servo motor startup speed

[GerryR]

When you say "smaller," from what diameter to what diameter.  In general, if the pulley it is driving remains the same, it would lower the speed and increase the torque, so there shouldn't be any problems.

[fibersport]

From what I can find, the original pulley on the Reliable/Sailrite motor is 60mm, I am currently running a 45 or 50mm pulley.  Sailrite specifies that you should not run their motor with their "Monster pulley", not sure if it's because of weight or diameter.  I do know that the Sailrite motor comes with a small diameter toothed pulley so I would think going with a smaller grooved pulley would work as well.  

[GerryR]

From what I could find on their website, it states that the "Workhorse Servo Motor (110V) should not be used with heavyweight balance wheels," so pretty sure it's an inertia problem.  Going down to the 45-50mm pulley gives you a slower speed and higher torque advantage over the 60mm, which I believe is in the direction where you were headed (?).

[fibersport]

Exactly.  I built a speed reducer and would loose some benefit using a 60mm pulley.  However, I would try the motor without a speed reducer first to see how I like it.  If it's not right, I can add my speed reducer and or look for a smaller pulley.  

[fibersport]

Got some interesting information tonight from Reliable.  I was told that the Quietsew 6000SM has a minimum speed of 500 rpm.  Different pulleys are able to be installed as well but the needle positioner will not work with different size pulleys.  I guess the benefit of the 6000sm might be the controllable startup speed.  It would be interesting to find out the minimum speed of the Consew 550 (and clones).

Edited September 28, 2023 by fibersport

[Wizcrafts]

1 hour ago, fibersport said:

It would be interesting to find out the minimum speed of the Consew 550

Are you referring to the Consew Premier CSM550-1 servo motor? If so, the start up speed is barely spinning. I have its predecessor, the Family Sew FS-550s on several of my sewing machines. Some power the machines directly, with a 50mm pulley, while others feed 2:1 or 3:1 speed reducers. If there is little to no load on the motor, it starts spinning very slowly. Under load I have to give it more pedal or knob rotation to overcome the resistance. The machine will still run very slowly unless I turn the limiter knob up high. Even then, the slow speed is fairly easy to control with my steady foot.

One of my machines fed directly from a FS-550s is a long bed walking foot machine with a 5" hand wheel pulley. I can run the machine at 1 stitch per second with ease and it ramps up from zero smoothly. I frequently use that machine to sew patches onto the back of bikers' vests. The analog servo gives me total control over the speed. I can stop it with the needle down to turn corners.

[fibersport]

Yes, that's the one.  I'm still on the fence over the digital and analog motors, or do I just sit tight and live with what I have - decisions decisions ..... I really think all would be fine, I just need to dive in and spend more time sewing, if only my job didn't require that I be there every day!  Thanks again for your input Wiz -

[CowboyBob]

12 hours ago, fibersport said:

Got some interesting information tonight from Reliable.  I was told that the Quietsew 6000SM has a minimum speed of 500 rpm.  Different pulleys are able to be installed as well but the needle positioner will not work with different size pulleys.  I guess the benefit of the 6000sm might be the controllable startup speed.  It would be interesting to find out the minimum speed of the Consew 550 (and clones).

I got my tachometer out & the lowest speed running a machine is 150rpm with a CSM-550-1 and that's why we use them on everything.No boards to blow either.

[GerryR]

1 hour ago, CowboyBob said:

I got my tachometer out & the lowest speed running a machine is 150rpm with a CSM-550-1 and that's why we use them on everything.No boards to blow either.

Is that motor shaft speed or gear reducer output speed?

[Gump]

Hate to argue with Reliable, but my Sewquiet 6000 runs at 198 rpm minimum at a steady rate. I used a laser tach directly on the motor pulley.

[CowboyBob]

1 hour ago, GerryR said:

Is that motor shaft speed or gear reducer output speed?

Shaft speed

[GerryR]

3 hours ago, CowboyBob said:

Shaft speed

So, with a 5:1 reducer you would have 30 stitches per minute, or 1 every 2 seconds, as your slowest speed: am I interpreting this correctly?  If so, there should be plenty of starting torque to pierce most any thickness of leather.

[CowboyBob]

12 hours ago, GerryR said:

So, with a 5:1 reducer you would have 30 stitches per minute, or 1 every 2 seconds, as your slowest speed: am I interpreting this correctly?  If so, there should be plenty of starting torque to pierce most any thickness of leather.

The 150 is w/o a reducer,the motor will run slower with one since there's less friction.Our box style reducer has a 4:1 ratio & the speed is 15 RPM sewing 20 oz of leather on a CB341,so motor is down to 120 RPM.

