Jem
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Post by Jem on Jan 22, 2021 12:22:33 GMT
I have an enamelled coffee pot (see pic below) with a very weak spot on the point I have circled. Without doubt it will break before too long as it's been bent a few times and is flimsy now the enamel has cracked off. I could cut a piece of soft steel and rivet it , but would much prefer to do a neater job with a braze. It's not a case of 'is it worth doing?' , as I could probably buy a replacement for very little. It's a case of "is it possible, how do I do it, and is it economical by the time i have bought any gear I need? " But any gear I buy might be useful for other little jobs. Thanks in advance for any thoughts  image by
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Post by brianbutler on Jan 22, 2021 14:09:56 GMT
That looks superficially similar to the frame crack I worked on. From the photo, I would guess your main problems will be eliminating the rust in the crack and heating the enameled surface without cracking it. Clean the crack on both sides with a wire brush and maybe some acidic rust remover.
For my purposes, I found the best brazing material to be silver solder. According to the specs, it is stronger than brass material. It is more expensive. I think that is why its use is limited in bike production.
The gear you will need is (are) a torch, gas, solder, flux, and "acid": brushes. You won't need clamps because the piece is still attached.
These torches are vastly better than the standard plumbing torches we are all used to.
I used propane gas, which works fine, but recently bought a canister of MAPP gas because I saw it at the home improvement stiore. It supposedly produces a hotter flame.
Brush some flux along and into the crack on both sides, then braze one side at a time. Evenly heat the area to a bright orange, almost yellow heat and touch the end of the soldering wire to the crack. Ideally it will immediately flow into the crack and stay there by surface tension. Turn the piece over and do the same on the other side. If you have globs of solder, you can douse them with water while hot and they might come off easily. Otherwise file them down or live with them as a testament to your early days as a soldering guru.
I do not claim to be a brazing expert and my work so far has been fairly sloppy. It seems the required skill/knowledge ratio is heavily weighted toward skill (i.e. practice). I was able to repair my frame crack and it seems solid. I plan to go back and neaten it up a bit. I also brazed on some top-tube cable guides and plan to put in some bottle cage bosses. If you plan to join separate pieces, look into special welding/soldering clamps and or a "third hand."
The process is fun and rewarding even when it turns out a mess. Good luck.
Brian
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Post by oldroadietehachapi on Jan 22, 2021 14:57:10 GMT
I think a bit of raw brazing would add wonderful character to the little coffee pot. Rivets would add a cool "steam punk" look. Nevertheless, for a simple fix, JB Weld might be the way to go. The stuff is amazingly strong (when used correctly) and can be painted. Either way, all the rust and paint must be removed.
Be Happy
Jim
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Post by wheelson on Jan 22, 2021 15:11:32 GMT
I have nothing to add to Brian and Jim's excellent methods and suggestions having successfully used all of them over the years.
My only caution is that something about the whole process is strangely addictive, and the next thing you know you'll want to be doing major frame repairs and even building frames. Ask me how I know!!
Best,
John "wheelson"
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Post by brianbutler on Jan 22, 2021 16:03:42 GMT
I have nothing to add to Brian and Jim's excellent methods and suggestions having successfully used all of them over the years. My only caution is that something about the whole process is strangely addictive, and the next thing you know you'll want to be doing major frame repairs and even building frames. Ask me how I know!! Best, John "wheelson" Ditto, I'm thinking oxy-acetylene but so far resisting. Brian
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Jem
Viscount
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Posts: 3,391
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Post by Jem on Jan 22, 2021 16:11:42 GMT
That looks superficially similar to the frame crack I worked on. From the photo, I would guess your main problems will be eliminating the rust in the crack and heating the enameled surface without cracking it. Clean the crack on both sides with a wire brush and maybe some acidic rust remover.
For my purposes, I found the best brazing material to be silver solder. According to the specs, it is stronger than brass material. It is more expensive. I think that is why its use is limited in bike production.
The gear you will need is (are) a torch, gas, solder, flux, and "acid": brushes. You won't need clamps because the piece is still attached.
These torches are vastly better than the standard plumbing torches we are all used to.
I used propane gas, which works fine, but recently bought a canister of MAPP gas because I saw it at the home improvement stiore. It supposedly produces a hotter flame.
Brush some flux along and into the crack on both sides, then braze one side at a time. Evenly heat the area to a bright orange, almost yellow heat and touch the end of the soldering wire to the crack. Ideally it will immediately flow into the crack and stay there by surface tension. Turn the piece over and do the same on the other side. If you have globs of solder, you can douse them with water while hot and they might come off easily. Otherwise file them down or live with them as a testament to your early days as a soldering guru.
I do not claim to be a brazing expert and my work so far has been fairly sloppy. It seems the required skill/knowledge ratio is heavily weighted toward skill (i.e. practice). I was able to repair my frame crack and it seems solid. I plan to go back and neaten it up a bit. I also brazed on some top-tube cable guides and plan to put in some bottle cage bosses. If you plan to join separate pieces, look into special welding/soldering clamps and or a "third hand."
The process is fun and rewarding even when it turns out a mess. Good luck.
