A Little Mistake This Morning

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I guess it's human nature to only show off our successes: bright shiny perfectly fabricated parts we can be proud of. But we know it doesn't
work that way all the time. Today's sample is tube adapter made from two turned parts soldered together. (Yes, aluminum solder.) The
solder joint is great, but the parts got a little warmish in the process and started melting. I've used this stuff before, but it's tricky because
the temperature difference between a nicely soldered assembly and disaster is just a few hundred degrees, and unlike steel, the aluminum
does't change color with temperature. As I was headed for the garage, the thought crossed my mind that I should knock out a quick practice
part to get me back up to speed on technique, but of course I thought "I've got this covered since I've done it before". Sure saved a lot of
time with that thought...
 
Oops!
You are not alone. I even make mistakes in the process of recovering/re-making the first mistake :frown:
Re: Aluminum. Soldering is supposed to happen at a temperature lower than melting the whole shebang. Is that a special solder for aluminum?

Anyways, the way aluminum gives no feedback as to it's temperature, and if reasonably pure, will suddenly melt without warning, make jobs like that one of the more tricky. There may be some mileage in using one of those color crayons made for various temperatures, where you mark it, and see the point you heat up past the crayon temperature
 
There is a special solder for aluminum, I'm not sure what it is made of. I've seen it demonstrated at the local flea market so I don't know how well it really works or how strong it is. Kind of a "novelty" product I think
-Mark
 
Last edited:
markba633csi said:
There is a special solder for aluminum, I'm not sure what it is made of. I've seen it demonstrated at the local flea market so I don't know how well it really works or how strong it is. Kind of a "novelty" product I think
-Mark
Click to expand...
It's been all over FB marketplace here recently. Supposedly works well once you get the knack, but the knack is on backorder.
 
Use epoxy.

I have some rated for HVAC coil repairs.

30 bucks for a set and takes a few days to fully cure but it is aluminum color so bonus.

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
markba633csi said:
There is a special solder for aluminum, I'm not sure what it is made of. I've seen it demonstrated at the local flea market so I don't know how well it really works or how strong it is. Kind of a "novelty" product I think
-Mark
Click to expand...
The stuff I'm using is sold by Muggy Weld and they say it's as strong as the parent material. It's tricky to work with because the
soldering/brazing temp is between 600 and 700 degrees, but aluminum gets soft only a few hundred degrees above that. The
first time I used it I practiced a couple of times before finishing the final part. The only indication of temperature is the melting
point of the flux, which is a bit below the soldering temp.
 
In my experience you end up sitting on in too long but I used butane and didnt really enjoy the process. I'm sure people get good at it. They say Map gas will get it there quicker. I just love tig welding aluminum to much to really worry about it. Once you solder that stuff on you cant weld the area. Seems to make a pretty strong joint though.
 
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