I just bought the VEX Pneumatics kits and I was wondering if a foot pump would work OK to charge up the air reservoirs or if a small air compressor would be better.
I was hoping that someone who has used the VEX Pneumatic kits before could offer some advice. Sears has a small air compressor for home/hobby on sale right now. It can pump up tires, balls, air mattresses, etc., but it’s still about $99 on sale. I really didn’t know if it would be worth the expense or not, especially when a foot pump is only about $15.
Any advice would be appreciated. BTW - I was thinking of using 3 air reservoirs just to make I have enough air.
Its a hundred bucks but that’s not that bad because you don’t have to pay shipping and its a fairly reputable brand. There are lots of cheap compressors out there but beware of them because they are equally as cheap in construction (won’t last long).
I bought this compressor for working with my tools and other pneumatic related projects.
I paid $300 for it and got the 10 piece tool kit for free (wait for the sale’s). This is MUCH larger than a 1.5 gallon compressor try 22 times larger (tank capacity) and a pump that puts out WAY more than the 1.5 gallon tank. Its quiet, trust me this thing may seem loud but my first compressor was a mini 6 gallon husky and you could hear it through 3 floors lol!
So if all you need is to pump up the air tank then the $100 compressor will serve you well. If you intend to use it for tools however (impact wrench, cut off disc, grinder ect…) or other high load (sand blaster ect…) then it will not work and you need something with more air capacity like the 33 gallon compressor.
BTW Craftsman is a decent brand and their warranty service is nice as you just walk in and exchange defective products. Stay away from the less known brands.
I inherited a small storage tank (about 1 foot by 1.5 feet) from my father’s workshop. If has ordinary tire (schrader) valves on it. One for filling it, another on a short hose for filling tires. There is also a pressure gauge on the tank (or he added it?). You can put 100 PSI into the tank pretty quickly at home (it has a 125 PSI max), and when all you are taking out is enough to fill one or two Vex tanks, the pressure stays plenty high for many rechargings of the Vex tanks (maybe some ambitious student out there can do the math for us. I think you could start with PV = nrT and be successful).
The advantage of using the portable storage-only tank is that it is super-easy to toss into the trunk of a car and go. No power is needed at the other end. You can even take the tank close to the competition field in case of emergencies there.
The disadvantage is that the pressure eventually does fall (for one team, I wouldn’t worry - for several teams I would think about buying another tank or two); and that if your robot has a temporary leak, you can vent the tank through that leak when you try to fill up the robot’s storage tank(s). You also have to have some reliable way to fill up the storage-only tank (I bought a compressor, but you might find high pressure air at a local garage, or body shop, or at a carpentry shop, or…)
Do you have to use air? How about CO2 from a regulated tank? For that matter, is there a volatile liquid (with vapor pressure around 100psi at room temperature) that could be put in the reservoir. I’m thinking some form of freon or the like. Nothing flammable. Do the rules specify air only or exclude other materials in the reservoir?
I own a Co2 regulator system (the same one that was listed above) and it works very well so this could be used in place of a compressor. It simply takes the tank pressure and drops it to a max of 150psi with a standard quick disconnect adapter.
One 24 ounce tank from walmart would fill the reservoir many many times.
At room temperature 70 degrees Fahrenheit a 24 ounce tank would hold about 13.1115 SCF (standard cubic feet). The pressure would be only 1 atmosphere or about 14.7 psi which isn’t that useful in this situation.
Now through some math I found that it contains about 1.0527 cubic feet at 100psi. Now the vex pneumatics tank holds 9.153 cubic inches of air at 100psi.
That means that it contains 1819.0656 cubic inches of Co2 at 100 psi so how many times could this fill a 9.153 cubic inch tank?
So I found that you could fill the vex reservoir to 100psi over 195 times off a single 24 ounce Co2 tank!
And in case you don’t know walmart does Co2 tank exchanges where you buy the tank (full) for $25 and then exchange it for a full one when its empty (for about $7). If there is a paintball shop near by its cheaper just to get it filled and some hardware stores also fill the tanks up.