Brian
I really appreciate your comprehensive post Brian - that is going to point me in the right direction straight away, without the need for huge amounts of searching the internet for methods and recommended bits to buy. I think starting on £10 coffee pot is going to help my confidence, and what is the worst that could happen?! I've got some time on my hands at the moment too, so a new skill to get practised in. Once again thank you for taking the time Jem |
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Jem
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Post by Jem on Jan 22, 2021 16:19:22 GMT
I think a bit of raw brazing would add wonderful character to the little coffee pot. Rivets would add a cool "steam punk" look. Nevertheless, for a simple fix, JB Weld might be the way to go. The stuff is amazingly strong (when used correctly) and can be painted. Either way, all the rust and paint must be removed. Be Happy Jim Cheers Jim, I have a little Dremmel hand held multi tool with attachments to get it back to the metal. I had to Google JB Weld, not heard of that before. I have something called Sugru, I use it quite a lot for fixing household items and making little mods to things (put hook on the back of my TV for my headphones on sit on the other day) It's is useful for various materials , but not as heavy duty as the JB weld, and can be snapped off if you need to remove it.It could possibly do this job, it's mouldable and heat resistant - but I think while I have some time and the inclination to learn a new technique , then I will. I've supported Sugru since their start up and they were a tiny one woman company (I think she's from Ireland?) sugru.com/what-is-sugruHandy stuff. |
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Jem
Viscount
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Posts: 3,391
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Post by Jem on Jan 22, 2021 16:20:04 GMT
I have nothing to add to Brian and Jim's excellent methods and suggestions having successfully used all of them over the years. My only caution is that something about the whole process is strangely addictive, and the next thing you know you'll want to be doing major frame repairs and even building frames. Ask me how I know!! Best, John "wheelson" Thanks John - It would open up a world of possibilities wouldn't it? |
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Post by wheelson on Jan 22, 2021 16:43:14 GMT
I have nothing to add to Brian and Jim's excellent methods and suggestions having successfully used all of them over the years. My only caution is that something about the whole process is strangely addictive, and the next thing you know you'll want to be doing major frame repairs and even building frames. Ask me how I know!! Best, John "wheelson" Thanks John - It would open up a world of possibilities wouldn't it? Jem, All those “value added” skills really contribute to the whole life experience. For me, my lifelong interest in bikes has enabled my post-engineering career. I’m still learning the new stuff but the old skills, especially wheel building, are in high demand, even in the off season. Best, John “wheelson” |
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Post by brianbutler on Jan 22, 2021 18:24:37 GMT
I will also mention UV eye protection. I bought some inexpensive "level 3" (whatever that is) glasses. I don't think propane or MAPP gas is hot enough to emit dangerous UV frequencies but not sure. I already have enough eye problems so decided to play it safe.
Brian
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Post by oldroadietehachapi on Jan 22, 2021 19:13:42 GMT
I have been a fan of JB Weld for many years; since I was auto "mechanicing" my way through college. As a demonstration, they used to bond two engine valves together and invite you to break the bond; we could not. We stuck one valve in a vice and beat the other with a hammer. Eventually we broke the valve stem; the bond was unscathed. If you overlapped and bonded angle stock, the metal would always bend and the bond held. We were able to break the bond when angle stock was bonded in a butt joint. We still had to put it in a vice and beat it with a hammer. Cheers Jim |
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Jem
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Posts: 3,391
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Post by Jem on Jan 22, 2021 19:19:23 GMT
I will also mention UV eye protection. I bought some inexpensive "level 3" (whatever that is) glasses. I don't think propane or MAPP gas is hot enough to emit dangerous UV frequencies but not sure. I already have enough eye problems so decided to play it safe. Brian Thanks for tip Brian- I hadn't thought about that kind of thing |
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Jem
Viscount
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Posts: 3,391
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Post by Jem on Jan 22, 2021 19:22:26 GMT
I have been a fan of JB Weld for many years; since I was auto "mechanicing" my way through college. As a demonstration, they used to bond two engine valves together and invite you to break the bond; we could not. We stuck one valve in a vice and beat the other with a hammer. Eventually we broke the valve stem; the bond was unscathed. If you overlapped and bonded angle stock, the metal would always bend and the bond held. We were able to break the bond when angle stock was bonded in a butt joint. We still had to put it in a vice and beat it with a hammer. Cheers Jim That sounds like something to have in the tool box for working on older cars/vans. I'm going to get some in. Not expensive either! |
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Post by brianbutler on Jan 22, 2021 20:41:15 GMT
I have been a fan of JB Weld for many years; since I was auto "mechanicing" my way through college. As a demonstration, they used to bond two engine valves together and invite you to break the bond; we could not. We stuck one valve in a vice and beat the other with a hammer. Eventually we broke the valve stem; the bond was unscathed. If you overlapped and bonded angle stock, the metal would always bend and the bond held. We were able to break the bond when angle stock was bonded in a butt joint. We still had to put it in a vice and beat it with a hammer. Cheers Jim That sounds like something to have in the tool box for working on older cars/vans. I'm going to get some in. Not expensive either! I will try it, too. |
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Post by dracco on Jan 24, 2021 20:27:35 GMT
+1 for UV eye protection. It was my aunt (!) who told me about the dangers of looking at welders in action without suitable eye protection. (She learnt to do it when she was in the WAAFs in WW2)
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