Brushless servo help

[chris032188]

I recently swapped from my TacSew clutch to a servo motor. I am wondering if there is a way to slow the motor down, I don't mean the RPM - I am using a servo and it drops to 100 RPM, but I mean when I hit the pedal it feels like the motor is either on or off, no real feathering like I could on the clutch motor. I was hoping there would be a way to adjust it so if I lightly hit the pedal the machine would slowly crawl? the TacSew  clutch motor was tuned pretty good and I was able to feather the peddle and get a little needle movement at a time / a single stitch (unless I goofed and hit it to hard) which is kinda what I am hoping to get

[Wizcrafts]

  On 10/3/2022 at 2:26 AM, chris032188 said:

I am using a servo and it drops to 100 RPM, but I mean when I hit the pedal it feels like the motor is either on or off, no real feathering like I could on the clutch motor.

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About a decade ago this was a major problem when the main leather machine companies began shipping digital servos. They started up at between 100 and 200 rpm with nothing between zero and starting speed. Leather Machine Company came up with a clever hack that let the motor start up controllably. It was a piece of clear plastic that was printed with a variable density that was placed between the light source and the photocell. One of those was connected to the speed control lever (I forget which). As the pedal was moved from the off position the density of the filter changed much more gradually than the original light beam shroud. It took a little manipulation to find the right spot to tape it down. Once that was done the motor would slowly speed up and was controllable down to under 1 stitch per second with a 1:3 speed reducer. I installed the filter on the servo motor that shipped with my cb4500 and left it in place for about 3 or 4 years. Then it began developing a dead spot and it had to go. So, I bought an analog servo motor, with a simple knob limiter. It is still on the machine after 6 years and lets me sew as slow as a 10th of 1 stitch per second.

I have the same motor on a long arm walking foot machine. It has a 2" motor pulley, no reducer, and the balance wheel has a 5 inch diameter pulley. That machine sews as slow as 1/2 stitch per second if I keep my foot steady.

[kgg]

  On 10/3/2022 at 2:26 AM, chris032188 said:

I am wondering if there is a way to slow the motor down,

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Some of the problems with the servo motors has to do with the number of internal coils the motor has. The more internal coils the better low start control you will have. I think maybe installing a speed reducer may help overcome this bottom end startup problem. I run 550 watt brushed servo motors with the simple knob limiter and no speed reducers on all my machines like Wiz has suggested.

kgg

[Constabulary]

The speed reducer probably is the best solution for you. It ads torque and slows down the sewing speed. So at very slow speed you are still able to sew quite very thick materials (depends on your work and material if you need that or not). I have speed reducer on ALL my industrial machine tables / stands.

Edited October 3, 2022 by Constabulary

[chris032188]

  On 10/3/2022 at 5:04 AM, Wizcrafts said:

About a decade ago this was a major problem when the main leather machine companies began shipping digital servos. They started up at between 100 and 200 rpm with nothing between zero and starting speed. Leather Machine Company came up with a clever hack that let the motor start up controllably. It was a piece of clear plastic that was printed with a variable density that was placed between the light source and the photocell. One of those was connected to the speed control lever (I forget which). As the pedal was moved from the off position the density of the filter changed much more gradually than the original light beam shroud. It took a little manipulation to find the right spot to tape it down. Once that was done the motor would slowly speed up and was controllable down to under 1 stitch per second with a 1:3 speed reducer. I installed the filter on the servo motor that shipped with my cb4500 and left it in place for about 3 or 4 years. Then it began developing a dead spot and it had to go. So, I bought an analog servo motor, with a simple knob limiter. It is still on the machine after 6 years and lets me sew as slow as a 10th of 1 stitch per second.

I have the same motor on a long arm walking foot machine. It has a 2" motor pulley, no reducer, and the balance wheel has a 5 inch diameter pulley. That machine sews as slow as 1/2 stitch per second if I keep my foot steady.

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I have a sailrite monster flywheel onone of my older machines, I wonder if that will fit my 111w

[dikman]

  On 10/3/2022 at 11:02 AM, Constabulary said:

The speed reducer probably is the best solution for you. It ads torque and slows down the sewing speed. So at very slow speed you are still able to sew quite very thick materials (depends on your work and material if you need that or not). I have speed reducer on ALL my industrial machine tables / stands.

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My approach too. It is usually possible to tweak the settings to some extent but this seems to be a common issue with most of the digital servos on the market.

[chisel]

Video shows a similar hack to the LMC one that Wiz mentioned:

https://www.youtube.com/watch?v=X6CCxv3i4No

 

[dikman]

Be aware that hack/mod doesn't apply to most, if not all, of the newer servos as they no longer use that method to vary speed.

[sbrownn]

  On 10/3/2022 at 12:43 PM, chris032188 said:

I have a sailrite monster flywheel onone of my older machines, I wonder if that will fit my 111w

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I'm running a Campbell Randall with a servo and speed reducer and it has a monster flywheel so I'm guessing you would probably be all right.  A lot depends on how slow you want it to run.