 The Clarinet BBoard
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Author: klook
Date: 2010-12-08 01:14
How does one know what pot metal is?
I'm working on this old Peddler bass clarinet. Its the 1st bass clarinet I've worked on after overhauling a bunch of sopranos.
I got hung up right off the bat on the C#/G# key. Its a 2 piece key unlike the simple setup on the sopranos. For whatever reason this thing kept me busy for a long time, battling spring tensions for the 2 parts and key cork in the right spots etc.
Anyway, I finally got it okay and I proceeded to put the rest of the clarinet together only to find out a few keys down the road that I had to pull the C#/G# key off in order to get another key on (I was following the order in my Reg Thorpe book...oops, just goes to show you that every clarinet is different!)
Long story short the finger touch piece broke right where it connects to the key shaft.
People often mention that the Peddlers use pot metal, which means I can't just solder this back together, right?
And if this is so, can I fix this with JB Weld or cold Weld, or what is the best solution?
Good news is the rest of the clarinet is together, and I'm gonna do the bottom half in the next few days and see how she sounds....without the C#/G# of course!!
klook
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Author: bmcgar ★2017
Date: 2010-12-08 02:08
In my limited experience, I've usually been able to tell pot metal by the way the surfaces of the break look. Pot metal is usually dull gray or dark gray, and at the break looks "granular."
Soldering or braising pot metal is almost impossible...or at least it has been for me when I experimented with it. If I were you, I'd use one of the "cold weld" substances.
Keep in mind that I might be entirely wrong on both points. As I said, my experience has been limited, and none of it has been with pot metal used for instrument keys.
B.
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Author: David Spiegelthal ★2017
Date: 2010-12-08 02:25
I would forget about trying to glue it either -- it won''t hold. That's a highly-stressed key if I understand your description correctly. If you can't solder the key, throw it out and replace (in the opposite order, that is -- find a replacement part, adapt it to match the original part, then throw out the broken part).
But before any of that, trying soldering it -- maybe you'll be lucky and it won't be pot metal (a.k.a. "Mazak").
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Author: jasperbay
Date: 2010-12-08 03:55
Chances of a bass clarinet key being made of 'pot metal' or 'mazak' is very low. Anybody who works on clarinet keywork much has to learn how to silver solder, or 'silver braze'. Soft solder and J-B weld just don't cut the mustard.
Jeweler's supply outlets like Rio Grande sell silver solders that melt from 1100 degrees F. to 1300. This is well below the melt point of brass or german silver, so its not that hard to silver solder. You need the right flux too. I like to use a small oxy/propane torch, but I've heard that plumbers MAPP gas gets hot enough. The plumber's torch would be a pretty big flame though, better to stick to a jeweler's type torch.
Clark G. Sherwood
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Author: clarnibass
Date: 2010-12-08 05:33
If I remember a Pedler alto clarinet I worked on was fine for soldering, made of normal metal. There's a small chance I'm confusing with another instrument so I can't say I'm sure 100%.
I agree with the posts that glue or soft solder isn't strong enough. It might be possible to get away with a weak silver solder like a type of soft silver/tin solder, but probably not for a key where exactly all the stress is in that soldered area like the G# lever.
You don't have to use an oxy/gas torch. Those get incredibly high temps and can even be risky. Some jewelers use those torches only sometmes, and other times specifically use lower temp torches because of risks. For silver soldering you need the metal to get to a temp at least as high as the solder flowing point. This is about 650C for most silver solders used for musical instrument keys.
Some people even use oxy/acetylene which can even get up to around 3400C. It can be ok but just need to be extremely careful and even then you can have accidents. Oxy/MAPP is around 3000C. Oxy/propane can get as high as around 2800C. You can use those, but all are considerably more than necessary and can be especially dangerous not only to the metal, but having the oxygen tank in your room. That's a reason I decided not to use this or even acetylene alone which is around 2650C.
