7 replies to this topic

[Blue Ice]

Heres what it looks like whan you are finnished. The gray tube is the body of a bicycle pump, the red is the rod and plunger, and the blue is a spring.

What you do is get an old bicycle pump, take the cap on the handle end off and take the plunger assembly out. Take the plunger off the rod (should just screw off). Get a spring, or two that are the lenght of the body or just shorter. They should be relativly hard.

Slip the spring(s) over the rod ans put the plunger back on. Put the whole thing back together only this time weld the cap to the body (so it doesnt pop off)

To fill the tank just pull the handle out (compresses the spring) this is assuming that you took the time to buy a pump with a flowback canceller. When you open the valve and let the air oyt of the tank/pump the spring relaxes and forces the air out.

In theroy this should work, but everything works in theroy.

Edit: couldnt get the pics to come up, ill go look at a post that i think was about pics. sorry

Edit again: Ok i confesses that i was bb, now can u please get rid of the liar.

Edit again: I'm having way to much trouble finding the topic on pics. I know im ask a question a second tim, but could someone tell me how to get a pic off a floppy, or at least point me to the right topic.

Edited by .:Blue Ice:., 02 February 2004 - 10:11 PM.

[Spectre2689]

First off, it's about time that you admitted to it, and thank you.

This bicycle pump idea sounds like complete and utter rambling, but it could work. You never know.

In answer to your picture questions, there was a topic a while back that cleared up some confusion about it. Completely different topic than the pics, but it's still there. http://nerfhaven.com...?showtopic=1443

I should probably post up a topic on uploading pictures, since a few of us don't know how. Maybe an admin could make it a sticky?

[Nerfer16]

I should probably post up a topic on uploading pictures, since a few of us don't know how. Maybe an admin could make it a sticky?

Please do that Spectre! That would be very helpful for all of us newbies.

[Zero Talent]

That actually sounds like a great idea, provided the O-ring keeps it's seal. Wasn't really much of an option on the old guns, with their flimsy rubber cup plunger seals, but could work just fine with a a tire pump. I'm not sure how it would be much better than a normal air gun, since a bike pump's handle is often your average density of steel ('cheep'), as opposed to the plastic plunger's most use. Granted, the mass can be overcome with a really strong spring...

Well, think of it this way. You pull back the plunger, air is drawn into the chamber. You release the plunger, air compresses to a certain limit, until the pressure on the plunger's area exerts a force equal to the force of the spring returning to equilibrium state. At this point, though, that force is relatively low, since the spring is pretty close to equilibrium position (unless you have a rather weak spring, which defeats the purpose), and only a small distance for plunger to travel when "released."

At this point, with the air pressure between the plunger and valve, and spring force equalizing pressure force, you've got two options:

1) Open the valve, let the plunger travel it's sad distance, with less than the pressure of one full pump behind it, and a low spring force creating low velocities due to a large plunger mass.

2) Bring the plunger back again. Assuming a check valve in the plunger itself, this means you can pressurize more air. But this is synonymous to pumping.

I understand your goal, and I think the alternate view offers some perspective, but I don't know if such an equilibrium state will offer a very powerful shot. I don't fully understand why a plunger gun seems like it would operate best at high spring constants and infinitesimally small plunger mass, but that's just due to the changing pressure systems, combined with the viscous friction that I can't yet mathematically describe. I hope you're onto something.

// Here's a thought, for those who are still reading this claptrap: Try a check valve on either side of the pump, both aligned in the same flow direction, and both attached to pressure tanks, so on a downward stroke air is pressurized into one tank, and on an upward stroke air is evacuated from the other tank, creating a vacuum in the other tank. Granted, max pressure is about -31PSI in the one tank, but it could be used for something... It would also make the upstroke of the pump have resistance, but granted a small pump (you know, the ones you usually need to pump 10 times to fully pressurize a tank, wasting more time than energy?), you could make more efficient use of reload time.
Vacuum pressure could be used for firing with an inverse valve system, or assisting the main shot, but that's no fun; You could use it to power onboard functions, such as pistons, for reloading, automatic stock extension, or whatever else you feel like. Just an odd thought. Naturally, you'd need to reroute incoming air once the tank is fully evacuated, so assuming a pump efficient in both directions, you'd need triple the volume of the evacuated tank for a working pressure of about 90PSI in the firing tank. \\

[Black Wrath]

First off, it's about time that you admitted to it, and thank you.

This bicycle pump idea sounds like complete and utter rambling, but it could work. You never know.

In answer to your picture questions, there was a topic a while back that cleared up some confusion about it. Completely different topic than the pics, but it's still there. http://nerfhaven.com...?showtopic=1443

I should probably post up a topic on uploading pictures, since a few of us don't know how. Maybe an admin could make it a sticky?

To clarify.

My post in that topic is how to post images, follow it and you won't have trouble.

Spectre's post was to clarify that you cannot upload a picture from a floppy disk or digital camera directly. Keep this in mind, you seem to want to use a floppy. You have to first get the picture on your computer from the external memory devices before they can be uploaded onto this forum.

We really need a 'How To' sticky. I checked help, and it doesn't give clear instructions... and there are typos. Me and Spectre would be more than happy to make a thread like that if it would be made into a Sticky.

[Blue Ice]

I got to thinking about it and the idea is no different than a regular spring gun. Just homemade, i think that I'll try it.

Probably going to loose range.

[Langley]

I got to thinking about it and the idea is no different than a regular  spring gun.  Just homemade, i think that I'll try it.

You would probably have to cut a hole in the end of the pump where the nozzle/hose is, because the nozzle or the hookup for the air hose on the pump is probably alot smaller than the ID of the barrel you would be using.

If you still don't get it, think about it as if you're modding the plunger tube on a crossbow. You're cutting away the part with the tube attached and you're jaming a barrel directly into it.

If you had a picture of the pump you have in mind, that would help alot. Photobucket.com is a good place for image hosting.

Edited by Langley, 03 February 2004 - 11:45 AM.

[cxwq]

Ok i confesses that i was bb, now can u please get rid of the liar.

You confesses eh?

I wants to get rid of the liar but in your case, it would hose access for a more productive member of our society at the same time. Of course I could just require that IS either dump AOL or move farther away from BB/BI if he wants to use the forums...

For now the liar stays. So does his title.