Newsgroups: rec.crafts.metalworking
Subject: Re: Rifling Leads
From: Robert Bastow <"teenut"@ hotmail.com>
Date: Fri, 05 Nov 1999 07:12:40 GMT

Commercial, practical rifling leads go all the way from 1turn in 6" to 1 in 72"
or more.

generated by:

Single point methods for cut rifling..

Spiral gear train
Sine bar rifling machine
master spiral and follower
copying old barrel with cast in follower

Multi point methods......

broaching
Button rifling
Hammer forging

Pictures of machines...

Few and far between that would tell you anything useful!!

Very little on the net.  Try a search on barrel rifling and rifle barrel, there
is only one site I have found where a barrel maker goes into much more detail
than "we drill, ream and then rifle"!

There is one site, in England, that goes into a bit more detail and actuall has
a photo of an old Pratt & Whitney Mk 1 Sine bar rifling machine sat forlornly
outside a Scottish barn.  You are not going to build one from that photo!!

Very few Gunsmithing books give more than a half a cursury page on the actual
rifling machines...and I think I have a copy of every book ever published on the
subject.  Building up a knowledge base on the subject has taken me about forty
years and That is only a cursury knowledge.

If all you want to do, is make a shootable muzzle loading rifle barrel, get a
copy of Ned Roberts  "The Muzzle Loading Cap Lock Rifle"..find out how the old
smiths did it with string and a roller to lay out the pitch!!  The methods
worked then and still do!

If what you have in mind is a modern, high powered target or hunting rifle
barrel..Good Luck!!   The few people that REALLY know how to do it are not about
to tell you a great deal.  

Your searches may lead you to a couple of books published by Hoffman Publishing,
purporting to tell in detail how to  build the equipment and Make rifle
barrels...be warned,,the material is badly presented, badly written, badly
spelled, badly edited and even badly printed!  

Having already read pretty well everything ever written on the subject, I can
tell you..so has this guy, and some of it is copied verbatim, stupid errors
included, from people who never made a barrel..repeated by someone who I
seriously doubt ever made one either!!

teenut

Newsgroups: rec.crafts.metalworking
Subject: Drilling and rifling barrels
From: Robert Bastow <"teenut"@ hotmail.com>
Date: Sun, 07 Nov 1999 02:54:14 GMT

Someone asked recently about rifle barrel making, and I referred to an article
on the net, which is, IMHO the most comprehensive description I have found so
far..

After diligent serching I managed to find it again...

http://www.border-barrels.com/articles/bmart.htm

It includes pictures of a sine bar rifling machine.

Enjoy

teenut

From: Robert Bastow <"teenut"@ hotmail.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: Rifling Leads
Date: Tue, 09 Nov 1999 06:16:59 GMT

"Spiral Gear Trains" are covered amply in Machinery's Hand Book..Just like a
gear train for thread cutting on a lath exept that they are much "Over geared"
Ie if you set up to cut a lead of 1 in 72" on a lathe and then tried to turn the
headstock it would jam and break something!  However if you were to turn the
LEADSCREW, the headstock would be turned  by the gearing, at the correct rate to
generate the spiral you needed.

This can be done on a lathe with a milling head on the toolpost, It can be done
on a mill with the correct spiral milling attachments, or it can be don on a
special machine..purpose built in this case to pull a rifling head,attached to
the carriage, through a barrel blank held in the headstock.

A sine bar machine works in a very similar way to the taper turning attachment
on your lathe.

The barrel is held in the headstock which does not turn during cutting, but is
simply indexed between strockes to generate the required number of rifling
grooves.   The rifling head and its pull rod are held in a free running bearing
in a bracket on the carriage.  The bearing incorporates a small gear that
engages in a rack mounted to a free sliding bar that runs under or over the gear
and can move only at right angles to the main bed ways (like the cross slide on
your lathe, with the feed screw removed)

The end of this slideway has a shoe or "slipper" that engages the sine bar..the
taper turning slide on your lathe.

If the sine bar is set parallel to the bed ways, then no amount of carriage
movement will cause the cross bar to move in or out..the gear will not be turned
and the grooves you cut will be straight!!

However, if you set the sine bar at an angle to the bed ways, then, as the
carriage moves the cross bar, with its rack, is forced to slide in or out and
the rack causes the gear and the rifling rod to rotate as it moves though the
barrel.  Changing the angle or gradient of the sine bar changes the pitch of the
riflig that is cut.

If you refer back to the picture of the machine at Border Barrels....

<http://www.border-barrels.com/workshop.htm>

....you will see the same elements arranged in a slightly different way.

The Sine bar is suspended and adjustable inside the large "O" shaped casting.
Beneath it, at right angles to  the bed, is the cross slide bar, and the rack is
mounted to its underside.  Beneath that is the "Pull Bracket" housing the gear
and the bearing in which the holder for the rifling rod is mounted.

Most modern rifling machines, whether for single point, broaching or button
rifling, have been purpose built by their users to do a specific rannge of
twists and many have dispensed with any means of "generating" the required
twist.  Rather they use an interchangeable twist guide..A groove milled in a
large round bar, geared directly to the pull head.

