Interesting brazing & magnets!
02-12-22, 07:34 AM
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Interesting brazing & magnets!
Yesterday I was working on the rear rack for my wife's bike. I was using a few rare earth magnets to hold some tubing while I talked the joint. One fell off as soon as I finished and afterwards I found that they had lost their magnetic force.
Thoughts?
Thoughts?
02-12-22, 07:43 AM
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Yes, I discovered that heat kills magnets exactly the same way. Gets those electrons spinning around like crazy
https://van.physics.illinois.edu/QA/listing.php?id=2744
https://van.physics.illinois.edu/QA/listing.php?id=2744
02-12-22, 08:25 AM
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You found "critical temperature"! The heat energy allows the once aligned electrons to run free and un-aligned.
I use this to heat treat blades as a temperature measurement; heat to critical (usually orange-red) and a magnet no longer sticks to the blade steel, and you know it's time for an exciting dunk into coolant.
I use this to heat treat blades as a temperature measurement; heat to critical (usually orange-red) and a magnet no longer sticks to the blade steel, and you know it's time for an exciting dunk into coolant.
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02-12-22, 09:22 AM
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It's really hard to hit that temperature a motor when you are trying to make one fail.
I have some Strong Hand grasshopper welding fingers that are nice, but sticking them to the same tube as you're working on is probably a bad idea.
I have some Strong Hand grasshopper welding fingers that are nice, but sticking them to the same tube as you're working on is probably a bad idea.
Last edited by unterhausen; 02-12-22 at 09:39 AM.
02-12-22, 10:46 AM
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Alnico
Alnico magnets are what you need. My magnets are six or seven years old and going strong. You have to limit the heat into the magnet, I have only used them with silver (45-56%) rod.
02-13-22, 06:39 PM
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02-14-22, 08:00 AM
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It's been known by smiths for centuries. Really highlights the difference between the public exchange in science and private proprietary technology (Old guilds held the heat treat IP closely).
