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.
User avatar
Gippeto
First Sergeant 3
First Sergeant 3
Posts: 2491
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Has thanked: 1 time
Been thanked: 6 times

Donating Members

Mon Jan 21, 2008 12:20 am

All metal co-axial design.
Piston to be piloted by a hammer valve.
"Bullpup" configuration to keep it short.

All tubing is 1026 DOM (Drawn On Mandrel)
All internals are 1045 annealed for machining

Barrel 36" 1"od. x .120" wall = .760" bore
Chamber 1.51"id.x1"(barrel od.)x10" (.120" wall) about 10 cu.in
Pilot area .062in2 (.280in dia) minimum throughout hammer valve.
Piston weight ~3 oz

Calculated burst pressure of chamber accounting for variations in wall thickness 9000psi - should easily take 3000psi (hpa)

Calculated shear strength of a single 1/4 x 28tpi socket head cap screw (using the lower YIELD strength) 3488 pounds of force (I'll be using 6 on the chamber front and 12 on the rear (hammer valve block).

Calculated burst pressure of check valve, 9000psi (using yield strength)

ggdt predicts good things

Anyone got a scuba tank for sale? :twisted:

Finished piston.
Finished hammer valve.
Finished milling tube.
Finished barrel.
Finished check valve and barrel plug
Finished New check valve with probe style fill
Passed hydro testing. 6000psi for 3hrs.
Finished sear arrangement
Stock completed
Trigger group completed

Initial test firing demonstrated the need for a couple improvements.

New valve stem (teflon seat) and hammer spring (heavier)

Scope rail completed
New slug mold completed

Regulator arrived. Tescom 6000psi inlet, 2500psi outlet. Overhauled and re-ranged to 4000psi outlet. :twisted:

Time to cast some slugs and punch some holes. :)


Test fire vid;

[youtube][/youtube]



Shooting vid;

[youtube][/youtube]
Attachments
Piston is now complete.
Piston is now complete.
Hammer valve parts.jpg
Rear plug w/spring seat, spring and hammer, Hammer valve, piston, ring to be sectioned for centering of barrel, Quad ring
Rear plug w/spring seat, spring and hammer, Hammer valve, piston, ring to be sectioned for centering of barrel, Quad ring
Hammer valve finished.jpg
Passed hydro like 6000psi was nothing!
Passed hydro like 6000psi was nothing!
Finished my new check valve with probe style fill. Plug and play. : )
Finished my new check valve with probe style fill. Plug and play. : )
Parts.jpg
Stock mounted 2.jpg
Completed sear.jpg
Slug came out at 830 grains. Far heavier than I wanted. Will make some changes to reduce the weight and improve the mould.( its a bugger to get the slug out, need a split mould)
Slug came out at 830 grains. Far heavier than I wanted. Will make some changes to reduce the weight and improve the mould.( its a bugger to get the slug out, need a split mould)
Reworked my slug mold. New Foster slug comes in @ 550 grains. &amp;quot;Skirted&amp;quot; slug is 520 grain. <br />.177 swiftflite and .22 Benji dome for comparison
Reworked my slug mold. New Foster slug comes in @ 550 grains. &quot;Skirted&quot; slug is 520 grain.
.177 swiftflite and .22 Benji dome for comparison
The end of the road for this thread. FINISHED. Test firing to start as soon as time allows.
The end of the road for this thread. FINISHED. Test firing to start as soon as time allows.
New split mold. A huge improvement.
New split mold. A huge improvement.
Last edited by Gippeto on Mon Oct 19, 2009 4:15 pm, edited 23 times in total.
User avatar
LikimysCrotchus5
Sergeant
Sergeant
Posts: 1099
Joined: Tue Sep 04, 2007 10:16 pm

Mon Jan 21, 2008 12:22 am

wow looks great, especially your piston.

I expect great things from you :)
4SPC, My 4" piston 3" porting cannon
Memo:
Fix up copper cannon
Fix up 4SPC
Start Stirrup pump
Start Toolies piston bazooka
User avatar
Pilgrimman
Specialist 4
Specialist 4
Posts: 480
Joined: Thu Jun 28, 2007 1:10 pm
Location: Grants Pass, OR

Mon Jan 21, 2008 12:41 am

This is your 4th post, and you've surpassed my capabilities already! Needless to say, I'm impressed! :D
Yeah, we wouldn't want to anger the bees, now would we??

I HATE YOU BEES! I HATE YOU BEES! I HATE YOU BEES!

