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Short question topic

A place to ask general spud cannon related questions.
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Re: Short question topic

Unread postAuthor: farcticox1 » Tue Dec 18, 2018 5:45 am

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Re: Short question topic

Unread postAuthor: jackssmirkingrevenge » Tue Dec 18, 2018 6:18 am

Reminds me of the "missile launcher" Scrapheap Challenge episode:

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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Short question topic

Unread postAuthor: farcticox1 » Thu Dec 27, 2018 5:40 pm

Got compact non return valves from McMaster Carr and was able to easily hand pump over 160psi with no precharge, but volume is really small, will take a long time to fill a tank of any volume. :(

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Re: Short question topic

Unread postAuthor: hectmarr » Fri Dec 28, 2018 10:21 am

Similar to the air bombs in my arms. Unfortunately, it only drives small volume of air. To fill a deposit does not reach unless you are all the afternoon giving and giving pumping :?
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Re: Short question topic

Unread postAuthor: jackssmirkingrevenge » Wed Jan 02, 2019 9:46 am

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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Short question topic

Unread postAuthor: hectmarr » Wed Jan 02, 2019 4:28 pm

In this type of regulator, is it possible to use between 400 and 500 psi in the tank and between 100 and 150 psi at the exit? I have the possibility of getting one but I do not know if it is possible to use it within this range, which is what I need specifically :roll:
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Re: Short question topic

Unread postAuthor: jackssmirkingrevenge » Thu Jan 03, 2019 6:46 am

The critical element is the spring pushing against the pressure, as these things are typically made for a 850 psi output then the stock spring is going to be far too strong.

You can find low pressure kits for certain models but the output is typically higher than 150 psi.

Something like this will probably work better but make sure you have a safety pop-off or burst disk in your circuit, if a seal fails inside then it's full reservoir pressure to your system.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Short question topic

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Re: Short question topic

Unread postAuthor: wyz2285 » Thu Jan 03, 2019 7:57 am

jackssmirkingrevenge wrote:Something like this will probably work better but make sure you have a safety pop-off or burst disk in your circuit, if a seal fails inside then it's full reservoir pressure to your system.

I bought several of these, work wonders. Air flow is healthy and stable.
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Re: Short question topic

Unread postAuthor: hectmarr » Thu Jan 03, 2019 9:30 am

Something like this will probably work better but make sure you have a safety pop-off or burst disk in your circuit, if a seal fails inside then it's full reservoir pressure to your system.

It is definitely the best option for my project. :) Thank you
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Re: Short question topic

Unread postAuthor: Alex345 » Thu Jan 31, 2019 6:23 pm

Two non related questions here:

I was recently successful in filling my cannon from a scuba tank using a paintball fill station adapter and some 6mm pliable copper line by just opening the main valve at a VERY SLOW pace (i only needed 50-60bars). But turns out, i only had like 70bars left in the tank... If i were to refill it to 300 again, would this trick still work or would the pressure just shoot up way to fast?

Second one; For a potential future project, i'd need a way for a solenoid valve to act as a semi auto trigger in a way. What i would like is that when i press a momentary button, the solenoid would open and close immediately, even if i'm still pressing the button. releasing the button and pressing it again would restart the cycle.

This is probably gonna require some kind of circuitry i assume? The solenoid would pilot a QEV and the gun it will be used for will have it's own standalone reloading mech.
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Re: Short question topic

Unread postAuthor: farcticox1 » Thu Jan 31, 2019 7:50 pm

You could use a mechanical linkage that operates a pilot valve that breaks and resets.



Or Swan donavons exhaust mod




I would go for the exhaust mod
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Re: Short question topic

Unread postAuthor: Alex345 » Thu Jan 31, 2019 8:42 pm

Thanks! I knew these existed, but i would have never thought of using them in this clever way... Just ordered one hehe.
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Re: Short question topic

Unread postAuthor: Cthulhu » Sun Feb 24, 2019 5:38 pm

What's the best way to calculate performance for something like this in HGDT?
All three barrels are connected to the same combustion chamber and share the same ignition.
3barrelcombustion.jpg
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Re: Short question topic

Unread postAuthor: jackssmirkingrevenge » Mon Feb 25, 2019 4:32 am

Cthulhu wrote:What's the best way to calculate performance for something like this in HGDT?


I would combine all three barrels and projectile weight into one.

For example if they are 1.5 inch barrels, that's a cross-sectional area of 1.767 square inches each, for a total of 5.301 square inches each. This makes them equivalent to a single 2.598 inch diameter barrel. If your projectiles are 50 grams each, calculate for a projectile weight of 150 grams.

I was recently successful in filling my cannon from a scuba tank using a paintball fill station adapter and some 6mm pliable copper line by just opening the main valve at a VERY SLOW pace (i only needed 50-60bars). But turns out, i only had like 70bars left in the tank... If i were to refill it to 300 again, would this trick still work or would the pressure just shoot up way to fast?


I used to do it with my SCUBA tank filled to 300 bar, but it's advisable to have a pop-off or burst disk valve in your circuit if overpressure is a risk.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Short question topic

Unread postAuthor: wyz2285 » Fri Apr 05, 2019 1:35 pm

Any of you guys 3D print?
Looking to replace mine, for 1000 euros what would you guys get?
DO NOT say original Prusa i3, for 1000 euros I'm not paying for a printer with 3D printed parts with such a small build volume.
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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