Looking for a low speed start servo

[chrisash]

To go with my new (ish) 111, i am looking for advice on a new servo which will give me slow speed without a reducer and the power to get through say 2 x 3mm veg tan which is about average for what i do

I bow to your experiences

thanks

[Constabulary]

Most "cheap" servos start at 200-300 rpm and have a 70mm pulley. To slow down the motor far enough you may install a larger hand wheel instead of a speed reducer. I do not know of any "cheap" (meaning 100-200€ / GBP range) servo motor in the EU hemisphere that is extremely slow at the start and has a good amount of torque at slow speed. Not saying there is none but I do not know of any. The addition of a 40-50mm motor pulley + a larger hand wheel or a speed reducer is almost mandatory I´d say. I don't want to got without a SR - I have them on all my machines. Much more comfortable!

Maybe the HoShing series is what you need but I have no experience with them.

https://globalsew.com/ho-hsing/

Edited November 7, 2020 by Constabulary

[Wizcrafts]

My Family Sew FL-550s with a 50mm pulley meets that description. However, a lot depends on the diameter of the machine pulley. I use this motor on several machines and it has the most low speed torque on machines with larger top pulleys. The others need a speed reducer. I would say that if your machine has at least a 4" pulley you will be good to go with just this motor and its 50mm pulley.

In the event this exact motor isn't available where you are at, try to find a Consew equivalent and buy a 50mm pulley that fits its shaft (I think it is close to 5/8 inch, or a metric equivalent). Just make sure the motor has brushes and a knob to control the speed.

[Gymnast]

3 hours ago, Wizcrafts said:

My Family Sew FL-550s with a 50mm pulley meets that description.

I got no daubt that this is a good motor to use. But I am a bit puzzled by the specifications in the link:

110 volts AC, 550 Watts

3/4 HP output

3/4 HP output is the same as the same as 552 W shaft power. It is actually a bit more than the specificed input electrical power to the drive. I know something about this size of motors, and my estimate would be an effiency of about 60 % at max power output. So something is wrong with these figures. Perhaps the the specified shaft power is less or the specified input power is higher. If the motor provide 552 W shaft power at 60 % motor and drive efficiency, the input power should be 920 W.

Edited November 7, 2020 by Gymnast

[Pintodeluxe]

Motor HP claims are notoriously incorrect.  Just call it a 550 watt and use that to compare one model of servo to another.

I second the Family 550 servo (aka New Tech, Rex, Consew).  I use them with and without reducers.  Approaching 20oz of total leather sewn, the reducer is nice.  But with lighter / thinner leather than that, the reducer probably isn't necessary.  

Best of luck with it. 

[Constabulary]

yes but afaik the Family sew motors are not available on our sides of the pond (meaning EU and UK) and in 230V but I may be wrong.

[dikman]

The "generic" push-button servos work well with a small motor pulley and either a reducer or large pulley to replace the handwheel.  I know you said you don't want to fit a reducer, Chris, but you may not have any choice in order to achieve what you want.

[Gymnast]

2 hours ago, Constabulary said:

yes but afaik the Family sew motors are not available on our sides of the pond (meaning EU and UK) and in 230V but I may be wrong.

I just looked at motors from some suppliers in Europe, and I agree that it is hard to find the brushed DC motors. Almost all servo motors sold in Europe seems to be of the brushless type. I found one supplier in the UK via ebay with a brushed DC motor:

https://www.ebay.co.uk/itm/Industrial-Sewing-Machine-Servo-Motor-Mains-240v-with-On-Off-switch-Fittings-/263472630087 

I guess it will work like the Family motor Wizcrafts suggested.

If you go for a brushless servo motor, as it seems most users do in Europe, then look for a motor with a minimum speed at 100 RPM. Most motors got a minimum speed at 200 RPM or even 500 RPM. Do not trust a specifications that say 0 RPM to 4500 RPM. It do have a minimum speed higher than zero. This is one brushless motor sold in Europe, with a minimum speed of 100 RPM:

https://www.sewtex.de/Motore--Gestell--Tischplatte--Zubehoer-fuer-Naehmaschinen--Stuehle--Leuchten--Transportwagen--Industriestuhl--Schere/ZOJE-TZ-ZJ550W-S-Servomotor--Naehmaschinenmotor.html 

I guess you can find a supplier for that in UK as well. I never used a Zoje servo motor, but I have seen a few good reviews.

