First atempt at barrel turning. Need advice.

[Rolf]

First attempt at barrel turning.
I’ve never used a lathe before and the results did not turn out as quite expected. I wanted to make a barrel with molded flats and a sighting rail like this one. I’d like discuss what went wrong and would welcome suggestions how to get it right next time
 

I bought a caliber 62, smooth bore barrel blank from Blackley. The blank was 14” long and 1.125” in outer diameter. I threaded the barrel blank 3/4” x 16 and made the plug out of 40mm (1.5”) round stock, mild steel. Threaded portion of the plug is 15mm (0.6”) long. I messed up the first attempt at threading the barrel and had to cut it down to 13”.


Next step was to turn down the plug to the same diameter as the blank.
 

Next I used a vertical mill to mill the side flats.


Next I turned the outer profile of the barrel using the top slide for the tapered portions.


Final results.


Problems/mistakes discussion.
1.The flats disappeared when turning the taper.
Possible solution: Mill the tang stock square, so it can be used to hold the barrel in the mill vice.
Mill the flats after turning the profile.


2. The barrel is undersized. This is the profile I was trying for.
 

I was aiming for 23.2mm(0.913”) at the muzzle tapering to 21.0mm(0.827”) 40mm(1.575”)  and ended up with; muzzle 22.2mm(0.873”) tapering to 20.2mm(0.794”) 40 mm from the muzzle.
From the breech I was aiming for 28.6mm (1.125”) tapering to 21.0mm 275mm (10.827”) towards the muzzle and ended up with ; Breech 25.6mm(1.008”) tapering to 20.2mm, 275mm towards the breech.

The walls are now to thin, to file in new flats and sighting rail.
Two things caused this:
I. Not possible to use the automatic feed when using the top slide for turning the tapers.
Manuel feed gave a rough finish which needed a lot of filing.
Possible solution: turn the barrel 1mm (0.04”) oversized.

II. It’s hard to adjust the taper angel right on the top slide The smallest unit on the top slide scale is 1 degree. If adjusted too steep, the taper ends before it reaches the breech. If it is too shallow, the taper reduces the diameter at the breech, which is what happened here. I was aiming for 0.8 degree and ended up with 0.6-0.7. On the long taper on the barrel a tenth of a degree make a lot of difference.
Possible solution: Adjust the taper a tad too steep and cut off the breech were the taper ends.
But tapering the first barrel might cause problems threading the breech afterwards.

3. Is the barrel I made safe, or are the walls too thin at the breech? What proofing loads would you recommend?

Best regards
Rolf

[JDK]

I'm no machinist....but I am looking at the picture of the original gun.

It appears to me that the sighting rib, flats and breech mouldings are all proud of (or above) the rounded surface of the barrel.

Are you attempting to turn the barrel and then relieve the metal around these surfaces?

If that is the case it seems you will have to turn it oversized and then file the flats to the desired dimensions and then file the decorative mouldings in low relief.

Good Luck, J.D.

[Rolf]

Are you attempting to turn the barrel and then relieve the metal around these surfaces?

If that is the case it seems you will have to turn it oversized and then file the flats to the desired dimensions and then file the decorative mouldings in low relief.

Good Luck, J.D.

Yes, the idea was to relieve the edges of the flats with an end mill and files, leaving the edges
0.6mm (0.025") proud.

Best regards
Rolf

[D. Taylor Sapergia]

An ambitious project.  You will have to turn the barrel to the major dimension of the corners of the flats, plus several thousandths for filing.  Then file the flats, and then mark out their extremities and file away the ground barrel steel to leave them proud.  I'm a hand tool guy when it comes to that detail, so I cannot advise on use of a mill to reduce the ground.  But Bob Roller certainly can!

[Jim Kibler]

Yes, the sighting plane and flats near the breech are somewhat proud of the radius of the surrounding areas.  So if you are going to turn it, the idea is to imagine a cross section at any particular location along the barrel and turn to a radius that is the maxim radius of the cross section at that location.  Hope that makes sence.  For example at a point along the sighting rib, you will have a maximum radius at the corner of the sighting rib.  You must turn to this diameter and then remove the remaining material to form the rib and rest of the barrel.  Now with this said, they sometimes cheated a tad, making the sighting plane very slightly rounded and they sometimes cut into the barrel along the rib a touch more to accentuate the feature.  A barrel like this is not easy to make and will require a lot of hand chiseling and filing to get the shape.  

