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Mk IV QEV Popoff. Updated 22 Feb

Built a pneumatic cannon? Then post it here! This section is for completed, finished cannons that you have built. Please include pictures and information.
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Unread postAuthor: Mitchza89 » Tue Apr 21, 2009 7:30 am

I love the design mate. Looks like I'll have the catch up a bit. Nothing wrong with a bit of healthy competition right? :twisted: :D

It's ON!




I really do hope to see the new concept in action. It looks gorgeous.
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Unread postAuthor: SubsonicSpud » Tue Apr 21, 2009 7:34 am

POLAND_SPUD wrote:jesus I need to buy a drill press... you used a drill press to make the T right ?? it seems so clean and easy to build - I've been struggling for weeks to add some sort of a detent to minimize double feeds


Yep a drill press was used, and also what I plan to use to make the QEV/Tee Mag block.
You would be suprised what you can make on a drill press, just takes a while to work out what holes to drill in which order, but it is really easy to stuff up a few hours work by getting the order wrong. Actualy you don't even need a drill press, just a normal drill would do the job with some due care. using a clear plastic makes the job very easy too

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Unread postAuthor: Mitchza89 » Tue Apr 21, 2009 7:36 am

I'm very curious to know where you got the clear poly block from. I've been looking everywhere for it.
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Plastic Blocks

Unread postAuthor: Technician1002 » Tue Apr 21, 2009 8:05 am

Mitchza89 wrote:I'm very curious to know where you got the clear poly block from. I've been looking everywhere for it.


Check for a plastics dealer near you. In my area I use Tap Plastics.

Many dealers are online. Save shipping and find one close.
http://www.tapplastics.com

Many a project come from a piece cut from a sheet. Check their catalog.

If possible find a fabrication shop that will let you buy scrap bits per lb. A full sheet is huge and spendy. A 24 inch square of 2 inch thick acrylic sheet is $360. I pick in Tap Plastics fabrication shop boneyard for 1.75/lb.

I make my smaller HDPE valves out of HDPE sheets. 1 inch valves are turned from blocks cut from 1.25 inch thick HDPE sheets. It is what is in the valve for my marshmallow cannon. Laminated, it is what is in my prototype competition t shirt cannon.

***Edit***
Polycarbonate is clear. Polyethylene and Polypropylene is not.
Acrylic is clear, but brittle.

***edit***
SubsonicSpud said the photos here are OK. I'll leave them.

Later I'll put them in a how-to.

I put this here for those who want to make their own larger QEV valves. The dimensions on this valve make it a QEV.

Here are a couple photos showing the replacement of a cracked 1 inch PVC pipe cap used as a piston in a 1 inch coaxial. This cannon is now retired as it was dropped once too many times. The other end of the chamber cracked the coupler and 2 inch to 1 inch reducer. :( This is now retired. I know :!: FAIL :!:
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Attachments
BrokenOriginal.JPG
Original PVC crazed and cracked in an unexpected place. Repeated stress, not impact killed this piston. This is the 3rd failed piston in this cannon. The other 2 failed by ejecting a chip out of the center of the face, an area not in contact with anything. I need something better.
PICT243.JPG
Old piston on a sheet of HDPE. It is easy to see the diameter of the valve seat in relation to the OD of the piston.
PICT244.JPG
Block cut
PICT245.JPG
Drilled for drill press arbor (bolt)
PICT246.JPG
Turned on the drill press to proper diameter
PICT248.JPG
Cutting board wrinkle finish machined off
PICT249.JPG
Swim noodle cut for the bumper
PICT250.JPG
Ready to assemble
PICT252.JPG
Piston in place in the new home. Cylinder is 1.5 inch pipe inside a female 1.5 threaded adapter. Assembly is swedged in the end of 2 inch pipe. It's ready for the bumper and plug with the trigger.
PICT229.JPG
Valve cylinder and seat seal. The large seat makes this a QEV as the piston diameter to seat diameter is a low ratio.
Last edited by Technician1002 on Wed Apr 22, 2009 4:28 am, edited 9 times in total.
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Unread postAuthor: Mitchza89 » Tue Apr 21, 2009 9:09 am

Very nice mate. Thanks a lot for the information. I'll have to look around. For now it's time for bed. Have to get up early tomorrow. No work so lots of spuddy making :D.
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Unread postAuthor: SubsonicSpud » Tue Apr 21, 2009 10:37 pm

Mitchza89 wrote:I'm very curious to know where you got the clear poly block from. I've been looking everywhere for it.


The block of plastic is Acrylic, but it would be better to use Polycarbonate.
To be honest you would be better off using Acetal, or another low friction plastic that machines well. The only problem with that is it will not be clear and you cannot drill it out by eye, meaning lots of time measuring :?