Remember that nickel silver melts at around 1200C, much lower than any of those torches. Of course it won't get as hot as the flame itself and also depends on how long you heat it. The smaller higher temp torches are more accurate but for me not worth the risk. It's completely possible to do all silver soldering with a good butane (about 1400C) or propane (about 2000C) jeweler torch, as long as it's not too small. This is what I decided to use, a torch with detachable tips for different sizes, after considering and checking all options mentioned above. You only need the heat to transfer to the part to get it hot enough, faster than the heat will transfer away from it. The smaller padding torches (e.g. Blazer) are usually too small for this but even those might be able to do it for a very small part.
Maybe you (OP) don't need any of this info, I just replied seeing the mention of an oxy torch in one of the posts.
Post Edited (2010-12-08 05:44)
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Author: Chris P
Date: 2010-12-08 06:27
If the C#/G# touch came off the key barrel, chances are it's a dry solder joint which means it wasn't prepared well before soldering when it was made - the solder hasn't flowed into the joint but has only tacked the touchpiece onto the key barrel around the outside of the joint.
So clean up the joint surfaces of the dry joint so you get clean, shiny metal (though you don't have to remove the existing silver solder - just scrape all the oxide off to leave it shiny), jig them together with some flux in the joint, heat until red/orange hot and then apply silver solder. The plating may be damaged, so paper up the scorched area and polish up to a bright shine to make it look better.
It's very unlikely that it's made of mazak as bass clarinet keys do take a lot more punishment due to their lengths than soprano clarinet keywork and mazak won't be up to the job on anything larger than a soprano clarinet.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: SteveG_CT
Date: 2010-12-08 12:15
This surprises me as I have a Pedler bass clarinet and the keys are definitely nickel silver that has been silver plated. They are also rather soft as I've had to bend a few of the spatula keys back into position more than once. I've never heard of Pedler's using pot metal keys but I guess maybe they did on some of their lower end instruments.
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Author: Chris P
Date: 2010-12-08 12:39
Not on basses they wouldn't have.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: jasperbay
Date: 2010-12-08 15:31
I probably should have mentioned that oxy-propane can easily get way too hot for clarinet work, so care and practice on a scrap piece is in order!
Many silversmiths silver braze with a small single-valve acetylene/air torch (non-pressurized air mixed at nozzle), that puts out a gentle flame, of the right temperature to avoid 'burning' or overheating. The oxy-propane torch I use is very small, the flame tiny like a pencil lead, and I don't use much oxygen, just enough to turn the yellow flame blue. Too much oxygen will 'burn' things in a hurry. If the flame 'hisses', thats probably too much oxy for delicate work.
Most people use Chris's method of adding the silver solder after the metal reaches a dull red, but lately I've had excellent results by putting a small piece of solder into the flux at the solder joint. The flux keeps the solder from oxidizing and when the metal reaches the right temp, the solder 'bead' magically wicks into the joint. This keeps the joint very clean, and little cleanup or sanding afterwards is required.
Wish I could have watched some of the old metal clarinets being made. Probably done in an oven of some sort? I've heard that some old-timers used propane and low pressure air in a two-valve torch. Might try that someday.
Clark G. Sherwood
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Author: Tony F
Date: 2010-12-09 07:00
Years ago I did an emergency repair on an old Boosey and Hawkes Regent with pot-metal keys. I drilled the broken-off key touch piece and inserted a length of fretsaw blade bedded in Araldite, drilled into the key shaft from which it had broken and seated the other end of the bit of saw blade, also in Araldite, and supported the joint in a plasticene bed overnight with some more Araldite around the join. The key was one of the l/h pinkie keys, can't remember which one. It was only ever intended to get the owner over the Christmas break, but it was years before the key was replaced. I wouldn't recommend it as a regular method, but it got a young player out of a hole when the shops were shut.
Tony F.
