[raindog]

So, I wanted to learn silver soldering/brazing, and as a practice project, decided to design a pants guard for my bari. Something along the lines of Martin saxes.

I tend to hold the sax, especially the bari, to the side of my body, it's just the most comfortable and natural way for me, ill-adviced or not. I'm loving everything about the King, except that the split bell design is such that I worry constantly messign up the alignment of posts bumping it to a chair, my hip or clothes.

Here's some progress pictures, temporarily taped to the body. I ran out of gas and silver messing about with a torch maybe too anemic for this purpose, so it will take a while before I can finish this thing. The longer vertical rail protecting the rods in the main body is still unattached. It's a bit annoying that I had to bend the shorter vertical rail at the middle to allow enough clearance for the B-key, but I can live with that.

This is all very messy since it's a prototype to test the concept, unfinished at that also. I might finish this or refine the design and just make a new one. Doesn't look too bad to me even at this point, kinda fits to the theme of wire guards.

Anyone tried to do something similar? I'm not gonna go close the sax with a torch, so this will be a completely removable attachment.

The brass wire is about 6mm thick. Thinnest that was easily available, I would like a bit thinner but also 6mm feels like it has just enough surface area to stand on their own without additional support at the solder point. They are attached to pretty hefty C-shaped feet made from 2mm x 20mm brass bar. It was a proper PITA to get everything lined up with the shape of the horn, and needs to be rebent after soldering since its hard to get the angles right and the brass tends to live due to the heat.

I was thinking to braze small hooks to the ends of the C-feet, to fix them around the body with rubber bands or something. The placement of the contact points are such where there are no tone holes or anything in the way of said rubber bands. Might need additional foot near the thumb hook, but I'm gonna see if four feet is robust enough.

Of course cork, velvet or something soft is going to be glued to the C-feet where they contact the sax body.

I'm open to any suggestions to improve the design, any dangers I might have overlooked, and would like to know experiences if someone has attempted to do this kind of thing before.

 

[raindog]

The problem with brazing was probably that I wasn't able to get enough heat in the pieces anymore. Partly because as the combined mass of attached parts grew, it acted more and more like a heatsink.

But maybe the main reason was the cheapish Sievert 2281 torch was loosing power, although I had about half a bottle of gas left. I used Sievert 1925C powergas cartridge which is a mix of propane and butane. Not only does the torch loose power when pressure drops, apparently the hotter propane tends to burn first, leaving the more anemic butane (so I was told). I need a bigger torch or many more bottles which I can only use halfway ($$$). The torch can use more expensive, hotter Sievert 2100C ultragas which is a mix of propane, propene, and butane and acetone. Not sure if that would work better/longer. (my brazing stick was 45% silver with a melting point of 670C and flux ready layered on top of the stick)

 

[raindog]

It would also be possible to make the C-feet significantly longer towards the... uh... inner bow, or the area between the parallel bell and body tubes. Not sure if I can explain it clearly. Anyway this way they could act as a spring clamp of sorts, and snap in to place without any rubber wires or such. Very easy to attach and remove but that would make it even harder to bend the shapes just right, and not sure if it would be robust enough of a connection.

 

[turf3]

It's not clear to me how you're going to make this removable and not solder any fittings to the body.

I've done a lot of this kind of work and I've always used soft solder and haven't had any of them pop off in the last 40 years, so I think brazing is overkill.

 

[raindog]

It's not clear to me how you're going to make this removable and not solder any fittings to the body.

I've done a lot of this kind of work and I've always used soft solder and haven't had any of them pop off in the last 40 years, so I think brazing is overkill.

Each of the C-shaped support feet are supposed to get rubber bands installed that go around the sax body tube and hold the thing in place. I don't want to do any modifications to the instrument.

Silver soldering is a skill I need to learn anyway, for work stuff unrelated to saxophones. I do know saxophones have both silver soldered and regular soldered parts, and if I were to do modifications to the actual instrument itself, I would consider regular soldering first, and silver soldering only if necessary.

