Servo motor speed limiter

[dikman]

11 hours ago, JeffHami said:

 I was thinking it should be easy to put a speed limiter inline between the speed controler and the motor........ I'm no electronics guys , but this seems like something that could be made.   Is there a reason this couldn't be done?

Yes, there is a reason this couldn't be done - it would be a complex bit of gear. DC servos generally use Pulse Code Modulation to control the motor, such a controller is not something you can whip up quickly. I'm surprised that the minimum speed is 500 rpm as mine can be set much slower (different brand). There is a speed reducer that consists of an open box that bolts in place of the motor and the motor then bolts to the bottom of the box, with the reducing pulleys mounted to the box. Probably the simplest way to mount a speed reducer, I think some of the advertisers here sell them.

[JeffHami]

It looks like an electronic speed reducer is out so I decided to go with the Techsew speed reducer. I didn't want to mount all the pulleys and bearings on the top of the table and the Techsew had the smallest footprint and looks well made. Thank you to everyone for all the help and ideas. 

[keithski122]

A nice easy way to make a servo motored machine easier to use is to extend the arm on the pedal that attaches to the rod and also to extend the coresponding arm on the motor switch unit.This means your foot has to move further to speed the motor up.I've added an extra 2 to 3 inches to each of my machines arms.

[JeffHami]

4 hours ago, keithski122 said:

A nice easy way to make a servo motored machine easier to use is to extend the arm on the pedal that attaches to the rod and also to extend the coresponding arm on the motor switch unit.This means your foot has to move further to speed the motor up.I've added an extra 2 to 3 inches to each of my machines arms.

Thanks, I never thought of that.

 

[Constabulary]

But this does not slow down the motor it still starts at 500RPM min. In the accelerator unit you can move the small black lever a bit to the left or right to get more or less "play" in the foot pedal. Its a bit trial and error. Not sure if your look the same but I guess it does.

Edited January 3, 2018 by Constabulary

[Gregg From Keystone Sewing]

I think I understand what you are are asking; you are looking to "add" a speed control knob or dial to an existing motor to be able to adjust the upper limit of the maximum speed.

Either the motor has the ability to input this through the use of a potentiometer, such as some of the Efka motors, or you are going to have to be an electronic genius and be capable of making up something on your own for your specific model motor.

I do not know of any digital brushless motors that have an input like this, and as said you can adjust in the motor parameters as per the instructions for your specific model.  

Other motors like the with brushes Consew CSM550-1 have a dial like this.  

Edited January 3, 2018 by Gregg From Keystone Sewing

[Gregg From Keystone Sewing]

On 1/1/2018 at 8:53 PM, JeffHami said:

Wiz,

 Where so I buy this 3:1 speed reducer? Does it mount under the table and do I have to move the current position of the motor?

 

The unit has a 3" pulley

Jeff

Yes, the motor will have to shift off to the side to accommodate the speed reducer.  This is why a new setup with this is often a cleaner setup, if you can't deal with three extra holes where the motor was.

[JeffHami]

Gregg,

 What my original idea was to make a box that would go inline and limit the RPMs so I could run the machine slow no matter how hard I pushed on the pedal. After all the advice on the forum I decided adding the pulley was the best idea because it also increases the torque while slowing the machine speed.

 I am going to remove the machine and flip the table over then rework everything when the new pulley comes in. I hope to be able to buy the new belt sizes I need at my local auto parts store.  

 

[Wizcrafts]

4 hours ago, JeffHami said:

I hope to be able to buy the new belt sizes I need at my local auto parts store.  

 

Only if that store stocks type 3L v-belts. They are 3/8inch wide at the top. Most auto belts are 4L, or 1/2 inch wide. This is way too wide for industrial sewing machine pulleys.

[JeffHami]

22 hours ago, Wizcrafts said:

Only if that store stocks type 3L v-belts. They are 3/8inch wide at the top. Most auto belts are 4L, or 1/2 inch wide. This is way too wide for industrial sewing machine pulleys.

Is there a local store that might sell belts like Ace Hardware or a mower shop?