Intro: Custom Wood & Aluminum Magnets From a Hard Drive
As a hobbyist woodworker, I thought it would be fun to experiment with some of the higher-end hardwoods. Watch the video (and read this Instructable) to see how I made some fancy hardwood & aluminum magnets, using scrap hardwood, and magnets salvaged from a computer hard drive.
Step 1: Gathering Hard Drive Magnets and Aluminum
If you work around technology, or know somebody who does, chances are you'll have a few old hard drives lying around which contain some pretty strong rare earth magnets. These old hard drives can be easily disassembled with a screwdriver (usually phillips and torx screws). Inside you'll find two flat magnets glued to metal backer pieces. This metal bends fairly easy, so if you clamp them in a vise and bend the metal back, the magnets will pop right off easily.
On the hard drive's spindle, after removing the top piece, you may also find a small aluminum ring. My hard drive only had one platter, so this ring was relatively thick (about 1/4"), so it would work well for the outer rim of one of my magnets. However, to fit the magnet inside this small circle, I scored and broke the magnet in half. Note, handling these magnets with metal tools (knives/pliers/etc) is difficult since they'll want to stick. Hold everything steady and be mindful of what you're doing. Also, I've read that rare earth magnets can be be damaged by heat, and the dust can be harmful, so it's not advisable to cut them with a blade or cutting wheel.
Our other hard drive magnet will be used in a bigger assembly. I picked up a scrap of 2" aluminum square tubing from a local metal supplier, and sliced off a piece on my miter saw for the rim of our larger magnet.
Step 2: Making the Wood Blank(s)
I happened to come across a bunch of hardwood scraps for sale on craigslist. They came from somebody who makes picture frames, and these were various cutoffs. I cut down some strips and glued them up in different patterns for this project. One blank was a combination of walnut, padouk, and maple. The other (for the larger magnet, not pictured on this step) was walnut with a maple stripe through it.
They were glued up with wood glue and clamped, and let dry overnight. These blanks were then run through the table saw. The first cut was made while clamped up in a jig to get one straight side. The next cut was made up against the table saw fence. The end result was a nice looking smooth wood blank, a little bit thicker than the aluminum we'd be putting it into.
Step 3: Prepping the Aluminum Rims
Later we'll be gluing the wood and magnet inside of these aluminum rims with epoxy. Epoxy typically bonds well to metal, but I added some grooves on the inside to give the epoxy more surfaces to flow into and grab hold of. These were made with a metal cutting disc on a rotary tool. The aluminum chewed up the cutting disc fairly quickly, so there's probably a better way to do this, but it's what I had on-hand. This should provide a better mechanical connection between the wood, epoxy, and metal later on.
Step 4: Cutting Wood Shapes & Pockets
Our wood blanks will need to be cut & sanded down to fit the inside shapes of our aluminum rims.
For the small circle (three-color) wood blank, I cut a small channel using the bandsaw and chisel, to give the magnet a place to fit. I then cut the circle oversized on the bandsaw, and sanded it down until it fit inside the aluminum ring.
The square piece was easier to cut, using only the table saw to cut it to the appropriate sized square to fit inside the slice of square tubing. To cut the magnet pocket, I used a router to mill out a pocket roughly the same size, shape, and depth of the large magnet.
Step 5: Slicing Off a Cover Piece
With both wood blanks, we have a thick piece of wood with a pocket on one side. For the final magnet, this pocket needs to be covered up with more wood. To get this "cover piece," simply cut a slice off the back.
Since this is such a thin slice, I used the fence on my bandsaw to make sure I cut a consistent thickness. To keep my fingers safer, I made a small push-block with a notch in one corner to move these small pieces through the saw.
Step 6: Bringing It All Together With Epoxy
Everything gets glued together at this point. I'm just using a basic fast-curing two-part epoxy. Mix it up according to the manufacturer's instructions. The basic process is as follows:
- apply epoxy to the inside edges of the aluminum rim, to make sure it gets into the grooves cut earlier
- insert the "pocketed" piece of wood, with the pocket on the inside
- add epoxy to the pocket and submerge the magnet in the epoxy
- add the cover piece of wood, adhering it with the epoxy.
- push the wood/magnet assembly through a little bit to make sure you have wood sticking out from both sides of the rim
Step 7: Smoothing Everything Over
Once the epoxy has cured (at least overnight is best), you can begin to remove the ugly exterior to reveal the beautiful hardwood underneath.
To remove the bulk of the excess wood, I first ran it through the bandsaw, running the blade along the aluminum as a guide. Hold your workpiece in a clamp, not with your fingers like I did.
Next step is rough sanding. I ran each piece over the power sander to get it relatively smooth on all sides. There were still some scratch marks from this stage, but those will get cleaned up next.
For the fine sanding, I laid down 500 grit (and later 1200 grit) sandpaper on my work table, and sanded each piece smooth, and wiped off the excess dust with a cloth.
Step 8: Oooh SHINY!
To protect the wood and make these magnets really stand out, I added a layer of two-part resin on both sides.
In my case, I used Envirotex Lite, which is designed for making durable glossy table & bar tops, but there are a variety of two parts resins available on the market. Whatever resin you use, read over and follow the instructions carefully. It took me some practice to get mine to turn out nice and bubble-free. They also usually take multiple days to fully cure. Be patient and don't rush this process. If you stick the magnet to something before it's totally hardened, you can damage & dent the nice smooth surface.
To cover my magnets, I poured small amounts of resin and spread it out to the edges with a stick. As the resin self-levels, the surface tension of the liquid will keep it from flowing over the edge as long as you don't use too much. Once applied, work on removing the bubbles as recommended by the resin manufacturer (torch, breathing on it, heat gun, etc), then cover them to keep dust from sticking to the wet resin.
Step 9: Done!
So you may be asking yourself... all this work for a fridge magnet? Well, maybe nobody else will appreciate what went into making this (unless they see this Instructable), but there's an undeniable sense of accomplishment and satisfaction when you get to see and use something that you made on a regular basis. I also gained some good practice in the shop and built up my skill set in the process. And I personally love the look of contrasting hardwoods and metal.
Thanks for reading.