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Attaching platinum to gold: solder v. weld

Hey everyone!
I’ve got a minor argument to settle over here, and was hoping to get some input from y’all.

In the process of replacing a 14kt head in a 14kt yellow gold ring with a hand fabricated platinum head, the discussion came up as to the best way to attach it.
I’ve always been of the mind to use the highest temp gold solder possible, ensuring a clean and solid bond. My coworker believes that the only way to do it right is to use the laser welder, as “the solder joint won’t be strong and will break”.
Now I fancy myself as a pretty decent torch operator, and feel that a well soldered joint is just as strong as what we can achieve with a welder.
I’ve searched through the forums a bit, and can’t find anything definitive one way or the other.

I appreciate any and all input!

Thanks!
Scott

I have @25+ years experience riding the laser, and 35 riding the bench. The laser is an amazing tool, but then so is the torch.
Together they give me far more range than either one would, alone.
When installing a new head, after fitting it well, I will lightly weld it in place with the laser, more of a light tac weld.
This allows me to make any minor adjustments, before continuing.
For the final assembly, I always use the torch to pull the solder completely through the joint.
In my experience the solder does a far better job of fully securing the setting to the shank than the laser.
I will often then go back and use the laser to fill any voids and, or “flash” recessed areas that are hard to polish.
It is not unusual for me to use both tools on a variety of jobs, as each has its advantages and uses, and each has its areas where it is simply not as good as the other option at hand.

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In my opinion, this is the right answer. We spend a lot of time pitting tools against each other instead of using them in symphony with one another. I also feel that the laser isn’t going to give a secure enough weld and you’ll have voids in the joint that solder would easily fill.

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There are plenty of applications where the laser gives me a perfect weld, but not when attaching settings.
For this I want to see that flash of molten solder pull through the joint so I can trust that there are no voids.
Having said that, if im working in all Platinum i use the laser exclusively.

Are saying in easier language, using Laser soldering to Platinum to 22 karat gold, is easy or more delicate? I need to know this in the near future.

Gerry, on my iPhone

The Laser does not “solder”, it welds by melting or fusing metal on both sides of a joint.
You can melt silver, platinum, gold or stainless steel wire (etc), to fill the gap, but you are not flowing a solder
With solder you are melting an alloy with a lower melting temperature than the flows through the very very thin joint.

I use a pulse arc welder rather than a laser but I believe that the nature of the weld is close enough. What I think is important is the mechanical difference between a brazed (solder) joint and a weld, which is fused or melted together (sometimes with a filler material, usually the same as the “parent” materials)

A welded joint—depending on the metals involved, can be in my experience, a more brittle union. It has to do in part with the recrystallization of the molten metal. While a brazed (soldered) joint does rely on molten material it is the solder that it is flowing, the parent metal remains solid. I’m not sure about the recrystallization (grain growth) in the parent metals in soldering/brazing…

The fairly broad surface area of a head/ring joint makes it ideal for soldering in most cases. As has been mentioned, the solder is pulled through and permeates the seam. In a way, it’s like a sweat soldered joint and is strong because of the broad surface area of the joint.

A good weld lies, in part, with the depth of penetration of the molten material. It only goes so deep and may not penetrate through the depth of the seam.

Additionally when you weld there is often a depression left. Either the molten metal shrinks as it cools or some is vaporized in the welding. In any case, those joints sometimes need to be filled. This means more cleanup as well as a loss of demarcation between two different colors of metal—white to yellow, for instance. Because the weld melts the two metals together a new alloy is made at that joint. This can sometimes be beautiful but if you want a crisp line between the two colors you have a problem…

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Yes, I have also tried the pulse arc welder, and the results are very similar in almost every case.
If I am bonding 2 different metals I definitely prefer to lightly tack weld the joint with the laser, a joint prepared for a tight solder joint, and then flow solder fully through that joint with the torch so that i can both see that the bond is complete, and I have not visibly fudged the 2 different metals together.
I may use the laser to lightly flash polish, or fill a pit in the surface when my soldering is done ( not something the pulse arc can do, i believe).