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| julktyl |
 Posted: 11/22/2009 16:18 PM Post subject: First post and first gun- 6mm SML (Small Munitions Launcher) |
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Private
Joined: 20 Nov 2009
Posts: 22
61.01 Spud Bux
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Hey everyone, this is my very first attempt at a pneumatic cannon so I decided to start small and make a mini. First, I will list the specs for the 6mm SML:
Projectile - 6mm, .20g plastic airsoft BB
Barrel - 5 in. steel brake line
Piston - 1/2" steel rod attached to 1/8" section of pencil eraser (sealing face)
Chamber - 3" section of 1-1/2" dia. Sch. 40 PVC pipe
Filling valve - 1/4" quick connect
Firing valve - Air blow gun
Piston housing and the rest of the gun - 1/4" brass pipe fittings
Overall, the SML cost less than $15 to build. The only things I had to buy were all of the brass fittings and the brake line, the other things were laying around in my dad's garage.
Next on the agenda:
- laser sight (the octagonal shape of the piston is perfect for attachments)
- custom paint job
- more ergonomic hand grip/trigger
- stand for stationary use
I have yet to test the SML and will hopefully be able to tonight or tomorrow. As soon as I figure out if it will work I'll post demonstration video with damage. More pictures are soon to come as well.
Questions/comments/constructive criticism are always welcome.
Last edited by julktyl on 11/22/2009 18:48 PM; edited 2 times in total |
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| maverik94 |
| Posted: 11/22/2009 16:29 PM Post subject: |
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Mandolin Man
Joined: 21 Jan 2009
Posts: 560
55.88 Spud Bux
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| cool, I like it. It is simple yet effective. Have you modded the blogun for efficiency? |
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| POLAND_SPUD |
| Posted: 11/22/2009 16:30 PM Post subject: |
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Lieutenant General
Joined: 13 Oct 2007
Posts: 4387
11901.36 Spud Bux
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wow that's pretty cool.... nice first build
you probably are aware that it would be better to use all metal chamber and use high pressures, right ? |
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| julktyl |
| Posted: 11/22/2009 16:37 PM Post subject: |
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Private
Joined: 20 Nov 2009
Posts: 22
61.01 Spud Bux
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| maverik94 wrote: | | cool, I like it. It is simple yet effective. Have you modded the blogun for efficiency? |
No I haven't, I was unaware that you could. I'll have to check into that.
| POLAND_SPUD wrote: | wow that's pretty cool.... nice first build
you probably are aware that it would be better to use all metal chamber and use high pressures, right ? |
I thought about that at first but couldn't find any kind of metal tubing. What do you suggest using for a metal chamber?
Thanks for the comments  |
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| jackssmirkingrevenge |
| Posted: 11/22/2009 16:45 PM Post subject: |
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aspiring machinist
Joined: 15 Mar 2007
Posts: 18061
32519.23 Spud Bux
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Not bad for a first effort but agreed with the above suggestion that for smaller calibres, a smaller high pressure chamber would be much better in terms of performance Case in point  |
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| POLAND_SPUD |
| Posted: 11/22/2009 16:51 PM Post subject: |
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Lieutenant General
Joined: 13 Oct 2007
Posts: 4387
11901.36 Spud Bux
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it's all about the pressures you can generate... with a fridge compressor you could sacrifice chamber volume for pressure and still get better performance
so even a length of 1/2" 3/4" iron pipe would be ok or copper pipe if you are concerned with weight |
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| julktyl |
| Posted: 11/22/2009 18:01 PM Post subject: |
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Private
Joined: 20 Nov 2009
Posts: 22
61.01 Spud Bux
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Ok, so I've been running some calculations...
The pen gun that jackssmirkingrevenge made has a chamber volume of approx .5 cubic inches without anything in it but with the stuff you have in it it would be less than that (assuming the length is about 10 in. and the inside diameter is about 1/4 in.)
The PVC chamber on the SML is about 6.1 cubic inches based on a length of 3 in. and an inside diameter of 1.61 in.
I thought about it for a bit and the answer was so simple, the gun itself is big enough to be the chamber, assuming the pressure rating is high enough, which I think it is.
So, with some modifications, here is the new version, minus the barrel.
