Another Treadmill Motor Speed Controller conversion thread

Inferno

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Please move this ti a better thread if you want.

I have a Smithy 3 in 1 and I want variable speed.

Treadmills are often found in the FREE section of Craigslist and, well, now I have the motor from a treadmill.
It's a pretty common 130V 2.5HP motor.

I tested the motor with a variable power supply I have that only goes up to 24V. The motor is fine. I need to remove the balancer "pulley" to get a V-belt pulley on it. No problem there. I also need to find a way to mount the side-mount motor in the face-mount machine. I'll figure it out.

Here's where I'm less confident.

I'm a cheap bastard with too much free time, knowledge, and skill, to pay $100 for a speed controller. I don't want to use the speed controller from the treadmill because of it's slow start "feature". I do like that the treadmill motor controller will adjust the voltage to accommodate for load. The motor has a built in tachometer.

I watched this video (and a couple others that have the same components)
and it looks pretty easy.
There's talk about adding a capacitor to handle sparking but don't know what value to add.

Does anyone have any input? Better ideas? Any other advice that will help?

The motor is basically this: zdy082-mnt-075

Treadmill_Motor_295727__18929.1476455978[1].JPG
 
So, I removed the centrifugal pulley. It was pretty easy, really. All these motors have a left hand thread. You just spin the pulley off.

The shaft seems to be an odd size. A little over 17mm (17.05mm) and a little under 11/16.
Any ideas on what's going on there?
 
So, I removed the centrifugal pulley. It was pretty easy, really. All these motors have a left hand thread. You just spin the pulley off.

The shaft seems to be an odd size. A little over 17mm (17.05mm) and a little under 11/16.
Any ideas on what's going on there?

I am in the process of doing this conversion on my lathe. I have a 2.5 hp - 130 volt motor but the flywheel wasn't threaded on. It actually used an shortened MT2 taper with a 5/16 -18 r.h. threaded screw to secure the flywheel.

I chose not to use triac or SCR control largely because of electrical noise as I have sensitive electronics in my DRO and ELS. Additionally, pulse width modulation tends to give better low speed performance because full voltage pulses are delivered to the motor instead od a much reduced d.c. voltage

I finished laying out a PWM circuit board this afternoon. The intent is to use a full wave bridge on the line voltage followed by a capacitor filter. The resultant d.c. voltage will be controlled using a pulse with modulator with a MOSFET transistor output. I will also add a reversing switch. I don't need a tachometer as my ELS encoder provides that information.

I can't help you with the shaft size except to suggest boring out your pulley to match. I had to machine an MT2 to 19mm straight shaft adapter for my setup.
 
I am using that exact setup on my belt sander and drill press (with an on/off power switch) and they have been working very well for over a year now.
 
The one in the OP video.
AH, OK.

As much as I like the idea of PWM and believe torque would remain more steady using it, I don't see a path to PWM for $30.
I'll get the whole thing set up with the SCR controller. I'm not happy about the noise potential but will add in a couple ferrite cores to help smooth it out.

Today I worked a little on the mount for the motor.

Here's the existing mount. It's not a good picture. I thought I had gotten a better angle.

20200816_135519.jpg
20200816_135700.jpg
20200816_135522.jpg

Since the new motor is a side mount, and not a face mount, I have to be creative.
The top part of the connection to the machine is complete. I can't do the side mount for the new motor until I take some measurements. Problem is that I need a pulley to make the measurements.
Also, I'm disabling the mill/drill every time I take the existing motor off to make a measurement. It's a tedious process.

Here's the beginning of the new mount.

20200816_184041.jpg

20200816_194531.jpg

20200816_194552.jpg

The next piece will be the bridge between the motor and this piece.
 
So, I removed the centrifugal pulley. It was pretty easy, really. All these motors have a left hand thread. You just spin the pulley off.

The shaft seems to be an odd size. A little over 17mm (17.05mm) and a little under 11/16.
Any ideas on what's going on there?

I’m not sure about your TM motor but the ones that I am using for various tools have a cooling fan incorporated in the factory pulley. Just something to be aware of. Out of curiosity I purchased one of those SCR controllers and my experience with it was it is extremely noisy. I abandoned it and went back to the treadmill controller.
I am interested in the PWM control that @RJSakowski is putting together. I had to put together a PWM board for one of my TM controllers and I’m not completely satisfied with its performance so I’ll be watching to see if RJ offers any updates.
Good luck with your conversion. The variable speed is nice to have.
 
So far, my cost for the PWM is zero,, due to parts on hand. The electrolytic capacitors come from computer power supplies. If I were buying all parts new, the most expensive parts are the MOSFET power transistor, the bridge rectifier, the potentiometers, and the high voltage electrolytic capacitors .

From DigiKey, a 15 amp power transistor can be had for less than $1 and 25 amp bridge rectifier for less than $2. The combined total of the remaining i.c.'s for less than $2, a handful of resistors and a half dozen capacitors for around $1. The power supply for the control circuitry would be one of the ubiquitous wall warts.

Jameco has a variety of potentiometers for under $2. The electrolytic capacitors are fairly expensive bought new but every computer power supply has several, as do all switching power supplies. Banggood has 5 pcs. 680mfd 300v elctrolytics for $12.65. Miscellaneous components are a p.c. board, enclosure, heat sink, and wiring. I haven't done a a full BOM as some parts may change depending on what I have on hand and test results.
 
I’m not sure about your TM motor but the ones that I am using for various tools have a cooling fan incorporated in the factory pulley. Just something to be aware of. Out of curiosity I purchased one of those SCR controllers and my experience with it was it is extremely noisy. I abandoned it and went back to the treadmill controller.
I am interested in the PWM control that @RJSakowski is putting together.
Good luck with your conversion. The variable speed is nice to have.

So far, my cost for the PWM is zero,, due to parts on hand. The electrolytic capacitors come from computer power supplies. If I were buying all parts new, the most expensive parts are the MOSFET power transistor, the bridge rectifier, the potentiometers, and the high voltage electrolytic capacitors .

Thanks to the both of you for your informative and useful posts and have questions to the both of you that I hope you don't mind answering. I'm currently restoring several different machines for myself and for a friend and only recently began starting to play with treadmill motors (DC) and with 3 phase motors with VFD's. These will be for two Lathes, drill press, mill and belt sanders. I would prefer to use DC motors if I can have good torque at lower rpm's?

I'm not good at cobbling together electrical components soldering them up and was wondering if you could recommend a ready-made DC controller that is economical? It needs to provide good torque to DC motors at various speeds (within the ability of motor) especially when running at lower rpms. I can construct a cabinet for it or one that comes with one is fine as well. The Baldor/KB DC controller is great but out of my budget to get more and need to find a much cheaper solution without having to do a lot of electrical work.

Also looking for advice for replacing the cooling fan for treadmill motor? Mine and others I've seen are built into the large treadmill pulley that is no longer being used. Wondering what is the most painless way to restore cooling to the motor?

Thank you

PS: This is a pic of what I'm currently building with items I had laying around but looking for new sources for a good economical DC controller that I can buy to work with treadmill motors and can handle good CHP rating (10-18 amps). The Treadmill motor in the pic has approx a 16mm/.63 diameter drive shaft.

fullsizeoutput_1fcc.jpegfullsizeoutput_1ff1.jpeg
 
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