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A 2 stage manual pump.

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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A 2 stage manual pump.

Unread postAuthor: boyntonstu » Sun Jul 05, 2009 10:49 am

Beautiful work.

However, I believe that a free piston driven by a 250 psi 12 VDC air compressor would be easier to build.

http://www.uksgc.co.uk/forums/index.php ... =0&start=0

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Unread postAuthor: inonickname » Sun Jul 05, 2009 10:55 am

Well thanks a lot, it's already been posted here man..

Please drop the tire inflator thing, they're absolute rubbish.
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Unread postAuthor: pizlo » Sun Jul 05, 2009 11:02 am

You made a topic to tell us that you think a crappy 12v compressor which will break in a few days could ever be better than that?

Please delete this or something... and stop posting here until you get maybe 2 years older.
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Unread postAuthor: boyntonstu » Sun Jul 05, 2009 11:22 am

inonickname wrote:Well thanks a lot, it's already been posted here man..

Please drop the tire inflator thing, they're absolute rubbish.


Have you ever been on the roar and used one to inflate a tire?

I have 4 of them in 4 cars and they still work.

At 6 bucks apiece, not too shabby.

As I see it, a chamber can be pumped up for a single shot in less than a minute.

If you do not like my posts, please ignore them.

Thanks,

BoyntonStu
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Unread postAuthor: boyntonstu » Sun Jul 05, 2009 11:24 am

pizlo wrote:You made a topic to tell us that you think a crappy 12v compressor which will break in a few days could ever be better than that?

Please delete this or something... and stop posting here until you get maybe 2 years older.


I am 70 years old and perhaps a bit senile, but I still have some manners and civility left.

Please ignore my posts.

Thanks,

BoyntonStu
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Unread postAuthor: Ragnarok » Sun Jul 05, 2009 11:32 am

boyntonstu wrote:Have you ever been on the roar and used one to inflate a tire?

More importantly, have you ever tried to use one for a spudgun?

We're not talking about pumping a car tyre to 30 psi once in a blue moon, we're talking about lengthy and heavy use.

Seriously, emergency compressors are a poor choice for a spudgun, as they're slow and prone to giving up if worked hard.
There are more considerations here than just peak pressure.
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Unread postAuthor: boyntonstu » Sun Jul 05, 2009 12:13 pm

Ragnarok wrote:
boyntonstu wrote:Have you ever been on the roar and used one to inflate a tire?

More importantly, have you ever tried to use one for a spudgun?

We're not talking about pumping a car tyre to 30 psi once in a blue moon, we're talking about lengthy and heavy use.

Seriously, emergency compressors are a poor choice for a spudgun, as they're slow and prone to giving up if worked hard.
There are more considerations here than just peak pressure.


Specifically in measurable terms what does lengthy, slow, and heavy use mean?


Have you experienced all brands and models of 12 V air compressors to make a general impression about all of them?

In an small caliber airgun the volume of air required in the chamber for a single shot is tiny in comparison with any car tire volume.

I accept your opinion, and it may be completely valid, but as you said and I agree "There are more considerations here than just peak pressure."

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Unread postAuthor: MRR » Sun Jul 05, 2009 12:15 pm

@Stu
Some people here on the forums have read so many posts and have build so many things that they kinda feel elite (don't care about it).

In most cases every idea has been done before, in one or another way. There are only few ideas that are new and fresh.

It is presumed that a user first uses the the search engine (which sucks) before he/she opens a new topic.

If you think that you have a good idea and everyone else say it stinks...
...build it and proof them better.
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Unread postAuthor: velocity3x » Sun Jul 05, 2009 12:18 pm

boyntonstu wrote:Specifically in measurable terms what does lengthy, slow, and heavy use mean?


Are you familiar with the term...."DUTY CYCLE"?
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Unread postAuthor: boyntonstu » Sun Jul 05, 2009 12:38 pm

velocity3x wrote:
boyntonstu wrote:Specifically in measurable terms what does lengthy, slow, and heavy use mean?


Are you familiar with the term...."DUTY CYCLE"?


Yes indeed.

What duty cycle would you expect to operate one of these pumps?

10%, 50%, 90%?

