Looks like...I'm getting my butt kicked here. Anyone have a smoke?

You guys are reading my mind and I only did a rough jig drawing. I remember once seeing a patent for a "shot bow", a barreled bow or crossbow assembly shooting sabots that opened like a clam and were filled with shot or small darts/nails. ...[now got to get home to finish up the post]
Geezer wrote:Geezer here with comments on rifled bullet-bows. It
seems to me that the biggest difficulty with rifled bullet-bows would be
to make the projectiles 'take' the rifling, without an excess of
friction.
Back in the 19th century, various gun-makers, like
Armstrong and Whitworth, experimented with artillery shells fitted with
studs to ride in the rifling. If you could make darts, equipped with
thin plastic ribs that would ride in the grooves... or a barrel with
pronounced spiral ridges that would fit into a grooved projectile, that
might be a reasonable way to proceed. If the projectiles could be cast
to shape out of some inexpensive resin, you could probably keep costs
fairly low... just thinkin' Geezer
********
Or how about inventing some form of magnetic rifling? If we can get
mag-lev lift and accelerators, why not a system that imparts spin? Too
weird? Geezer
Regerald wrote:Interesting idea about the magnets.. But it means
that bullets themselves have to be magnetic too, which make some
expense. And also, barrel material has to be paramagnetic, better if
insulator (pvc tube?)
How about to use as a bullet shortened vertion of those?

Could be made of full metal by casting or something..
Magnets?...not impossible

......a magnetic arrow rest is already old news on the archery market...a bit pricey, but real non the less.
the use of a power source other than human muscle power can already be
seen in commercially manufactured pneumatically spanned crossbows, so it's possible that
electricity is on it's way too.
Basilisk120 wrote:Hey Ivo, it looks like a decent simple solution.
Now for some questions:
1. How are you controlling the cutter depth?
2. What materials are you looking at for the barrel?
Couple of ideas:
for
chip removal. Extend the cut where the mounting screws are for the
cutters then add a groove in front of the cutters that goes to the
extended side cut. Make sense?
Depending on the barrel material and
lenght of the barrel extending the coupler to going more over the barrel
might not be a bad idea to prevent bending. Depending on the cutters
depth it could put a decent compression load on the barrel which could
lead to bending or binding of the cutters shaft.
I second
Geezers comment on projectile selection. I have anouther idea to think
about. using some kind of sabot or soft driving bands.
You might
want to make your grooves wide and deep. the bullet in a soft sabot
could engage the lands but not have to bottom out on the grooves. For a
firearm a tight fit of bullet and barrel is a must but for this a tight
fit would be detrimental. Basically think about engaging the lands
but not filling the grooves. or just minimize surface contact
Thanks for the good words Basilisk...a few years ago I got a glimpse at a
similar rifling setup and just now it surfaced in my mind...I can't remember
how it was completed and/or if it worked at all, so every design detail
is being reinvented.
I
didn't decide on the barrel material yet, but considering the
application I Didn't the need for a steel barrel...I was leaning towards
aluminum tubes about 1/2" OD that I've seen at the hardware store
or a combination of this tube with a composite outer shell(fiberglass)
and/or a plastic(castable resin) inner lining to cut rifling in.
Funny, I went picking in the hardware store and it's the same story as with board bows...with bows it's grain run
out, here it's irregularity in wall thickness/center...4 out of 5 I didn't
even bother getting the caliper out and same thing with caliper in hand
4 out of 20 were only marginally acceptable. Finding the more or less
decent tube was just part of the story...the steel rods I was thinking
of using for the cutter don't match the ID of the tube by about .7mm
....suddenly I remember Tomas Edison's words >>> "To invent,
you need good imagination and a pile of junk"
As for the cutter design...I'm ashamed to say...I was just going to wing
the cutter position and bolt it in place, Just couldn't think of
anything and left the cutter pressing against the bolts and the inner
wall of the slot.
There is a possibility that I will take a steel
rod, cover it with some sort of insulator, give it a few layers of
resin, let dry and then make the barrel around it by rolling the resin
covered rod in fiberglass cloth...then just heat it a bit and slide the
rod out....then cut the rifling in the resin.Think this might be the
most accurate match that will eliminate the cutter rod rattle.
kiwijim wrote:Hi Guys, Geezer is right. In order for the projectile to engage the rifling excessive friction is generated.
Also,
as the projectile is usually small, round and heavy, (say a 0.50-0.60
cal. lead round ball ) and is not traveling at particularly quickly its
momentum will keep it on track - making it very accurate to the
distances such a weapon is useful.
If you have your heart set
on putting some spin on the bullet how about devising some kind rifled
choke, like shooters use to spin shotgun slugs. This will keep the
friction down and projectile speed up.
Something else to
consider is that the barrel does not need to be round, infact a round
barrel would generate the most friction with a round bullet