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Author: David Spiegelthal ★2017
Date: 2010-12-09 13:27
I get good results using high-temperature silver solder (~1000-1100 degree F melting point, as I recall) which I get from Ferree's Tools, along with the paste flux they sell to match the solder; melted by a MAPP gas torch (propane and butane are not quite hot enough to melt this particular solder). The resulting joints are as strong as the metal of the keywork and are very smooth.
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Author: clarnibass
Date: 2010-12-09 15:29
>> ~1000-1100 degree F melting point, as I recall... propane and butane are not quite hot enough to melt this particular solder <<
Strange. I use a silver solder that has a higher melting point than that and have no problem with either butane or propane.
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Author: David Spiegelthal ★2017
Date: 2010-12-09 15:31
My recollection of the melting point may be wrong. If it matters, go to the Ferree's Tool website and see what they say.
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Author: clarnibass
Date: 2010-12-09 15:40
OK I checked Ferree's catalogue. their silver solder melts at 1125 and flows at 1295. What I use melts at 1145 and flows at 1205. Butane and propane are about 2500 and 3600 respectively (in air) but I guess maybe that small difference of 90F degrees in the flowing of the solder is exactly the boarder (seems doubtful)?
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Author: David Spiegelthal ★2017
Date: 2010-12-09 16:31
I've found that propane will eventually melt the high-temperature silver solder and produces (just) enough BTUs to solder very small parts, but for quicker action and on larger parts I need to use the MAPP gas.
Argue if you like, but this is what I've seen in practice.
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Author: clarnibass
Date: 2010-12-10 03:25
I'm not arguing. I just asked about the details because I was surprised. It's strange because the difference between the solders is tiny in comparison with how much hotter even butane is. Maybe I'll try the Ferree's silver solder sometimes and see for myself if I can use my butane torch with it.
Curious, what butane/propane torch did you try to solder this type of silver solder unsuccessfully?
Post Edited (2010-12-10 04:07)
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Author: jasperbay
Date: 2010-12-10 20:50
I've tried to silver braze with several screw-on-the-little-tank propane torches, and like Dave says, they don't get hot enough, in any time frame that will let the solder flow before the metal is too oxidized. I've tried just propane with 3 different solders that melt from 1000 to 1200 deg. F. (silversmiths use all three, when soldering different items on the same piece), with no luck. Try the "turbotorch" nozzle, that mixes in more air, and gets hotter, but it's still the type of flame best suited for sweating a 3/4 inch copper T fitting !!
This may be one of those times that "in practice" trumps "in theory". Sometimes it just doesn't matter what the charts say, but go forth and try for yourself, and let us know if you somehow succeed!
Clark G. Sherwood
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Author: clarnibass
Date: 2010-12-11 14:09
>> screw-on-the-little-tank propane torches <<
Can you give a link to one of those? I'm not sure what you mean.
>> it just doesn't matter what the charts say, but go forth and try for yourself <<
That's exactly what I meant. I silver soldered with the type I mentioned, melting at 1145 and flowing at 1205, no problems with butane or propane torches.
The type of torch and/or size of flame definitely is important. For example, a Blazer is also butane and the flame itself is probably as hot as my jeweler torch, but I can't silver solder with the Blazer. Once, as a test, with help from an assistant, I used two Blazers to silver solder and it worked. The temp of the torch was exactly the same whether one or two torches. The two torches just moved the heat fast enough to the part while only one couldn't.
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Author: Chris P
Date: 2010-12-11 14:27
Are the "screw-on-the-little-tank propane torches" Primus gas torches?
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
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Author: BobD
Date: 2010-12-11 16:18
I've never been able to tell the difference between a discussion and an argument.
I soldered all the copper lines in my first house back in the '50s with no leaks. In recent years I find that "they" eliminated the lead and now you need hotter flames and the new lead free solder. Yes, "pot metal" will show a "grainy" fracture surface since the end products are as cast. All nickel silver keywork is forged which destroys the as cast grain structure even more than the prior cold drawng.
I've never mastered silver soldering and respect anyone who has.
Bob Draznik
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