I was thinking of pumping for a shot, cool off when loading and firing, etc.

I wouldn't imagine more than a 25% duty cycle.

12.5% if you had a pair of $6 pumps.

(That's what mine cost direct from the CH 'refurbished' factory)

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Last edited by boyntonstu on Sun Jul 05, 2009 2:34 pm, edited 1 time in total.
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Unread postAuthor: velocity3x » Sun Jul 05, 2009 12:43 pm

What about the rating....."CFM@90psi"? Those tire inflaters will be stone cold dead long before they EVER produce a useable volume at a respectable, useful pressure.
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Unread postAuthor: pizlo » Sun Jul 05, 2009 12:47 pm

stop

making

your

posts

look

longer

this

does

not

add

value

or

substance

!
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Unread postAuthor: velocity3x » Sun Jul 05, 2009 12:53 pm

boyntonstu wrote:I wouldn't imagine more than a 25% duty cycle.


In Heaven... where nothing breaks, you'd be lucky to get 10% on a warm (or any) day.

I wouldn't imagine more than a 25% duty cycle.

12.5% if you had a pair of $6 pumps.


Duty cycle is the rating of run time per hour for one compressor. Duty cycle rating remains the same regardless of the number of compressors used.
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Unread postAuthor: POLAND_SPUD » Sun Jul 05, 2009 2:26 pm

you've expressed this opinion because you can't compare its performance with somehting else...
I've had one of these tire pumps and it broke down... since then I've been using fridge compressors... there is a world of difference between the two compressors


as a new member you can assume that we don't know how good tire compressors are... and that's normal becasue you can't expect that we know everything... I had a hard time convincing people here that fridge compressors can be used as a rally good high pressure pumps...
most of the people were rather skeptical at first....

quite a lot of members said they had been using tire compressors in the past and, roughly, 95% of them were not satisfied with their performance...
so you can either compare its perfomance with something else and decide whether it's worth it yourself or take our advice

I am not saying they are no good... but it's like cutting the lawn with scissors when you can use your lawn mower
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Unread postAuthor: Ragnarok » Sun Jul 05, 2009 4:31 pm

boyntonstu wrote:Specifically in measurable terms what does lengthy, slow, and heavy use mean?

Lengthy is any active session longer than it's intended run time. ie - how long it takes to fill a single car tyre to 30-50 psi.
Longer than this and it'll start too get too hot and damage itself.

Heavy use means using it more than a few times in its life.
While a tyre compressor might possibly do a a car's worth of tyres in a decade, that would still count as exceptional use for one of these things.

Slow means "I can get there faster with a hand pump".

Have you experienced all brands and models of 12 V air compressors to make a general impression about all of them?

No, of course not. Have you experienced every example of anything?

I ask you this: do you have to be mugged by every mugger to get the general impression that it's an unpleasant experience?
Do you have to try every brand of cheese as a stain remover to know that none of them work for getting coffee out?

Same thing with 12V compressors - you don't have to experience everyone to know that they're bad for this job.

There is this thing known as an assumption. Sometimes it's a problem, but 99.999% of the time it's a brilliant thing.

Seriously. You make millions of assumptions in a day - you assume you'll not have any problems with rabid squirrels*, meteors braining you, lightsaber wielding Scotsmen**, small furry creatures from Alpha Centuri...
*Perfectly valid, there are no cases of squirrel bites causing rabies within the United States (they can however be carriers, but it's rare).
**Not so valid, lightsaber wielding Scotsmen are very dangerous. Just take the example from the films.


You have to make these assumptions or you'd not get anything done. I'm not about to waste my life and money because of the slight possibility that my assessment of 12V compressors might be wrong.

In an small caliber airgun the volume of air required in the chamber for a single shot is tiny in comparison with any car tire volume.

Depends on your definition of small calibre.
The air in a car tyre at average pressures is very approximately 24 litres (at atmospheric pressure). For a cannon with which I know you to be familiar - Copperhead Prime.

Copperhead uses about 3 litres of air per shot. That's a significant proportion, and a shooting session would still do more damage to a 12V pump than what one used for normal purposes would suffer in an entire human lifetime.
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