I have a 2hp 180VDC treadmill motor sitting in the Project Pile, and I'd like to repurpose it to replace an AC motor on my drill press. I've searched the forums and found a million people trying to repair or replace their treadmill control boards, but I don't have a controller. I've seen people elsewhere take a cheap 10kW AC SCR (~$12) and run it through a cheap 50A diode bridge (~$3). I'm all about a $15 solution, but I'm skeptical. This would seem to provide a pretty dirty 60Hz pulsed signal to the motor, particularly at low SCR settings, where there would be tiny spikes with large gaps in between.

So my question is two-fold: 1) Is that dirty signal sufficient for a drill press? and 2) If not, how do I clean up that signal? It seems like a capacitor between the diode and motor might do it, but I have no idea how to spec a capacitor.

 

The better option is the MC2100 TM board, it has PWM control, smooth and quiet, the second best is the MC-60, but is SCR bridge and a little noisier and not so smooth at low RPM's.
I think you may be a little disappointed with the simple Triac/bridge combo.

 

How much speed control do you need? And is it a permanent magnet motor, or does it have field coils? Is it a brush type motor, or a brushless DC motor? And how much speed control do you need? There are many options available, some are cheap and easy, some are not.

 

How much speed control do you need? And is it a permanent magnet motor, or does it have field coils? Is it a brush type motor, or a brushless DC motor? And how much speed control do you need? There are many options available, some are cheap and easy, some are not.

If it is a DC TM motor, the chances are it is PM field.
Never seen a wound field on one yet. Except an old version that was \universal motor (rare)

 

"" I'm all about a $15 solution, but I'm skeptical.
This would seem to provide a pretty dirty 60Hz pulsed signal to the motor,
particularly at low SCR settings,
where there would be tiny spikes with large gaps in between. ""

You should be skeptical, I consider it to be nothing more than crude hack,
but building a properly Filtered PWM-Power-Supply is not necessarily simple or cheap.

There are readily available Buck-Regulator-Chips designed to drive external FETs that will work really well,
the expensive part is the Filter-Section,
which requires a Huge Choke and a Bank of Capacitors.

It can be done for ~$100 to ~$150 Dollars, if you're handy with building your own Electronic-Projects.
It still won't be as silky-smooth as an Induction-Motor, but fairly close.
.
.
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ALL of my DC motors that use a higher voltage have wound fields, and that is several of them. Mostly shunt fields. And I just figured it out that a TM motor is a tread mill motor. I have not played with one of those yet.

 

. And I just figured it out that a TM motor is a tread mill motor. I have not played with one of those yet.

Most DC TM motors now originate from China, This where the main source of rare earth magnets, hence the PM fields.
Some are quite nice motors in the 2hp to 3.5hp range, The popular MC2100 board I previously mentioned provides a nice ramped up PWM speed controller.
As smooth and quiet as you can expect.
One good source is there is usually at least one TM per week offered free for pick up/not working in this area,.

 

Most DC TM motors now originate from China, This where the main source of rare earth magnets, hence the PM fields.
Some are quite nice motors in the 2hp to 3.5hp range, The popular MC2100 board I previously mentioned provides a nice ramped up PWM speed controller.
As smooth and quiet as you can expect.
One good source is there is usually at least one TM per week offered free for pick up/not working in this area,.

Thanks for the suggestions. I'll take a look at the motor tonight to confirm what type it is. Initially the price point of the MC2100 hurt, but I'm not in a rush so I can keep an eye out for a cheap/free broken treadmill locally.