Push Pin Magnets

I’ve got a number of small cylinder magnets around the work area for holding different pieces of paper or what have you. Decided a wanted an easy way to pick up some of these. Designed some small holders for some 3x8mm Nd magnets. Printed in PLA.

I designed them to have the magnets to be press fit tight. Which worked great when I printed one, but when I went to print 12 at a time the magnets no longer fit. :grimacing: Probably due to some shrinkage as each one cooled between layers? :man_shrugging:

This was better for the round upper part but not so much for my magnet fit. I used a micro torch to slightly heat the cavities and pressed the magnets in. Had to use some CA glue on some, but they work great


Note that for metal inserts that aren’t magnets, you can heat the metal just enough to melt the plastic around it barely enough to insert. But for magnets you don’t want to do that because you can permanently demagnetize them by heating them up too much. (Curie temperature - Wikipedia)

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But isn’t the Curie temperature like RED hot (590–752F)?
That would require a MAP torch or better?

I use this technique to determine temps when blacksmithing my cutting tools.

It’s not red hot for neodymium magnets. You have to buy high-temperature variants even to make them safe to 130°C for use for heated magnetic 3D print beds. Apparently that’s operating temperature, and their Curie point (permanently completely demagnetized) is around 300-400°C, but they are permanently partially demagnetized above their working temperature.

Here’s a random reference:

On the other end of the spectrum, some AlNiCo magnets have a Curie temperature of 900°C — which blows my mind.