Reply by Abbott

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Posted on Motor for a sander

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2570 posts in 3298 days

#1 posted 04-10-2010 07:16 PM

Hi Brian,

I am converting an upright wood cutting bandsaw to a metal cutting saw. I realize you are after a different configuration for a belt sander then I am for building an upright metal cutting bandsaw but I hope some of the following information will be useful;

I need to slow the blade speed way down so I am using a variable speed 2.50 horse DC motor from a Craigslist treadmill. BE CAREFUL a DC 130 volt circuit can shock the hell out of a guy!

The control pad with it’s digital controls is a real PITA (pain in the ass) and I don’t want to use it. With it’s push and hold controls of Mode, Incline, Speed, On/Off plus large black plastic control panel it’s pretty much useless for anything but a treadmill.

The power board, control board and transformer all need to be retained to make this work. The power board and control board on the unit I’m using was one board with two sections between the heat sinks. You can tell the difference by following the power wires to the board and the control wires to the control pad. (The controls on the unit I’m using are digital, real old units still use analog circuits).

To get rid of the large useless treadmill control pad I opened up the wire harness between the control board and the black plastic control pad’s board. While they were on a work bench I then traced the wires down by cutting one and marking both ends with tape and a number and powering the unit back up. (Not much to worry about here, these are low voltage digital circuits coming off the control board). Caution needs to be maintained if the controls are using larger analog circuits/wires. A larger voltage rheostat (then the digital one below) will also be needed for analog circuits.

I observed what each wire controlled as I powered the unit up then shut it back down and continued the observation. After awhile I had the control wires down to three. Two power wires and a voltage control wire which is the variable speed control.

I went to Radio Shack and picked up a low voltage (milivolt) rheostat. The center pole is the voltage control. I then hooked up the two power wires and the variable speed wire and I can now toss the big bulky control pad in the trash. I am left with a On/Off button and a small twist variable speed control.

My bandsaw is still in the process of being converted from a single speed 110 volt 1/2 horse analog motor (which was stock) to a much more powerful 2.50 horse 110 volt (because of the transformer) DC motor with precise variable speed controls. Total cost so far has been the time and gasoline used to pick up the old throwaway Craigslist treadmill, a few hours of labor and a $4.00 Radio Shack rheostat.

I still need to convert the serpentine belt treadmill motor pulley to a V belt. I don’t own a metal lathe so I am either going to have the serpentine pulley machined to handle a V belt. Or I am going to purchase a new V belt pulley and drill it out to fit the DC motors 43/64s shaft.

If I replace the pulley with a V belt pulley then I will also have to add a cooling fan as the DC motors original pulley also has fan blades on the back of the pulley to cool motor and circuit board. I have a small $6.00 household 3” or 4” 110 volt fan from Walmart that I will just wire into the conversion if need be.

-- Ohh mann...pancakes and boobies...I'll bet that's what Heaven is like! ♣ ♣ ♣ ♣

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