Brazing v silver soldering v TIG?



Chrisbee

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Jul 24, 2004
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Hi

New member first post. Do we have any frame builders on board? :)

I'm building an upright trike and have ready access to (oxy-acetylene) brazing, silver solder and TIG.

I'd value (knowledgable opinions) on relative strength of these different joining methods. I'll be using a filleted, lugless construction with recycled old bike frame parts. No 'fancy' steels or light guages involved.

I'm getting conflicting advice from the expert welders as to which to use.
I can braze & silver solder myself. But would need to get a colleague to do the TIG welding to be sure of a nice, neat, safe joint. Which would rather spoil the fun of making the trike myself.

Thanks
Chrisbee
 

boudreaux

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Oct 16, 2003
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Chrisbee said:
Hi

New member first post. Do we have any frame builders on board? :)

I'm building an upright trike and have ready access to (oxy-acetylene) brazing, silver solder and TIG.

I'd value (knowledgable opinions) on relative strength of these different joining methods. I'll be using a filleted, lugless construction with recycled old bike frame parts. No 'fancy' steels or light guages involved.

I'm getting conflicting advice from the expert welders as to which to use.
I can braze & silver solder myself. But would need to get a colleague to do the TIG welding to be sure of a nice, neat, safe joint. Which would rather spoil the fun of making the trike myself.

Thanks
Chrisbee
No difference if done right. Brass and silver brazing is done with lugs,and fillet brzing is usually done with silver and requires the most sikll.But I don't think you have a clue. Frame building isn't sweating some copper plumbing together.
 

Chrisbee

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Jul 24, 2004
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boudreaux said:
No difference if done right. Brass and silver brazing is done with lugs,and fillet brzing is usually done with silver and requires the most sikll.But I don't think you have a clue. Frame building isn't sweating some copper plumbing together.
Why do you say I haven't a clue? :)

I was building my own long wheelbase recumbants well over 20 years ago. Fillet brazing (with brazing rods not silver) using a turbo propane torch and using sawn up old bike frames for materials. It was rather slow compared with oxy-acetylene but quite acceptable with patience.

I have rather longer experience with silver solder but haven't tried my skills on frame building with it.

Talking of plumbing I have plumbed (and drained) my last two houses from scratch. :D

I was actually hoping for a more technical response with some actual idea of relative strengths. :cool:

But many thanks for your reply. ;)

Chrisbee
 

wildearth2001

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Nov 19, 2003
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What concerns me is that you are using "recycled old bike frame parts" which can be dangerous. I am not a frame builder but am a welder with 2 years of professional instruction. It is always advisable to purcase your metal new so that you know what you are dealing with. You need to know what type of metal you are working with (low carbon vs high carbon steel etc). Used bike frames may have been tempered which requires special welding/braze/soldering techniques, and at the very least knowledge of this condition. It is always best to use new metal that is labled to its metalurgical contents when injury can occur if a faliure were to occur. Personally I would arc weld it in some way (SMAW, GTAW or GMAW) but braze, braze welding or soldering work just as well if done properly with the proper filler material and flux.
 

Chrisbee

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Jul 24, 2004
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wildearth2001 said:
What concerns me is that you are using "recycled old bike frame parts" which can be dangerous. I am not a frame builder but am a welder with 2 years of professional instruction. It is always advisable to purcase your metal new so that you know what you are dealing with.
Thanks for your concern. It is true that a degree of interal rusting seems to be the norm rather than the exception with bike frames. Even with fairly modern bikes! Safety is of course absolutely paramount. I was simply following the practice of many home bike builders. Many recycled bikes & trikes are shown online these days.

Ironically we use literally kilometres of steel in a huge range of sizes each year where I work. But not one inch (or centimetre) of light guage tube.(i.e. 1.5mm wall thickness or less)
Naturally old bikes offer exactly what is needed in raw materials. Which makes for almost free building materials (including all the wheels & accessories completely gratis) I doubt I could buy a single tube from a frame builder for what 10 oldish bikes cost me. (£2-5 each) (I am of course using the correct rods, wires and fluxes)

I shall give this matter very serious consideration and will price some new metal. Even if I do have to buy it in minimum 6 metre lengths. :p

Thanks again
Chrisbee
 

hughes

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Jun 2, 2004
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boudreaux said:
No difference if done right. Brass and silver brazing is done with lugs,and fillet brzing is usually done with silver and requires the most sikll.But I don't think you have a clue. Frame building isn't sweating some copper plumbing together.
Silver is not used for fillets. It flows too thin.
 

