Dovetail Depth on a musket

[Scota4570]

I am assembling a Baker.  The tenon castings suggest a dovetail depth of 0.062"  I say that is too deep.  The one nearest the muzzle will have gone half way through to the bore.  I am thinking that I might go half that deep and add solder.  One of the tenons will secure the front sling swivel, it needs to be strong.  The plans do no address the question. 

Second, the bayonet stud is called to be brazed or silver soldered in place.   I am hesitant to do that because I do not have any argon to put in the bore and prevent heat damage inside.  Since the rifle will not see a bayonet is there any reason not to soft solder it on? 

Finally, I found a gold/tin (80:20)  eutectic solder that melts at 800*F but is super strong.  Has anyone messed with it?  I also have "easy" silver solder that might be done with a plumber's gasoline torch.  Comments?

Thanks,
Scot

[bluenoser]

You might consider cutting the dovetails on the shallow side and upsetting the under-cuts to create the equivalent of additional depth.

[rtadams]

9-4-22

Scota4570,

I use a dry Nitrogen purge thru the barrel with a regulator on the high pressure Nitrogen tank. Use only enough purge pressure to create a slight constant flow of dry Nitrogen thru the barrel which will keep the Oxygen in the air from accumulating in the barrel. This is a required procedure in the HVAC (Heating Ventilation and Air Conditioning) industry for pipe work when the soldering, welding or brazing temperature is above approximately 800 degrees Fahrenheit to prevent scaling etc..

Best Regards,

Robert

[satwel]

Have you cut the dovetails yet for the barrel lugs? I lay a flat file on my benchtop and run the flat side of the barrel lug up and down on it to thin the wedge. They do not have to be .065" thick. One builder I know cuts his dovetails .040" deep. I thin mine down to around .050". Because of the taper on the sides as you thin the thickness of the wedge they get narrower so you have to thin them down before you cut your dovetails.

[Scota4570]

I have not cut anything yet.  I can make the wedge tenon base any thickness I want on the mill.  The plans show the wedge holes as in line with the bottom of the barrel in one place an and a bit proud in another.  I cut dovetails on the mill.  Unless someone tells me otherwise I guess I'll go about 0.040"  deep a the muzzle and a bit deeper toward the breech where the barrel wall is thicker. 

As for not scaling there bore.  I will have to look into options to get some inert gas.  Are there other anti-scale options?  Trashing the bore is not acceptable to me. 

Thanks

 

[Bob Roller]

Maximum pressure is at the breech when the powder lights up and it drops a lot by the time it gets to the front sight and zero at discharge. .062 (1/16 of an inch) will secure a sight at the muzzle.Take your time and get that dovetail right the first time.
Bob Roller

[satwel]

I long time ago I read on an on-line forum (probably this one) that a guy filled the bore of his barrel with finely ground charcoal to keep the oxygen out of the bore brazed the  the barrel lugs on. I've never done anything like that so I can't speak to the effectiveness of that approach.

[yulzari]

I make no claim for or against it but one old way was to plug the barrel at the point of contact with a piece of raw potato to control the interior heat when soldering a sight or lug onto a barrel.

But then the old boys were not always miracle workers. I have a Westley Richards Monkey Tail carbine whose rear sight was soldered right over the bluing and made absolutely no penetration under the sight. It must have just clung on by the fillet at the edge until it came off. All one could see was a faint rectangle where it sat outlined by a tiny thin dribble of solder. Perhaps a ten minutes to knocking off time job?

[kutter]

For an inexpensive heat scale preventer, I've always used Boric Acid.

I was shown the trick very early on in the early 70's when making engraving tools, punches etc.
Hardening them w/o heat scale forming was a must.
A jewelry engraver showed me to use Boric Acid. It was used quite a bit in that trade when hard soldering.
It comes in powdered form and from the drug store,,or you can easily buy it by the pound now on Ebay and other places on the net.
This will be 'pure' Boric Acid and works the best.

Common ant & roach killer powder from the garden center is also Boric Acid (99%). I've used that a few times but with not as good results as I will explain.

The powdered Boric Acid is simply mixed with alcohol to a paste.
Then the metal is coated with the paste.
Brush it on or dip the part(s) into it.

Small tools like the gravers and punches we just dipped the ends in the stuff and built up layers like making a candle.

The alcohol dries off fast, but you can light up the coating and burn the excess alcohol off. That leaves the coating a hard shell. Fragile,,but air tight.

Now heat to the temp you need for HT. When you quench, the 'shell' will break/shatter and leave the part clear and clean of any scale. The steel will be light grey in color.

Used inside a bbl bore the paste can be thinned quite a bit and a few layers built up on the bores surface. Then allowed to dry or burn it off.

Not being something that you will quench obviously but just let the solder joint cool on it's own,,the coating will be there when the job is done.
At that time you can remove the still hard shell by inserting the muzzle into boiling water to disolve the Boric Acid.

In using the insecticide Boric Acid,  I found that it did not form the smooth coating on the surface as it did when using the pure form. Both mixed the same with alcohol.
The insecticide version then did not form the best 'shell' around the part when heated leaving a few very tiny holes in it where small discolorations from the HT scale (?) showed on the final surface . Nothing major on a punch but not something I would want on the surface of a bbl bore.

I'm guessing that somewhere in the inactive 1% ingredients there may be something like a filler, clay, silica or something like that that interupts the pure boric acid from completly forming the shell around the part.

The insecticide Boric acid shell did not completely shatter and break free of the surface during quenching when used that way in most instances either. Some remained on the surfaces but would eventually disolve in the same boiling water after treatment.


On the Musket bbl loops,,I'd cut a very shallow dovetail for them,,very shallow.
Kick the insides of the dovetails open with a chisel to increase their height above the bbl surface.
Then fit the loop into place securely in that dovetail along with soft soldering them in place.

Or just soft soldering  in place with a well fitted concave base to fit bbl contour.
Properly fitted and sweat soldered, they will not come un-done.

Bayonet Lug,,I would  probably High Temp Hard Solder and use anti scale technique.

[Scota4570]

I went about 0.050" deep on the dovetails for the wedges and sling loop.  It went slow an they all fit very nicely.  I may solder them later.  I also used my lathe as a make shift shaper to trim the wedge and sling loops to the barrel contour.  That worked out really well to make them look neat.   

Now I have to worry out the wedge slots in the wood.  Normally I would drill the lugs with the stock and work the hole into a neat slot.  This one has the under lugs cast with slots in them already.  That may be an issue if the drill bit catches and edge on the steel and breaks.  I will drill them on the mill.  Since it has no decorative wedge escutcheons there is no room for error.  Any sage advice on how the get the slot in the wood to fit  the lug and to look perfect from the outside? 

I do enjoy these problem solving puzzles.