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Rat Trap torsion spring idea to trigger ball valve.

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Rat Trap torsion spring idea to trigger ball valve.

Unread postAuthor: boyntonstu » Thu Mar 04, 2010 4:28 pm

We want to open a ball valve as fast as possible for a main or for a pilot.

The action is rotation and somewhere between 45* for a pilot an 90* for a main is required.

It seems to me that a torsion spring would serve the purpose better than a linear spring.

I believe that a common rat trap spring is about half the strength needed.

I guesstimate about 20 inch pounds of torque.

Any ideas for an off-the-shelf torsion spring?
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Unread postAuthor: Hubb » Thu Mar 04, 2010 4:31 pm

Two rat trap springs?
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Unread postAuthor: boyntonstu » Thu Mar 04, 2010 4:42 pm

Hubb wrote:Two rat trap springs?


Yes, that would give us the force, but the packaging is awkward.

What is needed is a single spring about 1" in diameter with a few turns of thicker wire.

We may be able to mount it directly on the ball valve.

Can you picture it in your mind?
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Unread postAuthor: clemsonguy1125 » Thu Mar 04, 2010 6:26 pm

I considered this for my first spring loaded but decided against it because I could buy a commercial spring for the same price and I never came up with a good way to trigger it
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Unread postAuthor: Hubb » Thu Mar 04, 2010 8:43 pm

boyntonstu wrote:
Hubb wrote:Two rat trap springs?


Yes, that would give us the force, but the packaging is awkward.

What is needed is a single spring about 1" in diameter with a few turns of thicker wire.

We may be able to mount it directly on the ball valve.

Can you picture it in your mind?
Actually, yeah. It's such a simple concept that would improve the basic or current spring loaded ball valve tremendously. It's kind of a shame that it hasn't been thought of before.

If you can't find one, have you considered making one?
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Unread postAuthor: boyntonstu » Thu Mar 04, 2010 9:03 pm

Hubb wrote:
boyntonstu wrote:
Hubb wrote:Two rat trap springs?


Yes, that would give us the force, but the packaging is awkward.

What is needed is a single spring about 1" in diameter with a few turns of thicker wire.

We may be able to mount it directly on the ball valve.

Can you picture it in your mind?
Actually, yeah. It's such a simple concept that would improve the basic or current spring loaded ball valve tremendously. It's kind of a shame that it hasn't been thought of before.

If you can't find one, have you considered making one?


http://home.earthlink.net/~bazillion/torsion.html

I can use some help here.

Anyone care to run a few and try it?
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Unread postAuthor: Hubb » Sat Mar 06, 2010 10:11 am

I've never made a torsion spring before, so I'm sorry I probably wouldn't be able to help with that.

But here's another thought: A larger rat trap. The standard mouse trap is probably what you are talking about, but a lot of hardware stores sell giant rat traps (for giant rats). They may have the right spring tension you want.
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Unread postAuthor: john bunsenburner » Sat Mar 06, 2010 12:30 pm

Torsions springs are used to open the boots in some sedans, have a look at an Auto shop or something similar.
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Last edited by john bunsenburner on Sat Mar 06, 2010 2:54 pm, edited 1 time in total.
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Unread postAuthor: Big-E » Sat Mar 06, 2010 1:09 pm

I've actually thought of that idea before, the trick is finding the appropriate spring.

They make springs for air chisels that would probably work perfectly. Torsion springs aren't usually a universal application though, they're more purpose built.

I've considered turning my own springs, the trick is getting a high-temp oven or Kiln to stress-relieve the coils after tuning them.
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Unread postAuthor: Labtecpower » Sat Mar 06, 2010 2:19 pm

Are you just looking for a strong enough spring or a quick way to open a ball valve?

If you're looking for a quick ball-valve opener you may be interested in this;

http://www.spudfiles.com/forums/my-thir ... 20335.html

This is the system I use on my own gun.
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Unread postAuthor: D_Hall » Sat Mar 06, 2010 7:33 pm

As with so many things... mcmaster.com carries a pretty sizable selection of springs. Even torsion springs.
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Unread postAuthor: boyntonstu » Mon Mar 08, 2010 7:52 pm

I took a spring clamp apart for its torsion spring.

Image

It is powerful enough to open the 3/8 BV however its spring rate is not very fast.

Back to longer, faster springs.
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Unread postAuthor: boyntonstu » Wed Mar 10, 2010 11:00 am

I have decided that a torsion spring is too slow.

OTOH I have been shooting quite a lot lately, and since I have repeated the speeds, I am confident that I can manually trigger the BV fast enough.

The early Prochrono shots were too optimistic.

I have been speaking with the company to find out why I have gotten high readings.

Glints, distortion, lighting, etc.


Here are some results.

400 psi 10 d nails + cork with Vaseline lube
gr fps
75 819 (plain cork)
162 587
162 593
168 608
166 607

112 Marble on cork 686

500 psi 204 16d nail 651

Image

About 8 shots in the board at 20 feet. (hand held)

I have been using junk cork tails (for muzzle speed testing) that will tumble as may be clearly seen.

What do you think?
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