McSeem Posted May 18, 2010 Report Share Posted May 18, 2010 Hi, a couple of weeks ago, while waiting for the parts, I decided to make a sustainer coil. Since my goal is to make a truly hexaphonic sustsainer, I'll wind coils for each string. 6 of them, and, maybe, even 12. So, this is also my early experiment, I came up with just a single coil, that works perfectly and has proper parameters. I took pole pieces from a cheap humbucker, but you can order them for a much lower price. You can also use alnico magnet poles for that. The reason I used just metal is to tweak the permanent magnetic bias, using different magnets. But if alnico works well, as I assume, it's even better. So, you take a pole piece, you take a drill like that: http://antigrain.com/hex_project/coils001.jpg Well, there's a trick. You don't want your drill to rotate at its full speed. You need to adjust it. And you also don't want to hold your finger all the time to keep proper speed. So, what you gonna do? It's called TRIZ, http://en.wikipedia.org/wiki/TRIZ. I'm a big fan of TRIZ. I have a 300W lamp with a dimmer, and I just rewired two plugs, so that, they connect the drill and the lamp in series: http://antigrain.com/hex_project/coils002.jpg http://antigrain.com/hex_project/coils003.jpg So, with the dimmer you can perfectly control the RPM and use your drill to wind the coils. And you also use it as a lathe machine! Next, you saw the pole piece in the following way: http://antigrain.com/hex_project/coils004.jpg http://antigrain.com/hex_project/coils005.jpg http://antigrain.com/hex_project/coils006.jpg The tricky part is to accurately measure the height. But you can make a coil of any height you want, even 3mm or so. Then you take a suitable plastic pack to make the washers. You cut them, stack, and drill a slightly smaller hole like this: http://antigrain.com/hex_project/coils007.jpg http://antigrain.com/hex_project/coils008.jpg You also cut it of course, so that the washers would be approximately round. An octagonal shape is OK. Then you slightly cut the hole and put them on: http://antigrain.com/hex_project/coils009.jpg http://antigrain.com/hex_project/coils010.jpg And, of course glue them. I use Elmers Ultimate Hight Performance glue. Make sure to use vinyl gloves, because this glue is really bad for your fingers. The tricky part is to set up the washers as perpendicular as possible. I use a toothpick, while rotating the drill: http://antigrain.com/hex_project/coils011.jpg And then you gently remove it trying not to touch the washers. You can use a magnet for that, with a combination of plastic tweezers. http://antigrain.com/hex_project/coils012.jpg The next day, when the glue dries, it's time to lathe the plastic and wind the coil. http://antigrain.com/hex_project/coils013.jpg It can be dangerous for your fingers and your eyes! So, do it at your own risk! Eyeglasses are MANDATORY! After that, you insulate the core with a piece of plumbing seal tape. It's very thin and provides enough insulation: http://antigrain.com/hex_project/coils014.jpg http://antigrain.com/hex_project/coils015.jpg You gently tighten it with a piece of plastic, while the bobbin is rotating. Then I use the very same drill to wind the coil: http://antigrain.com/hex_project/coils016.jpg http://antigrain.com/hex_project/coils017.jpg http://antigrain.com/hex_project/coils018.jpg Well, I admit it could be more accurate, but as the practice shows, it works perfectly. The modern magnet wires have very reliable insulation, so, don't worry too much about potential shortcuts and the accuracy. The only problem is how to count the winds. With the drill I have no good solution for that. If you wind it manually, you can use a simple step counter, put on your hand. It works perfectly. But with the drill it's not that simple. I didn't count the winds at all. Just I assume that 10-15% of difference is OK. I'm anyways going to adjust the response with the amp gain, since I will have 6 individual channels. So, more or less the same physical size is good enough to me. I used 36 AWG wire, and with this size, 6mm polepiece, about 4 mm space between the washers, and 10mm outer diameter, I've got almost exactly 10 ohms of DC resistance. It drives the string perfectly at about 4-5 mm distance. Well, after attaching the magnet you will have about 8 mm height, which is still OK in my case. I still have about 1.5 mm extra for the underneath binding, without having to mill a cavity. But once again, with this homemade technology you can wind coils of any size, 3 mm if you want. You can also use thiner plastic. The only thing is left is to cut it off. I use the very same drill and the very same metal saw: http://antigrain.com/hex_project/coils019.jpg http://antigrain.com/hex_project/coils020.jpg http://antigrain.com/hex_project/coils021.jpg It may look very hard to make, but if you make a number of coils, at least 6 of them, it takes about an hour per coil. Well, plus the time to let the glue dry, of course. So, enjoy with homemade engineering, as I do! My girlfriend does not appreciate it, though... :-) Quote Link to comment Share on other sites More sharing options...
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