Following a discussing in the knife thread, decided to put a little prototype together.
Concept:
Here it is in action at 300 psi in real time, 420 frames per second and 1000 frames per second:
[youtube][/youtube]
[youtube][/youtube]
[youtube][/youtube]
The knife blade is from a cheap little made-in-Taiwan knife, the rest of it is in Delrin. Chamber is an aluminium tube with a Delrin collar and 3mm steel bearings as a detent.
Some photos:
Posted: Sat Sep 03, 2011 8:18 am
by al-xg
I'd be interested to know at what pressure the ring fails.
Interestingly this is one occasion where slow motion does not make it look cooler
Posted: Sat Sep 03, 2011 8:22 am
by jackssmirkingrevenge
al-xg wrote:I'd be interested to know at what pressure the ring fails.
I made it out of Delrin because it's so easy to work with, seems ok at 300 psi. I'll take it higher after I'm sure the epoxy is fully cured.
Interestingly this is one occasion where slow motion does not make it look cooler
hehe that's exactly what I was thinking
Posted: Sat Sep 03, 2011 8:31 am
by LeMaudit
Great work
I love it!
Posted: Sat Sep 03, 2011 8:48 am
by Gun Freak
That's so cool!!
Posted: Sat Sep 03, 2011 9:20 am
by jackssmirkingrevenge
Cheers guys, this thing is really a lot of fun! Here's some more shots, with a little something the Dutch members might appreciate
[youtube][/youtube]
Posted: Sat Sep 03, 2011 9:20 am
by warhead052
Nice job! Are you going to try a higher pressure when the epoxy has fully cured? If so, I may try making one of these.
Posted: Sat Sep 03, 2011 9:38 am
by jackssmirkingrevenge
Took it to 400 psi and the shoulder on the "handle" which comes into contact with the detent deformed and released the knife. A brass collar would have been a good idea
One other thing worth noting, the collar is extremely difficult to push forward past 350 psi.
Posted: Sat Sep 03, 2011 10:06 am
by Labtecpower
Heineken! because it's empty i'll take it as a compliment
I prefer Hertog Jan, Palm, or Grolsch however
If you polish the thing, and make a brass collar it will look very nice.
Posted: Sat Sep 03, 2011 10:17 am
by clemsonguy1125
That looks pretty cool, but in america I know spring powered ballistic knives are illegal and can carry jail time. My guess would be pneumatic ones as well. Since I have no idea what country you are in.
Posted: Sat Sep 03, 2011 10:51 am
by jackssmirkingrevenge
Labtecpower wrote:Heineken! because it's empty i'll take it as a compliment
Do I sound like a guy who would shoot a full can of beer, even if was a shÃtty brand
I prefer Hertog Jan, Palm, or Grolsch however
It's not the best Dutch beer but definitely the easiest to get hold of outside of Holland.
If you polish the thing, and make a brass collar it will look very nice.
Yeah, cap for the schrader, strip down and polish the blade... but you know me and aesthetics.
That looks pretty cool, but in america I know spring powered ballistic knives are illegal and can carry jail time. My guess would be pneumatic ones as well. Since I have no idea what country you are in.
Sounds a bit silly in a country where you can freely buy a semi-automatic rifle, unless they are considered to be in the same category as a suppressor - but even so, this is a horrible choice of weapon, you only get one shot and unless you have spare blades to hand, you're just left with a handle.
For scale, here it is with my 7 inch blade spec plus - if it didn't have sentimental value, I would be thinking of scaling up and launching the latter knife...
A heavier knife and a longer handle would give a bigger impact....
Oh...I don't like beer...Heineken especially!
Thanks for killing the can!
I prefer Jack Daniels on one of those rare occasions....
Oh forgot to say:
This puts you up there with Chuck Norris you know..
Just the two of you!
Posted: Sat Sep 03, 2011 6:00 pm
by Fnord
JSR,
If you ever have money left over from lathe/mill stuff, you may want to get an entry-level table top belt sander. A knife blade that fits your purposes could easily be done in less than an hour with one. You would probably want to heat treat it... not hard but just springy enough to keep the tip from bending over. That could be done with a simple propane torch.
But overall I'd say it turned out pretty well. I don't think it's very dangerous compared to running up and stabbing someone with it, but I guess that wasn't really the purpose of the build
if it didn't have sentimental value
I'm guessing that means you were jabbed with it repeatedly by a deranged leather-clad Russian?
Posted: Sat Sep 03, 2011 8:32 pm
by Goats spudz
i think my country's laws about guns and knifes are dumb they should only be enforced in london
