Need help building a label rewinder

I need to build 3 different sizes of label rewinder for a customer of mine, and the whole system is pretty simple. But I am drawing a blank when coming up with a slip clutch, bearing, design so the shaft spins but the labels dont spin. If you dont know what a rewinder is, this is needed so when the label printer stops, it doesnt burn the motor up, or knock it down itself.

I will need to build one like the size in the picture 8" diameter, and up to full size rolls at 12" diameter.



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Reel to Reel tape machines use a "torque motor".

You can look here for inspiration:

Torque-Limiting Shaft Couplings

But you might think about doing this electronically, with a current limit sensor circuit that's set for a reasonably low current level that is still beyond the draw of the normally functioning device. You can add a timer so that brief spikes (like starting up) don't prematurely turn off the motor.

some magnets on a plate, make a magnetic coupling.

Since I have to build a few different versions and this one they already have is getting old (China stuff). I may just buy a nee one for them and strip the old one to find out.

Doug, I was thinking something like UHMW washers tighten against each other inside the shaft.

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Bondo said:

Since I have to build a few different versions and this one they already have is getting old (China stuff). I may just buy a nee one for them and strip the old one to find out.

Doug, I was thinking something like UHMW washers tighten against each other inside the shaft.

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So what speed will the motor run at ?
Fast enough when the roll is new (very small) and you'll need a higher speed.
When the roll fills up, you'll have too high a speed, and the clutch will be making heat.

Try magnets.

Are you allowed to have a tension arm? If so just make it with adjustable spring tension so that once it lifts with the paper tension it hits a microswitch and the motor stops.

A belleville washer preloaded clutch (brass maybe?) wouldn't hurt if the motor has significant inertia and gearing.

PTO clutches (or AC clutches) are great for mounting on shafts and the pulley can be either engaged or disengaged, if you don't have the ability to make the spinning stop (if it has to be synchronized to something else)

It appears that this is the "takeup" roller from a printer, which may stop and start at any point, with any amount of paper on the roller. a 12" diameter roll of paper has significant inertia, so a spring loaded roller that can take up slack may very well be your friend in any case.


I potentiometer feeding into a servo loop is the smoothest approach, but a microswitch as mentioned will work.

I've used magnetic particle clutches. Placid Industries was the brand name. Tension was adjustable by a potentiometer.

Another drive that seems to have fallen out of favor is an eddy currant drive. They were popular before all the computer tech. Maybe a little to bulkey for your app.
Friction drives require pressure changes with roll diameter as mentioned above so can get complicated.
We have some machines that apply film to cartons that use an E-P valve with a dancer pot for control and an air clutch.Would work for you but would be pricy. I don't like them for our application because of an interupted feed which requires an accumulator and makes them kind of finiky to adjust.
I have wanted to swap over to a mag particle clutch which would seem to be ideal.
Your rewind stand has its own drive?Why not start and stop with a signal from the printer?