[Acer Saccharum]

For forming the raised areas, you will need to cut down the material next to the section. There are some tools that look like saws, but they are wider in tooth. I think they are called 'floats'. Maybe James Wilson Everett has some documentation on these.
Some have a curved profile to the tooth, so that the float can be push along the length of the barrel, and conform to the curvature, while shaving down the steel of either side of the raised rib.

I think you will have much hand filing to make this style barrel. I am very excited to see your progress. You are a very determined man, Rolf.

I suspect an iron barrel would cut much easier than a steel barrel, but you must work with what you have.

Tom

[Dave B]

Here are some Floats from the Italian double gun makers bench. They use them for clearing the solder from the barrel joining at the rib seam.

[Bob Roller]

Floats or float files were special tools used in the days of leaded
panels in car bodies and in body repair shops. I once stripped the paint on
a 1937 Cord and was amazed at the leaded panels in the top of that car.
On a gun barrel,I used a vertical mill to cut two seperate ribs on the top
flat and then used a checkering file to dress them up a bit.
IF I were going to make an integrated rib on a round barrel by hand,I'd
use a new,sharp flat float file and TRY to file the contour of of the barrel
from round into the shape of a cam lobe as seen in car engines and THEN
file the "point"of the lobe flat as possible.I get tired just thinking about a
project like that.When I was 18,I filed a pistol barrel from round to octagon
but now I am almost 77 and I lost interest in that much work.
New float files are available in good car parts stores like NAPA and in
industrial supply houses as well. I have several and used a small one today to finish
the taper on the upper limb of a mainspring.
A float file as Acer describes is probably not available today as it would have a concave
radius in the cutting surface. I have a big one that is "half round" but it would be
no use in this project.

Bob Roller






Bob Roller

 

[Bob Roller]

Take the chuck off the lathe and put a live center in the tapered hole
if it has a spindle with a taper.A lot of them are Morse #2 or 3 tapers
and put the barrel between centers and the the spindle will turn but
the barrel won't. You will have to devise a way to hold the barrel steady
between the centers but this will make a planer out of a lathe. A bit
of practice to get used to this idea is advised.

Bob Roller

[KNeilson]

I would agree that this is sure an ambitous project. Imo, starting from octagon and filing to round would be easier than starting from round, to then flats for sighting rib and side panels, and then back to round between flats.  If barrel was left same dia. fwrds of muzzle as at breech plug. It could be held in V blocks on crosslide, side and top flats milled flat. Then layed out for width of finished flats. Corners files round to layout lines and then either whittled with small dia end mills to lines, rotating in V`s or chiseled and filed as suggested. With no taper attatchment on lathe, I would cut taper roughly and file to shape. It will be quite hard if not impossible to turn taper and leave sighting rib raised. How about making a tapered barrel, then silver brazing the raised portions on separately, carefully removing evidence of solder when finished. Just thinking out loud... Kerry  
PS I have tried before as Bob R has just suggested, and have scraped external tapered keyways. Another possible solution for sure..K

[Dave B]

 I have a early horse pistol barrel by Lazaro Cominazo and the barrel is not round its kind of ovoid with the center flat relief making the flat area stand proud. You will have to be over sized and dress it down to shape. Here is what this sort of pistol barrel with breach  yet to be shaved down looks like just off the lathe. It looks way too big but by the time you put the flats on the breach section it will slim it right down.

[Paul Griffith]

One possible way to do this on a manual milling machine. If the taper was uniform & not swamped. Starting with a dimension large enough to include all raised areas you would center up the barrel  between a dividing head & tail stock in such a manner as to establish the proper taper. This would allow a slight cut to be made raising the rib above the milled surface. The barrel would then be turned a degree or so & another cut made. By repeating this numerous times the bottom dimension would be established. Of course the small flats left by the flat bottom milling cutter would need to be dealt with & corners & crannies not reachable with the milling cutter would have to be finished up by hand.

