Auto Winder

[John_H]

I looked at the thread. There's good information in there. I like the way that you measured the resonance of the dancer with a pickup, and I assume a scope. It's much more scientific than my "Kentucky windage" approach.

I do like the similarities in our thought processes. It lends me to believe I was initially on the right track. Thanks Joe.

[David King]

Midwest products makes 1/16" dia solid CF round spar that's going to be a lot lighter and stiffer than any music wire. It's available in 1 foot pieces at any hobby shop at about $1. You could try a glass bead for the tip of the dancer. Nicer fishing rods have ceramic guides that you can buy individually. Of course you could spring for a ruby wire guide. I'd just drill a 1/16" hole in a chunk of delrin and check it for wear every few months. If the CF is too stiff you can also buy it in .005" and .010" flat CF strips. Alternatively you could anchor it into a blob of elastopolymer. Think the goop they use to stick new credit cards to the paper inside the envelope. That stuff can probably move really quickly and yet dampen effectively too. Pure silicone caulking ought to have the right properties as well but it won't be self healing the way the sticky stuff is.

[Joe Gwinn]

Midwest products makes 1/16" dia solid CF round spar that's going to be a lot lighter and stiffer than any music wire. It's available in 1 foot pieces at any hobby shop at about $1.

I assume that "CF" is carbon fiber.

The dancer arm must be elastic, and the CF spar may be too stiff, and may not allow enough deflection. An experiment will tell.

You could try a glass bead for the tip of the dancer. Nicer fishing rods have ceramic guides that you can buy individually. Of course you could spring for a ruby wire guide.

The glass bead could work, so long as the inside is perfectly smooth, and does not have a little ridge from hot-pressing the glass into a bead. The ceramic guides and rubys are probably quite smooth.

In all cases, they can be attached with a not quite rigid adhesive.

I'd just drill a 1/16" hole in a chunk of delrin and check it for wear every few months. If the CF is too stiff you can also buy it in .005" and .010" flat CF strips. Alternatively you could anchor it into a blob of elastopolymer. Think the goop they use to stick new credit cards to the paper inside the envelope. That stuff can probably move really quickly and yet dampen effectively too. Pure silicone caulking ought to have the right properties as well but it won't be self healing the way the sticky stuff is.

Delrin is hard to glue, but can be press fit. What I did to attach a delrin eyelet assembly to the music wire dancer was to force the wire (which had been somewhat pointed on a sander) into an undersize hole in the delrin using a hammer.

[Joe Gwinn]

I like the way that you measured the resonance of the dancer with a pickup, and I assume a scope. It's much more scientific than my "Kentucky windage" approach.

Yes, a Tek TDS2012B scope. Many digital voltmeters can measure frequency as well, but may be difficult to use on the exponentially decaying signal.


As for damping the dancer, one approach (discussed in one of my threads) is to put a small plate made of aluminum flashing on the dancer, causing some air drag as the dancer bobs. One can move the plate up and down the dancer arm to vary the amount of damping (max samping near the wire eyelet, min damping near the stationary base.

[David King]

Or one could make an eddy current damper with a couple of Neos and strip of aluminum flashing that slides through an adjustable airgap. Hard to beat air for simplicity and it probably has a more constant damping factor at higher rates of speed whereas the eddy currents will go up with speed in either a linear (or exponential rate?)

[John_H]

Thanks for all of the great suggestions. It inspired my to look for solutions using common things that would serve as a dancer arm. For starter's I'm going to try some .063 dia. string trimmer line, and some plastic zip ties. I made 3 with different types of zip ties . and 3 new ones with guitar strings with different amounts of dampening.

I think the mass of the wire guide should be as small as possible. The less that you have flying around at the end of the dancer is less that you have to dampen. I made the wire guides with some .023 MIG welding wire.

I've got a few to try, but one cool thing is that I'll be able to switch them mid wind for comparison.

