# Controlling wire tension in a coil winder

#### Tonyr1084

Joined Sep 24, 2015
6,269
A dancer roll? Isn't that when you drop the toilet paper roll and try to prevent it from getting away by pulling on the paper?

#### bertus

Joined Apr 5, 2008
21,549

#### cmartinez

Joined Jan 17, 2007
7,417
Now I remember the "dancer roll" ... it's just that we know them by a different name down here

Danko, I'll be aquiring two of these for testing purposes. I'll also buy a few of the caps they say are needed, those caps are easy to find where I am, but I just want to make sure they're the right ones. The page says that it's a 1.3uF cap, but the picture says that it's 1.3MFD ... and I'm wondering if it's 1.3 millifarads instead (I doubt it)

#### cmartinez

Joined Jan 17, 2007
7,417
Hello,

The internet is full of images for dancer roll tension control:
dancer roll tension control

Bertus
thanks, Bertus ... as a matter of fact, I'm quite familiar with dancer roll mechanisms. What I ignored was what they were called in English

#### Danko

Joined Nov 22, 2017
1,134
Danko, I'll be aquiring two of these for testing purposes. I'll also buy a few of the caps they say are needed, those caps are easy to find where I am, but I just want to make sure they're the right ones. The page says that it's a 1.3uF cap, but the picture says that it's 1.3MFD ... and I'm wondering if it's 1.3 millifarads instead (I doubt it)
Please, look at my post #40
There is more cheaper motor.
Edit: MFD is uF in theirs interpretation.

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#### cmartinez

Joined Jan 17, 2007
7,417
Please, look at my post #40
There is more cheaper motor.
I did read the post, thank you. But the motor in post #40 is rated at 1.1 oz-in torque, while the other one has 1.8 oz-in. I'd rather have that extra torque in case I need it, and I can always bring it down by using a smaller capacitor. Plus, the motor I chose has a straight shaft and is easier to adapt to what I'm doing, while the other one is a spline. And a $6 dll difference is not that important. #### Danko Joined Nov 22, 2017 1,134 I did read the post, thank you. But the motor in post #40 is rated at 1.1 oz-in torque, while the other one has 1.8 oz-in. I'd rather have that extra torque in case I need it, and I can always bring it down by using a smaller capacitor. Plus, the motor I chose has a straight shaft and is easier to adapt to what I'm doing, while the other one is a spline. And a$6 dll difference is not that important.
OK. This is your circuit: Black capacitor is 1.3uF. Red capacitor you will select for tension, you need.
1.3uF - it is value for full speed of motor, but in your case motor is stopped.
For this mode max torque will with value of black capacitor about 13uF. Torque is almost proportional to value of C_black.
Then you will select C_red for torque you need.

#### cmartinez

Joined Jan 17, 2007
7,417
OK. This is your circuit: View attachment 151167Black capacitor is 1.3uF. Red capacitor you will select for tension, you need.
1.3uF - it is value for full speed of motor, but in your case motor is stopped.
For this mode max torque will with value of black capacitor about 13uF. Torque is almost proportional to value of C_black.
Then you will select C_red for torque you need.
Just to verify, and to make sure that I understand what you're saying, for testing purposes I need a 13µF for the black capacitor, and 1.3µF for the red one? So the black capacitor stays fixed at 13µF, and then I just change the value of the red one to adjust torque?

#### Danko

Joined Nov 22, 2017
1,134
Just to verify, and to make sure that I understand what you're saying, for testing purposes I need a 13µF for the black capacitor, and 1.3µF for the red one? So the black capacitor stays fixed at 13µF, and then I just change the value of the red one to adjust torque?
Yes, you are right.
Because of stopped (start) mode, black capacitor should be 1.3 * 10 = 13uF for max torque.
Then experiment with C_red. Begin with small value, about 1uF.

#### BobaMosfet

Joined Jul 1, 2009
1,850
I see a much simpler solution using a physical spring. Wondering if that would make sense to anyone.

