com/forums/showthread.php?t=129321 easily which had a spreadsheet that gave a lot of useful info that helped us decide on the compressor.