my golfball valve (pics)

Post questions and info about pneumatic (compressed gas) powered launchers here. This includes discussion about valves, ratios, compressors, and anything else relevant to launchers powered by compressed gas.

Postby clide » Sun Dec 07, 2003 12:42 am

Ok, I have been working on this sucker for a long time(probably about 2 months) and I finally got it to where I wanted it for the most part. I still have a small leak problem I need to take care of, but hopefully it wont be too much of a problem. My goal was to build a valve that allowed full 1.7"(1.68 acctually, but im rounding) flow for a golfball and I wanted to be able to build it in a 2" tee, which is much harder than it sounds. Also, there were no special machines such as lathes used when making these valves, only a saw, dremel, drill, and one of those grinding wheels, and all the parts were found at my local Ace hardware store. I went through 3 1/2 different versions of this thing and 2 piston designs until I finally got it working. I have noticed several people talking about valves similar to this lately so I figured I would share my experiences so people can have more to base their designs off of.

My first design was a piston in 2" pipe that blocked a hole in the side of the pipe leading to the barrel, and I was hoping releasing the pressure on one side would slide the piston sideways and open the hole. But when I released the air I could never get the piston to slide enough to allow full flow. It just opened partially and let out all the pressure through the small crack it made.

My second design was similar to my final (diagram below) but instead of the bushings and 1.5" pipe as the barrel entrance I tried to use slit 2" inside 2". and on this version I neglected to make sure the sealing surface was flat before glueing it into the tee. I couldn't get the thing to seal very well at all.
This is where the 1/2 version comes in. I kept the same tee, but I busted the slit 2" out with a screwdriver and air pressure. The air pressure was a bad idea, it sent a piston flying into the ceiling in the garage(pics below). Then I cut a shorter piece of slit 2" and reglued it in there, but this time I left about a quarter inch of 2" unsleaved on the inside of the tee. I was hoping I could use an o-ring to seal against the wall of the unslit 2". Well, this acctually worked and I managed to get a perfect seal after much testing and retesting. Well why did I build another version then? Well the way I finally got it to seal involved a loose o-ring and whenever I would fire the gun it would shoot the o-ring out at very high speeds (put 2" holes in a cardboard box and dented the ceiling) No matter what I tried to glue the o-ring to it would shoot off still.

That brings me to my final version, it was easier to make and should be easier to seal (still working on that :(), and it uses my simple piston and opens all the way. I forgot to mention that on my previous versions that I had to build a complex version of the piston because the valve would only crack open sometimes and not fully open. Ill stop yakkin now and show you the valve [:p])

concept
<img src="http://members.cox.net/clide/GOLFBALL%20VALVE.JPG">
<img src="http://members.cox.net/clide/tee.jpg">
<img src="http://members.cox.net/clide/fullview.jpg">
view of my simple and complex piston and my bumper which is a rubber 1.25" coupler
<img src="http://members.cox.net/clide/disassembled.jpg">
simple piston
<img src="http://members.cox.net/clide/golfpiston.jpg">
complex piston. basically the back end is built on a lamp bolt(hollow) and when the air pressure is dumped the back end slides back, compresses the spring, then unseals the front end from the barrel when it reaches the back of the bolt, and the compressed spring pulls back the front end away from the barrel once it is unsealed. I will see if performance is affected any with this one vs. the simple one once it warms up and i get around to doing some testing
<img src="http://members.cox.net/clide/golfpiston2.jpg">
I also had many many different ends for the pistons when tring different sealing methods, in these pictures they just have the classic rubber washer

and finally heres my blooper of shooting my pison into the cieling
<img src="http://members.cox.net/clide/oops.jpg">
<img src="http://members.cox.net/clide/oops2.jpg">

If you have any questions let me know. And is anyone interested in seeing a video of it in action? I haven't shot projectiles(golfballs) with it yet, but when I do I will make a video if anyone wants to see it.
clide
 
Posts: 2488
Joined: Thu Aug 07, 2003 2:52 am
Location: USA
 

Postby chewy » Sun Dec 07, 2003 3:49 am

great job. it pays to not give up right away. my 2in piston has a scond disk or tail on it and it works great.
chewy
 
Posts: 2661
Joined: Tue Jul 29, 2003 12:08 am
Location: USA
 

Postby akb » Sun Dec 07, 2003 5:31 am

Nice job, clide.

Some of my (so far untested) piston designs have looked similar to your simple piston. Very interesting to hear how it worked. Impressive to see the ceiling test.

Innovative ideas on the complex piston. Should be a bit faster to open, but this valve is so large compared to your bore that I suspect it will be hard to see the improvement via measurements.

