soldering long span bridge

[2thm8kr]

I used to be in awe watching an old Cuban master tech solder like this that worked for me. Its a fine line between a perfect joint and a rolled margins. the laser welder made my life so much more predictable with out any bone dances.

This old school way in the hands of a skilled tech is awesome unfortunately the strength of the joint isn't anywhere near the strength of the parent alloy. This is another reason why a laser is far superior in every way.

If you bury the margins in the investment you get zero roll. The trick to this technique is setting up the investment for the solder job.
The only solder joint I have had break in 20+years (knock wood) was a Downs syndrome patient that was a hard-core clencher.

 

[rlhhds]

I have a phazer welder from Primotec. I tack a spot on the buccal and lingual to hold the sections together then solder the connector with my torch. This takes about 2 minutes literally. I have tried welding the whole connector but no matter how careful and slow I try it still rocks when finished It takes a long time to weld a connector even if it does work compared to the technique I described above.

 

[martintay]

I have a phazer welder from Primotec. I tack a spot on the buccal and lingual to hold the sections together then solder the connector with my torch. This takes about 2 minutes literally. I have tried welding the whole connector but no matter how careful and slow I try it still rocks when finished It takes a long time to weld a connector even if it does work compared to the technique I described above.

Sounds good, do you invest the bridge after tacking or will the tack be enough to not need support ? If so not as much heat needed i guess !

 

[rlhhds]

Sounds good, do you invest the bridge after tacking or will the tack be enough to not need support ? If so not as much heat needed i guess !

The reason to tack weld is so you don't have to invest that is why I say it takes about 2 minutes for the whole process. I have never had a bridge not fit after using this technique. The first time I tried this I was leery of it working but it works like a champ.

 

[2thm8kr]

I have a phazer welder from Primotec. I tack a spot on the buccal and lingual to hold the sections together then solder the connector with my torch. This takes about 2 minutes literally. I have tried welding the whole connector but no matter how careful and slow I try it still rocks when finished It takes a long time to weld a connector even if it does work compared to the technique I described above.

Have you ever cut a welded joint to see how far the weld penetrated? Just curious.

 

[martintay]

The reason to tack weld is so you don't have to invest that is why I say it takes about 2 minutes for the whole process. I have never had a bridge not fit after using this technique. The first time I tried this I was leery of it working but it works like a champ.

Really great time saving idea ! Thanks Martin

 

[rlhhds]

Have you ever cut a welded joint to see how far the weld penetrated? Just curious.

The few I tried to weld, yes because they did not fit. The welds do not penetrate very deep. Did not measure so I can't tell you how deep. You get the solder to completely flow through the connector using the tacking technique just like any other soldered joint.

 

[martintay]

So just to be safe lol, you tack bridge joint- then just sit it on soldering block or stand and then solder with a flame ! Sounds to good to be true ! And i bet its superior to a lazer weld ! Thanks

 

[2thm8kr]

The few I tried to weld, yes because they did not fit. The welds do not penetrate very deep. Did not measure so I can't tell you how deep. You get the solder to completely flow through the connector using the tacking technique just like any other soldered joint.

That's why I would rather solder, the whole joint surface area is soldered
rather than tack welds all the way around the perimeter. Just has to be stronger.

 

[martintay]

I think this may be the tip of the decade ! I presume you could also tack with a lazer and then solder ? Got to give this a go !

 

[rlhhds]

I do just 2 tack welds one on the buccal one on the lingual. Enough to stabilize the bridge but leaving the connector open to accept the solder. You will get full penetration of the connector with solder. All in a couple minutes been doing this for many years.

 

[rlhhds]

I think this may be the tip of the decade ! I presume you could also tack with a lazer and then solder ? Got to give this a go !

Yes you can. How long does it take you now to fully weld a connector with the laser?

 

[martintay]

Yes you can. How long does it take you now to fully weld a connector with the laser?

I haven`t got a lazer , but have friends who have, and they say good welding is not easy ! Can this technique also be used easily on Ni/Cr ? Thanks

 

[rlhhds]

I haven`t got a lazer , but have friends who have, and they say good welding is not easy ! Can this technique also be used easily on Ni/Cr ? Thanks

I would imagine so but the only Cr I do is a clasp repair on partials I don't do NP bridges.

 

[martintay]

Really appreciated. Lots of Cr here ! Thanks again for your time. Martin

 

[cumino]

Yes, have been using the same technique myself...works really well.

 

[JohnWilson]

Sorry John physics proves you wrong! a correctly soldered joint is as strong as the original!

Just saw this reply and I am always willing to listen to all contradictory reply, so Lucy splain it to me

 

[2thm8kr]

Just saw this reply and I am always willing to listen to all contradictory reply, so Lucy splain it to me

Technically we are brazing not soldering. A brazed joint is stronger than the filler metal alone,
but not stronger than the parent metal. Since I'm no physicist I'll leave it at that.

 

[JohnWilson]

Technically we are brazing not soldering. A brazed joint is stronger than the filler metal alone,
but not stronger than the parent metal. Since I'm no physicist I'll leave it at that.

So like I said its weaker than laser welding and only as strong as the solder that you are using correct?

Where as when you laser-weld the joint it is as strong as the metal that was cast,milled, or printed.

 

[2thm8kr]

So like I said its weaker than laser welding and only as strong as the solder that you are using correct?

Where as when you laser-weld the joint it is as strong as the metal that was cast,milled, or printed.

A brazed joint is stronger than the filler metal, but not as strong as the parent metal.
This info can be readily found on a welding/brazing info site on the intraweb thingy.

Like I said, I'm no physicist but laser welding does not weld the whole joint like tig welding.
Yes you are welding with the same alloy as the framework is made from, but the penetration
is only 'x' deep where as capillary action pulls the filler alloy into the brazed joint filling it completely
giving it a larger surface area to bond to.
It would be interesting to see how two identical frames one laser welded and one brazed/soldered
would compare on an Ingstrom tester.