pudster

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Aug 20, 2003
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Fillet brazing is done with either brass which works great and with nickel silver. Nickel silver alloy is the only type on brazing material with silver in it that can be fillet brazed for bicycles but for larger fillets it should be brass. As far as the steel that you are using it is fine to use old material as long as the steel you are using has not been welded before. I think that you will find brazing lighter gauge steel to be easier that heavy gauge material. I use a #3, #5 and a #7 tip for bigger joints. It sounds like you have expierance so go for it.
 

boudreaux

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Oct 16, 2003
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pudster said:
Fillet brazing is done with either brass which works great and with nickel silver. Nickel silver alloy is the only type on brazing material with silver in it that can be fillet brazed for bicycles but for larger fillets it should be brass. As far as the steel that you are using it is fine to use old material as long as the steel you are using has not been welded before. I think that you will find brazing lighter gauge steel to be easier that heavy gauge material. I use a #3, #5 and a #7 tip for bigger joints. It sounds like you have expierance so go for it.
Sure the silver is an alloy.Anyone imply it wasn't. Brass and nickel brazing midums are also aloys.
 

Chrisbee

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Jul 24, 2004
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boudreaux said:
Yeah, some of the 'experts' here could make better use of it.I'm too much a slacker to do their homework for them. Let em remain fools.
Are always this abrasive? :D

Chrisbee
 

Chrisbee

New Member
Jul 24, 2004
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pudster said:
Fillet brazing is done with either brass which works great and with nickel silver. Nickel silver alloy is the only type on brazing material with silver in it that can be fillet brazed for bicycles but for larger fillets it should be brass. As far as the steel that you are using it is fine to use old material as long as the steel you are using has not been welded before. I think that you will find brazing lighter gauge steel to be easier that heavy gauge material. I use a #3, #5 and a #7 tip for bigger joints. It sounds like you have expierance so go for it.
Thanks. Just the sort of information I wanted to hear. All my tube donors are brass brazed lugged roadsters. Raleigh, BSA etc. Roughly 1.5mm wall.

The only problem with a few trial joints is that (it seems) the pressure of the gas flame seems to spread the brass too wide. I play the flame over the fillet to smooth it out and ensure a good wetting and it then starts to run rather too freely.

Any tips on managing a smaller fillet please? The welding foreman looked at my work, grinned and walked away. I haven't worked out whether that was good or bad. (I haven't touched a torch in 15 years) I'm using the smallest flame I can manage with the fitted tip. I'll check which tip is fitted. :)

Thanks
Chrisbee
 

boudreaux

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Oct 16, 2003
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Chrisbee said:
The welding foreman looked at my work, grinned and walked away. I haven't worked out whether that was good or bad. (I haven't touched a torch in 15 years) ....................
Suppose he was being charitable?(AKA, non abrasive)
 

Chrisbee

New Member
Jul 24, 2004
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boudreaux said:
Suppose he was being charitable?(AKA, non abrasive)
It seems I'm using a bit too much heat and rather too much flux. Using fluxed rods with powdered flux is overkill in my hands. I'll fit a No3 tip next time and see how I get on with that. I'll try and use the rods without extra flux.

He doesn't need to be charitable. My joints were okay. They would just need a bit of tidying with a file and abrazive paper (if they were the real thing)
I must make a proper jig though. Working freehand is not conducive to accuracy. No matter how nicely my mitres fit the adjoining tube.

Onwards and upwards.
Chrisbee
 

pudster

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Aug 20, 2003
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Use the heat of the torch to build up the brass in certain areas, don't be making the whole area of the fillet hot. The brass will flow to the hottest part of the joint so use the heat at specific areas to add brass to the fillet. Something else that can help is when you cope the joint do not leave a feather on the end of the cope, grind it a little on the end of the cope to make the wall thickness at the edge of the cope the same as the wall of the tube. Hope that makes sense.
 

Chrisbee

New Member
Jul 24, 2004
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pudster said:
Use the heat of the torch to build up the brass in certain areas, don't be making the whole area of the fillet hot. The brass will flow to the hottest part of the joint so use the heat at specific areas to add brass to the fillet. Something else that can help is when you cope the joint do not leave a feather on the end of the cope, grind it a little on the end of the cope to make the wall thickness at the edge of the cope the same as the wall of the tube. Hope that makes sense.
Thanks for those valuable insights. I do tend to use far too much heat to flatten everything out and make it look "prettier". I'll cut down on the heat and work more locally. In my defence: I always have this fear of lumpy joints that haven't wetted the metal properly. I have seen so many bad examples of welding over the years. (though not usually on bikes)

By "cope" I presume you are talking about the extreme end of the tube where I have formed the mitre? It does tend to go feather-edged at the tangents to the matching tube. I'll try your advice and file them off a bit.

As in all things an ounce of practical experience is worth a pound of theory. :)
So I had better practice a lot more.

Thanks again
Chrisbee