High pressure co-axial build log- updated 11/14/08

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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john bunsenburner
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Mon Jan 05, 2009 5:44 am

after -10 you dont notice the temperature as much i.e. when you have 2°C and -2 there is a huge differnce from the way it feels while between -10 and -15 the change is much slighter, when i lived up by st.moritz we had -20 to -25 in the winter but it really was not much of a problem, so i guess it is 50% being used to it and another 50% of it not being all THAT bad once it gets cold eanoth, especially when there is little wind and it is dry, that it is acctually pretty confortable.
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Gippeto
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Mon Jan 05, 2009 7:45 pm

Comfortable? REALLY?

I had to change the cord end on my block heater saturday morning. It was NOT comfortable.

Try working without gloves @-39C. Then add in a light 15km/h breeze. See how "comfy" you are.

That works out to ~ -52C if you were curious.
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pocket
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Mon Jan 05, 2009 10:10 pm

lol were are u Alberta? my cousins live there and there advised not to leave there house! good luck hope it warms up there nice build BTW oh and just outta curiosity whats your profession?
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crashrun
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Thu Jan 15, 2009 8:11 am

I have found that quicksteel works better than led for slugs it comes out 1/3 of the weight but does just as much damage. jus remember to use crc or wd40 in the mould before you put the quicksteel through it to stop stick.
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frankrede
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Thu Jan 15, 2009 3:39 pm

crashrun wrote:I have found that quicksteel works better than led for slugs it comes out 1/3 of the weight but does just as much damage. jus remember to use crc or wd40 in the mould before you put the quicksteel through it to stop stick.
Quicksteel? As in an epoxy?
I highly doubt that an epoxy slug would fare better than a plain lead one.
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crashrun
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Fri Jan 16, 2009 8:48 am

no quicksteel isnt epoxy and they do fair better than led not as heavy either
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chrissilvermancs
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Sun Mar 08, 2009 8:54 pm

wow thats has to be the best piston i have ever seen. u have alot of time on your hands.

what do u use to get 6000 psi?
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Lentamentalisk
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Sun Mar 08, 2009 8:58 pm

read.
learn.
read.
learn.
read.
learn.
post.

You got the order wrong. The answer is all over the thread.
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trae08
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Sun Mar 08, 2009 9:42 pm

trae08 wrote:just curious how do you get to 6000 psi?
Gippeto wrote:Thanks guys. :)

trae08, I used the dead weight tester at my work.

It's essentially a hydraulic pump with a hydraulic piston and calibrated weights.

Lift the weights which are stacked on the piston, and you know how much pressure is in the system.

Super accurate to put it mildly. It goes up to 15 000psi.
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Lentamentalisk
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Sun Mar 08, 2009 9:49 pm

No, that is how he is sure that it can take 6000psi. He is using nitrogen if I am not mistaken, but I don't remember exactly what he said. I was trying not to misinform, but I am not about to read through this tread for someone else.
Do not look back, and grieve over the past, for it is gone;
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Live life in the present, and make it so beautiful that it will be worth remembering.
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Gippeto
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Sun Mar 08, 2009 10:11 pm

chrissilvermancs wrote:wow thats has to be the best piston i have ever seen. u have alot of time on your hands.

what do u use to get 6000 psi?
Well, thanks! And...I wish. :)

As mentioned I used a dead weight tester for the hydrotest.(6000psi)

I'm shooting with nitrogen. Planned maximum operational pressure is 3000psi, and no more.

So far, I've tested to 1000psi with no problems. I'm currently waiting on warmer weather to resume testing. This will (hopefully) get me to 2000psi, and then I'll move on to full pressure.(3000psi)
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john bunsenburner
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Mon Mar 09, 2009 10:46 am

Deoending on where you live you might be able to get 300bar instead of the common 200 in bulk tanks, as 300bar is used in certain diving places, it give longer diving times, but i am not sure if there is a diving shop which has tanks and 300bar at hand, worth a try though if you deicde you want to up the pressure.
"Did you ever stop to think that out of the seven deadly sins envy is the only one which doesn't give the sinner even momentary pleasure"-George Will
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frankrede
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Sun Jul 05, 2009 3:22 pm

Any updates on this Gippeto?
Current project: Afghanistan deployment
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Gippeto
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Sun Jul 05, 2009 10:02 pm

I replaced the hammer spring, and made a new slip on charging handle for cocking it. (~50 lbs cocking effort, too much for one finger and a thumb :lol: )

Testing proceeded smoothly to 1500psi (three shots) where recoil and muzzle blast were...in abundance. :D ggdt estimates 727fps and 646ftlb @ 1500psi N2, but I'm not ready to risk my chrony just yet to verify the numbers.

The pilot volume at 1500psi, "puffed" the valve spring out and forced it over the head of the valve stem. This resulted in an end to testing for that day.

I've re-routed the flow through the valve to go around the valve spring rather than through it (WHY did I do it that way??? :x )

I do believe (hope) I've got it largely sorted at this time. It was punching nice round holes at 20 yards before the new failure.

We'll see. :)

I've been working till late most every night for the last while, and that does not look to be about to change. Further testing is on the back burner for now.

I do appreciate your continued interest though. Thanks. :)

I shall try to do better with updates should they become available.
"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
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skymeat
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Tue Dec 29, 2009 10:21 pm

Gippeto,
I posted about a year ago. Glad to see you've made some progress. I'd love to see an update.




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