Thursday, October 9, 2014
Mill Motor and Pulleys
The large pulley is made of solid maple. I turned the OD on the wood lathe, and the ID on the metal lathe with a vacuum next to the cutter. The small pulley, and bushing inside the large pulley are made of delrin. The white tube in the upper right contains the run capacitors and a leprechaun.
Above, a fuller view. Below, you can see the bottom of the bushing that interfaces the pulley with the spindle. There are two 4-40 clamping screws, radially symmetrical. 90º from the clamping screws on the flange are 1/16" dowel pins, parallel with the spindle. These stick up into the wooden pulley to prevent slippage. I could have made the wooden pulley press-fit on the spindle, but I thought it would crack over time. It probably will anyway, but there was no decent plywood around. The wooden pulley ID is a slip fit onto the bushing. The delrin motor pulley is a press-fit.
Below is the first iteration of drive belt. It's made of a bicycle inner tube. It won't last forever but it works for now. Maybe a piece of thin leather will find its way into my hands by the time it breaks. If not, there is a steady supply of inner tube rubber. The pulley ratio ended up bringing the no-load RPM to 490 RPM. The motor can put out about 25 watts of power. I'm certain that a 16" bastard file could remove metal more quickly, but a 16" bastard file can't drill bolt patterns.
Above is the enclosure mounting bracket, also made of 3/4 maple. Made it with a jeweler's saw! Took a while.
Here is a video of it working: