Instrument repair

[Chuck(G)]

I've never done any soldering on a brass instrument but I've been a sheet metal worker for nearly 40 years, so I've done a lot of soldering. My experience is the solder is controlled by the flux - if you don't want solder there, don't put flux there. Don't know if that applies to brass, but it sure does work with copper and galvanized steel.

In theory, that's the way it works. However, the moment you apply your torch to a fluxed joint, the flux is going to boil out and flux the areas wherever the vapor hits. If you're not careful, you'll get solder where you don't want it.

On large joints, I like to tin both surfaces first (after masking them off), then assemble without flux, just joining the already-cleaned-and-tinned surfaces with solder only. This keeps the solder migration down.

[Dan Schultz]

This topic interests me because I've seriously considered doing this when I retire (which will be soon)....... I think many of my skills would be useful in instrument repair, but I guess I won't know till I try it.

Your knowledge of metalworking will go a long way towards learning brass instrument repair. Start now. Pick up a few junkers and learn all you can. A little machine shop experience is also helpful. Go for it!

[Daniel C. Oberloh]

[prototypedenNIS]

silver plate, we use what we call "soft silver solder" or in my emergency kit, I use lead free. I still use 50/50 for most brass though... I've experimented a little with leadfree wire solder but I've found the flow to be different, the melt temperature to be higher, and the smell to... well... smell. When I run out of 50/50, I'll probably go looking again.

the dremel works because most of the time I leave very small amounts of extra solder, thin wire solder and liquid flux go a long way to making this easy. Heat by torch (move flame to lessen burn damage (Endust also protects against lacquer burn) and tilt the soldering so that gravity and heat can bring the solder to where you need it.

[Tubaryan12]

"Have you considered nursing school?"

probably the best advice in this thread.

[Chuck(G)]

silver plate, we use what we call "soft silver solder" or in my emergency kit, I use lead free. I still use 50/50 for most brass though... I've experimented a little with leadfree wire solder but I've found the flow to be different, the melt temperature to be higher, and the smell to... well... smell. When I run out of 50/50, I'll probably go looking again.

I still don't understand why 50-50 is used. Here's what I found:

70/30 = liquid at 188C, Solid at 183C, 4C plastic range, tensile strength 7800 psi

60/40 (or 63/37) = liquid at 183C, no plastic range, tensile strength 7500 psi

50/50 = liquid at 212C, Solid at 183C, 29C plastic range, tensile strength 6000 psi

50/50 melts at a higher temperature than either of the other alloys, stays "mushy" for a long time and isn't nearly as strong. I know plumbers like to use it (if code permits), because it can be used to plug gaps in fittings (wide plastic range) and it's cheaper than the other alloys.

[prototypedenNIS]

it's not that I've tried other mixes, if we were going to change types of solder we use, we'd probably go lead free.

Occasionally we have had to use 50/50 to fill gaps... not of our own judgement, we'd rather fix the dent and get a stronger bond but the customer wants a cheap fix that will hold, for now instead of the proper fix which should hold under most circumstances. It's good to have for that even.

I may have to look at 60/40 next time we need to get thin wire solder, compare it side to side and such but we go to 50/50 because we know what it's like.

The plastic state can be useful in keeping work clean. Less drippage, no?

[Chuck(G)]

The plastic state can be useful in keeping work clean. Less drippage, no?

No, you still have to heat it to the liquid state to get it to flow--and then keep the parts stationary until it solidifies (any movement during the plastic phase results in a very weak joint).

Dan's using 63/37 is why the alloy's used in electronics. Either the solder is liquid or it's solid--many fewer "cold" solder joints.

I like 70/30 because the plastic phase is still very narrow and the joint's stronger--and if any solder shows, it's brighter and less noticeable.

I'm using some lead-free now, but only as a way to get used to it. You can't apply it to old joints with lead-bearing solder on them already, as the lead will contaminate the new solder and weaken the joint.

[iiipopes]

If you don't want solder or flux spread on other places, do what pipe organ manufacturers do on their pipes, where they are soldering metal that is the same consistency (and therefore the same melting point) as the solder: coat with whiting, or powdered calcium carbonate mixed with basic gum arabic. Coat everything in whiting, scrape off where you want to solder, use a good steady hand of flux and solder as described above, and the whiting will repel the flux and hence the solder, making a clean joint. Then after it cools you wash everything off and buff to a perfect solder joint.

[Chuck(G)]

If you don't want solder or flux spread on other places, do what pipe organ manufacturers do on their pipes, where they are soldering metal that is the same consistency (and therefore the same melting point) as the solder: coat with whiting, or powdered calcium carbonate mixed with basic gum arabic. Coat everything in whiting, scrape off where you want to solder, use a good steady hand of flux and solder as described above, and the whiting will repel the flux and hence the solder, making a clean joint. Then after it cools you wash everything off and buff to a perfect solder joint.

Commercial solder mask is much easier to work with--just paint it on, peel it off.

http://www.wassco.com/kestcpeelmol.html

[pulseczar]

I forgot to put that I use 50/50 for gap filling like French horns, where the wrap is very tight and in the places that are too narrow for braces, 50/50 is much easier to handle than having 63/37 drip everywhere.