So if your looking for the ultimate in portability the Co2 tank is the way to go, it makes next to no noise when filling stuff when compared to an air compressor. Plus it weights only 5 or so pounds when fully assembled so it can be taken anywhere.
I still think the compressor is a good idea but if you think the Co2 regulator would be better due to its compactness and portability than go for it, its a nice tool.
One of the Chinese teams at worlds last year had a small portable BATTERY powered compressor that was ideal. They could charge their cylinders while waiting in the queue (and sometimes at the table - even though technically they weren’t supposed to)
I had never seen a 12v compressor with an integrated battery pack so that’s pretty cool but I don’t know how effective that would be. Pretty much all 12v compressors are cheap so if will put out very little air and pull lots of current in the process. The fact that its battery powered makes it portable but it will run out very quickly.
For example I pressurized a 20 ounce co2 tank with air (it was modded to hold air) with one of those 12v mini compressors to see what happened and it practically caught on fire. The thing hit 200 psi (it was rated for 250) after a good 5 MINUTES then it started smoking so I turned it off and returned it.
There are only a few that are actually good but most are just cheap junk.
Something like this is a real 12v compressor with a 100 percent duty cycle at 100psi meaning it can run non stop.
The only problem with these compressors is that once the battery runs out you have to recharge it to use it or get a high current 15 amp 12v DC power supply to run then. On top of that some of them are really LOUD so if the objective is portability and not trying to attract lots of attention then get a Co2 regulator setup as its silent and very portable.
I wanted to thank everyone for their advice - it was really helpful. I hadn’t thought about using a portable tank to charge the air reservoirs. I think that I will probably go with the air compressor though. It might come in handy in case I need to inflate something.
This is the one that I was thinking about getting - I saw it in a Sears ad that my father got in the mail. I really didn’t think I needed the bigger one, but it’s something to think about in case I ever want to use any pneumatic tools.
254 uses a regular bike pump that works really well for pressurizing the pneumatic tanks. I have found decent bike pumps for around 20 dollars that are easily capable of supplying the pressure (100psi) required for filling the reservoir.
Actually, the one the Chinese team was using at worlds last year was about the size of a large lunch box - maybe 12"x12"x8" - ran quietly and did a great job. They just kept it plugged in in the pit area to keep the batteries charged.
I was going to go with the small air compressor from Sears, but I wasn’t sure if I should spend that much money after buying all the VEX pneumatics parts. Besides, the compressor doesn’t actually have a gauge showing the pressure that you charging things up to. I would either have to use a tire gauge to check the pressure or add about $20 or so worth of parts to add a gauge to the compressor.
I did some looking and found this foot pump at Toys R Us which looked like it might work
Despite the various negative reviews, I have never had a problem with it, although I wouldn’t trust my life on the gauge. Not to unduly promote buying from REI, but they have a 100% satisfaction guarantee that they will honor regardless of how trivial the problem is. I would try this pump, and if you don’t like it, you can always return it for your money.](http://www.rei.com/product/722267)
We use a bike pump too. To prevent the loss of air when disconnecting the pump, we use two finger valve on/off switches instead of just one. One is between the tanks and the air input, the other is between the air input and the rest of the pneumatic circuit. When we fill the tanks with air, we turn the switch between the tanks and the input “on” and the other switch “off”. Before we disconnect the bicycle pump we turn the first switch off. Turning the switch off only looses 5psi rather than the 20psi lost when the bike pump is disconnected without the extra switch implemented.
I would recommend being very careful with how you attach and detach whatever you are using to fill the tank with air…
As a side-story, during the World Championship last year, my team (177) picked two of the 254 teams… We were careless in pulling our bicycle pump off after refilling our tanks, going into the semi-final rounds…
We had to take a time-out, and thankfully, 254 had a similar setup, and we were able to swap adapters. However, later, 254 had some problems, and we didn’t have adequate time to fix the problems…
This, with some other things is what I believe led to us being eliminated in the divisional semi-finals…
Anyways… Just a warning with how you treat your equipment… You never know when it might come back to haunt you…