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Destroyer Valve MKII [POWER TESTS 9/6/09]

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: Willdebeers » Thu May 14, 2009 2:24 pm

I just got hold of megah amounts of neoprene. lucky me! :D
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Unread postAuthor: Technician1002 » Thu May 14, 2009 2:36 pm

Biopyro wrote:I could NEVER find small amounts of neoprene or similar in the UK. I asked in 3 auto stores, and asked a few ebay sellers for samples, but had no luck.
I used inner tube in the end, with a penny washer to keep it from curling off the piston face.
I guess if you're going to be making a few, you could get a sheet though.


My hardware (not auto parts) store has it by the Lb. Small amounts is no problem. :)

just got hold of megah amounts of neoprene. lucky me! :D

Well done. I found the easy to "trim it" is to chop off a chunk and attach it to the piston in the lathe or drill press and using a moderately fast speed, use an abrasive tool such as a bastard cut file and do a tire burnout with it until it is the right size and perfectly round. :D

Edit Added photo of the neoprene with a reciept in my prior post. 70 cents/lb. :D

OOPS. EDIT rechecked the receipt. It's 1 LB at 3.5/lb. The 70 cents is for another item. Added a zoom in on the receipt to the earlier post.
:oops:
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Last edited by Technician1002 on Thu May 14, 2009 4:19 pm, edited 2 times in total.
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Unread postAuthor: Moonbogg » Thu May 14, 2009 3:40 pm

Hey, if you buy a Venom i'll buy some of your valves :lol:
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Unread postAuthor: jmccalip » Fri May 15, 2009 8:02 am

Technician1002 wrote:
Jogumpie wrote:Ok, i'll look into sealing face alternatives.


Even a piece cut from an inner tube would work better, but often this is not perfectly flat and smooth. If you are in the US, hit some True Value hardware stores. Some have sheet neoprene rubber by the sheet.

EDIT Promised photo added of neoprene at 70 cents/lb.

I need to get my glasses fixed. I didn't pay enough attention. I added some other stuff at 70 cents. It's a pound of neoprene at 3.50/lb.
:oops:



Haha, True Value. That's the same place I go to! Just get their fender washers instead, they go all the way to 3" and they're already cut.


BTW, Lowes sells an orange 1/8" neoprene gasket sheet in the plumbing section. It's like 6"x6".
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Unread postAuthor: Willdebeers » Fri May 15, 2009 5:56 pm

I need to order the parts to build Destroyer MKII but I just got a cash injection so you probably won't have to wait long. Piston will be with o-rings and a check valve - can anyone suggest where to buy a check valve to fit my needs?


Jogumpie :)
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Unread postAuthor: jmccalip » Fri May 15, 2009 11:11 pm

Jogumpie wrote:I need to order the parts to build Destroyer MKII but I just got a cash injection so you probably won't have to wait long. Piston will be with o-rings and a check valve - can anyone suggest where to buy a check valve to fit my needs?


Jogumpie :)


I would suggest McMaster, but they don't ship internationally. A check valve would cost you about $9, kinda expensive. You could make your own check valve with a ball bearing if you can't find one.

Do your really need one anyway? As long as your pilot is large enough, and the equalization hole is not more than 1/16" it should be OK.
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Unread postAuthor: Biopyro » Sat May 16, 2009 2:54 am

Use a hole through the piston, coming out behind the sealing face. That way, when there is pressure on the sealing face, it will seal the hole.
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Unread postAuthor: Willdebeers » Sat May 16, 2009 3:23 am

Hey, thanks biopyro!




I am ordering from Hendersons.
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Unread postAuthor: jmccalip » Sat May 16, 2009 11:07 am

Biopyro wrote:Use a hole through the piston, coming out behind the sealing face. That way, when there is pressure on the sealing face, it will seal the hole.


Isn't this a barrel sealing piston valve with a 3" tee and 2" porting? If so, that will not work.

There is not enough free space around the edge of the pipe.

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You would be much better off drilling a hole through the side. Here is what I did for my PVC coupling piston.

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Unread postAuthor: Willdebeers » Sat May 16, 2009 2:40 pm

No, its 63mm (3 inch) tee, with 40mm (1.5 inch) port.

But trust me, the flow rate is ridiculous. :D
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Unread postAuthor: jmccalip » Sat May 16, 2009 5:33 pm

Jogumpie wrote:No, its 63mm (3 inch) tee, with 40mm (1.5 inch) port.

But trust me, the flow rate is ridiculous. :D


Why not 2" porting? You're wasting the 3" tee without the larger porting, might as well use a 2" tee.
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Unread postAuthor: Biopyro » Sat May 16, 2009 5:42 pm

It's not possible to use a 50mm tee with 40mm porting, because the ID of the tee and the OD of the pipe are too close. I built one like that only to have to re-build it :(
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Unread postAuthor: mark.f » Sat May 16, 2009 6:27 pm

How close are they? All the piston valves I've built had a difference of about 0.5 square inches between faces, with about a 0.17" difference in diameter. If they're well lubed, they'll work much better than one built in a larger tee with the same porting.
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Unread postAuthor: STHORNE » Sat May 16, 2009 7:57 pm

*OFF TOPIC*

omg, nice avatar mark.f lol


Anyway.... as of the valve, GOOD STUFF!!!
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Unread postAuthor: Biopyro » Sun May 17, 2009 5:19 am

5mm (0.19"). If the piston had an O-ring it might be possible because the sealing face could be larger, but my piston wasn't good enough. If you're using 16bar rated pipe, it definately isn't possible.
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