Non vex pneumatics!!!!!!!

VEX V5 General Discussion General Forum
1

Vex pneumatics have a 1in stroke or something very low like that, I configured a 10in stroke single acting 3/4in piston for less than $150 I did not buy it I just put it together in my head.

That includes a piston, solenoid valve, QEV, regulator, All Connecters and tubing, and an optional air source. With such a large cylinder its best to stick to an air compressor and not a small tank because it will run out fast. Or an HPA tank.

Now what I came up with is much larger than the vex pneumatics but the beauty of my idea is that you just have to build the air source, then its a walk in the park to change cylinders, I can have cylinders configured to a specific stroke length ect… But you can get mini cylinders smaller than vex if you want or bigger.

Here is the pricing that I found.

3/4in cylinder, 10in stroke, spring return, magnetic cushion, rubber cushion. $45

http://www.poweraire.com/series-cylinder-bore-p-803.html

1/4in Solenoid valve $27 with shipping new

http://cgi.ebay.com/1-4-Electric-Solenoid-Valve-12-Volt-DC-GREAT-ITEM-B20N_W0QQitemZ300225252273QQihZ020QQcategoryZ87087QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

**NAQ Series Quick Exhaust Valve 1/4" Thread Size
** $16

http://www.poweraire.com/series-quick-exhaust-valve-thread-size-p-399.html

Hose Barbs X 5 $8

http://www.poweraire.com/14b6-barb-p-4965.html

**1/4in hosing 100ft
** $7.50

http://www.poweraire.com/blue-polyethylene-tubing-100ft-p-2259.html

Air regulator $20

http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100082550

Vex explorer motor adapter $10

http://www.vexrobotics.com/vex-robotics-cables-accessories-parts.shtml

Relay $9

http://www.radioshack.com/product/index.jsp?productId=2049722&cp=&sr=1&origkw=relay&kw=relay&parentPage=search

Resistors $2

For current limiting.

Grand total $145

The air tank is provided by you, it can be a large pvc tank with a bike valve and 1/4in npt out or an air compressor.

Keep in mind this is a much better kit that vex because the cylinders themselves include features like magnetic cushions which help smooth out the cylinders operation and make it much less jumpy.

This also adds much more functionality when you can get 10inches of linear motion, thats a lot more than the vex cylinders can put out.

If you take the time to look at what I made you might understand how its constructed but if not heres a picture.

2

Excellent work!

Thanks for showing us everything that you bought and explaining how you used it.

3

he hasnt bought it yet…this is a possible design

this is very good work…for a comperresor if you want a continous source i suggest an electric pump, i have one i got for $90 dollars at canadian tire and it works amazingly

4

I have not bought this stuff and if I am going to build this it will be in September or October when I can get some cash.

As for a compressor as a continuous source… I have a Craftsman 33 gallon compressor max 150psi so there would be no shortage of air!!!

I did not take this into account but I am unsure as to how fast this pneumatic cylinder can cycle, It depends mostly on the solenoid valve speed and the cylinder speed. I can see this doing 1-4 cycles per second at most.

I never described really how it works so here you go, The regulator reduces the pressure, which goes to the solenoid valve. The solenoid valve is triggered by the vex motor ports and a relay. When the valve opens air rushes through depressing a small pin in the quick exhaust valve which causes the valve to seal. The air then rushes into the cylinder pushing it forward. When the valve is closed the air no longer pushes the pin in the quick exhaust valve down. This means that the air in the cylinder is vented allowing the cylinder to return via an internal spring.

Its a very simple design but it sure packs a punch at a 140psi!!!

5

I’ve found Surplus Center to be an excellent source for small (and relatively cheap) pneumatics, as well as other nifty robot parts.

I picked up some small single-acting cylinders for just $6 each to use in a claw. They were new and arrived in perfect condition (nice and shiny!). They work very well with Vex, but you have to provide your own hose connectors, since they just have threaded 10-32 holes for the air ports.

Cheers,

  • Dean
6

That is the coolest website EVER! Well at least I like it. :slight_smile:

By the way for people that do not know this website is also amazing as well http://www.mcmaster.com/.

7

I just went searching over this website, http://www.surpluscenter.com/air.asp?UID=2008051522154841&catname=air

I basically found out that my original design includes unnecessary parts like the QEV.

Instead I found a 1/8in 4 way 5 port valve for $40, its basically a valve that is specifically designed to run a double acting pneumatic cylinder and if you cap one of the holes it can run a single acting cylinder. I also found some nice double acting cylinders 7in long retracted with a 4in stroke for $6, you can’t beat that! Then you need all the connectors and tubing which is another $15. You can buy the regulator if your tank pressure will be higher than the solenoid valves max (100psi). And you need the the vex explorer motor adapter and relay $20.

Add it up…

$40 Valve
$6 Cylinder
$15 Hose+Fittings
Regulator Optional (+$20)
$20 Vex parts

WOW!!!

Without the regulator you get a working double acting cylinder for…

$81

With the reg its…

$101

+Shipping

Tell me what you think, If you need an animation of how the valve works go here. It should be pretty self explanatory.

http://www.teamdavinci.com/understanding_pneumatics.htm

Scroll half way down and find the valve animation.

This might look like a small set but I found a cylinder for $30 that is 17 3/4in long retracted and almost 30in extended!!! All you need to do is change the cylinders because they are all 1/8in.

And now I have about $100 to spend on building this so I will try to buy it tomorrow so it gets here by Friday.

8

I ordered my parts yesterday so they should be on there way soon.

I ended up getting the larger 1/4in 4 way 2 position solenoid valve because it can take more pressure and the flow rate is higher meaning that you can use small cylinders or large cylinders if you need them.

I got a double acting cylinder, its 7 in long retraced and 11in extended for $6 with a 1/4in rod for mounting stuff.

I did find out that this solenoid can run 2 single acting cylinders at differnt times so if 1 cylinder is extended the other is retracted.

Since this valve has a very high flow rate of 10cfm at 125psi you can run a lot of cylinders off of just one valve. I would say that you could probably run 5 or 6 double acting cylinders off of one valve with no problems.

My design is not vex compatible yet but I am going to get a relay and that parts to build the I/O interface as soon as I get it and test the setup.

As for the air tank and regulator, I am using my compressor because it serves as both and has a vast supply or air so I will never run out. But I suppose you could build your own pvc air tank and get a cheap regulator but the air will drain rapidly.