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QDV-Tee-1.5-porting

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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QDV-Tee-1.5-porting

Unread postAuthor: dewey-1 » Thu Sep 03, 2009 5:17 pm

Here is a preliminary CAD model for a QDV in a Tee.

The Tee (Dark Blue) is a 2 inch that has 2 to 1-1/2 bushings (Red) on each end.There are Adapters (Purple) that are threaded on each end.

Male end gets a Cap (Orange) and the female is barrel side.
The chamber port is yet to be determined.

The piston pipe (Green) is 1-1/2 inch with 3 holes at 1-3/8 inch.

The piston (Light Blue) is 1.590 x 2.250 long with 2 O-rings.
The piston is mechanically actuated via Pull handle attached via 3/16 Rod.
The bumper is not shown yet.

Open for constructive comments and criticism.






Image


Image

Image

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Unread postAuthor: spudtyrrant » Thu Sep 03, 2009 5:40 pm

nice looking cad, i get what you were trying to show last time now.
One question, why don't you just make it 2 separate sections of pipe instead of having 3 holes I'm sure it would help increase performance.
I would also make the housing just long enough to get full porting and the cut the pipe down for a more compact valve
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Unread postAuthor: Technician1002 » Thu Sep 03, 2009 5:43 pm

Very nice. For an FYI, rectangular ports open more area suddenly with the same piston speed as more area is exposed in the same movement. I use rectangular ports in all mine for that reason.

For larger porting, the threads can be ground out of the T and a 2 inch valve body made and welded in. A single port facing the inlet would work well. I am considering building one this way just to see if it can be done. If it works, I may build a 4 inch so it is easier to aim than a coaxial with a large diameter chamber.

I learned a lesson making this. Sand it smooth before cutting the ports. The ports snag the sandpaper. The Marshmallow cannon got sanded then the ports cut. It made a much nicer valve.

@ Coolhwip
One question, why don't you just make it 2 separate sections of pipe instead of having 3 holes I'm sure it would help increase performance.


Without the link bars from the front and back to keep o rings in the grooves, they tend to lift out of the groove and get launched. Trust me on that one. :D
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Attachments
QDV ports.JPG
2 inch QDV valve ports. This photo is prior to massive sanding inside and rounding of all edges.
Valve Open.jpg
The 1 inch valve is sanded inside to a smooth finish for a great seal.
Last edited by Technician1002 on Thu Sep 03, 2009 6:19 pm, edited 3 times in total.
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Unread postAuthor: jeepkahn » Thu Sep 03, 2009 5:48 pm

Now, Imagine if you will, A spring between the pullknob and the cap, and a triggered sear to hold the knob in the closed position... Light trigger pull(because you're only holding back spring pressure with the sear) and a fast valve that will force itself open once the spring breaks the seal...
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Unread postAuthor: dewey-1 » Thu Sep 03, 2009 6:11 pm

jeepkahn wrote:Now, Imagine if you will, A spring between the pullknob and the cap, and a triggered sear to hold the knob in the closed position... Light trigger pull(because you're only holding back spring pressure with the sear) and a fast valve that will force itself open once the spring breaks the seal...


I had that in mind, but did not get that designed and modeled yet.
The full throw to full open is about 2 inches.

I will await for more ideas and suggestions.

I won't be able to build it so it is up to any others who want to try and construct it. (Health reasons) Hint Hint jeepkahn! :D

I can do designs and CAD, just not building it!

A two inch porting version is next.
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Unread postAuthor: Technician1002 » Thu Sep 03, 2009 6:26 pm

On the CAD, is the piston attached solidly to the rod? This is best permitted to slide on the rod using a pin in the rod to push the valve closed. The pin should retract fully out of the piston travel space before the rod end starts to pull the valve open.

A solidly attached rod can be hazardous to the operator as the opening forces are quite strong. On my 2 inch the force exceeds 300 lbs at 100 psi. The piston hits the bumper, not the rod and thus my hand. My QDV video shows this "reset" pin operation with the sliding piston on the rod.
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QDV-tee-15-3D-RR.jpg
Edited to show the reset pin pushing the piston closed. Rod and pin would retract to a safe location before the piston is pulled open.
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Unread postAuthor: dewey-1 » Thu Sep 03, 2009 6:45 pm

spudtyrrant wrote:nice looking cad, i get what you were trying to show last time now.
One question, why don't you just make it 2 separate sections of pipe instead of having 3 holes


I think you are referring to hubb's drawing aren't you?
The alignment of two different pipes will be very difficult!

Tech; I can easily change the ports to rectangular, I also did not show any chamfering on the ports either.

I was also concerned about the handle rod. I will have to investigate that further.

Keep up the good suggestions!
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Unread postAuthor: POLAND_SPUD » Thu Sep 03, 2009 6:58 pm

you know that you could attach an air cylinder to the rod and use it to open the main valve ?

Image

to avoid air losses when the main valve is in open position one could attach a valve that would open to fill the gun when the piston is closed position.. it wouldn't really be that difficult
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Last edited by POLAND_SPUD on Thu Sep 03, 2009 7:10 pm, edited 2 times in total.
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Unread postAuthor: Technician1002 » Thu Sep 03, 2009 7:00 pm

dewey-1 wrote:I think you are referring to hubb's drawing aren't you?
The alignment of two different pipes will be very difficult!

Tech; I can easily change the ports to rectangular, I also did not show any chamfering on the ports either.

I was also concerned about the handle rod. I will have to investigate that further.

Keep up the good suggestions!


I put a mechanical piston stop internal to my valves so the reset pin has a location to retract into behind the bumper. When the piston flies open the piston can't hit the pin on the way back. It is already retracted into this space before the nut or pin on the other side of the piston hits and starts to move the piston.

