[Galane]

I picked up a treadmill for $20 and spent a while yesterday taking it apart. It was exactly what I was looking for, an older model (1995) with a power supply/speed control completely separate from the display and other extras.

The motor is a 1.5HP, American made, 110VDC GS Electric with a big steel flywheel and ribbed pulley. In contrast, the power supply/speed control is ATR Manufacturing from China and looks rather primitive. Just five transistors (SCR's?) on a heat sink and a bunch of resistors, capacitors and five adjustable pots. There's also a good sized transformer wired in. Fortunately the wiring diagram was in it so I'll be able to reconnect things.

I'm figuring for starters to mount the control and transformer inside the original box on the back of my 9x20 lathe and substitute a rotary potentiometer for the creaky old linear one from the treadmill. What ohm meter measurement do I need to get an equivalent replacement?

I know a PWM control would give smoother, less noisy, more efficient control. This is a low budget build. Any sources out there for a good used PWM control for a 110VDC brush type motor? I also want to use the hall effect sensor from the treadmill as a spindle rotation sensor, already have its belt pulley mounted onto the lathe spindle.

Lathe $50
Stepper motors, linear actuator, ball screw and other sundry bits of another person's failed project $300
Treadmill $20
Aluminum plate for Z axis motor mount $0 from scrap (not counting the $2K CNC mill I used to machine the plate and will use on more pieces for the lathe...)
$370 total so far.

Still looking good to be a sub $1,000 build.

[Al_The_Man]

First it is recommended that you remove the flywheel, many are LH thread, that is if you want any kind of snappy response from the motor and not blow a fuse or one of the semi's.
The Pot for control is normally 5k to 10k linear (not logarithmic!).
You could also measure the original to be sure.
There are PWM controllers made by KB and Baldor, many of the ones on ebay etc are SCR bridge.
When mounting the board and pot, keep in mind that there is no galvanic isolation so the chassis can be live.
Al.

[Galane]

No danger of anything unscrewing as the orientation of the drive will be identical to how it was on the treadmill. Flywheel and pulley are one piece. Good old American made quality stuff. I could turn it down a bunch to lighten it, if it will come off the motor shaft. Chassis won't be live, the heat sink was screwed directly to the metal treadmill frame, to which the metal handrail was bolted. Duplicate the original mounting and I'm not getting zapped.