You hook the treadle (foot pedal) up to a servo motor just like you do a clutch motor. No, your servo motor does not need to be more powerful than a clutch motor. I replaced 1/2 H.P. clutch motors with 1/2 H.P. servo motors on both of my industrial machines. They work beautifully, and I sew every day for a living. I've been sewing for almost 35 years, and I can't tell the difference.
A servo motor is a constant torque device, so you will get the same amount of power throughout the speed range of the servo. What is the difference between a clutch motor and a servo? The servo theoretically will have less power at slower speeds than a clutch motor, but a servo will have more power at higher speeds. What does this mean for average sewing? You won't be able to tell the difference. The problem with a clutch motor is that it is either on or off. Unless you are willing to spend enough time to be comfortable with the machine, you will still have accidents and screw something up. The servo motor gives you the option of having true variable speed control over the motor immediately. In other words, the less you press on the foot pedal (treadle) the slower the servo will go. The clutch motor is always going at its base speed, usually 1750 RPMs, and you need to slip the clutch to be able to sew slower. This takes a LOT of practice to do it consistently and effectively.
If you want to slow down your clutch motor, you have two options. You can possibly have an electrician re-connect the wiring in your motor down to 875 RPMs, ( depending on the motor) or you can replace the pulley on the clutch motor with one of smaller diameter, or both. If you reduce the RPM of the clutch motor by 1/2 through a pulley on the clutch motor 1/2 the diameter it is now, you will go 1/2 as fast as you do now. The same is true of re-wiring the motor. If you reduce the RPM by 1/2, you will go 1/2 as fast as you do now. If you reduce the pulley diameter on the clutch motor by 1/2, and reduce the RPM of the motor by 1/2 as well, the clutch motor will run at 1/2 of 1/2 of its full speed, or 1/4th the speed it runs at now. Now the bad news........you can do all of this and STILL not slow it down enough to where you are comfortable sewing. A servo motor eliminates that problem. Servo motors are the perfect choice for novice sewers. You can sew as slowly as you want at first and then speed up if you want to. This is not the case with a clutch motor.
No one lives forever, the trick is creating something that will.
Last edited by DanTwoLakes; 01-11-2009 at 05:20 PM.