Sunday, April 14, 2013

Slow progress

The wire wrapper is complete, and works pretty much as designed.  I did have to add a guide bar, which the Stewart-Macdonald one has, because I kept having the wire 'jump' out of the bobbin.  At more than a revolution per second, that made a mess quickly.
The main problem I'm having now with the coils, is that I haven't succeeded to get a good contact solder between the lead and the starting end of the wire.  Magnet wire is coated to prevent shorting across the coil, but the coating has to be removed to make a good solder contact.  Unfortunately, while I can get good solder flow, I don't seem to be getting through the coating with heat alone.  This has meant a number of redos.  After the first redo, I replaced the servo with a motor controlled by the ardumoto shield, which boosted me from 1 rev per second to almost 2.  There was an even faster motor, but as speed goes up, stall torque goes down.  This comes into play because the motor is driving a spinning, weight (my bobbin) and that weight is increasing as wire is laid down.  I also geared the shaft down a bit, to try to give myself an additional buffer.  Even with this, I've found that if I pull too hard on the wire, I can stall the motor.
On the other side of the project, I've definitely figured out why jointers were made.  A jointer is used in wood working to establish two flat, perpendicular sides.  Then the opposite wide dimension is made parallel using a surface planer, and the opposite narrow dimension is set using a table saw.  Well, I didn't have a jointer, so after cutting apart my maple billet, I used a hand plane to establish a good joint, and glued the two halves together.  I am now in the very slow, manually intensive process of using a hand plane to get the resulting board flat.  I have to push through and do it manually (or buy another billet) because most jointers only have a little over six inch wide blade.  Also, because I got excited and cut out the shape, it no longer has sides parallel to the grain.

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