Page 2 of 2
Posted: Fri Aug 14, 2009 5:57 pm
by al-xg
Ooh I only just saw this topic, I have nail gun wich seems very similar to yours.
I'm assuming yours also uses a coaxial airchamber to push the piston and blade back (then venting through the piston valve piston)... mmm too many pistons

If that is the case could you not put your blowforward mechanism inside the body with just the breach sticking out ?
I was forced to rebuild mine because I actually had to use it as a nail gun, but I have used it with a 6mm barrel and its pretty impressive. (oh and it still works fine after being used at 27bar

the weak bit on mine seems to be a small platic disk in the 3/2 trigger valve)
Have you considered using 6mm fishing weights as ammo ?
Not always perfectly smooth spheres but they fly straight thanks to their weight. Pressing them back to shape isn't too much trouble, still worth it in my opinon compared to airsoft BBs.
Posted: Fri Aug 14, 2009 6:33 pm
by theBOOM
Posting in old threads can get you in trouble :/ read the rules bro
Posted: Fri Aug 14, 2009 8:40 pm
by jackssmirkingrevenge
theBOOM wrote:Posting in old threads can get you in trouble :/ read the rules bro
Nowt wrong with posting in old threads if you hvae a valid point to make and on the face of it it seems he did, Ill read it propleklty and reply when im sober, good night
wibble.
Posted: Fri Aug 14, 2009 8:43 pm
by theBOOM
Well.. the pm function is there for SOME reason O.O
Posted: Fri Aug 14, 2009 9:10 pm
by inonickname
jackssmirkingrevenge wrote:theBOOM wrote:Posting in old threads can get you in trouble :/ read the rules bro
Nowt wrong with posting in old threads if you hvae a valid point to make and on the face of it it seems he did, Ill read it propleklty and reply when im sober, good night
wibble.
I wouldn't complain, because we get to see Jack P.U.I.
Posted: Sat Aug 15, 2009 1:42 am
by jackssmirkingrevenge
I have yet to explain the compulsion to check spudfiles (in preference to email etc.) when getting home somewhat fishmuzzled at half three in the morning *sigh*
I'm assuming yours also uses a coaxial airchamber to push the piston and blade back (then venting through the piston valve piston)... mmm too many pistons
I had taken it apart and posted pics
on spudtech but the pictures have disappeared, but yeah, they're basicalyl all the same coaxial piston design. I attached a photo to the end of this post.
If that is the case could you not put your blowforward mechanism inside the body with just the breach sticking out ?
This is how I had modded mine to take the breech:
Basically very little dead space, the breech is accessible and I didn't have to mod the nailgun in an irreversible manner
Have you considered using 6mm fishing weights as ammo ?
Not always perfectly smooth spheres but they fly straight thanks to their weight. Pressing them back to shape isn't too much trouble, still worth it in my opinon compared to airsoft BBs.
I'm quite finnicky about ammunition efficiency
for national socialist reasons so if it isn't a consistent sphere, I wouldn't use it. Also, if lead projectiles can be reshaped and reused, then you're not throwing them had enough
I never revisited this one, probably because now that I have my FX Monsoon I never felt the need to build a powerful semi-auto, at least in small calibre.
By the way, with some judicious use of lego and epoxy I had also turned this nailgun into a
coin launcher 
Posted: Sat Aug 15, 2009 12:19 pm
by al-xg
oh yes indeed, must check dates... :/
Near exactly the same nail gun, and yep did the same thing, but I'm pretty sure one could contain the blowforward setup inside the body.
But as I now realise neither one of us it going to do that, so yeah should have checked before kicking the topic
Oh, picture of my ghetto bullpup nailgun setup. Not semi auto, just a BB in the breach and hold the barrel

But the trigger is.
As far as fishing lead is concerned I'm not talking about reusing it, It just tends to be split when you get it so it can be crimped onto the fishing line. To make them spherical they need pressing.
One couldn't reuse the lead unless it was fired at a soft target and dug out, after all the nail gun was equiped with 1m barrel and 27bar pressure source...
Some of the fishing lead I'm on about.