-- akb
akb
 
Posts: 1055
Joined: Sun Sep 14, 2003 10:39 pm
Location: USA
 

Postby clide » Sun Dec 07, 2003 3:26 pm

well I tested it today, but unfortunately I only got one shot off. On the plus side I did find a weak spot without a violent explosion. When I fired the shot I felt the blowgun on my sprinkler valve come off in my hand, I figured the threads had ripped out of the top of the sprinkler valve, so i was afraid to look back. I was supprised to see my male adaptor to the sprinkler valve snapped off. I got a speed of 397.3 fps on the one shot so with that and knowledge and ggdt it should have an opening time of about 50ms possibly faster because i was guessing that I put 70 psi in it, but that guess is probably a little high.

<img src="http://members.cox.net/clide/ouch.jpg">

also I realized that I didnt have any pics of the inside of the valve, here is one showing how far it opened after I fired the shot.
<img src="http://members.cox.net/clide/inside.jpg">

Edit: thanks for the compliments. akb what do you mean valve big compaired to bore? the valve is the exact size of my bore.
clide
 
Posts: 2488
Joined: Thu Aug 07, 2003 2:52 am
Location: USA
 

Sponsored

Sponsor
 
 

Postby Aaron » Sun Dec 07, 2003 4:37 pm

That's a Toolie Valve. Go check his site and you'll see what I mean.
Aaron
 
Posts: 784
Joined: Thu Jul 31, 2003 10:51 pm
Location: USA
 

Postby Bartman007 » Sun Dec 07, 2003 9:15 pm

Aaron: I was thinking the same think, sorta like a mini-version of my valve:
<a href="http://devinexecution.com/airpower2/data/media/1/STAG5Piston.jpg" target="_blank"><img border=0 src="http://devinexecution.com/airpower2/data/thumbnails/1/STAG5Piston.jpg"> <br />Click image for larger picture</a>

clide: nice job on the valve. I've been designing a similar valve, cept the piston was going to be either SDR-21 without, or 1 7/8" solid pvc rod with, an o-ring. I was planning to use a normal piston body instead of a Toolies' style piston because I suspect that the air-pressure on the back of the front piston body (the part that seals against the barrel opening) slows down the opening of the valve.
That all-metal/rubber piston looks badass. Too bad that isn't your final design.


Peace,
-Bartman007
Bartman007
 
Posts: 2506
Joined: Tue Jul 29, 2003 11:58 pm
Location: USA
 

Postby clide » Sun Dec 07, 2003 10:56 pm

Aaron: It is similar, but it is slightly different in the fact that the piston doesnt have to be much larger than the barrel port. Note that in toolie's design the air has to flow around the sealing piece to get to the barrel, in mine it does not.

Bartman: I dont know that a normal piston would work because there is no surface area for the pressured air to push the piston back into the pilot area once it is dumped. That is just my theory, I guess you can try it and find out. I would give it a go with my original piston (not pictured) but I probably wont get around to fixing my broken gun until much later in the week or maybe even next week.

Edit- after looking at the thread of boogie's valve I just realized that I should be able to use a normal piston and switch the barrel and chamber and have a valve that seals off the chamber rather than the barrel and all I have to do to switch between the 2 different types is unscrew a couple things and change out the piston. I could easily do some tests on which gives more power. I wish I wasn't so busy this week :(
clide
 
Posts: 2488
Joined: Thu Aug 07, 2003 2:52 am
Location: USA
 

Postby akb » Mon Dec 08, 2003 12:12 am

Ouch on the break. Good velocity. Great that you got a measurement.

Did the piston hit anything down where it broke? Is there a bumper in the design to absorb the piston energy??

Large valves give great performance.

If the valve were smaller the system would be more sensitive to changes in it (valve limited performance). When it is bore size like this, changing it has smaller effects on the total performance (many other factors also control performance).

That valve should be moving pretty fast. At 75 psi it has up to 200 pounds of force on it when opening. So it might be accelerating at up to perhaps 500 G's. (Note these are not very accurate values, just estimates).

-- akb
akb
 
Posts: 1055
Joined: Sun Sep 14, 2003 10:39 pm
Location: USA
 

Postby boogieman » Mon Dec 08, 2003 2:12 am

:( darn. that sucks that it broke. It looks like an awesome design, that piston setup looks slick! Good power too. When i built my first(now dead) i had it set up to seal the barrel. It leaked like mad, so i changed it around.

Do you think you can fix the valve, or will you need to rebuild?
boogieman
 
Posts: 2683
Joined: Fri Jul 18, 2003 11:25 am
Location: USA
 

Postby pacogoatboy » Mon Dec 08, 2003 8:56 am

Is there a lot of weight resting on that joint? Can you figure out any good reason why it might have broken there?

This is a very cool design. Basing the piston on a lamp bolt is inspired. Where can you find them? Great work.
pacogoatboy
 
Posts: 2820
Joined: Tue Jul 29, 2003 1:27 pm
Location: USA
 
 
Next

Return to Pneumatic Launchers