This whole set up would be childs play on a four axis CNC mill.

Paul

[runastav]

Hi Guys!
Rolf, do you remember the Scottish metal pistol I made? You can use the lath as a scraper
Runar

[Acer Saccharum]

Thanks for that picture, Runa. You and Bob Roller are onto it.

If you had a taper attachment on the lathe, you could convert it to follow a curved template.

[Rolf]

Thank you all for your input.

Scraping with the lath looks like the way to go. I'll also try to make floats from an old metal rasp I have. I've orderd 2 more blanks from Blackley. I post pictures of the next attempt. But it will be awhile before I get time to do it.

Best regards
Rolf

[Jim Kibler]

A barrel like this is not a straight taper.  Scraping with a lathe as shown becomes quite difficult in a situation like this.  I actually started a barrel like this a while ago but haven't finished it.  The process I chose was to basically form it as a swamped barrel in octagon profile with the top flat slightly higher than the rest.  This gives material for the rib and then the other corners can be cut off and the rest of the barrel shaped by hand.  The major work was done with a mill.  No matter how you slice it, there is going to be a lot of hand work and it isn't going t be easy.  An option....  Octagon to round profiles were used in the same period and can be made quite easily.  Some were nice long barrels with a pleasing profile as well.  Might be an option...  Good luck!

[Acer Saccharum]

If the barrel is 12L14, you may be able to scrape the details. I'd try a hook scraper, pulled along the barrel, against a fence. If you start developing ripples in the surface, you'd have to file them flat.

You'll have nice strong arms and back by the time you're done.

In the inside corners, where a moulding meets a rib, you will have to use hammer and chisel.

Bon voyage, and keep us posted.

[Jim Kibler]

One more note...  I think Bob Roller's suggestion of shaping like a cam lobe first is a good one.  I'd guess this is how barrels like this were originally rough forged.  Problems with barrels like this are basically due to their being very free from in shape and less easily replicated with machines. 

[Acer Saccharum]

Jim, to agree with what you have said,  I also believe barrels were forged with final shape in mind, to conserve effort and materials.

[Acer Saccharum]

Thinking about this, there were so many barrels done in the manner with raised ribs, and relieved panels, wraps at breech and muzzle, there could have been a scrape or milling machine. I would have invented one if it didn't exist! 

[Bob Roller]

My computer server has been dead until a minute ago so I am going to play
"ketch-up".
The comment about chatter in 12L14 would probably be due to an inconsistency
during the making of that materail. I was turning a 1/2"piece of 12L14 recently
and hit a hard spot that made sparks fly for a second.
I have doubts about the steels that are now on the market and I have also found
"hard spots"in 1018 as well during a milling operation. So far so good on the last
1075 I bought.

Bob Roller

[T*O*F]

Thinking about this, there were so many barrels done in the manner with raised ribs, and relieved panels, wraps at breech and muzzle, there could have been a scrape or milling machine.

I'm surprised that Bob hasn't mentioned this.  He gave me a VCR tape of an English gunmaker making an English Sporting rifle.  The barrel had Rigby type flats on the top and sides.  The guy literally carved them out with cape and die sinker chisels and filed them to finished form.  The chips were HUGE.  He did use a lathe for some of the other operations, but not this one.

[Acer Saccharum]

Dave, Bob is getting up there, so you gotta cut him some slack.

I am getting up there, too. I'll be 60 in Jan, last time I checked I was 20. A lot has happened between now and then.

I hope to try my hand at one of this kind of barrel some day. It had better be soon. A lot of folks say 'I'd like to see Budapest before I die, or the rainforest, or, or'...but seldom do you hear I'd like to make a raised rib barrel before I kick the bucket.

[Bob Roller]

I remember that tape about the English rifle maker doing such
work with a chisel and it was impressive.What wasn't impressive
was the poor groups when the rifle was tested.

Bob Roller

[davec2]

Tom,

Don't you have a CNC mill?  I would hate to try my hand at the G coding for a raised rib barrel, but you could sure make the barrel a $#*! of a lot quicker.