Not sure but I think maybe saxophone posts are typically silver soldered to the small support plate, then the plate is just low-temp soldered to the body. In this application, the contact surfaces are quite small, so I think silver soldering is warranted for the greater strength.

 

[turf3]

Each of the C-shaped support feet are supposed to get rubber bands installed that go around the sax body tube and hold the thing in place. I don't want to do any modifications to the instrument.

Silver soldering is a skill I need to learn anyway, for work stuff unrelated to saxophones. I do know saxophones have both silver soldered and regular soldered parts, and if I were to do modifications to the actual instrument itself, I would consider regular soldering first, and silver soldering only if necessary.

Not sure but I think maybe saxophone posts are typically silver soldered to the small support plate, then the plate is just low-temp soldered to the body. In this application, the contact surfaces are quite small, so I think silver soldering is warranted for the greater strength.

OK, I see what you're talking about.

I have done a lot of adding bars to key guards and I always design it so there's plenty of surface area (for example, cut the rod to half thickness and wrap it round the other rod). However, I do use silver soldering when I have really tiny contact surface, or like you're saying when I'm attaching a foot to a rod - because the soft soldered joint to the body would melt a soft soldered joint to the rod just a mm or so away.

Another thing to consider would be to flatten the end of a rod and make a "duck's foot" like old Selmers (Radio Improved) had.

I wouldn't use rubber bands, myself - they get brittle and sticky really fast. If you can find something made of neoprene or Buna you'll have better luck. Viton O-rings, maybe?

I can just barely get brazing to work with a MAPP torch. You really need oxyacetylene or oxypropane. The thing with brazing (as with almost any kind of soldering, brazing, welding) is that your best results will come if you can put a LOT of heat into the joint FAST, get the thing joined FAST, and get out. Using undersized heat sources is the best way to burn up everything attached due to heat transfer and get lousy joints because the thing is covered in oxide before you can get it up to heat. I wouldn't use any kind of flux covered rods, I've never had good luck with those. Get a bottle of Harris Stay-silv flux adn use it liberally.

 

[JayeLID]

Each of the C-shaped support feet are supposed to get rubber bands installed that go around the sax body tube and hold the thing in place. I don't want to do any modifications to the instrument.

Silver soldering is a skill I need to learn anyway, for work stuff unrelated to saxophones. I do know saxophones have both silver soldered and regular soldered parts, and if I were to do modifications to the actual instrument itself, I would consider regular soldering first, and silver soldering only if necessary.

Not sure but I think maybe saxophone posts are typically silver soldered to the small support plate, then the plate is just low-temp soldered to the body. In this application, the contact surfaces are quite small, so I think silver soldering is warranted for the greater strength.

Some techs would argue that using more conventional feet or escutcheons to connect the neds of your pantguard to the body, then simply soft soldering them on, would actually be a better solution than rubber bands or some sort of removable tension ring or the like, aesthetically speaking. If then a future owner cared not for your mod, it'd be a simple matter of removing a few soft solder points.
I understand your intent, I guess I just wonder if you are trading off something which after all your work, is still gonna look very DIY given rubber bands/rings, as opposed to quite finished if soldered to body.

You are correct, wire guards are soft soldered to body but the pieces of the guards themselves were hard soldered to each other (for obvious reasons, one would not want the entire guard to fall apart if they simply were trying to soft solder it to the body).

It's an interesting prototype. I would say the proportions of it could be improved (again for aesthetics) if you chose to produce another one. But an interesting experiment you have going there.

 

[raindog]

OK, I see what you're talking about.

I have done a lot of adding bars to key guards and I always design it so there's plenty of surface area (for example, cut the rod to half thickness and wrap it round the other rod). However, I do use silver soldering when I have really tiny contact surface, or like you're saying when I'm attaching a foot to a rod - because the soft soldered joint to the body would melt a soft soldered joint to the rod just a mm or so away.

Another thing to consider would be to flatten the end of a rod and make a "duck's foot" like old Selmers (Radio Improved) had.

