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servo pressure ratings

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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servo pressure ratings

Unread postAuthor: jackssmirkingrevenge » Sat Jul 10, 2010 5:32 pm

Clutching at straws here, any reason why this would not work, assuming I'd drill a couple of equalisation holes in the servo casing to avoid it imploding?
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Unread postAuthor: jrrdw » Sat Jul 10, 2010 5:39 pm

As long as the circuit board and motor housing has EQ holes as well. Make sure the motor in the servo isn't oil bathed, some are...
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Unread postAuthor: jackssmirkingrevenge » Sat Jul 10, 2010 5:49 pm

jrrdw wrote:Make sure the motor in the servo isn't oil bathed, some are...


Doesn't look like it, what do you think?
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Unread postAuthor: al-xg » Sat Jul 10, 2010 5:51 pm

1mm holes in the casing ? :)
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Unread postAuthor: jackssmirkingrevenge » Sat Jul 10, 2010 5:55 pm

4mm, to match the flow from the HPA feed ;)
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Unread postAuthor: jrrdw » Sat Jul 10, 2010 6:02 pm

Pull the motor check for slots in the casing (where tangs are made to hold the field magnets). Factory EQ's. Nope, not a swimmer!
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Unread postAuthor: al-xg » Sat Jul 10, 2010 6:03 pm

I'd be more worried about the grit you're using as ammo getting caught in moving parts.

Any particular reason why the barrel protrudes so much into the chamber? A piston similar to your first shell ejecting designs seems like a better option to me, for flow and feeding. (and in fact, the same goes for piston valve designs)
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Unread postAuthor: jackssmirkingrevenge » Sat Jul 10, 2010 6:14 pm

al-xg wrote:I'd be more worried about the grit you're using as ammo getting caught in moving parts.


Fair point, perhaps some sort of mesh is in order :)

Any particular reason why the barrel protrudes so much into the chamber? A piston similar to your first shell ejecting designs seems like a better option to me, for flow and feeding. (and in fact, the same goes for piston valve designs)


I thought it would stop the piston being jammed open by the "grit" when it comes to re-close. Which piston are you referring to?
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Unread postAuthor: al-xg » Sat Jul 10, 2010 6:24 pm

err, oh dear i'm helpless at using the search... AHA

http://www.spudfiles.com/forums/cartrid ... t7176.html

Long piston instead of long "inner barrel", and seat could even be cone shaped or profiled to which ever curve works best. The overall flow would be improved.

Instead of the spring you could just use the servo to return to initial position ? Or have a spring on the servo arm instead it might help making the design simpler and more reliable.
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Unread postAuthor: jackssmirkingrevenge » Sat Jul 10, 2010 6:27 pm

Image

You mean it should be oriented upwards? I fear that would cause feed issues.
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Unread postAuthor: al-xg » Sat Jul 10, 2010 6:33 pm

Oh I added to the previous post...

Just using a longer piston and a shorter seat tube on piston valves. It just makes the air (and ammo) flow much more straight forward.

But I do see the anti-grit jamming advantage in this case
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Unread postAuthor: jackssmirkingrevenge » Sat Jul 10, 2010 6:40 pm

Interesting thoughts. I'm wating for some CF tubing to be delivered for use as a barrel, I think I'll give this idea a go.

It avoids using a ball valve which saves a not inconsiderable amount of weight, plus the chamber is guaranteed to be at the full 800 psi before firing, surely the resultant flow will be enough to agitate the BBs and feed reliably...
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Unread postAuthor: al-xg » Sat Jul 10, 2010 6:54 pm

Make sure you leave enough wire length for soldering etc... before passing through the epoxy wall, in case hacking and chipping is required later on :)

It should just work like any other cloud BBMG, mmm actually isn't there a certain danger of exploding ? I'm guessing the chamber has to be quite a large diameter, and the epoxy plugs will have to be quite thick...
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Unread postAuthor: jackssmirkingrevenge » Sat Jul 10, 2010 7:02 pm

It will fit into the copper tube I used for the 12 bore, should be quite safe.

Alternatively I could have the piston rod extend out of the chamber and have the servo externally mounted, but that would mean tiny o-rings which I'm not terribly keen on...
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