I have been mostly working on a shelf this weekend. It is very needed because there is more than enough stuff just cluttering up the house and it is getting on my nerves.
But I also had worked on my little project involving the magnets that I have salvaged from defunct HDD a few months ago.
First I took a piece of 3 mm thick, 20 mm wide galvanized mild steel and I cut off a piece big enough so I could bend it into a U-shape in such a way that the magnets can sit inside with about 2 mm free space between the magnets and the bends. then I also cut two just 3 mm bits of the same stock. When put together as seen on the picture, you get a very strong magnet that only pulls in one direction (up). Plus the way the HDD magnets are magnetized means that this magnet now has four poles N-S-N-S. Also that the magnetic field is very strong, but has a very short reach. I tried to measure the force with which it holds a piece of steel and it was about 65 Newton, which is impressive for such a small thing cobbled together from scraps.
After this, I cut a few pieces of brass to fill the spaces as tightly as possible, and I drilled and cut an M5 thread in one arm of the U. Precision is essential here. Unfortunately, we do not get along very well and she is a mere nodding acquaintance, despite my best efforts, so everything was a bit wonky.
I have no pictures of that work because I still did not figure out exactly how my new phone works – I thought I took pictures, but apparently not.
When I had everything cut, I mixed a generous amount of quick drying epoxy and slathered it all around and glued everything together. And after the epoxy hardened enough I have ground off (manually) excessive material and I trued and polished slightly the magnetic surface.
So now I have this strong, one-directional magnet 50x20x10 mm. So far everything goes as planned, and I hope that the next step in this project will go similarly well.