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Pneumatic / CO2 megathread
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miles&Jules
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So would you still need a buffer tank for a compressor based flipper
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Post Wed Jul 08, 2015 1:00 pm 
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marto
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Yeh do you remember naked turtles setup?
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Post Wed Jul 08, 2015 1:10 pm 
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Knightrous
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quote:
Originally posted by miles&Jules:
So would you still need a buffer tank for a compressor based flipper


Yes, although you can make a pneumatic lifter with the compressor feeding straight into the ram. One of the first few QLD featherweights used this setup, it was a robot called Mite and was built by Marshall.
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Post Wed Jul 08, 2015 1:29 pm 
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miles&Jules
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also one of the vivid opera house bots had that.

i never could workout what everything was under naked turtles bonnet.
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Post Wed Jul 08, 2015 2:09 pm 
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marto
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So it had a compresser and buffer tank with just a valve.

I also had Flying V which was a test platform for glens custom compressor, ram and a QEV. Too bad it never drove.

Both of these used deoderant cans as buffer tanks at around 100PSI.
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Post Wed Jul 08, 2015 2:14 pm 
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seanet1310



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quote:
Originally posted by Knightrous:
quote:
Originally posted by miles&Jules:
So would you still need a buffer tank for a compressor based flipper


Yes, although you can make a pneumatic lifter with the compressor feeding straight into the ram. One of the first few QLD featherweights used this setup, it was a robot called Mite and was built by Marshall.


Wouldn't that be more like a lifter unless you have quite a good little compressor under the hood?
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Post Wed Jul 08, 2015 3:59 pm 
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Glen
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You need to be able to dump all of your gas into the pneumatic cylinder as quickly as possible, in a co2 setup, the main tank has a tiny tiny hole in it (its less than a mm) so you need to store it in the buffer tank with big fittings and hoses to allow that to happen.

In a compressor setup you won't have that restriction, just charge up your buffer directly with the compressor and fire that into the ram Smile

A compressor directly into the ram itself would make for quite a reliable lifter really Smile Would just need a single valve, cylinder and any old compressor - cheap as.

edit - Sean, it was, he said it was a lifter haha. From memory it would built up a bit of pressure then "pop" up. Was definitely faster than an electric lifter anyway.
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Post Wed Jul 08, 2015 4:39 pm 
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Valen
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If you did penumatic lifter you could put a much smaller ram in to get the speed up, you don't need the size to get the force. I think el-bravo used bike pumps for the rams?
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Post Wed Jul 08, 2015 5:29 pm 
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Nick
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What's the point of a pneumatic lifter, other than to be different? Its cheaper, lighter and much simpler to make an electric lifter. Go full pressure or go home! Laughing
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Post Wed Jul 08, 2015 5:36 pm 
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Valen
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I'm thinking reliability and speed could be better with pneumatics, you don't wind up with a big gear train that you then beat the crap out of ;->
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Post Wed Jul 08, 2015 6:00 pm 
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Knightrous
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quote:
Originally posted by Nick:
What's the point of a pneumatic lifter, other than to be different? Its cheaper, lighter and much simpler to make an electric lifter.


Avoids mechanisms that can jam up like threaded rods and gear motors when they don't have limit switch or they fail.
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Post Wed Jul 08, 2015 8:36 pm 
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Nick
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I could say the same about pneumatics: retracts snapping, gas leaks, limited number of lifts etc. I'm just saying that if you are going pneumatic, at least take it beyond what electrics can do.
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Post Wed Jul 08, 2015 9:12 pm 
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Glen
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This setup would be really reliable imho,

one decent quality compressor driving into a 5/2 solenoid valve, then plumb that into whatever size ram one desires. That way you get powered open and close, and it would be quite quick. A pop off valve at a low ish pressure would keep the compressor happy and prevent any back driving of the arm damaging things.

Would be more reliable than a chain driven motor aka farmboy and scarab with the same sort of robustness a linear actuator would give. Looking at the cost of those parts from Daniels links, the only real cost would be a good compressor.

Kinda wanna make that now haha!
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Post Wed Jul 08, 2015 10:58 pm 
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Nick
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I can see I'm not going to be able to talk anyone out of this Smile. All the mini compressors look virtually identical, about the only thing that changes is the size of the lie about the maximum pressure. Perhaps the first thing to do is replace the standard motor with a smaller, lighter brushless unit that can increase the rpm and pump to a higher pressure?

I found a slightly more honest site that quoted "Performance = 0 - 43 PSI / 3 Bar < 8 Minutes" - so maybe two lifts in a 3 minute match unless there is a pretty large buffer.
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Post Thu Jul 09, 2015 12:14 am 
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Glen
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I wouldn't have a buffer at all on a "lifter" type setup, to the contrary keeping the volume of the system as small as possible would be best so the compressor would pump up quickly until there was enough force to lift whatever is on the arm.

Here's a highly techmological diagram! -



Maybe Aaron can dig up vids of mite or mite-e-er but from hazy memory it did work, the lift started off about the same as a linear actuated lifter then had quite a pop to it.

edit - Performance = 0 - 43 PSI / 3 Bar < 8 Minutes - that doesn't really mean anything without knowing what volume it's pressurising. Presumably a tyre Razz but yeah they would take a while to get a decent buffer to pressure if you wanted more of a flipper.
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Post Thu Jul 09, 2015 12:29 am 
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