Double Bass 1950 American Standard neck removal

[robobass]

Chet,
I'm gonna PM you for advice on avoiding firescale when torch soldering brass!

 

[Don Kasper]

Chet,
I'm gonna PM you for advice on avoiding firescale when torch soldering brass!

Yes! - now we know who the "Alpha Males" are around here!

 

[1st Bass]

Chet,
I'm gonna PM you for advice on avoiding firescale when torch soldering brass!

Well... I hate to disappoint you, but I have very seldom soldered brass, and when I did I got the scaling you are trying to avoid.

There are other means of soldering...doing it with an electric heat source, especially in an inert gas environment, would avoid the atmospheric contamination, for sure...but, truly, I'm the wrong guy to ask. Sorry.

 

[1st Bass]

Because soldering does not fuse the base metal, but only the filler metal, it is important to have the base metal in the (closely fitting) joint absolutely clean, and to use the correct flux for the base-metal/filler-metal combination. Then heat the joint (not the filler metal) until the base metal has enough residual heat to melt the filler metal. When that temperature is reached, the filler metal will flow into the fluxed joint like water, almost, and make a very strong joint as it cools.

The technical difference between soldering and brazing, BTW, is that soldering is done below 840 degrees Fahrenheit, and brazing above that temperature. The melting point of the filler metal is the deciding factor. There are "silver solders" available, whose melting point is typically over 1000 degrees. Despite the name, they are true brazing processes, and very strong. A classic example would be the carbide teeth on a circular saw. The tungsten carbide bits are far too hard to weld, so they are brazed in place with "silver solder". If you look closely when they are brand-new, you can see the shiny line of the filler metal in each joint.

 

[robobass]

Chet,
I'm using a jeweler's "soft solder" which melts at 1425°F, and a butane torch. The joint comes out plenty strong. The real problem is that I'm soldering brass threaded rod, which is quite challenging to clean and polish compared to most shapes people might want to make shiny. The current process involves preheating the work and then spraying on an anti-firescale compound I got from Rio Grande. Works well, but the stuff isn't available in my country, and I can't find a substitute here. I've got some ideas, but at the moment the technique is simple and effective, so I'm gonna keep doing it until the firescale dope runs out

 

[1st Bass]

Well, we used to use a product for antispatter that (as far as I could tell) was just an aqueous suspension of kaolin clay, with a consistency about like paint. It protected polished surfaces (such as bearing journals) from welding spatter. When everything was cool again, we could wash it off with a wet cloth very easily.
Maybe something like that would work.

 

[Ortsom]

Mr. Bishop, thank you for sharing this metallurgical information!

Interesting to hear that James reinforced the (new) neck in this classic ply bass with CF, and this & a few other current threads set me thinking on yet another tangent. Of course all-CF bodies exist, but can anyone share information/experience on reinforcing a (ply) top with CF?

 

[james condino]

Are you asking about reinforcing the ply top with carbon fiber or reinforcing the neck on a plywood topped bass with carbon fiber? Over the last year I have posted a couple of threads on both areas, all with positive success. If Tony Stradivari was alive today, he'd have a commercial account with Dragonplate / Alred carbon fiber!

 

[okcrum]

Chet,
I'm using a jeweler's "soft solder" which melts at 1425°F, and a butane torch. The joint comes out plenty strong. The real problem is that I'm soldering brass threaded rod, which is quite challenging to clean and polish compared to most shapes people might want to make shiny. The current process involves preheating the work and then spraying on an anti-firescale compound I got from Rio Grande. Works well, but the stuff isn't available in my country, and I can't find a substitute here. I've got some ideas, but at the moment the technique is simple and effective, so I'm gonna keep doing it until the firescale dope runs out

You might be able to make a substitute.

Society of American Silversmiths - Firescale Issues

 

[Ortsom]

reinforcing the ply top with carbon fiber

That one.

After weeding through neck reinforcements & CF SP's, a plan for a CF-laminate spruce bridge, and some other bits & bobs, I find this one about a repair in a ply top using a CF patch. Horrific damage, excellent repair! Thanks for sharing. (There may be more which I haven't found.)

In a repair you don't have the option to do a before/after comparison, but of course you know what such a Kay sounds like without such a patch. How would you describe the effect of the CF patch?
Have you ever tried a reinforcement by laminating CF directly onto the wood? (That is: as the race car & surfboard guys do.)
I appreciate your point that the outer layer should best be wood, for SP friction reasons.

Once again: a big Thank you for sharing, and for your creativity.

 

[robobass]

Thanks Chet and Chuck. I invested in a cheap airbrush, which solves the problem of wasting the precious anti-firescale juice, and a huge brass brush (10" dia. x 2" wide). Between cleaning the screw rod first and getting a good spray coating before soldering, I've got the problem licked!