Edited November 8, 2020 by Gymnast

[Constabulary]

1 hour ago, Gymnast said:

just looked at motors from some suppliers in Europe, and I agree that it is hard to find the brushed DC motors. Almost all servo motors sold in Europe seems to be of the brushless type. I found one supplier in the UK via ebay with a brushed DC motor:

https://www.ebay.co.uk/itm/Industrial-Sewing-Machine-Servo-Motor-Mains-240v-with-On-Off-switch-Fittings-/263472630087 

I guess it will work like the Family motor Wizcrafts suggested.

Look at that - so I better shut up 

But 0 is off, right? And next step is 350 or is there an acceleration ramp between 0 and 350 when the knob is on 0?

Edited November 8, 2020 by Constabulary

[chrisash]

Looking at the Jack 513A does anyone have any knowledge of it

See it comes in 550 watt and 750 watt with only £20 difference in price

750 watt has top speed of 3500 compared to 550 at 4500 so does this mean  a probable lower starting speed i.e. 100 rather than 200rpm

Can you overpower machine in normal use

Be nice if we had a section on servo motors and what people thought of their model for use on leather

[Constabulary]

I run 2 Jack Servos with 750w. One on a 111G156 with 1:3 speed reducer. No problems since 2014. The 111G155 / 156 machines have safety clutches if something goes wrong but generally you cannot overpower these machines. The safety clutch will not release just because of a higher power motor you need a resistance like needle hitting a hard spot in the material or the needle plate or at the hooks thread has accumulated a bird nest and blocks it but other than that you motor will run without problems. I sew really hard cotton webbing. BTW - I never have released my safety clutch.  At slow speed you rather hear the motor knurling when sewing hard material but again the safety clutch never released. Thats at least my experience.

[Wizcrafts]

5 hours ago, Constabulary said:

Look at that - so I better shut up 

But 0 is off, right? And next step is 350 or is there an acceleration ramp between 0 and 350 when the knob is on 0?

If that Eagle brand motor works like my Family Sew motor, the speed settings around the dial are the maximum motor speed, not the minimum. these motors start at zero and increase linearly as you depress the pedal. there is no ramping up to speed. There may or may not be enough turnover power at the slowest setting until one gives it about half pedal. But, mine all have a 50mm pulley and can keep a machine spinning a stitch or two per second. I am satisfied with my Family Sew motors.

Regarding servos feeding reducers, that's the cat's meow. My Cowboy CB4500 is geared down 9:1 from the motor to the reducer to the hand wheel. I can sew at a minimum speed of watching grass grow.

[Gymnast]

9 hours ago, Constabulary said:

Look at that - so I better shut up 

But 0 is off, right? And next step is 350 or is there an acceleration ramp between 0 and 350 when the knob is on 0?

I agree with Wiz. For the brushed DC motor type, the motor is controlled from zero. However the drive types with a brushed DC-motor do not have a steep moment curve as a brushless motor with more drive electronics. If you run a brushed DC motor drive for sewing machines very slow, and it gets some high torque load, the motor can be stopped. A brushless motor drive running slow will resist being stopped with all its torque available. In this way these servo motors are different and some may like one more than the other. And they may each be better for different jobs. This video show how this response to torque works on the two motor types: https://youtu.be/SOyQtt3eDLw

The Jack servo motors are of the brushless type. I tried to look for their specification regarding lowest constant speed, but I could not find it.

[chrisash]

On 11/8/2020 at 12:50 PM, Constabulary said:

I run 2 Jack Servos with 750w. One on a 111G156 with 1:3 speed reducer. No problems since 2014. The 111G155 / 156 machines have safety clutches if something goes wrong but generally you cannot overpower these machines. The safety clutch will not release just because of a higher power motor you need a resistance like needle hitting a hard spot in the material or the needle plate or at the hooks thread has accumulated a bird nest and blocks it but other than that you motor will run without problems. I sew really hard cotton webbing. BTW - I never have released my safety clutch.  At slow speed you rather hear the motor knurling when sewing hard material but again the safety clutch never released. Thats at least my experience.

Hi

Have you run the 750 watt jk563a at the quoted 200 rpm and does it have power  at that speed to sew 4 mm leather

Have just measured the hand wheel at 80 mm diameter and the intended drive pulley at 45 mm

Edited November 16, 2020 by chrisash