Cowboy Analog Servo Motor Modifications?

[JoMama]

....Try a 3 phase clutch with a Frequency converter...

Cheap 3 phase motors do not do well with VFDs at low speed. They heat up and the voltage spikes can breakdown the insulation. Inverter duty motors can be run down below 10% of the normal speed, but cheap 3 phase clutch motors probably would not last long running below 25% of rated speed. The "servo" motor being discussed in this thread is a two pole DC motor with PWM driver, not really a servo.

[Trox]

Like I said I have expensive Efka`s and Chinese Eco motors, but the 3 phase clutch with freq. converter works almost better than the expensive ones (part from the needle position that is). I even used such converter on a 3 Ph Efka varistop with no problems (only on the motor part, single current direct to the control box). It has worked for ten years no with out any problems, with out any extra heat from the motors. I only uses the same as they do in all modern industry today; Ac motor with a frequency controller. I currently have three setups that has worked flawless for many years. I am sorry for the off topic, this is for all the others looking for motor alternatives.

Thanks

Tor

[Wishful]

I have the same problem as stated above. The speed at the low end cannot be adjusted just a bit, it jumps to too fast from zero so a speed reducer is next.

[Constabulary]

Like I said I have expensive Efka`s and Chinese Eco motors, but the 3 phase clutch with freq. converter works almost better than the expensive ones (part from the needle position that is). I even used such converter on a 3 Ph Efka varistop with no problems (only on the motor part, single current direct to the control box). It has worked for ten years no with out any problems, with out any extra heat from the motors. I only uses the same as they do in all modern industry today; Ac motor with a frequency controller. I currently have three setups that has worked flawless for many years. I am sorry for the off topic, this is for all the others looking for motor alternatives.

Thanks

Tor

I have no clue what the frequeze converter does and how it works with a clutch motor...

Does it slow fown the speed and how can you control it? Can someone explain it to me in plain english?

Trox - can you post pictures of your setup?

[Trox]

It coverts to normal single house hold current in to 3 phase current; to run the motor. And lets you control all the motors parameters, such as speed, torque, start time, stop time...... you name it. You can set the max speed as low as you want and let the motor have maximum torque at that speed. Like one stitch a minute if you want to. You can also attach a pot meter to regulate the speed, like a pedal just as you like. (otherwise you got to use the buttons and the display to control it).

I do not have 3 phase current in my workshop so I use this systems on my 3 phase motors. You loose a couple % of the power this way, not much. Sometimes the motor makes some noise (wrong frequency), just change the speed a bit and its gone. You need one that can handle the amps rating on your motor. Its easy to connect; single in on the top (on this one) then the four motor cables out underneath. Earth to earth and just change the other three around until your motor turns the right way. You got to download the pdf to find out how to program it, its not very difficult. Every electricians know how to do it. Or send me an PM and I tell you how to do it. Thats it

Tor

[Trox]

Constabulary,

Here is an other one I use on my skiving machine. (on the wall, laying on the top of the machine is a bigger controller not in use)

I run this on full speed all the time, its for the bell knife motor only. It has a little 220 v servo motor for the feed wheel that goes direct in single phase outlet.

Actually this machine has three electric motors; one for the knife (380v- 3 Ph), one for the feed wheel (220v- single Ph with a pedal for the speed) and one for the exhaust (220v -single Ph). So I connected the two single direct to the outlet and run the Freq. converter on the bell knife motor (on full speed 50 hertz all the time).

These controllers regulate frequency on your AC motor; 50 hertz are full speed. If you give it 25 hertz it runs on half speed and so on. (all clutch motors are AC motors, and all AC motors are originally 3 Ph. Some are rewired into single Ph motors)

A normal 3 Ph sewing machine clutch motor is much simpler to hook up than this one.

When you look for a controller for your clutch motor find one that can handle a bit more than your motors Watt and Amp ratings. You find than info on the motor sign.

Good luck

Sorry for the off topic.

Tor

[Constabulary]

I will keep that in mind - but I will try a servo motor + speed reducer first as I don´t like the idea of a permanently running clutch motor.

But always good to see how others have solved their motor problems. Thumbs up!

[BDAZ]

I finally received my 100K log pots from China. The connectors arrived a week ago. I soldered the connector leads to the pot, plugged it into the board, reassembled the motor cover I was done. There was a noticeable improvement. The slow speed selection has much greater range than before. I would say 3 times the movement of the knob from just starting to move to around 1 stitch per second. Not a great as I had hoped BUT it will still reach stitching speeds higher than I will ever need.

Next I will try lower resistance pots to increase the range. There is a threshold of minimum resistance when nothing happens. I am not sure if that is adjustable, but the new pot has to be turned a bit before the motor kicks in.

In summary, well worth the couple of bucks spent and the few minutes involved but I suspect the lower value pots will bring a bigger improvement in low speed control.

I will be trying the magnet mod once I finalize the replacement pot.

Cya!

Bob

Edited June 8, 2014 by BDAZ

[Random]

I did mine last week with the 100K Pot and a 50K pot. I adjusted the 100K Pot to just below the thresh hold where the motor started (12K ohm) and then used the 50k pot for fine control. Substituting a 10K or so resistor for the 100k pot would do the same thing. I also modified the magnet positioning as was also suggested and I now have fantastic control.

[Wizcrafts]

I finally received my 100K log pots from China. The connectors arrived a week ago. I soldered the connector leads to the pot, plugged it into the board, reassembled the motor cover I was done. There was a noticeable improvement. The slow speed selection has much greater range than before. I would say 3 times the movement of the knob from just starting to move to around 1 stitch per second. Not a great as I had hoped BUT it will still reach stitching speeds higher than I will ever need.

Next I will try lower resistance pots to increase the range. There is a threshold of minimum resistance when nothing happens. I am not sure if that is adjustable, but the new pot has to be turned a bit before the motor kicks in.

In summary, well worth the couple of bucks spent and the few minutes involved but I suspect the lower value pots will bring a bigger improvement in low speed control.

I will be trying the magnet mod once I finalize the replacement pot.

Cya!

Bob

Bob;

Are these mods for the Family Sew FS-550 motors? What is the mod to the magnets?

Re the 100k pot. Is it a 10% center, log taper clockwise, carbon pot?

Edited June 8, 2014 by Wizcrafts