[kayakerca]

Thanks for all of the great suggestions. It inspired my to look for solutions using common things that would serve as a dancer arm. For starter's I'm going to try some .063 dia. string trimmer line, and some plastic zip ties. I made 3 with different types of zip ties . and 3 new ones with guitar strings with different amounts of dampening.

I think the mass of the wire guide should be as small as possible. The less that you have flying around at the end of the dancer is less that you have to dampen. I made the wire guides with some .023 MIG welding wire.

I've got a few to try, but one cool thing is that I'll be able to switch them mid wind for comparison.

I always wondered how the end of an old fishing rod would work. I'll have to see if I can find one kicking around somewhere and maybe give it a try.

[John_H]

I always wondered how the end of an old fishing rod would work. I'll have to see if I can find one kicking around somewhere and maybe give it a try.

I thought about trying a ceramic, or carbide rod guide, but I was hesitant because I wanted to keep the weight of the guide to a minimum. I think too much weight at the end of the dancer would result in it's own inertia causing erratic behavior.

[David King]

Weight is definitely the enemy especially when it's out at the end. BTW delrin glues just fine with CA if you rough it up a bit first and wipe it down with acetone to degrease it.
I bet your plastic wire tie ends will be the winners here though honestly I've never been clear on what the dancer is trying to accomplish for us. good old felt tensioners just work fine without anything else in the way.

[John_H]

I bet your plastic wire tie ends will be the winners here...

I haven't tried them all, but the medium sized zip tie's are getting good grades so far

...though honestly I've never been clear on what the dancer is trying to accomplish for us. good old felt tensioners just work fine without anything else in the way.

One advantage is that you can "see" the tension by how much deflection there is in the dancer. Should the "good old felt" start to loosen, You can see it in real time, and adjust the tensioner accordingly. I do believe that the dancer lays the wire at a more consistent tension. The coils seem to bulge less at the long sides.

[Joe Gwinn]

Weight is definitely the enemy especially when it's out at the end.

Yes. Lowers the resonant frequency. If too low, resonance happens, and the dancer starts to flail around.

BTW delrin glues just fine with CA if you rough it up a bit first and wipe it down with acetone to degrease it.

I have to wonder how secure this glue bond really is. Press fit isn't subtle, and so is reliable.

... I've never been clear on what the dancer is trying to accomplish for us. Good old felt tensioners just work fine without anything else in the way.

The purpose is to soak up the jerking due to the oblong bobbin, yielding a more uniform winding tension. Felt isn't bad at low tension, but even then a dancer can help, and dancers aren't exactly complicated.

[Joe Gwinn]

Thanks for all of the great suggestions. It inspired my to look for solutions using common things that would serve as a dancer arm. For starter's I'm going to try some 0.063" dia. string trimmer line, and some plastic zip ties. I made 3 with different types of zip ties and 3 new ones with guitar strings with different amounts of dampening.

I bet that the plastic dancers won't really work that well - not elastic enough.

I think the mass of the wire guide should be as small as possible. The less that you have flying around at the end of the dancer is less that you have to dampen.

Yes. The is why I ended up with a bit of delrin with two holes drilled in it.

[Chris Turner]

Hey John_H,

I'm thinking of adding an auto traverse to my own winder, using the same sort of setup you've got here, with the fishing reel, etc. What kind of eyelet are you using on the traverse arm to guide the wire?

[John_H]

Hey John_H,

I'm thinking of adding an auto traverse to my own winder, using the same sort of setup you've got here, with the fishing reel, etc. What kind of eyelet are you using on the traverse arm to guide the wire?

That's cool that you're going to give it a try. I'm anxious to see your results. Let me know if I can help.

The wire guide is a folded terminal eyelet. I polished it with some embroidery thread that I soaked in metal polish.

[Chris Turner]

That's cool that you're going to give it a try. I'm anxious to see your results. Let me know if I can help.

The wire guide is a folded terminal eyelet. I polished it with some embroidery thread that I soaked in metal polish.

John_H, can you post some closeups of the folded eyelet? Thanks!