Eagle EA-750 Servo Motor

[EdCubberly]

Just bought the Eagle EA 750-P Servo motor. Trying to sew as slow as possible (1 stitch/sec) but cant set the speed below 500 rpm. How can I change the Minimum Speed Parameters ?  Also, it has a "rough start" (noisy and a bit eratic) when I slowly depress the foot pedal. 

Theres also no explaination for the codes U 1 through U 8. Any ideas ?  Thanks guys

 

[AlZilla]

Is it that there's a setting for startup speed and 500 is the lowest?  I *think* my Eagle 550's have a setting that let me adjust minimum speed. Mine start at 200.

[kgg]

11 hours ago, EdCubberly said:

Trying to sew as slow as possible (1 stitch/sec) but cant set the speed below 500 rpm. How can I change the Minimum Speed Parameters ?  Also, it has a "rough start" (noisy and a bit eratic) when I slowly depress the foot pedal.

My take:

i) Lower startup speed is determined by the amount of bottom end torque it was designed for and how good the electronic closed speed loop controller. Even if you can change the startup parameter to something less then 500 rpm the motor you will introduce some annoying things like stalling, surges and poorer rpm regulation.

ii) The cheaper servo motors have 6 internal coils while the better ones have 12 coils which will typically provide better lower startup speed that is more consistent and smoother not just because of the added coils but chances are of they will have better electronic controls. I could not find any information on that particular servo motor but it would be a safer bet to assume it has 6 internal coils or call / email the manufacturer. 

iii) The only way of getting a reliable slower, smoother startup speed with the brushless servo motors is to install a speed reducer or buy a better servo motor. Getting the 1 stitch per second is probably equal to about 60 RPM. This I think is a bit unrealistic. If you really need that low a speed you would have to build an 8.33 to 1 speed reducer and probably change the servo motors shaft pulley. Keep in mind that an off the shelf speed reducer is 3 to 1 which will give you about 166 rpm. 

iv) to properly determine a realistic sewing speed you would need to do a pulley calculation knowing the size of the sewing machines handwheel and the size of the servo motors pulley based on the minimum startup speed.

kgg 

 

[fibersport]

One other possibility is to install a smaller pulley on the motor, 45mm is typical.  One problem though is the motor shaft on that motor might have a tapered shaft.  Tapered pulleys for that are difficult if not impossible to find.  The next choice was already mentioned, that being a speed reducer.  One other option is going to a larger pulley on the sewing machine.  A friend of mine did just that and really liked the reduction in speed.  He used just an off the shelf 1/2" bore, 6" pulley that you can find at a good hardware store or order on-line - as long as your machine handwheel shaft is 1/2" that is.

[nejcek74]

my solution for low speeds is a needle positioner,  going from up to down and back up with as much time in between as you want. No problems with low speed/power ration and the needle always finish the cycle (locks).

For a cheap servo is usually also a cheap needle positioner, sometimes they come included. All you need is half an hour to instal it, even if you get the instructions they are often just for something else :)))))

[friquant]

20 hours ago, EdCubberly said:

Just bought the Eagle EA 750-P Servo motor.

Can you upload the user manual? That hopefully will show us how to set the start speed  and the maximum speed. Also it may say what the absolute slowest the start speed can be set to. Once you know how slow the motor can go, you can do the math to figure out what pulleys will get you to your goal of 60 stitches per minute when the motor is at its slowest setting.

As others have indicated, smaller motor pulley, larger handwheel pulley, and/or gear reducer in the middle are all options to get you to your goal speed.  I also like what @nejcek74 said about a needle positioner giving you "as much time in between [stitches] as you want".