SpudFiles

The idea of this design was that you could could get high performance with relatively low pressure, because of the large area of the piston - with the added benefit of not being so loud

Here's a nice example of the concept fleshed out.

Thanks JSR excuse the noobishness (is that even a word?) , but I don't exactly get how it works. Does the plunger kind of act like a pneumatic ram that pushes the small tube, firing the knife?

sharpshooter11000 wrote:Does the plunger kind of act like a pneumatic ram that pushes the small tube, firing the knife?

Precisely.

The quick connect has no sealing function, it just holds the blade in place and serves as a "trigger".

Again by using a relatively large diameter plunger you get a lot of force for low pressure.

If you do end up building this, you will want to make it serviceable. I usually take mine apart and lubricate it every 20-30 shots.

As for operating pressure, I've pushed mine up to 350 psi but the trigger is REALLY hard to pull at that pressure.

pneumaticcannons wrote:I usually take mine apart and re-oil it every 20-30 shots.

Oil?

Never a good idea with syringe seals in my experience, the rubber tends to absorb it, causing it to expand and gum up.

jackssmirkingrevenge wrote:

pneumaticcannons wrote:I usually take mine apart and re-oil it every 20-30 shots.

Oil?

Never a good idea with syringe seals in my experience, the rubber tends to absorb it, causing it to expand and gum up.

sorry, I forgot to mention that I use silicon oil

Sharpshooter: Have you noticed a place called "Epoxyland" at UK? I bet you havent, so JSR can be from UK

jakethebeast wrote:Sharpshooter: Have you noticed a place called "Epoxyland" at UK? I bet you havent, so JSR can be from UK

Hmm no I forgot about that and...

Google Maps wrote:No results found for "Epoxyland"

JSR how much pressure should a syringe hold? Also that must be a very big syringe, where do you get them?

sharpshooter11000 wrote:JSR how much pressure should a syringe hold?

Syringes aren't really meant to hold pressure, the above design was thought up to work at 20-30 psi using the benefit of large piston area to compensate. If you intend to use higher pressures, the syringe should be sleeved in a stronger tube and the gap between syringe and tube filled with epoxy.

Also that must be a very big syringe, where do you get them?

http://www.amazon.co.uk/60ML-SYRINGE-CA ... 890&sr=8-2

Also, ag stores are a good place to get syringes, I paid $4.50 for a 60ml, but I didn't need to order it in.

And I got a bag of sulphur, but I shan't go into that.

Ah thanks. I might get a handle machined, that would be safer.
Hmm... Zeus, I'm not even gonna ask

sharpshooter11000 wrote:Ah thanks. I might get a handle machined, that would be safer.

If you have that option, go for it!