[Daniel C. Oberloh]

All this conversation about different solders, flux, masks, etc. Makes me think I am doing something wrong....... No, I'm pretty sure I know what I am doing. I have been known to perform some of the most extensive repair out there and I only use 70/30 and Nokorode paste flux. Silver-solder or brazing? sure, all the time. Now and then I will use a lead free or low temp silver bearing solder for piston port repairs in order to avoid plating problems that lead solder can cause when building up a piston for a valve job. Fill gaps and voids? I don't do that, it goes against my grain and I don't offer it to my clients. The job is in to be "repaired" i.e. damage corrected properly. I guess I suck at cutting corners, oh well.
If you offer bargain basement and cut-rate, thats the kind of work you get, over and over.
Advice to me when I was an apprentice was to simply learn how to make a good proper fitting joint, if it is distorted, correct it, if it means spending an additional half hour to get it right, don't piss and moan about it, (whiny voice " I'm not getting paid enough to do this kind of work") just shut up and do it. Silver plate? same process, but with a little more care. Not rocket science, just lots of practice until you have it down pat. I know, there are all sorts of aids such as masks and heat fences and I have experimented with a lot of them. I have found none that out perform mastering the control of heat and good preparation.

Brass band instrument repair skills that must be mastered are:
Soldering and brazing
Dent work
Polishing and buffing, A chimp can spray lacquer.

The above are the things you MUST fully understand if you want to repair brass. It will take years to get it down and it will take longer to develop personal standards of quality. I had those standards hammered into my thick skull by craftsmen who new there sh** and that was the toughest part of all. Just like learning to play an instrument, the more study and practice you do the better you will get.

Daniel C. Oberloh
Oberloh Woodwind and Brass Works
www.oberloh.com

[pulseczar]

Fill gaps and voids? I don't do that, it goes against my grain and I don't offer it to my clients.

I'm curious. When you say gaps, do you include tubing to tubing solder work? I personally dislike having to goop solder to bridge a gap. Whenever I do the tubing to tubing solder work, I try to make each part touch as well as make sure the brass is not stressed before soldering it down.

[Dan Schultz]

Brass band instrument repair skills that must be mastered are:
Soldering and brazing
Dent work
Polishing and buffing

Very well stated, Dan. I would add one more item to your list:

Use of a three-cornered scraper!

They could (should) teach a full semester of how to use a machinists scraper and another semester of how to use 'Machinerys Handbook'. Most everything else can be OJT!

[Chuck(G)]

The fallacy in filling gaps with solder is that there's no structural integrity in solder. Eventually, it will fatigue and break. A well-soldered joint should last pretty much forever.

Where a soldered joint gets its strength is by molecular bonding to the base metal, not in solder's affinity for itself. If joints don't fit well enough to "wick" solder into the joint by capillary action and solder must be pushed in to fill a gap, there's nothing but trouble ahead.

For an example of what's going on, take two very clean sheets of window glass and place a drop of water between them. You'll find that it's almost impossible to lift one piece right off the other. Yet, if there's a small gap, the sheets of glass are quite easy to separate.

[iiipopes]

As usual, Dan, Chuck(G), and Lee have cleared the slag off the molten metal and poured a pure ingot once again. Of course, whiting would not be used on brass as the solder and the brass are dissimilar metals; I just wondered if anyone would bite.

[Daniel C. Oberloh]

The fallacy in filling gaps with solder is that there's no structural integrity in solder. Eventually, it will fatigue and break. A well-soldered joint should last pretty much forever.

Where a soldered joint gets its strength is by molecular bonding to the base metal, not in solder's affinity for itself. If joints don't fit well enough to "wick" solder into the joint by capillary action and solder must be pushed in to fill a gap, there's nothing but trouble ahead.

For an example of what's going on, take two very clean sheets of window glass and place a drop of water between them. You'll find that it's almost impossible to lift one piece right off the other. Yet, if there's a small gap, the sheets of glass are quite easy to separate.

Thats the sort of stuff one needs to learn and apply. There are a number of Techs. who do improper repair not because they don't care but because they don't know better. The best training does come OTJ but only under the supervision of a Master Journeyman Forman, preferably one with a good deal of patience, unlike myself.


Scrapers have there place but I really don't use them that much. (except for cleaning tube ends on the lathe. It all goes back to having really good soldering technique. Its all in how you go about it i
as to how much scraping one is called to do. I am assembling a B&S Crown BBb and have yet to do one bit of scraping. I will let you know when I get out the hook.

The key to good quality solder work:

-Excellent surface prep.
-Well fitted parts,
-Good heat control

(No, I don't tin my joints. In my opinion, Its an extra step that takes more time and wastes material and delivers nothing in the quality of the final product)


Daniel C. Oberloh
Oberloh Woodwind and Brass Works
www.oberloh.com

[Daniel C. Oberloh]

I'm going to risk assuming that Dan will agree with me when I state that *any slight difference in tin-lead percentages and flux make-up can MORE THAN EASILY be overcome by a clumsy end-user.



bloke "Just hand me a spool of solder and get out of my way."

Alas, I fear this statement is true. Both for technician and player alike.


Daniel C. Oberloh

[Chuck(G)]

Boy, Joe--you're really high class! I'm stuck using this "amateur's solution":

<img src="http://www.bondo-online.com/fileshare/p ... es/294.jpg">
<img src="http://www.lacywest.com/EmeryPaper.jpg">
<img src="http://www.eurofixings.co.uk/images/rustins/gold.jpg">

[Dan Schultz]

Duct tape!