. The barrel could have a square or diamond section. Making a bullet
spin in a square barrel without generating excessive friction is an much
easier problem to solve.
Regards James
********
Something else to consider is that in order of the bullet to spin around
it's axis it must overcome the friction between itself and the string. I
don't think this would be possible without fitting a (cast robbing)
spinning attachment onto the string. With this in mind, the most
effective rifling will be placed at the very end on the barrel- like a
rifled choke
Pavise wrote:Yes,
kiwijim is right about the effect of the
string-pressure-to-base-of-projectile. But I really wonder why folks
don't bother to read the works of others who have gone down this path
before and have left a trail that we can easily follow. Again I suggest
the "Practical Guide to Manpowered Bullets:" by Richard Middleton.
Search Google books for a sample of what this man has discovered and
made available to us. According to him, the "rifling" doesn't have to be
very agressive at all in order to impart resistance and thus spin to
the projectile. But, I am not convinced that the string slots on either
side of such a barrel would not have more influence and thus negate any
rifling effect. Not unless these slots could be cut in such a fashion as
to not interfere with the sides of the moving projectile.
And welcome to latest member Wendy Allen too.
Pavise
Kiwijim, Pavise, you guys.
I want to comment, but I'm held in suspense...I have a copy of
Middleton's book in e-book format...started reading it from the
middle(one of my countless bad habits), I have to scramble through my
hard drive and take a look at what the man said about these barrels...I
really
do want to build this thing or perhaps even a few...so we'll see if the
Middle ton can shine some light on it and I will quote what ever I
can to add to the conversation.
Also I was thinking about the
rifling on my own and have to agree with all of you...there is too much
interference from other grooves, the string, perhaps even the angle at
which the crossbow is held, so the choke idea is reallylooking
awesome....Loving it since the ability to shoot the earlier mentioned
shot filled sabots and when necessary simply snap on a rifled choke for
bullets...brilliant! That and rifling a choke and rifling a barrel are
like night and day.
Again I'll look into the book in hopes of finding something good.
Geezer wrote:Geezer
here on rifled bullet-bows. I agree wholeheartedly that the level of
discourse would be raised by actually referring to expert sources, but
that isn't the nature of the beast. The gang are having arguing the
question, and in a social sense, that's what important here.
In
fact, I abandoned bullet-bows and stonebows years ago, thanks to
personal misfortune. I have no intention of revisiting the decision to
cease experimentation on bullet-bows. But the guys are having fun, so
why not keep the ball rolling? Geezer, the Gadfly.
Sorry to hear about your eye Geezer, that really sucks.
I
remember talking about these bows a while ago on another forum and when
we stated talking about shooting shot out of then...a red flag went up
in my head and despite how cool they look with that pouch bow string
assembly - I've decided to never (or at least not in the near future)
try building one of these and took up this project from the maximum
containment standpoint...plus it's an added challenge since we are
technically building a low power slug/shot shooter combo while
attempting to maintain maximum efficiency...I'm too excited to sleep on
it...
Definitely,
let's keep the ball rolling!...book is good, discussion is good, a
discussion with book material set as ground = Great! I'll try to grab as
much as possible from the book and will add a the illustrations of the
more refined (and hopefully final) design of the rifling jig and a sketch of the rifling profile I've decided on.