VERA + bonsai kitten = ballistic kitten delivery over a 2 mile range. Need I say more?

foot/pounds are a measure of torque, not velocity. Are you sure you don't mean feet per second? A quick calculation assuming around 20g for an AA battery gives around 3⅓ Joules. Or maybe you meant foot pound *force*, which is a measure of energy and not velocity, in which case that's around 81 joule...

Centring is key, yes.

http://www.ebay.com/bhp/center-finder-tool

Also be aware that a static drill bit will "seek" the centre of a piece of rotating work, which is why lathe drilling is usually done with a static drill in the tailstock.

The majority of drill press spindles have a number 2 Morse Taper fitting. The drill chuck itself is fitted using a tapered attachment - removal of the chuck is done by shoving a tapered flat through a slot in the spindle, and knocking the tapered attachment out. You can get loads of stuff that fits ...

It's enormously sketchy. The collet idea is good. Very good, even. But there's a reason chucks like that are known as "knuckle busters". I'd also point out that you've got way, way, way, too much unsupported work poking out of the chuck. Everything from the drill chuck itself, all the way down to th...

Of course it does. It shoots wookies.

Seriously, there's a huge difference between pressure rating something for liquids and pressure rating something for gases. There is. Why do you think hydrostatic pressure testing involves water rather than air? The important bit of hydrostatic testing is not the "hydro" bit, which is all about saf...

The problem is that the fueling system requires air flow through the gun's chamber, which is kind of hard to do with ammo in the barrel. True. You would need another valve on the opposite end of the chamber from the air/fuel inlet point. Not true. There's any number of reloading options that could ...

I don't see why it shouldn't work on a larger scale if you can get the mix right; effectively it's a primitive (and not very tunable) carburettor. That kind of setup is probably going to give an over-rich mix for petrol, you'd really want something like methanol, I'd think, along with a reed valve o...

mark.f wrote:Can anybody think of a way to keep the menus from running off the edge of the screen?

I'm not sure you can without requiring javascript.

Give in to your interior machinist...

I think what m-c is talking about is having one or several o-rings on the outside of the barrel towards the tail of the arrow, which will avoid air pressure leakage "out the back" of the arrow; with some tuning they might also provide a frictional lock on the arrow that's enough to hold it back a bi...

If you're holding the arrow back until the barrel pressure reaches a certain level, you can consider your barrel to be the chamber, and your arrow to be the piston. At that point, you're probably better off working out a way to make the barrel seal properly against the arrow, forget any high speed v...

That's a pretty good result, right there. Nice.