There's a lot of sophisticated techno-goodness hiding in that treadmill.
Treadmills are more than just fitness equipment, and old treadmills are far more than just dust collectors. The average treadmill contains an assortment of powerful motors, sophisticated speed controllers and load sensors that can allow a savvy builder to construct all sorts of useful devices and machines. The best part is that it all comes as a single, working package; no shopping around or component-matching required.
Treadmill Function
A treadmill's trump card isn't its powerful motor or speed controller; you can find those in any standard washing machine. A treadmill works by sensing the load on the tread surface and varying motor power via the speed controller. This makes the treadmill a perfect start for projects that require varying torque loads to maintain a given speed.
Shop/Machining Projects
A number of different shop tools require varying torque loads to maintain speed. These include bandsaws, drill presses, metal-wood-cutting lathes and sanders. Old-school or bargain-priced machines may use a set voltage to maintain a given speed. This can work fine for a drill press as long as you go slowly, but rapid RPM changes can be disastrous for precision lathe work. Bandsaws are an excellent application for torque-varying setups like this, since constant blade speed can be an important factor where safety and consistency are concerned.
Retrofitting Stationary Projects
Retrofitting a treadmill system for a stationary project like a lathe or bandsaw is fairly simple in principle, but the devil is in the details. Theoretically, you're only replacing the standard motor with the treadmill motor and utilizing the treadmill computer to control the motor. However, retrofitting in this way may require substantial fabrication to fit the motor to the project chassis, and to mount the device drive mechanism (be it gear, pulley or direct-coupling) to the motor output shaft. You might get lucky and find that the drive motor output uses a keyed output shaft of the same diameter as your project's drive, but don't expect it. If you can't build the coupler yourself, a local machine shop can help.
Electric Bicycles
Modern electric bicycle kits are fantastically simple and efficient; most use simple hub motors integral to the wheel in place of the traditional chain-drive assembly. However, commercially available hub motors have three basic problems. The first is that they are direct-drive, so you don't have the option of changing gears for increased acceleration. The second is that voltage input is generally constant; as such, speed may drop when going uphill. Thirdly, the heavy hub motor adds weight to the wheel, which affects handling, reduces ride quality and increases the odds of vibration-related damage.
Building an E-Bike
This is a fairly straightforward project if you're skilled with welding thin-wall tubing and basically building a low-speed, electric motorcycle that you don't want to pedal. The electric motor replaces the crank set (pedal assembly). You'll connect it to the rear wheel with a heavy-duty chain, and utilize the strongest hub-shift transmission that you can find. Use a single 55-pound car battery mounted low in the frame (as close to the crank set as possible) or a pair of smaller 25-pound batteries. As a frame of reference, the two smaller batteries will yield about 50 miles worth of range at 20 mph with a 200 pound rider on a 100 pound bike. Use an inverter--available at any truck stop--to convert the batteries' 12-volt signal to household current, and plug the treadmill power-input directly into it. You can use a separate voltage controller to vary voltage input to the motor and act as a throttle; the treadmill's computer will essentially act as a cruise control to maintain speed. A number of states (like Florida) put a 750 watt motor and/or 20 MPH limit on electric bikes, so plan accordingly.
Tags: treadmill, projects, given speed, loads maintain, maintain given, maintain given speed, maintain speed, more than, more than just, motor output, output shaft, require varying
