# Clausing 8520 Dc Motor Conversion



## spongerich (Sep 28, 2015)

I recently acquired a couple of nice Baldor heavy duty treadmill motors.  These aren't the little beer can sized ones from home treadmills, they're the huge ones from medical grade equipment.   I took the smaller 1-1/2 HP 2400 RPM motor and mated it to a Baldor DC motor controller that I picked up off eBay for $50.

I kept the standard pulley system in place by using a small bushing to fit the motor shaft.  At pulley position 1-B which gives 1000RPM with a 1725RPM motor, I can get speeds from about 280 RPM up to 2200 RPM which will nicely cover about 90% of my needs without changing belts.  I also picked up a hand held tachometer for $15 that I'm using to measure the speeds.  Adding a 'real' tach might be a nice addition.  I also might make a new dial with the approximate speeds marked on it.

If I really need to, the 1-A pulley position should get me down to about 60 RPM and the 2-B position will get me up to and beyond the max stock speed of 3250 (Which I'd be reluctant to exceed for fear of damaging the bearings, belts, etc).

To test it, I took a 5/8 end mill (which is about the largest I'd ever really want to run in that machine), set the RPM to about 800 and tried my damnedest to stall or slow it in a chunk of 2" steel.  It ran like a champ and didn't bog down at all no matter how hard I pushed it.   

Changing speeds used to be a PITA.  The motor that was on that machine was an old Hoover 3/4 HP and it weighed a ton.  Because I really can't get behind it, slackening the rear belt was really tough without loosening and swiveling the head.   

I added a DPDT toggle to select fwd/reverse and used a push start/stop which I think is an improvement over the old rotary drum switch that was on there.  A couple of times, I missed the center 'off' position when I was in a hurry to stop the mill and it either kept running or reversed on me.

All in all, I'm extremely happy with the conversion.

At some point, when all of my other projects are complete, I'll probably clean up and paint the control box.. right now,  it looks like I should get to that in about 2025.



	

		
			
		

		
	
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## brino (Sep 28, 2015)

Fantastic upgrade! That looks extremely useful....nice job



spongerich said:


> At some point, when all of my other projects are complete, I'll probably clean up and paint the control box.. right now, it looks like I should get to that in about 2025.



whoa now....let's not rush in to anything.....

-brino


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## spongerich (Sep 28, 2015)

brino said:


> whoa now....let's not rush in to anything.....



Well yeah.. that assumes that no other new projects follow me home.


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## mattthemuppet2 (Oct 6, 2015)

sweet upgrade! I'm looking forward to getting more time on the DC motor I put on my lathe and converting the DP/ mill too. I used a cheap eBay tach on the lathe ($12?) which works very well as far as I can tell!


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