Build a Coil Winder

copyright © 2006 by Larry J Solomon

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This picture shows the coil winder in operation. Although it can operated without hand guidance, I have found the manual guidance gives more control. The winder consists of two primary parts -- the winder itself and a coil spindle. The winder is motorized using a microwave turntable motor. I used a Sanyo 3 rpm motor used for Sharp microwave ovens, models R-4075, 4080, 4180W/R/Y/P, 4275, and 4230.  This speed motor is just right for me. It supplies high torque for such a small motor and operates on ordinary house current.

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Operation can be done without hand guidance as below. A weight holds tension on the wire as it winds.

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The white AC line cord is connected to the microwave motor through a footswitch (above) to turn it on or off in an instant. The motor will operate clockwise or counterclockwise for winding or unwinding. The following picture also shows space-winding by eye.

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The motor mounting is very simple, and the gear drive is self-contained. The hole for the recessed motor was made with a forstner bit. Note the square connecting interface on the gearbox.

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The following shows the spindle chiseled with a square hole to interface with the motor. The spindle holds the conical wings, fashioned from thirty-second inch (.02 mm) sheet metal. A cylindrical coil form up to 4 inches (10cm) in diameter can be held securely with these wings and removed or replaced at will. Small diameter coils can be wound with a second, smaller spindle. Or, the spindle diameter could be smaller and the wings larger.

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This is a detail of one of the conical quad-wings. The wings are held together with pop rivets. The diagram shows one rivet per wing but in two cases another was added to increase stability. If you have a lathe, two cones could be fashioned to fit a spindle.

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These are the dimensions/plans for making one wing, to fit a dowel/spindle of 32 millimeters in diameter. Eight are needed to make the two quad-wings. All the numbers are in millimeters.

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The next picture shows two coils wound in tandem on one coil form. This shows the versatility of the winder and is a better way of space-winding by winding two coils in tandem (parallel), applying a layer of lacquer as a fixative, and then removing one coil. This creates a beautiful, uniform spacing. In this case the second winding is only partially removed, because that is what is needed for the particular circuit for which this coil is used.

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Here is the finished coil.

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The next picture shows the coil removed from the winder, but still on the spindle. The wings, which should be snug, are slid off the core, which then releases the coil completely. Note the nylon bushing in the right wooden frame wing. The screws (pegs or dowels could also be used) hold the right wing in place when winding, and are removable to release the coil. The winder can also be used for varnishing the coil to achieve a uniform coat without dripping.

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A few more photos. This one shows space winding without any spacing wire.

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This is the spindle for holding wire.

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This coil winder is a joy to use. I have found it to be invaluable.

Please send questions and comments to Solomon's Clinic at: http://www.solomonsmusic.net/musiclinic.htm

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