Last edited by julktyl on 11/22/2009 18:51 PM; edited 2 times in total |
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| jmadden91 |
| Posted: 11/22/2009 18:19 PM Post subject: |
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2nd Lieutenant
Joined: 07 May 2009
Posts: 247
204.09 Spud Bux
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Looks great, now grab yourself a Shock Pump and get 300psi into her  |
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| Techie |
| Posted: 11/22/2009 18:24 PM Post subject: |
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Specialist
Joined: 15 Nov 2009
Posts: 55
83.29 Spud Bux
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| no damage pics? video? and i dont think your going to be doing much with a chamber that small, but before coming t a conclusion, how much pressure can you generate? |
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| roboman |
| Posted: 11/22/2009 18:33 PM Post subject: |
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Sergeant Major
Joined: 25 Nov 2008
Posts: 176
127.42 Spud Bux
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Very nice! I've always liked minis...
<sarcasm>
It's a small arms launcher? Does that mean it launches other weapons? 
</sarcasm> |
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| julktyl |
| Posted: 11/22/2009 18:40 PM Post subject: |
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Private
Joined: 20 Nov 2009
Posts: 22
61.01 Spud Bux
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| jmadden91 wrote: | | Looks great, now grab yourself a Shock Pump and get 300psi into her |
That's another thing I was wondering, maybe the quick connect isn't the way to go... I might put a schrader valve on instead. But suppose I didn't, would a regular air compressor be able to pump 300-400 psi into the quick connect?
| Techie wrote: | | no damage pics? video? and i dont think your going to be doing much with a chamber that small, but before coming t a conclusion, how much pressure can you generate? |
| julktyl wrote: | | I have yet to test the SAL and will hopefully be able to tonight or tomorrow. As soon as I figure out if it will work I'll post demonstration video with damage. More pictures are soon to come as well. |
According to the data collected from Burnt Latke's Chamber to Barrel Ratio Tests (granted, he uses spuds and not airsoft BBs), the optimal chamber volume for my barrel (~.2262 cubic in.) would be between ~.13572-.18096 cubic in. Currently, the volume of my chamber is ~.5 cubic in., which well exceeds that. The volume of jackssmirkingrevenge's pen gun chamber is less than .5 cubic in. and has been tested at 400 psi.
EDIT: roboman, maybe I should change the name haha. How does SL (Small Munitions Launcher) sound?
Last edited by julktyl on 11/22/2009 18:47 PM; edited 1 time in total |
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| roboman |
| Posted: 11/22/2009 18:47 PM Post subject: |
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Sergeant Major
Joined: 25 Nov 2008
Posts: 176
127.42 Spud Bux
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| julktyl wrote: |
But suppose I didn't, would a regular air compressor be able to pump 300-400 psi into the quick connect?
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No. That is, I'm assuming you're talking about a normal shop air compressor. If you get a fridge compressor, that's a totally different story. |
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| jmadden91 |
| Posted: 11/22/2009 18:48 PM Post subject: |
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2nd Lieutenant
Joined: 07 May 2009
Posts: 247
204.09 Spud Bux
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| julktyl wrote: | | That's another thing I was wondering, maybe the quick connect isn't the way to go... I might put a schrader valve on instead. But suppose I didn't, would a regular air compressor be able to pump 300-400 psi into the quick connect? |
A regular air compressor will get you about 100-130psi that sort of range. If you want to use the quick connect I suggest you get a fridge compressor hooked up. That will pump to around ~ 500psi and do so through a quick connect. Here is the thread on Fridge Compressor's
http://www.spudfiles.com/forums/my-compressor-300-psi-and-more-much-mo re-d-t11866.html
Edit: Beaten |
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| julktyl |
| Posted: 11/22/2009 18:56 PM Post subject: |
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Private
Joined: 20 Nov 2009
Posts: 22
61.01 Spud Bux
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| Ok so a schrader valve is definitely the way to go then for simplicity and cost. I'll look more into finding a shock pump, thanks for the links too. |
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| Techie |
| Posted: 11/23/2009 16:04 PM Post subject: |
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Specialist
Joined: 15 Nov 2009
Posts: 55
83.29 Spud Bux
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| Quote: | julktyl wrote:
I have yet to test the SAL and will hopefully be able to tonight or tomorrow. As soon as I figure out if it will work I'll post demonstration video with damage. More pictures are soon to come as well. |
My bad  |
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