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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jackssmirkingrevenge
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Sun Sep 16, 2018 4:44 am
Flounder wrote:I am at a loss for the required information for the valve information. I plan to use Mcmaster Carr part number 6646K23 That I have seen used for several builds on the forum all ready. Any advice you can provide would be appreciated.
This should give you a very good approximation:
- 6646K23valvedata.png (2.81 KiB) Viewed 2099 times
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Flounder
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Tue Sep 18, 2018 9:04 am
Thank you for that information. I had to poke around to find how to change Flow Coef to Cv instead of %.
On to another question. Has anyone tried using a slide gate valve for a breech? I have found a few but they only have a 40 psi rating. I think that would be ok since I am running relatively low pressure in this thing, but I was hoping for input from the people who have been doing this a long time.
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iknowmy3tables
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Wed Sep 19, 2018 5:53 am
should be okay, you still wanna make sure your ammo is ahead of the valve outlet while keeping the dead space to a minimum. a lot of designs like the coaxial gun in the website banner used built in ram rods to push ammo into the correct side pipe fittings
A lot of other breech designs incorporated these camlock fittitings which weren't exactly high pressure fittings either I'm sure a 40psi gate valve is at least as strong
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jackssmirkingrevenge
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Wed Sep 19, 2018 5:58 am
Flounder wrote:Has anyone tried using a slide gate valve for a breech? I have found a few but they only have a 40 psi rating. I think that would be ok since I am running relatively low pressure in this thing
I can't think of any examples but you should be fine, peak pressure in the barrel is usually significantly less than the chamber pressure and in any case it only spikes for a moment. GGDT will actually give you an indication of barrel pressure if you select the correct Y axis on the graph bottom left.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Flounder
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Sat Sep 22, 2018 6:19 pm
using GGDT I came up with a peak of less than the 40 psi limit. I also sourced an old oxygen tank today for free while out at a paintball event. I may end up using that for my pressure chamber instead. Hope to have a firing unit next weekend and then start building the carriage for it the following week if my work schedule permits it.
