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Caught Out By A Smart Servo Motor

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My 441 clone has an old Ho-Hsing HVP-58 motor on it that I pulled off of another machine. It's got plenty of power, needle positioning, and what seemed like a useful range of adjustments to pickup speed etc.

The problem with it is that its low speed setting is still 200spm, which is a bit too fast for me. "No problem!" thinks me, "I'll just put a smaller pulley on it". No such luck.

I replaced the 100mm pulley with a 50mm pulley, got a new belt to go between the motor and speed reducer, and tried it out.

It runs at exactly the same SPM. :ranting2:

The problem is that it's too clever for me. It's not getting its rotational speed from the motor, it's getting it from the NPS unit on the shaft on the machine. In addition to the usual needle-up and down position sense wheels, it also has a speed sensor wheel so the net effect of putting the smaller pulley on is that the machine runs at exactly the same speed but the motor is whirring away much faster.

post-13283-0-71078300-1427150231_thumb.j

*sigh*. Time to save up for a dumber motor.

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LOL - pull of the NPS if it will let you

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Sorry to hear this. As I said earlier I´m done with these NPS on servos. My work is too simple and I figured I don´t really need it at slow speed.

College Sewing offers a "new" servo for "Heavy Duty" machines.

https://www.college-sewing.co.uk/SV71-650-WATT-220V-0.87-HP-SERVO-MOTOR-WITH-NEEDLE-POSITION

See attachment for a brochure for this motor.

Seems the accelerator unit is attached to the control box - I don´t think thats clever but thats how they make it.

Not sure if this is really an alternative...

SV-71.pdf

Edited by Constabulary

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I will have 550W and 800W servos in stock soon. The 800W have NPS but run without it - many won't

$450 plus postage from Australia for the 800W

Also have speed reducers at $295

Can probably knock a dollar or two off for the pair

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LOL - pull of the NPS if it will let you

Nope. Without the positioning unit plugged in the motor just spins at top speed as soon as it's powered on.

I just put a dumb servo from another machine that isn't getting much use at the moment on the 441. It's only a 400W, but it seems to do the job and it's slow enough to control. It'll get me by until I get a better one.

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Sorry to hear this. As I said earlier I´m done with these NPS on servos. My work is too simple and I figured I don´t really need it at slow speed.

I don't need NPS, but it is nice. Not at the expense of basic functionality though.

College Sewing offers a "new" servo for "Heavy Duty" machines.

https://www.college-sewing.co.uk/SV71-650-WATT-220V-0.87-HP-SERVO-MOTOR-WITH-NEEDLE-POSITION

See attachment for a brochure for this motor.

Seems the accelerator unit is attached to the control box - I don´t think thats clever but thats how they make it.

Not sure if this is really an alternative...

Thanks for that. I'll probably go for the 750W Jack one the next time I'm ordering something from them, which will be after I've got another job, but the machine is working for now.

Treadles are so much easier!

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Very sure. Have 30 motors coming soon.

These prices are Aussie dollars

Sorry Darren but are you sure about these prices?

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