#### cmartinez

Joined Jan 17, 2007
7,417
I see a much simpler solution using a physical spring. Wondering if that would make sense to anyone.
Yes, I thought about a mechanical solution to the problem as well. A spring is one of them. But that is what I call a passive mechanism, which would still need a slip-clutch or a friction "shoe", and the spring would vary the tension on the wire when it becomes stretched, which is undesirable. Also, I intend to run the winder backwards in parts of the process which will change the direction of the winding (by reversing rotation) where needed. So in some parts the motor applying tension to the wire will rotate forwards and in other backwards, as it is being dragged or released by the winder motor. A spring and/or a clutch or friction brake are incapable of compensating for that. In the end, it is much simpler (mechanically speaking) if a counter-motor directly coupled with the spool is used. Such as I intend to do.

#### cmartinez

Joined Jan 17, 2007
7,417
Yes, you are right.
Because of stopped (start) mode, black capacitor should be 1.3 * 10 = 13uF for max torque.
Then experiment with C_red. Begin with small value, about 1uF.
Danko, your advice (which I'm sure is based on experience) is proving invaluable. I want you to know that I thoroughly appreciate all the help you've been giving me on this (and other) threads. Many, many thanks.

#### btebo

Joined Jul 7, 2017
100
Not familiar ... a sketch would indeed be appreciated ... thanks for the offer
Crude drawing - I saw some better drawings on subsequent posts....

The key thing is, the WEIGHT of the dancer roll determines tension.

When the dancer rolls gets lifted up to the top part of travel, I use a sensor to turn on the unfeed roller motor (which is the main roll of unused wire) which spins it off until the dancer gets to the lower part of travel. The dancer sees a lower limit and shits of the unfeed roller motor....

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#### cmartinez

Joined Jan 17, 2007
7,417
Crude drawing - I saw some better drawings on subsequent posts....
I see nothing wrong with your work of art ... ... seriously, it's easy to understand and that's what counts

#### btebo

Joined Jul 7, 2017
100
I see nothing wrong with your work of art ... ... seriously, it's easy to understand and that's what counts
I'll be sure to put it on my refridgerater tonight!!!

Good luck.

#### Danko

Joined Nov 22, 2017
1,134
Danko, your advice (which I'm sure is based on experience) is proving invaluable. I want you to know that I thoroughly appreciate all the help you've been giving me on this (and other) threads. Many, many thanks
I am embarrassing.
I see a much simpler solution using a physical spring. Wondering if that would make sense to anyone.
First thing we need avoid is mechanical contact wire to anything, because of possibility of enamel damage.

#### cmartinez

Joined Jan 17, 2007
7,417
First thing we need avoid is mechanical contact wire to anything, because of possibility of enamel damage.
yes, that's another factor I forgot to mention

#### shortbus

Joined Sep 30, 2009
8,816
Use a dancer roll - if not familiar, let me know and I'll draw up a brief sketch...
That's how wire winding was controlled where I worked. But it was on way bigger rolls of wire than C is using. Though we called them "dancer arms".

#### cmartinez

Joined Jan 17, 2007
7,417
That's how wire winding was controlled where I worked. But it was on way bigger rolls of wire than C is using.
Oh yeah... I'm familiar with big winders ... but winding a gauge #32 to #42 in tiny coils with 10 mm id is an entirely different thing

#### shortbus

Joined Sep 30, 2009
8,816
Oh yeah... I'm familiar with big winders ... but winding a gauge #32 to #42 in tiny coils with 10 mm id is an entirely different thing
Before going into an electronic solution, the ones in Albert and Alex's posts #8 and 9 would be what I would try. With the tensioner in those posts on the center of the supply spools axis there shouldn't be a problem with over shoot/backlash in the winding. Another felt buffer on the supply spool would probably take care of any that did come up.

Or another thought would be to put the supply spool upright below the spool being wound and still using the tensioner. The spool upright would act like the spool on a fishing spinning reel.