Ollo,Hello

Been rolling the idea around for a while, had a bit of a nudge a few weeks ago for a paintball crossbow...and a curiosity driven google search led me here XD

So heyo, lol

What you'll want to research here and elsewhere is how to build a Stonebow or Pellet Shooting Crossbow. Payne-Gallwey's The Crossbow Book is a good place to start: http://www.crossbowbook.com/ Look at chapters 37-40 and the section around page 157...

Basically you need a mechanism that can hold at cock a pouch like a slingshot would have -- either with a single or double string. Also a tiller or stock shape that doesn't interfere with the paintball or other roundish projectile moving forward (usually not a grooved track like a conventional crossbow).

Just to inspire u.... And welcome!

And these!




Thesd

Ferdi - what museum are those in? They look more like slurbows for fletch-less bolts than pellet bows, but they sure are neat. I like the prod attachment system with round hole and half cylinder wedges, too.

One thing to think about is that the string/pocket is going to have to be in contact with the paintball as it would take very little 'slap' to explode the paintball and give 'in your face' a whole new meaning.

The designs Ferdi shows above wouldn't work. The bullet would have to pushed across open space from the rollernut and hopefully shoved perfectly into the butt end of the barrel; or the bullet would have to be inserted in the butt of the barrel and the string when fired leaps across the gap and slaps the bullet. Neither of which would work well with a lead bullet, let alone a paintball....

The pistols are bullet shooters, the last one is a arrow shooter.

Blue62


I have done quite a few experiments to
develop a workable and accurate bullet crossbow. I decided right off to use a
single string rather than the usual double string with pouch type. Some items
to consider are a moderate strength prod with a longer power stroke to give the
paint ball gentle but steady acceleration. Also if you want decent accuracy and
less complication I would use a track rather than a barrel. The ball needs to
be held in a string mounted slider or carriage that is held firmly in contact with
the track by the bowstring. This carriage along with its soft front material
can give added mass to achieve a minimum needed to protect the prod and
bowstring (dryfiring hazards). The only
real challenge is the method of holding the ball at the carriage front because
just laying it in the track will defeat our goal for accuracy. I use .375” ball
bearings mounted in a conical depression at the front of a slider (see my
avatar for the track profile).


The 9gram slider “shuttle” is made of
hmwpe plastic and has an imbedded pin at the rear for the release catch to hook
onto. A ball retainer is required only up to the moment of firing then
acceleration keeps the ball seated, therefore the retainer may be mounted above
but not interfering with the string etc. that is a design challenge.


SEE see post #3 below


https://thearbalistguild.forumotion.com/t696-groove-vs-rests#8779


sep

Wow, way more info than I expected, thanks all.

I'll have to try and get pictures of the model that's inspiring early designs, just a dart firing toy two of my cousins have- with a little work, it might work, but I'm not so sure it's got enough velocity to break a ball on impact, or if it'd just cut it on the rest.

I think Septua has the right idea for paintballs - a tracked carrier will keep the ball from getting broken prior to or during launch. You'll lose some efficiency from the track friction, but gain from a longer powerstroke

Its just a thought, but would it be possible to drive a piston instead of a shuttle? That way u could make a air-pressure powered ball shooter. That wont harm the paint ball because it would be sitting in the barrel at the end of the compression chamber. A hole would pass the air thru from the compression chamber to the barrel. U could even consider trying to cock the bow by using te barrel folding down the way air rifles do?!
I might even try this idea myself!

ferdinand wrote:Its just a thought, but would it be possible to drive a piston instead of a shuttle?

Sure!
There are even ready made products on the market.
I've seen one type that could be fixed to a long bow.

Also have made myself a scratch build piston-airgun that could use a bow as a spring. Piston was made of paper saturated with varnish rolled around aluminum shaft.

You can even easily mount one on an existing crossbow.
Just make a piston shaft shaped like a crossbow bolt,
fix it on the string
and then fix the cylinder with a short muzzle-loading barrel in front of the crossbow.