The stop assy does not have to be this long. In the cannons it was made this long as it was decided to locate the ports near the far end of the chamber nearest the screw on barrels.

The pins in both my cannons are 1/16th of an inch. The 2 inch uses a nut on the end of the rod. The one inch uses a pin.

The hole in the bushing on the stop assy is large enough for the reset pin to retract through.
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Attachments
WikiVavleCoreAssy.jpg
The valve core assy. Behind the bumper is a stop assy the reset pin retracts into before the piston starts to move open. The reset pin can be seen between the piston and bumper.
WikiVavleCoreAssy.jpg (35.85 KiB) Viewed 1642 times
ValveDetail.jpg
I just shot a picture to show the detail of the two pins that move the piston. At the far left is the end of the stopper assy behind the bumper. That poor bumper looks like it is due replacement. It has taken a beating.

The pin doesn't need to be huge and strong. The piston is easy to move.
ValveDetail.jpg (31.18 KiB) Viewed 1637 times
Valve core detail.jpg
The 2 inch valve uses the same 1/16th inch reset pin, but uses a nut on the end of the rod to open the valve. This old style bumper was a failure. It simply got pounded into the tube. This was later upgraded with a bushing on the end of the tube the same as the Marshmallow Cannon.
Last edited by Technician1002 on Fri Sep 04, 2009 10:17 am, edited 4 times in total.
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Unread postAuthor: THUNDERLORD » Thu Sep 03, 2009 9:55 pm

Excellent CAD drawings!

Of the thousands times I've looked at Tech's creations,
I FINALLY fully understand the valve now!!!

BTW, interesting design POLAND_SPUD added above,
looks like a simpler version of a spring plunger pilot I've been trying to build.
At this point the rest is coming along though, not to mention I just figured a way to eliminate all the restriction it has (also too late).
sort of a bad and a good thing! 8)
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Unread postAuthor: dewey-1 » Fri Sep 04, 2009 9:04 am

THUNDERLORD wrote:Excellent CAD drawings!

Of the thousands times I've looked at Tech's creations,
I FINALLY fully understand the valve now!!!



Thanks, hopefully my drawings approximate the theory of operation of the QDV by Tech.

@Tech; Thanks for the close up photos for the piston/rod assembly.
I will be updating the model with your recommendations. They are greatly appreciated.

The model updates will include bumper/cushion and sliding piston with front and rear piston stops.

Thanks you all for the suggestions! If there are more ideas I will consider them.

Watch this posting for more improvements and suggestions.
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Unread postAuthor: Technician1002 » Fri Sep 04, 2009 1:53 pm

Dewy,

I grabbed some measurements off the 1 inch to get you started modeling it. I put them on the following photos. If you have any questions as to what any of the dimensions go to, pm me.

The 3/4 inch pvc insert is 6.75 inches long. On the end is a machined bushing 3/4 inch thick with a sholder 0.2 inches on the end behind the bumper. The hole in the center is 0.375 inch in diameter, the same as the recess in the piston. The pins are steel welding rod. The rod is finished off by extending out the end of the pipe and a knob attached at the point where it hits the cap right where the piston is in the proper closed positon. These dimensions will vary depending on your selection of the pipe cap and how far it screws onto your pipe nipple. My overall rod length is 12.5 inches long. My knob is 0.838 inches long. The large diameter is 1.05 inches and the small diameter is 0.75 inches.

Edit; Added pictures for Dewey without bumping the thread.
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Attachments
piston dimensions.jpg
Dimensions of the 1 inch piston.
TankDimensions.jpg
Dimensions of the tank assy.
RodEndDimensions.jpg
Spacing of the stops and rod size.
3 Tanks bottom.JPG
Propane tank bottoms for comparison.
3 Tanks side.JPG
Tanks on the side. The launcher was made from the Coleman tank. The plastic foot is removed to reveal the 6 feet.
Trigger Detail.jpg
Detail showing the rear of the 3/4 inch pipe, the 1 inch cap, and the knob mounting detail.
Last edited by Technician1002 on Tue Sep 08, 2009 12:43 pm, edited 1 time in total.
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Unread postAuthor: jackssmirkingrevenge » Sat Sep 05, 2009 12:06 am

POLAND_SPUD wrote:you know that you could attach an air cylinder to the rod and use it to open the main valve?


Or combine it with a pop-off valve to make the ultimate reiprocating auto valve :D
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Unread postAuthor: POLAND_SPUD » Sat Sep 05, 2009 2:18 am

@JSR
you'd need a pop off valve with threaded port to attach an air cylinder and it'd would have to stay open long enough to let the air return from the cylinder back to the main chamber

since you're an expert on pop-offs and farting machines :wink: do you think it'll stay open long enough ?

of course the biggest advantage of my design or using a pop off is that you wouldn't need to use a 3 way valve at all and the fact that the bolt could be directly attached to the piston... since the piston is directly attached to the gun this means that there would be enough force to cycle to gun reliably
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Unread postAuthor: THUNDERLORD » Sat Sep 05, 2009 2:45 am

POLAND_SPUD wrote:...since you're an expert on pop-offs and farting machines :wink: do you think it'll stay open long enough ?


Not directed at myself, (although I was thinking of trying a co2 tyre filler connected to a whoopie cushion nozzle),

It would defeat the efficency some, but could the triggering chamber vent at the end of it's stroke (similar to a hobby gas motor) if that was a problem???

Also, maybe a lever could be used on the triggering chamber, rather than directly pushing the rod and smaller firing chamber used? 8)
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