[Gump]

Fibersport; What machine are you putting a servo on? Sewing at 1.7 stitches a second is a snails pace. You will grow tired of that really fast. These new servos have full torque at minimum rpm. I have the same variety of servo on Techsew 3800/cb 3200, and I removed the speed reducer as it wasn't necessary. It eases the needle through 1/2" vegtan for fun. My Artisan Toro also has a digital servo with 5:1 reduction that sew 7/8" without a hesitation. I can't compare them to a Consew servo, but I don't have a lack of torque problem.

[fibersport]

It's a Pfaff 545.  I already have a servo motor on it but it's a few years old and probably a low end one.  I'm not looking to sew at that speed, I just don't want to have the motor start turning at a high speed for the first few stitiches.  I built a speed reducer that is about a 5:1 ratio which really helps, I'm just looking to see if I can make it any better in terms of a slow ramp up speed.  The higher the max speed setting on mine, the less control I have on my ramp up speed.  It's like anything else, the less you spend the less you get, so my less expensive servo motor gives me less control.  

[Gump]

At 5:1 ratio, a sewquiet 6000 will give you 40 stitches per minute minimum. Thats 1.5 seconds per stitch, that is slooooow.

[fibersport]

Again, I'm not looking to maintain the slow speed, only to have a slow ramp up speed, 

[GerryR]

25 minutes ago, fibersport said:

Again, I'm not looking to maintain the slow speed, only to have a slow ramp up speed, 

Not trying to belabor an issue, (and I don't have any financial interest in 3-ph AC VFD's), but this is where 3-ph VFD's / motors excel over other systems.  You can set accell / decell speeds in Hz-per-seconds or some systems use time-in-seconds up to your programmed or foot pedal top speed.  One Hz per second would be a very long accelleration time.  Just something to think about.

On the system Gump is talking about, your foot would control the accelleration time from a very slow start, so either method should do what you want.  

[CowboyBob]

2 hours ago, fibersport said:

Again, I'm not looking to maintain the slow speed, only to have a slow ramp up speed, 

I checked the speed again you can ramp it up slowly with your foot anywhere from 25 to top speed of 410

[dikman]

The big problem with using a 3-phase motor/VFD combination, in this particular case, is finding/making a suitable foot-operated pedal to control it (not as simple as you might think). I just tried to make one for a speed controller for a small sewing machine motor and gave up.

[GerryR]

7 minutes ago, dikman said:

The big problem with using a 3-phase motor/VFD combination, in this particular case, is finding/making a suitable foot-operated pedal to control it (not as simple as you might think). I just tried to make one for a speed controller for a small sewing machine motor and gave up.

It really isn't that big an issue.  I have a Pfaff 1221 machine that I refurbished; it came without a foot pedal.  For ~$30.00 I bought a used Tig welder foot pedal (I have a TIG welder, so knew how they were made) which has a pot and a microswitch inside; the Pfaff requires a pot, but I also used the switch to my advantage.  The VFD's require a pot.  It was very easy to convert to run the Pfaff, and it is way more substantial than the plastic junk that passes for foot pedals these days.  I only offer these suggestions so others realize that there are options;  you don't always have to follow the "party lines."

[Wizcrafts]

The Consew analog servo motor sold by Toledo Industrial Sewing Machines is probably all you will need. It can be ordered with a pulley as small as 45mm. This is less than 2 inches diameter. I'm pretty sure that the pulley on your Pfaff balance wheel is at least 4 or 5 inches diameter, giving you more than 2:1 speed reduction/torque multiplication. You can install it yourself. Your local hardware or auto parts store will have a selection of type 3L v-belts to connect the motor and machine and leave 1/2 inch of slack in the center. The knob on the front of the motor limits the top speed and can be changed on the fly as you sew. I do it many times. I might start with a slow speed setting until I get to a long seam. Then, I reach down and spin the knob and it's off to the races. Still, it is possible to slow down the motor gradually from the top speed setting. It's just not as smooth on the ramp up compared to a much lower setting.

[Gump]

Get a treadle machine.

[dikman]

GerryR, I wasn't aware that TIG pedals had a pot inside, I'll keep that in mind, thanks.

[GerryR]

1 hour ago, dikman said:

GerryR, I wasn't aware that TIG pedals had a pot inside, I'll keep that in mind, thanks.

A pot and a switch.  The switch initiates the arc, and the pot regulates the welding current.  The pot can be used directly for the Pfaff machines with the built-in speed control electronics (minor mod), like the 1200 series, or you can install a triac motor speed control and use the pot to control the triac output.  Many options!