DC motor controller

Hmerkle

Hank
Corporate Member
I have a Leeson DC 1 1/2 HP motor and want to get a controller for it.
I plan to use 110V input.

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I came out of a treadmill and I do have that controller, but it is a little klugey...

I was thinking of trying this one I found on Amazon, but the only thing I am basing this on is the 0-90VDC

I found another controller I like better, but still no data on if it can be used with a 1.5 HP motor: L&Z DC Motor Speed Controller PWM 6-90V 15A Brush Motor Adjustment Control Module 1000W 16kHZ - - Amazon.com

In typical Amazon fashion - their "Frequently bought together" suggestion is a 3/4HP DC motor... and this is what has me concerned...

A little help from the NCWW hive mind?
 
Last edited:

Southern_Canuk

Scotty
User
I purchased these to convert my 3hp treadmill motor over for lathe use: (I have since sold it)


The 200k ohm potentiometer is not needed unless you just want more precise control, the 100k one on the scr moto controller wouldn't kick on until it was turned 40% up. I had no issues with this setup running the motor on a 15 amp breaker, my only issues was lack of torque at lower speeds, Tread mill motors are excellent if your running it 80% + speeds all the time
 

Hmerkle

Hank
Corporate Member
"lack of torque at lower speeds, Tread mill motors are excellent if your running it 80% + speeds all the time"
That is a concern of mine, but my plan right now is to have a jack shaft so I can run the motor at a little higher speed, but realise a lower speed at the lathe...
 

smallboat

smallboat
Corporate Member
I've been running a 2HP DC treadmill motor for a few years with a variety of controllers.
First I ran it with the controller it came with, worked fine until it died.
Then I tried the low dollar Triac + Bridge rectifier fix. It worked ok and I used it for about a year, but it lacked torque in the low range.
I was gifted another controller out of another treadmill and hooked that up. It is much better.
The first controller board included the PWM circuit so all I had to add was a potentiometer to control the speed.
On the current set up I had to provide a PWM signal as it wasn't part of the controller I had to work with. There are a couple good videos that will get you through that if you need it.
Along the way I've added a tachometer to show the speed.
The new set up also holds the speed so you can shut down and start back up at the same speed.

If you're interested I can share links for all of these, but I would skip the cheap version and go with true PWM control.
You'll just need to get a treadmill motor control board- free if you're patient or around $150 online.
 

smallboat

smallboat
Corporate Member
Hank if you can share some info on the controller it came with and/or a photo I might be able to point you inthe right direction to get it going.
 

Hmerkle

Hank
Corporate Member
Hank if you can share some info on the controller it came with and/or a photo I might be able to point you inthe right direction to get it going.
That would be great!
Probably tomorrow or more likely Monday as the “Honey-do list” is QUITE long for this weekend!


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Dee2

Gene
Corporate Member
I just use a computer power supply for my treadmill powered lathe. Simple pot for speed control. Had to add a 12v light bulb to the 5 volt power leg so the power supply would stay on.
 

Oka

Casey
Corporate Member
2 Guys who have some decent youtube videos on DC Motors are Jeremy Fielding and Clough42. Jeremy is more basic while Clough42 gets more in depth.

KB Electronic make a 130-150 buck controller that is decent.

Like others have stated Most DC motors have a very poor torque curve until about 35-50% of their rpm rating then it climbs to a near 100% rated torque. To buy a real decent DC Motor you can pretty much get an AC motor with a VFD for the same money and have the low end torque.
 

Charles Lent

Charley
Corporate Member
DC motors will have a significant speed reduction problem when the load is applied and varied and then speed up when the load is reduced or removed. A DC motor running at a higher speed with a gear or belt reduction to the load running at a lower speed will have more torque and be less affected by load changes. The greater the motor speed to gear output shaft speed reduction, the less speed variation will be seen by output load changes.

A DC motor with a tachometer generator connected to measure it's shaft speed that constantly measures and feeds the actual motor shaft speed back to the right kind of controller will maintain the motor speed at any speed setting through the motor's full power range. The controller will vary the output current as necessary to maintain the motor speed when load changes occur. This type of controller is called a "rate stable or servo type of control system".

