doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Invisible sleeve joints and damascus

I'm pretty sure that's what I was saying when I questioned the Met Engineer's use of the term "mono-metal". "Mono-metal" would certainly seem to imply homogenization. And I also said the following, which would indicate that they are more than "just stuck together."



I read several articles on Post Weld Heat Treatment which all suggest that there is more involved than simply playing a torch on the HAZ. It sounds as though doing some seat of the pants post annealing or heat treatment would be preferable to nothing at all. But some degree of control is necessary depending upon the alloys that have been welded, and the desired end result properties, ranging from full annealing to normalizing to stress relieving. Two of the factors are time and temperature which is why I questioned the possibility of affecting the brazing of the monobloc section. That could also be controlled with the use of heat sinks or heat control pastes. Here's a few articles to consider, but hardly all there is to know when the weld is subject to high pressures only inches from your face:

http://www.thefabricator.com/article/met...strengthened-st

http://www.superheatfgh.com/heat-treatment/heat-treatment-applications/post-weld-heat-treatment/

http://file.scirp.org/pdf/JMMCE20100600005_84007347.pdf

"the weld is subject to high pressures only inches from your face"

well said, and reason enough to accept the faintly visible line of a weld free solder joint.

I would like to see some images of the sleeving process especially the old barrel removal and metal preparation.

thanks j

jlb

My question is why you need to use an alloy steel for the tubes to begin with. Plain 1040 carbon steel is more than adequate for shotgun barrels and its strength is not degraded by brazing or welding.

Here you go jib

Pennsylvania Gunsmith School http://www.pagunsmith.com/photos3.php?g2_itemId=533

http://www.picturetrail.com/sfx/album/view/20580224 mostly courtesy of Toby Barclay www.heritageguns.co.uk

Because pretty much all gun barrel steel today is an alloy steel. We do not have the choices available today past gunmakers had.

Even if you had access to tubes made of earlier low alloy steel, the TIG weld joint would still have a Heat Affected Zone (HAZ) after welding that would have an altered metallurgy. I am absolutely NOT saying that TIG welded sleeving jobs are undesirable. But I've always been concerned whether the gunsmiths who do it fully understand the potential risks. I've told the story here of being totally blind for about a half-hour after a complete head separation on a .22-250 rifle. Anyone who experiences something like that has more respect for these kinds of things. Personally, I dislike seeing the joint of soldered jobs even on new manufacture monobloc guns. Some are very well done by real craftsmen, and some are butt-ugly. The jobs with the turkey-track engraving intended to hide the joint just scream cheap and dirty.

The idea of TIG welded sleeving joints is very appealing for obvious reasons. For proof that it could be done safely, one need only to examine the barrels of Thompson Center Contenders and Encores. The interchangeable barrels of these guns have the barrel lugs welded directly beneath the chambers of some pretty high pressure center fire cartridges. I would bet that there is some carefully controlled post weld heat treatment done to these barrels after welding and before chambering.

http://www.hellis.com/

whilst we're on the topic, thought this may be of interest. Towards the end of the page it tells of the first sleeved barrels to be submitted and pass proof. These were the work of Mr. Bill Roper who passed away last year.

There's also an interesting patent taken out by Henry Monk of Chester where he assembled his barrels in a similar way to the monobloc barrels we see on many OU guns which is basically the same way that barrels are sleeved. I can't find a link to that but there's a mention of it in Diggory's first book.

Neither of the above really contribute to this thread but may be of interest to those who like to read about these lovely old guns.

I wonder if the weld is there just to make the joint invisible. If the weld at the breech holds the tubes in place , would the weld around the joint need to penetrate the sleeve or just "fuse" the outer surfaces so it can be stuck up and re blacked ?
If the molten pool from the arc isn't too deep, it may not affect the tube beneath it too much.
Does that make sense ?
I realise there's heat present but it can be controlled and is localised so if the job is done slowly, maybe a pool at a time at one barrel, then the other, to allow for cooling, I'm pretty sure they wouldn't get too hot.
Another thought which leads me to think the weld is more cosmetic than structural is that they can't go all the way around, there's no room between the barrels between the top and bottom rib to work with.
I may be wrong but can't see a way to weld all the way around both tubes.

Welds can be made all the way around. I have a set of barrels that had a tiny crack welded dead between the barrels, on the right tube, about 8" from the muzzle. Don't know how he did it, but he did it.

SRH