I purchase all my plastic from this company http://www.cuttosize.com.au They are located in Brisbane and Sydney, and have a huge range of stuff. You don't have to buy a whole sheet from them, they will cut it for about $1 a cut. Polycarbonate is not cheap by the way :( but damn is it strong. I shot at a sheet of 6mm polycarbonate with the qev gun and the sinkers only left a smudge mark where they hit :shock: so I use the stuff to shield my camera when it is at the target :twisted:

Always happy to have some healthy competition Mitchza89
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Unread postAuthor: Mitchza89 » Tue Apr 21, 2009 10:47 pm

Oh nice, sounds like I might be in a bit luck. I would love to make my own T valves out of this stuff, all clear so you can see the inner workings.
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Unread postAuthor: Technician1002 » Tue Apr 21, 2009 11:42 pm

SubsonicSpud wrote:
Mitchza89 wrote:I'm very curious to know where you got the clear poly block from. I've been looking everywhere for it.

Polycarbonate is not cheap by the way :( but damn is it strong. I shot at a sheet of 6mm polycarbonate with the qev gun and the sinkers only left a smudge mark where they hit :shock: so I use the stuff to shield my camera when it is at the target :twisted:

Always happy to have some healthy competition Mitchza89


If you can find a sign shop where they assemble custom plastic signage or other plastic fabrication, sometimes they have a scrap bin. I snatch up the polycarbonate pieces at $1.75/Lb. I grab HDPE out of the same bin for the same price. I don't pay for cuts to get a smaller block! It pays to look for these sources.
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Unread postAuthor: SubsonicSpud » Wed Apr 22, 2009 7:34 am

Mitchza89 wrote:Oh nice, sounds like I might be in a bit luck. I would love to make my own T valves out of this stuff, all clear so you can see the inner workings.


By the way, just a quick tip for drilling in brittle plastics like Acrylic and Polycarbonate. It is better to use a drill bit that is not very sharp, if you try to drill with a new or sharp drill bit it will bite in and chip out the hole. also take you're time with the drilling and use some watter in a spray bottle to help cool the bit and plastic, it will give you a much better finish. :D

Anyway guys here is an idea I had to make a remote hopper and feed system.

Image

Basically the air bursts from the popoff will push back the piston back against a soft spring, this will alow a BB to fall into the plunger area. Once the air in the piston area has vented the spring will push the chain of BB's down a feed tube into the tee piece of the barrel. There would be a small spring check to stop the BB's being forced back by the firing air. The check enables a softer spring to be used on the piston which only needs to overcome the friction of the BB's in the feed tube. The system would probably need a fair bit of tuning to get it funning properly to get it to work, but I think it would be worth a shot. The only disadvantage I can see, is probably having to increase the pilot volume a little to get more air flow out of the popoff .

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Unread postAuthor: psycix » Wed Apr 22, 2009 2:07 pm

I like the idea.
Only point is that the hopper still may jam. I think we need to look at paintball hoppers, how do they work internally?
There it is just a motor with a "propellor" to stir the ammo right?
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Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

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Unread postAuthor: SubsonicSpud » Wed Apr 22, 2009 5:09 pm

psycix wrote:I like the idea.
Only point is that the hopper still may jam. I think we need to look at paintball hoppers, how do they work internally?
There it is just a motor with a "propellor" to stir the ammo right?


Not sure how the paintball ones work, but I could just have the air vent from the piston directed into the side near the base of the hopper, it should agitate the ammo enough.

Update, QEV Popoff Mk II Now started

Well today made my own QEV and Tee mag block from scratch, out of a 100mm x 80mm x 30mm block of acrylic.

Image

I used the piston from my 1/4 QEV, if it works with that I will make my own Piston for it. I have still not decided whether to enlarge the chamber port and make the chamber an integral part of the block or to stick with an external chamber. Once I have finished drilling out all the galleys I will trim the block down to make it look a bit more flash. I am going to try and make as much of the gun out of polycarbonate, including the barrel and barrel shroud/suppressor :twisted:

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Last edited by SubsonicSpud on Thu Apr 23, 2009 2:43 am, edited 1 time in total.
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Unread postAuthor: jackssmirkingrevenge » Thu Apr 23, 2009 2:34 am

Good to see the vented air from the pop-off not going to waste at least, looks very promising :)
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Unread postAuthor: Mitchza89 » Thu Apr 23, 2009 6:52 am

Looks absolutely terrific mate. I look forward to seeing great results :)
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Unread postAuthor: sniper hero » Thu Apr 23, 2009 8:44 am

that's looks amazing!
barrel?! that's really cool 8)
is it possible to make the hopper in the polycarbonate block?
I love it to see all different things move when a gun shoots. :D
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Unread postAuthor: SubsonicSpud » Thu Apr 23, 2009 9:20 am

sniper hero wrote:that's looks amazing!
barrel?! that's really cool 8)
is it possible to make the hopper in the polycarbonate block?
I love it to see all different things move when a gun shoots. :D


The hopper could be made out of polycarbonate, but it would be tricky to get a good finish. The piston feed for the ammo I intend to have seperate to the gun, as I want to make it into a gun turret. I'll make the piston and plunger assembly out of polycarbonate but the hopper itself will probably be a plastic funnel.

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