Treadmill motor adaptation for Bridgeport type mill.

[machiningfool]

Here are some pictures of the control box buttoned up. The reverse switch works. There are some treadmill motors have their brushes at an angle for only one direction and some are at 90 degrees. The 90 degree models should be more favorable for reversing. The angled brush type might work just as well, I don't know. Mine happened to be at 90 degrees. So, except for painting the box and wrapping some motor wires, this project is finished. Robert Brown machiningfool

[machiningfool]

I thought that I would share this little tip with you, it has to do with identifying the wires on a 3-phase reversing switch. There I was staring at six wires on the 3-phase reversing switch and without a wiring diagram. I am now trying to convert this switch to reverse a treadmill motor, only 4 wires are involved, two power and two for the motor. I reasoned that if I could identify two wires that, when a continuity meter is put across them, no register would be made when I switched from neutral to forward and then to reverse. Those two would be my power wires. I found them and then put a 9-volt battery across the two wires and then hunted two other wires that registered 9 volts , either Positive or negative on the meter when the switch was turned to one side or the other. Then when I switched the switch to reverse, the meter would read the opposite of the first reading, then I knew that I had the motor wires. Surprisingly enough, it worked, I now have a DC reversing switch from an AC 3- phase switch. If you have any questions, feel free to ask. One could also make a reversing switch from a double pole, double throw switch, but I already had this switch already mounted. Robert Brown machiningfool

[kbalch]

This thread has been moved to the Must Read subforum. Congrats (and thanks) to Bob for making such a valuable contribution!

[machiningfool]

Thanks Ken, I appreciate it. I was attempting to clean out my garage and throw away things I thought I would never use, but I am having a hard time since I always think I might use that item someday. While attempting to throw things away, I found one of those things that I previously didn't throw away, an ammeter. Today I think I will attempt to install the ammeter in order to see exactly what the draw in amps are drawn from my treadmill motor install, might be interesting. Bob. OK, continuing this thread, I installed the ammeter, but first consulted a youtube video, because it has been a long time since I installed one. When I found the ammeter in my garage, I also found the shunt that went with it. This is the kind of ammeter that requires a shunt. I am including the video that I watched and is very accurate on how to do it, better than I could explain. Also two pictures of the shunt and ammeter installed. The ammeter shows 6 amps running at full speed, way less than I thought. This treadmill motor can run at 12 amps continuously without cooling, well within the range for continuous running without a fan. I am lucky enough to have the motor in the path of my room fan. Bob.

[kbalch]

My recollection (it's been 13 years) is that the ammeter I installed in the RV also required an external shunt, one terminal of which supplied the voltmeter. If one wired it backwards, absolutely nothing worked. Don't ask how I know that!

Ken

[machiningfool]

I learned the hard way along time ago. Before I knew how to use a multimeter, I thought I would see how many amps a circuit was pulling, so I put the probes in parallel and blew the amps portion of the meter. I then learned that an ammeter is hooked in series and the voltmeter is in parallel. The guy in the video, I believe explained the ammeter circuit well. Bob.

[machiningfool]

I wanted to add to the amperage test, the 6 amps was in full throttle low speed and when I shifted to high speed, it pulled 8 amps, still well below the continuous operation level. In high speed, the spindle turned at 2000 rpm and could be increased with the variable speed belt system in the mill, if I needed it. So, there you go. Bob

[machiningfool]

Here is one more post, I think, to show what the final product looks like complete with the ammeter. The last picture is the beginning of a project, a CNC router, that I started a few years back. The building of my house got in the way, so I will begin again here shortly. I have everything for the project, except for 2 drives and rails for the table. This will be the type that the table moves and not a gantry. It is going to be 48 inches of travel, X and Y and 8 inches Z. I am using Adept type robot arms for all movements. I purchased them because everything is already installed, ball screws, rails and servos, not steppers. They are very fast in movement as they were designed for rapid movement for placing items. I am using KSI labs Centipede board and Granite drives. Bob.

[machiningfool]

I am a little slow to remember sometimes and when I was mentioning what adaptations that I had made using treadmill motors, I forgot to tell you about an outboard motor that I had converted. It was a Chrysler 8 horse motor, took the gas motor out and installed a 2.5 hp treadmill motor, the transmission had reverse, so I didn't have to reverse the motor. It worked fine until I got to the end of the cord, about 50 ft. from the dock and then it pulled out of the receptacle. Obviously kidding, the original design was to be a hybrid, powered by a Honda generator. Would have been better designed to have the DC motor a 12 or 24 volt motor, or just buy a trolling motor. It is obvious that I have too much time on my hands. Bob.

[Tonyg]

Hi Robert,
If you get DC motors without a speed controller you might want to have a look at 'The Aussie Shed", his is very simple, cost effective and works great.