AC motors hold their speed with varying loads, because the motor speed is controlled by the frequency of the power being supplied, but they don't do well when running at low speeds below about 30% of rated speed. In most cases though, you can run them at up to about 140% of their rated speed using the right controller. 3 phase motors are best, because there is no starting capacitor and centrifugal start switch in them. The big problem with slowing an AC motor significantly is that their cooling fan is mounted to the motor shaft, so slowing the motor also reduces the cooling air flow. Motors with separate fans that are fixed speed can eliminate this problem for all but the very lowest speeds.

My point to this is: Are you certain that a DC motor is the best choice for what you are doing? Can you live with the speed variation as the load changes? Will you have a high reduction gear or belt speed reduction system between the motor and the load? Did you save this part of the tread mill too?

Charley
 
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Hmerkle

Hank
Corporate Member
I just use a computer power supply for my treadmill powered lathe. Simple pot for speed control. Had to add a 12v light bulb to the 5 volt power leg so the power supply would stay on.
This is a 90volt 1 1/2 HP motor, I don’t thing a computer power supply would work, but I will look up those videos


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Hmerkle

Hank
Corporate Member
Hank if you can share some info on the controller it came with and/or a photo I might be able to point you inthe right direction to get it going.
O.K.
More pictures
Controller board
IMG_0080.JPG

HMI - this is what I think would be especially clunky to implement
IMG_0078.JPG

Back of the HMI
IMG_0086.JPG

The obligatory rat's nest of wires
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3 of these (relays?)
IMG_0084 (2).JPG

So, my thinking is I have 110 / 115 being rectified to ~90 VDC on the main board for the motor going through the relays and the 12VDC is going to the controller with guidence from the
HMI through the multi-colored cable....
But not even a clue with what I could keep from this controller and modify to make and keep it simpler...
 

Oka

Casey
Corporate Member
You know if you are willing to set up a simple system. Just get a AC-Variac (potentiometer) and buy a bag of bridge rectifiers I think a bag of 6 was 10-12 bucks. Then, just wire it up and the variac will control the voltage 0-120v -ac and the bridge rectifier will convert to dc 60 bucks and you have a operational machine. Maybe a little primitive, but it works fine. The bridge rectifier will eventually fry, then just replace with the others you have. They last about 6 month a rectifier give or take.
The poor man's DC controller.
 

smallboat

smallboat
Corporate Member
The controller in your photos is not the variety I am familiar with. Wouldn’t know where to start with it.
The ones I have had luck with are based on the MC2100. There are a variety of them but they’ll perform the same and wiring will be the same. Good guidance here-MC2100 youtube

A cheaper approach- similar in theory to OKA’s suggestion - is found here - SCR controller youtube
I used that as a quick fix until I found another MC2100 and it works with limitations.

There are filtered and unfiltered SCR controllers. I suspect the Leeson in the photos (and possibly your original) is a filtered design which will give you higher top speed and longer life.
Here’s one of the better explanations I’ve run across. SCR, PWM filtered and unfiltered
(The MC2100 is PWM)

And here’s the manual for that model Leeson controller - Leeson Manual

Hope this helps.
 

Hmerkle

Hank
Corporate Member
The controller in your photos is not the variety I am familiar with. Wouldn’t know where to start with it.
The ones I have had luck with are based on the MC2100. There are a variety of them but they’ll perform the same and wiring will be the same. Good guidance here-MC2100 youtube

A cheaper approach- similar in theory to OKA’s suggestion - is found here - SCR controller youtube
I used that as a quick fix until I found another MC2100 and it works with limitations.

There are filtered and unfiltered SCR controllers. I suspect the Leeson in the photos (and possibly your original) is a filtered design which will give you higher top speed and longer life.
Here’s one of the better explanations I’ve run across. SCR, PWM filtered and unfiltered
(The MC2100 is PWM)

And here’s the manual for that model Leeson controller - Leeson Manual

Hope this helps.
GEEZ!
I owe you an adult beverage the next time we are in proximity of each other! Thank you for the help and guidance...
 

smallboat

smallboat
Corporate Member
Another trip to the fab it hole. I wasn’t familiar with the filtered SCR controllers. Learned something new.
You might even find something in the troubleshooting section of that manual that could get your current controller back in action. as you say, it looks similar to the Leeson.

In general you can take all of the stuff from the treadmill “head” and remove it. You just need to determine where to hook up the pot. (Potentiometer)

My first MC2100 included the PWM generator on the controller board so I just needed a pot.
The second one is like the one in the video I included. It required a separate source for the signal. I have it set up as shown in the video along with a tachometer with digital readout. It is working quite nicely.
 

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