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The lack of homemade pumps.

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The lack of homemade pumps.

Unread postAuthor: Mitchza89 » Wed Jan 16, 2008 5:46 am

Argh this is annoying lol, there is a shear lack of homemade pumps on this site. People venture into making quite dangerous things but hardly ever a pump. Is it that people are happy with 160psi out of a floor pump or C02 to achieve high pressures?
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 16, 2008 6:00 am

Probably the reason is that if you've got the gear to make a high-pressure pneumatic, then you have the necessary contacts to get regulated bottles.

Still, if they could make a high pressure pump using eighteenth century technology, I don't see why it's such a great challenge.

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Unread postAuthor: Mitchza89 » Wed Jan 16, 2008 6:01 am

Yeah you make a valid point. Whats those last 2 pics? Looks like a weeeiird piston :?
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Unread postAuthor: Hotwired » Wed Jan 16, 2008 6:03 am

Oiled leather most likely.

I just dismantled my shock pump again and realised the floating o-ring pump valve idea is far from new :P
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 16, 2008 6:06 am

Hotwired wrote:Oiled leather most likely.


spot on, standard sealing material of the era:

The long pump has a snap-off foot pedal/combination tool which could be held to the ground with the user’s boots. By moving the cylinder up and down while it is attached to the pump, air could be pumped, into the air cylinder. The head of the piston consisted of a stack of seven, oiled leather washers. Note that the little cross sectional view at the top left shows that the full diameter bore of the pump continued right out to the end as the vent hole of the pump. This reduces the lost volume at the end of the pump, which needs to be kept to a minimum as air is compressed into this space as well and just expands again when the pump is extended.


Note that this pump did not need a check valve as it was threaded directly to the firing valve of the chamber (visible to the right of the above drawing)
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Unread postAuthor: Mitchza89 » Wed Jan 16, 2008 6:08 am

Thats unreal, so ahead of it's time. With that you said that the pumps aren't that much of a challenge, people still make crappy little pillbox combustions and simple pnuematics :D
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 16, 2008 6:11 am

Mitchza89 wrote:Thats unreal, so ahead of it's time. With that you said that the pumps aren't that much of a challenge, people still make crappy little pillbox combustions and simple pnuematics :D


People still use bows and arrows, just because technology has been rendered obsolete it doesn't mean it doesn't have a place in a hobbyist's repertoire ;)
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Unread postAuthor: Hotwired » Wed Jan 16, 2008 6:22 am

Anything is a challenge if you don't have the tools for it.

Those weren't made by an average bloke but in proper engineering workshops by proper engineers.

Practical working machines are exactly of the time they were made and still hanging on to the same principles many many years later just shows that really useful designs never die.


Back to the pump though, with no check valve in the stem, the poor sod pumping it would have had to pull the piston up against a vacuum until the head reached the vent in the cylinder wall. Talk about uphill both ways.
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 16, 2008 6:43 am

Hotwired wrote:Those weren't made by an average bloke but in proper engineering workshops by proper engineers.

Back to the pump though, with no check valve in the stem, the poor sod pumping it would have had to pull the piston up against a vacuum until the head reached the vent in the cylinder wall. Talk about uphill both ways.


True, but the average bloke now has a lot more tools and materials at his disposal.

You're right about the pump, though apparently each soldier carried enough prefilled chambers for your average military encounter.
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Unread postAuthor: Ragnarok » Wed Jan 16, 2008 9:52 am

Excuse me - lack of homemade pumps?

The thing is, people tend to either build large cannons out of PVC, so you can't use high pressures, or small ones out of metal where a shock pump can do the job.
Any larger high pressure cannons tend to use gas bottles or expensive compressors. I went different on that, building what is a pretty large high pressure cannon to still be using a manual pump, and I'm too cheap to buy a high pressure compressor, but I might be making one sometime.

Also, JSR has a good point, a lot of people still use bows these days, in spite of the fact they've not been used in a battle in well over a century - well, crossbows are a bit of an exception, because special forces still use them on occasion, but certainly not in a battle.
And even on this forum, people will build small replicas of mediaeval siege weapons.

I'm personally for moving on and developing spudding rather than just cloning older designs, because if you don't get a few new ideas, then things will grow stale. Even if that development is just a case of doing something already around a bit better.
My next project is going to follow this trend, but you'll have to wait a bit to find out what it is.
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 16, 2008 10:12 am

crossbows are a bit of an exception, because special forces still use them on occasion, but certainly not in a battle.


While they are supposedly held in SF arsenals, I doubt they would actually have much use for them. The only reason I would think one would use a crossbow in preference to a firearm is to avoid noise. A modern suppressed 22 pistol or rifle is as quiet as a crossbow, and much more lethal, plus a headshot is more likely to result in a quiet instant death as opposed to the prolonged screams of someone hit with an arrow or bolt that is more akin to being stabbed by a knife.
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Unread postAuthor: Ragnarok » Wed Jan 16, 2008 10:39 am

Well, I can't see much use for them either, but they are supposedly held in the arsenals, and that's the best information I have.
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 16, 2008 10:51 am

Ragnarok wrote:Well, I can't see much use for them either, but they are supposedly held in the arsenals, and that's the best information I have.


greek army

turkish army

indian marines

SAS crossbow

They're certainly kept, though are they ever actually used, I don't know.
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Unread postAuthor: Ragnarok » Wed Jan 16, 2008 10:58 am

Well, I think I heard they were used in Northern Ireland on a couple of occasions, but I'm not sure where I read that, so I can't confirm it.
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Unread postAuthor: jackssmirkingrevenge » Wed Jan 16, 2008 11:04 am

Ragnarok wrote:Well, I think I heard they were used in Northern Ireland on a couple of occasions, but I'm not sure where I read that, so I can't confirm it.


According to the Beeman website:

(Modern note: Powerful, modern, silenced, 9mm PCP airguns are being used by U.S. Seals in Iraq to snipe at insurgents. Firing an M-16 at dawn or dusk could attract a lot of return fire to the flash point.)


In the shadowy world of the elite special forces, who knows what's true and what isn't :roll:
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