Strange Attraction

Recently Aaron wrote in the Wild Gears blog about a new technique pioneered by u/HomegrownTomato from the Spirograph subreddit that Aaron called "Center Secured". I won't go into the technique in this post because it's quite complicated and just a contributing factor to what I'm writing about here. Plus, Aaron covered it rather thoroughly in his blog.



Trying this technique it quickly became obvious the only sane approach would be to use magnets to secure the ring and fixed center gear. The ring and fixed gear must be precisely positioned relative to each other and I could find no way to do it using just putty. I've used putty exclusively to this point, primarily because I never got around to getting a metal sheet to put under my drawing surface. I've long had a bit of a fascination with neodymium magnets and have quite a few of various sizes, but without the metal sheet to stick them to they were useless as far as holding rings in place.

So off to the home store I went to buy a sheet of galvanized steel. If you do this, take my advice and be extremely selective. You want a sheet that can be laid perfectly flat. Home Depot had them stored standing on edge. This is not the best method for maintaining perfect sheets. The sheet I got has a very slight bend along one edge and this has been a bit of a problem. I suggest you try to avoid this. The thinner gauges of steel will be flexible, so probably not totally flat when you pick them up, but you want them to lie perfectly flat when placed on a flat surface. You'll also probably want to very gently file the edges to smooth them and take off any rough spots.

As to magnets, I can recommend K&J Magnetics as a source. I've purchased from them many times over the last 15 or so years. They have a huge selection, have always shipped promptly, and I've never had an issue with any of their magnets. At least no issue that wasn't my fault. I suggest getting magnets that are rated at about 10 pounds of pull. I got some of the D66-N52 that have 9.86 lbs. of pull. Five or six stacks of two will firmly hold a ring in place and still be fairly easy to pull back off when you're done. You might also want to get one or two more powerful ones to firmly secure smaller gears where there isn't room for more than one magnet.

I should add here that the pull rating on the magnets is for the magnet directly against a ferromagnetic surface. Separating the magnet from the surface even a tiny bit will greatly reduce the pull. So a magnet rated at a ten pound pull will require ten pounds of force to remove from a ferromagnetic surface, but when separated from that surface by even a millimeter the force required to pull it further away is much less. With a ring and several sheets of paper between the magnet and the metal sheet, the ten pound magnet will hold with much less strength. I'd guess it takes about two pounds of force to pull a stack of two of the D66-N52 magnets off a ring.

I will also warn you in all seriousness to read the safety guidelines on the K&J web page and take them to heart. Magnets of this size are not toys and you need to be careful when handling them. Do not use them with small children around. I would suggest keeping them away from bigger children too, particularly the adult kind who think they have superior hand strength and can easily deal with some little magnets. These things have incredible attraction to each other and will slam together with enough force to shatter. (Voice of experience here.)

Having now used magnets to hold the ring in place I have to say it seems a better approach than putty. With enough magnets in place around the ring it feels more secure, to the point pushing on the ring would move the whole drawing table before it would slide the ring on the page. It also holds the ring perfectly flat against the page. This could be considered both a plus and a minus as having the ring slightly raised can help keep smaller gears from popping out quite so easily.

Which brings me to what actually prompted me to write this. I was working on a drawing using one of the very small gears and it kept popping out. I've tried various approaches to addressing this. The most successful had been using small nylon washers to pin the gear between the page and the pen. Until today. The washer technique wasn't practical for this drawing because there was too much gear repositioning and getting the washers lined up would be too time consuming.

As the gear popped out for about the 20th time I got the idea to try pinning it down with one of the magnets. The ones I used to hold the ring in place were too powerful, but I had some very small ones with about a one pound pull. Two of those on top of the small gear held it down nicely while not interfering too much with lateral movement. There was definitely more drag than without the magnets, but not enough to cause a problem. It was about like the drag you'd get using one of the much larger gears.

This was such a huge difference in the gear not rising up at all that I believe I'll be drawing on a metal sheet from now on if only so I can put some magnets on the moving gear to keep it from rising up. Even with some of the medium sized gears where popping out isn't usually a problem, a couple of these small magnets on top will be good insurance against a ruined drawing.

I know I may sound half mad ranting on about little magnets on small gears, but trust me on this. This is a game changer. Those gears that kept insisting on popping out three times a revolution won't be doing that anymore. I've avoided using the smallest gears on many occasions because it was too much trouble trying to keep them from popping out. That's all over now.

Addendum: I probably should have employed the magnet on moving gear trick a bit more prior to writing this entry. I just tried it on one of the very smallest gears and there turned out to be not enough room on the gear for the magnet to be far enough away to not be attracted to the little bit of iron in the tip of the pen. It kept getting pulled toward the pen and eventually got in the way.

But I have a solution... Putty! I secured the magnet to the gear with a small dab of putty. Now it pulls the gear toward the paper enough to keep it from popping out and it stays away from the pen. It looks a bit odd, but it works.