This faster, cheaper and more consistantly accurate to set up.  Once upon a time
this meant locating a shop with a universal milling machine and all the bits and
pieces (and skills) required to set up and mill a set of master guides.
Nowadays, any shop with a big enough CNC mill can knock them out quite easily.

tenut

sunworshiper wrote:
>
> Teenut; Great info. and sites. I don't want to make a gun. (Got one)
> I need to build a machine to go into production of my patented
> invention. Can you explain the spiral gear train and the sine bar
> helical generator? BTW I need the outside cut , not the inside.
> I was just curious as what the leads were. Mine is one turn in 6'.
> Need some different concepts before I go too far.

Newsgroups: rec.crafts.metalworking
Subject: Re: Rifling Leads
From: Ole-Hjalmar Kristensen <ohk@clustra.com>
Date: Tue, 09 Nov 1999 16:17:32 GMT

Robert Bastow <"teenut"@ hotmail.com> writes:

<stuff deleted>

> Most modern rifling machines, whether for single point, broaching or button
> rifling, have been purpose built by their users to do a specific rannge of
> twists and many have dispensed with any means of "generating" the required
> twist.  Rather they use an interchangeable twist guide..A groove milled in a
> large round bar, geared directly to the pull head.
>
> This faster, cheaper and more consistantly accurate to set up.  Once
> upon a time this meant locating a shop with a universal milling machine
> and all the bits and pieces (and skills) required to set up and mill a
> set of master guides. Nowadays, any shop with a big enough CNC mill can
> knock them out quite easily.
>
> tenut

I've seen a primitive version of such an arrangement, made mainly of
wood, and powered by hand. It was the actual machine used to produce
Sten gun barrels for the Norwegian resistance movement during the
war. They actually produced complete Sten guns in Oslo, farming out the
production of the different parts to various subcontractors, most of
whom were not aware that they were producing illegal gun parts.
It's still on display in the museum, I believe.

--
E pluribus Unix

From: Robert Bastow <teenut@Nospamhotmail.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: Gun Barrels
Date: Thu, 28 Dec 2000 23:29:58 GMT

Bray Haven wrote:
>
> >> Greg, Yes they did.  As I recall, the only way to get gain twist is
> >> using a hook shaped cutter and a sine bar rifling engine.  Buttons
> >> and broaches only cut fixed twist.  Dan
> >>
> >
> >Why would that be? Are the buttons/broaches so long that the twist can't be
> >progressively increased? Also, I have yet to see a good schematic drawing
> >that shows how the sine bar fits into this, although I've seen several
> >references to it's use in a rifling machine. I understand that the sine bar
> >would allow precisely setting the slope of the twist but I can't quite see
> >how the rifling machine uses the sine bar to rotate the cutting tool.
> >
> >I have no plans to make a barrel; I'm just curious about how it's done. The
> >more I learn about it, the more surprised I am that someone didn't introduce
> >mandrel forged barrels (ala Glock) long ago. It seems like an easier
> >manufacturing process than cutting the grooves.
> >
> >-B.
>  Because the pitch or twist is built into the button.  It's drawn through a
> worm type assist but there must be a slant in the swages built into the button
> so it follows the "lead" At least from the barrel shops I've toured.  Never
> made a rifled barrel.
> Greg

Button rifling heads have a very short length/diameter ratio and in order to
produce an ACCURATE fixed twist really do need to be pulled by a controlled
twist mechanism.  Gain twists can be and are achieved with pull buttons by using
variable twist pull devices.

teenut

From: Robert Bastow <teenut@Nospamhotmail.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: Gun Barrels
Date: Fri, 29 Dec 2000 00:49:56 GMT

veeduber@postoffice.pacbell.net wrote:
>
> > Someone opined:
> > > >>  As I recall, the only way to get gain twist is using
> > > >a
> > > >> hook shaped cutter and a sine bar rifling engine.   Buttons and broaches
> > > >> only cut fixed twist.  Dan
> > > >>
> >
> > To which Teenut replied:
>
> > Button rifling heads have a very short length/diameter ratio and in
> > order to produce an ACCURATE fixed twist really do need to be pulled
> > by a controlled twist mechanism.  Gain twists can be and are achieved
> > with pull buttons by using variable twist pull devices.
> >
>
> The buttons I have range in thickness from .090 to about .190.  Gain
> twist is easily accomplished using the same principle found in the
> rifling tool I described in an earlier post.  To stave off confusion,
> the original post was with regard to PISTOL barrels and the tool I
> described provides for hand-cutting of the rifling.  The buttons I have
> are for .30, .50 and 20mm bore, require a hydraulic puller and no, you
> can't borrow them :-)
>
> -Bob Hoover

Hook type rifling cutters can be as simple or as complex as you wish them to
be.  The olde tymie backwoods gunsmith used a lead slug, cast to the bore  in
which he cut a slot with his pocket-knife to take a simple hook or scrape
cutter, the depth of cut being regulated by paper shims.

My first, SUCCESSFUL muzzle-loader barrel of .437 caliber was made from a length
of mechanical (solid drawn) tube with a rifling guide made from a cold twisted
square steel bar that ran in an indexing head fitted with follower rollers.  The
bugger would outshoot anything else on the Range!

teeenut