I wouldn't use rubber bands, myself - they get brittle and sticky really fast. If you can find something made of neoprene or Buna you'll have better luck. Viton O-rings, maybe?

I can just barely get brazing to work with a MAPP torch. You really need oxyacetylene or oxypropane. The thing with brazing (as with almost any kind of soldering, brazing, welding) is that your best results will come if you can put a LOT of heat into the joint FAST, get the thing joined FAST, and get out. Using undersized heat sources is the best way to burn up everything attached due to heat transfer and get lousy joints because the thing is covered in oxide before you can get it up to heat. I wouldn't use any kind of flux covered rods, I've never had good luck with those. Get a bottle of Harris Stay-silv flux adn use it liberally.

Yeah. The duck foot is good idea, I'll try that if I decide to do another version of this with thinner brass rod, to match the original key guards material better.

The T joints where two rods go cross area bit tricky, considering surface area. Tried a small dremel sanding drum to make a shaped "slot" for one rod for the other rod to rest on, but that didn't work so well. I had better luck just sanding the contact areas of both rods flat. That wasn't too pretty either, but works for now.

Thanks for the tips regarding torches and fluxes, I will definitely research those further and consider changes on the setup.

 

[JayeLID]

Given the span of your guards I do not think your second version should 'match' the diameter of the existing key guards, which have much less of a span to ...span. It would be fairly delicate if they were that thin.

But just go for something a bit thinner than your first prototype.

 

[raindog]

Some techs would argue that using more conventional feet or escutcheons to connect the neds of your pantguard to the body, then simply soft soldering them on, would actually be a better solution than rubber bands or some sort of removable tension ring or the like, aesthetically speaking. If then a future owner cared not for your mod, it'd be a simple matter of removing a few soft solder points.
I understand your intent, I guess I just wonder if you are trading off something which after all your work, is still gonna look very DIY given rubber bands/rings, as opposed to quite finished if soldered to body.

You are correct, wire guards are soft soldered to body but the pieces of the guards themselves were hard soldered to each other (for obvious reasons, one would not want the entire guard to fall apart if they simply were trying to soft solder it to the body).

It's an interesting prototype. I would say the proportions of it could be improved (again for aesthetics) if you chose to produce another one. But an interesting experiment you have going there.

I agree with your worries about aesthetics, especially the rubber band part, lol. I try to get one working prototype done, work on my skills, and then see if inspiration and time permits, work on a more beautiful version maybe.

I think thinner brass rods and sheets would be the first step, should be easier to bend accurately too. I could have an experienced tech to solder it in place even. I want to learn to do minor work/repairs/maintenance on my saxes, but I think I'm gonna start those experiments with my Amati or buy some dumpster sax to learn on.

EDIT. If thinner rods would be used, I think it would definitely need a fifth support leg at the longest span, near thumb hook. Maybe more.

 

[raindog]

I can just barely get brazing to work with a MAPP torch. You really need oxyacetylene or oxypropane. The thing with brazing (as with almost any kind of soldering, brazing, welding) is that your best results will come if you can put a LOT of heat into the joint FAST, get the thing joined FAST, and get out. Using undersized heat sources is the best way to burn up everything attached due to heat transfer and get lousy joints because the thing is covered in oxide before you can get it up to heat. I wouldn't use any kind of flux covered rods, I've never had good luck with those. Get a bottle of Harris Stay-silv flux adn use it liberally.

Yeah, got a supposedly better gas for the small torch, but it didn't really make a difference. Then invested in a proper hose and pistol kind of torch for a 11kg propane bottle. Not cheap, but that seems to work much better. In fact, I did manage to almost melt the piece and may need to start over, lol. The sun was shining on the piece so I didn't see it getting red, and suddenly the brass rod was all limp... brass melting point is apparently about 900C, and the solder need 670C, so, need to hit between those and maybe rethink my clamping strategy as it may have played a part in the tragedy. Lessons learned haha.