LMAO Classic!!!! I love Family Guy!
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 25792
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 109 times
Been thanked: 64 times

Donating Members

Wed Mar 26, 2008 1:32 pm

How did I miss this :shock:

Looking great, what's the estimated time of completion? Or at least, when are the test firings planned :D
hectmarr wrote:You have to make many weapons, because this field is long and short life
User avatar
Skywalker
Specialist
Specialist
United States of America
Posts: 187
Joined: Sun Aug 05, 2007 7:22 pm
Has thanked: 1 time
Been thanked: 2 times

Wed Mar 26, 2008 1:40 pm

Holy figgin krap dude! :shock: Nice machining, and that'll be a kickin' gun too! What kind of nice things does ggdt say?
User avatar
Gippeto
First Sergeant 3
First Sergeant 3
Posts: 2491
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Has thanked: 1 time
Been thanked: 6 times

Donating Members

Wed Mar 26, 2008 1:41 pm

Thank you sensei;

I'm currently re-doing the check valve.

While building the fill set up for the copper gun, I thought "Why not do a probe style fill? So much easier to get the trigger/sear around.)

If I can stop finding new distractions :roll: , it could be ready in a couple of weeks.


ggdt PREDICTS 500grain slug @886fps
"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.
User avatar
Antonio
Corporal
Corporal
Posts: 508
Joined: Sun Aug 13, 2006 2:38 pm

Wed Mar 26, 2008 2:04 pm

Nice work, awesome stuff. I wish I could make guns of this quality. I am looking forward to the results:)
User avatar
POLAND_SPUD
Captain
Captain
Posts: 5402
Joined: Sat Oct 13, 2007 4:43 pm
Been thanked: 1 time

Wed Mar 26, 2008 4:49 pm

ggdt PREDICTS 500grain slug @886fps
I think its power would be better used with 500 grams... anyway sorry for complaining - your gun looks very promising
User avatar
SpudFarm
First Sergeant 3
First Sergeant 3
Posts: 2571
Joined: Sat Nov 04, 2006 9:39 am
Location: Norway Trondheim area

Donating Members

Wed Mar 26, 2008 5:29 pm

6000psi :shock:

that has to be an awesome gun :)
"Made in France"
- A spud gun insurance.
User avatar
Gippeto
First Sergeant 3
First Sergeant 3
Posts: 2491
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Has thanked: 1 time
Been thanked: 6 times

Donating Members

Wed Mar 26, 2008 7:53 pm

Thanks.

Time will tell whether ggdt is close on its estimate, I would certainly like it to be. :)
"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.
User avatar
pizlo
Corporal 3
Corporal 3
Posts: 783
Joined: Fri Dec 22, 2006 7:27 pm
Contact:

Wed Mar 26, 2008 8:14 pm

... this is now my new favorite gun, even though its not gun it just looks so damn sick! and could you actually take it up to 6000? Where do you work??
User avatar
Gippeto
First Sergeant 3
First Sergeant 3
Posts: 2491
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Has thanked: 1 time
Been thanked: 6 times

Donating Members

Wed Mar 26, 2008 8:27 pm

Sick is good? 8) It will look similar to a bullpup assault rifle when done.

Not only could I take it to 6000psi, I did...for proving (see the pic with the gage). Designed operating pressure is 3000psi. All parts exposed to pressure have a minimum rating of 9000psi. (calculated using yield strength of the material)

"Where do you work?? "

Only the shadow knows! :lol:
"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.
User avatar
lockmanslammin
Specialist
Specialist
Posts: 152
Joined: Sun Feb 10, 2008 3:22 pm
Location: Sioux Falls, South Dakota

Wed Mar 26, 2008 11:24 pm

>wipes drool from goatee<
WOW! This is the coolest thing I have seen on this site so far, hands down.
makes my current high of 315PSI look piddly. I am totally looking forward to some video. I bet it will sound like a d*mn real gun going off. This thing is a beast. H*ll you could probably hunt with the thing...lol.
Awsome..good work,

Lock
Last edited by lockmanslammin on Thu Mar 27, 2008 11:01 am, edited 1 time in total.
User avatar
jackssmirkingrevenge
Five Star General
Five Star General
Posts: 25792
Joined: Thu Mar 15, 2007 11:28 pm
Has thanked: 109 times
Been thanked: 64 times

Donating Members

Thu Mar 27, 2008 1:07 am

lockmanslammin wrote:This thing is a beast. Hell you could probably hunt with the thing...lol
An 0.76" slug with 800 or so ft/lbs behind it is more than enough for most medium sized game if you can get to within 50 yards of it.

Gippeto, you do realise this thing has the potential to seriously harm your eardrums, I hope you've made provisions for some sort of ear protection...
hectmarr wrote:You have to make many weapons, because this field is long and short life
User avatar
Gippeto
First Sergeant 3
First Sergeant 3
Posts: 2491
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Has thanked: 1 time
Been thanked: 6 times

Donating Members

Thu Mar 27, 2008 9:25 am

White tailed "prairie carp"? :lol:

Accuracy will be the issue not power. A mold for foster slugs will have to be made.

No worrys on the hearing protection, I have it and generally use it.
"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.
Post Reply