Hi Guys,

I decided that it was about time that I got my finger out and finished making a fan duct to go on top of the motor on the mill.

These DC motors get hot quite quickly and since all the heat is effectively trapped in the armature windings and it can only slowly escape via conduction through the spindle and top and bottom bearings. In addition to a very poor fan on the armature shaft sucking air in from the bottom and it being passed up the inside of the motor frame, providing not much cooling at all. Due to the centrifugal action of the spinning armature forcing the bulk of the air flow outwards and up between the gap inbetween the field magnets, I though that an auxiliary fan would be of benefit.

Also having a suitable 12 volt fan, wall wart, some PVC pipe and a tin of pvc cement decided to make a cooling system that sat on top of the motor and sucked the hot air out. This is what I came up with !

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I trepanned the centre out of this piece of plastic material on the lathe using a piece of 1/16" by 5/16" HSS that I had. I mounted the piece of material on a 1/4" mandrel and cut from both sides.

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I had some PVC pipe which was a little too big so I cut a slice out and used it to hold the gap together whilst the adhesive set. As can be seen I used a couple of tie-wraps to hold things in place. I made this pipe weeks ago but other things got in the way.

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This is how it looks now. The four mounting screws thread into the corner holes in the fan. The fan runs at 3K rpm and shifts a lot of air. I'll post a picture of it on top of the motor later, the camera battery went flat on me before I got chance to take its photograph.
Attached Images




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