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Cam Locks.

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Cam Locks.

Unread postAuthor: rna_duelers » Sun Sep 23, 2007 8:47 pm

Now I have come to a stage in my Hybrid Build were I am wondering what to do.I could use a Cam Lock as a burst disc holder or use a Union,both are made from Aluminium.A Cam Lock would be a lot quicker to use and doesn't have the problem with the tapered contact surface like in a union,I have heard that they have a problems with the burst discs being cut or sheared off from the tapered edge.But the Cam Lock has a rubber gasket to seal the join and this is a definite weak area and most probably would be ruined after a few shots with the gasket most probably being ruined from the temperatures,does anyone have an idea on why I should use one over the other?

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Rna

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Unread postAuthor: noname » Mon Sep 24, 2007 10:18 pm

I'd go with the union. All that a tapered surface means is that you get clean, circular bursts every time.
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Unread postAuthor: rna_duelers » Tue Sep 25, 2007 1:00 am

To late already grabed myself the Cam Lock,it is made from Aluminium though so it is fairly strong.
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Unread postAuthor: SpudBlaster15 » Tue Sep 25, 2007 1:14 am

A tapered union surface will allow the edges of any inflexible (aluminum cans) burst disk to develop grooves on it's sealing surface, preventing the disk from sealing at moderate to high pressures. I resolved this issue by grinding off the taper on my union and gluing a rubber washer to the now flat surface. This setup achieves a complete seal at pressures of at least 90psi.

Cam locks may not survive at higher pressures, as much less surface area is in contact between the 2 components of the mechanism, which means that they could potentially come apart should you use high mixes. I would go with the union.
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Unread postAuthor: noname » Tue Sep 25, 2007 8:34 pm

SpudBlaster, there are union gaslets for a reason, you know. :wink: I got one for $.20, and put the burst disc between it and the tapered surface. Not once have I had any leaks or anything, and no modifications were needed.
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Unread postAuthor: SpudBlaster15 » Tue Sep 25, 2007 8:49 pm

I originally used a setup similar to what is shown in the diagram, and after installing 3 layers of pop can material and pressurizing the chamber to 73psi, the pressure would drop at a rate of ~2psi/second. Since the grinding modification, no leaks have occurred, even when I simply hand tighten the connection.
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Unread postAuthor: rna_duelers » Wed Sep 26, 2007 4:23 am

Well I can always just get a Union if the Cam Lock fails But I have it already.I don't really plan to use this cannon up past 4x mix,the cam lock is rated to 400psi,so it should hold at the pressures generated and I am also going to be remote firing.

What Burst disc materials do you recommend?I was planning on using Soft Drink cans and scoring the material to create weak points to allow the burst disc to rupture more uniformly and how I would like it to.
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Unread postAuthor: jackssmirkingrevenge » Wed Sep 26, 2007 4:28 am

Mylar tracing paper?
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Unread postAuthor: rna_duelers » Wed Sep 26, 2007 7:58 pm

I'll just test a lot of things,tracing papper included.But I do think my best bet is Aluminium foil or Soft Drink can Aluminium
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