The close up view doesn't really help my point, but they are still reasonably spherical when pressed shut.
They might leak a little more air but are quite probably more efficient at transfering energy to the target (and just hitting it as a matter of fact, airsoft BBs would be at least transonic and would most likely not even hit the target at any range)
I did see the coin launcher, liked the idea, but was too impressed by the results

Posted: Sat Aug 15, 2009 1:59 pm
by jrrdw
theBOOM wrote:Well.. the pm function is there for SOME reason O.O
It's for PMing us mods when you think you see a rule violation, partly. For the rest of use it's for sending privet messages. Thunderlord kicked up this topic on page 1, go look it's legit.
Posted: Mon Aug 17, 2009 2:52 am
by THUNDERLORD
...Thunderlord kicked up this topic on page 1, go look it's legit.
Yep, Just today I was wondering about using an air-hammer as a pilot for a piston valve design (claim 1000-3000 pulses per minute...Nice!).
My idea is for a high pressure design.
A regulator would be connected between the pilot and air-hammer tool to get 125 or 150 PSI.
Unregged co2 would fill from a CO2 tank into the chamber.
A Blow-forward bolt would be used (in front of the piston valve).
Wondering, If it will work, perhaps the chamber will fill (unregged CO2 pressure) fast enough to keep up with the regulated air hammer pulses (piloting a piston valve)(???)
Also whether it would pilot at all given the lower pressure pilot(???)
BTW, Man I get a little P'd when people complain about kicking up JSR threads!

8)
Posted: Tue Aug 18, 2009 11:53 pm
by jackssmirkingrevenge
al-xg wrote:They might leak a little more air but are quite probably more efficient at transfering energy to the target (and just hitting it as a matter of fact, airsoft BBs would be at least transonic and would most likely not even hit the target at any range)
I guess you're better off buying lead 0.177" BBs though, ready to use and infinitely more consistent.
I did see the coin launcher, liked the idea, but was too impressed by the results.
I wasn't too impressed either to be honest, there was a lot of room for improvement but it was just one of those "because I
can 
" projects so once I got it shooting there was no scope for further development.
Wondering, If it will work, perhaps the chamber will fill (unregged CO2 pressure) fast enough to keep up with the regulated air hammer pulses (piloting a piston valve)(???)
Also whether it would pilot at all given the lower pressure pilot(???)
It would work, but I don't think it would offer any benefit over just having
a pop-off valve as a pilot.
Posted: Wed Aug 19, 2009 3:47 am
by al-xg
I guess you're better off buying lead 0.177" BBs though, ready to use and infinitely more consistent.
Yeah I was forgetting the .177 BBs... But then again if that caliber is too small, the fishing weights go through most sizes up to and over 14mm
With larger barrels they do become quite convenient compared to having to cast pellets or slugs, or make flechettes etc...
I notice you didn't not link to one of your own pop-off experiments Jack

Posted: Wed Aug 19, 2009 4:19 am
by jackssmirkingrevenge
al-xg wrote:With larger barrels they do become quite convenient compared to having to cast pellets or slugs, or make flechettes etc...
True, but for an auto it would probably be a bit fiddly.
I notice you didn't not link to one of your own pop-off experiments Jack

Fine,
here you go
The reason I didn't was because I'm assuming THUNDERLORD wants something in a larger calibre, and using the pop-off directly as a firing valve isn't really a good idea to scale up unless you have substantial machining facilities - reason being that the porting obviously increases with calibre, if you're going from 1/4" to say 3/4" the spring has to be almost 10 times stronger and things become increasingly difficult to work with. While less efficient than my design, for anything over airsoft calibre I think a pop-off piloted piston is the best idea for most builders.