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Adding a rib and mt'g brkt's to a trap bb'l

Jerald MI.

Hot Rolled
Joined
Oct 21, 2003
Location
Clio MI.,USA
I am changing the rib on a BT99 trap gun. I have stripped the old rib and made the new brk'ts which consist basically of steel blocks. Of course there is some shape to them and they need to be soldered to the rib.

I spoke to a welder today who suggested tig welding them instead to reduce the amount of heat required.

Basically, he will be using the technique of "skip" welding about 1/2" on each end of the mounting brkt's. I will chamfer the edge of the brkt's about .06" and file the excess weld off and finish the edges off.

So, what do you think? Should I let him tig it, or look for someone willing to solder?-Thanks, Jerald
 
Dont weld them welding melts the steel, soldering only hits about 1100 f for silver hard and 450 for lead soft.
Some of the ones done in the past have been
solder d with lead low temp. You will have to rust blue if you go that way.
 
I suppose a really good TIG welder could put in a little tiny bead between the posts and the rib but I would be concerned about welding the posts to the barrel. Might get hard/brittle spots in the barrel at the welds.
 
If you are thinking about welding the posts directly to the barrel, you may be asking for trouble. A trick welders use to straighten a slightly bent I beam is to put some welds along the outside of the bend. The weld material goes on liquid and as it cools it shrinks, straightening the beam. I am guessing that if you welded the psot to the barrel you end up with the same result but in this case you would be bending it. My vote is for soft solder or something like Brownells Hi Force.
 
I'm curious as to how you decided how high each "bracket" has to be. Professional rib smiths silver solder blank posts to the barrel and then mill the tops of the posts with the dovetail that allows the rib itself to float. You cannot solder the rib to the posts except at one end. If you do solder it at every post, the barrel will tend to bend upwards as it heats up from firing since the rib will be cooler and will expand less. This will change the point of impact and/or tear loose the posts from the barrel or rib. The rib itself has to be free to slide over the posts, allowing for the differential expansion.

Simmons(one of the top rib shops in the world)uses a custom built machine like a vertical mill that cuts the posts to the correct height and dovetail shape. The post's height determines the angle of the rib with respect to the barrel, but the rib also has to be supported in a straight line or it will look weird to the shooter. Each post height is different because of the barrel taper and rib angle.

TIG welding is asking for trouble.

RWO
 
RWO- since you asked: I was going to wait until I was complete with the project to offer this information.

The jig is incomplete as I intend to add some support to dampen the machining forces in the midle of the bb'l, once I am ready to cut the brk'ts. The jig will index along the table in the "X" to present (3) areas under the spindle for horizontal/verticle machining.
jig.jpg


This is the brk't to be soldered at the rear, with some minor changes yet to be done.
breech.jpg


And the middle:
middle.jpg


And the muzzle:
muzzle.jpg


The rib, yet to be machined, will be free floating and secured only in the middle so it can be adjusted to be viewed as "flat" by the eye. Of course, the butt stock is already fitted with an adjustable comb.

The rib ends will mosty likley be adjusted by means of a cam or threaded adjustment rod at the least.

Thanks for your comments, I too thought the "tig" to be a poor idea but I have read that a lot of tig repair is currently done and a "professional" welder recommended it. He said he has done a lot of tig welding for a local engraver.

I have the "Hi-Force" solder and Comet flux recommended by Brownells. I have had difficulty getting it to "flow" as described by Brownells and phone calls to them offer little help. I can get it hot enough to melt the solder, but it does not want to flow. As well. the flux appears to "burn" on the steel while I am attempting to tin the surfaces.

Thanks for your help-Jerald Ware
 
Jerald, it looks like you have the right idea and a good start. I have used Hi-Force solder extensively and have not had a problem unless I overheat the parts. I have done small parts with a hot-air gun and have never needed anything more than a propane torch for the most massive parts. The flux will burn easily with too much heat, but I have melted the solder and made a joint with out the flux even turning brown using a hot air gun. I can't do this with a torch, but it is possible to do good work with a small flame propane torch. O/A is simply too hot.

TIG welding has it place and I have done quite a bit of it on restorations where pits and gouges needed to be filled. No doubt engraving mistakes could be similarly repaired
However, it takes an inverter type welding machine that can maintain an arc at very low currents (1-3 amps) to do it right. The average welding shop TIG machine cannot do it and causes problems. Good luck!

RWO
 
RWO- thanks for the advice. It got me to wondering if maybe I too was overheating so I gave it another try. Yes, I was over heating the steel and burning the flux. Thanks for the help-Jerald
 
That looks like your making a bt-99 Plus copy? Is it a 34" ? I have a barrel that I fit to a plain bt-99 and after selling my bt am going to find another someday to put the barrel back on. It is nice to be able to adjust the rib too.

Toad
 
Toadjammer-yes, a plain BT-99. I traded for this gun intending a winter project. It is of the old vintage and shoots 100% high; much too high, so I stripped the rib.

After adding the blocks, I plan to machine a slot in the front braket, make an eccentric cam and use that as a test bead to determine the height difference I need between the front and rear of the rib.

When I remade a stock, I reduced the height of the comb until I could not see the front bead; only the rib at the rear. Then I installed an adjustable comb kit and added a small ramp of about .4" to the muzzle and I could just see the bead. That seemed about right.-Jerald
 








 
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