I'm looking to get into voice coil rewinding.
I have a few questions.
Where can I get some supplies?
Like a winder that can count turns?
Those metal cylinders of various sizes you use to build a new coil around? Not sure how to find these because I don't know what to call them.
Material to build the formers out of?
Is there anything I need to be aware of when buying magnet wire, other than gauge?
What do I use to hold the windings together? Epoxy? Varnish? Youtube videos showed epoxy. Slow cure?
I can replace voice coil assemblies and do reconing and refoaming already.
I have a few questions.
Where can I get some supplies?
Like a winder that can count turns?
Those metal cylinders of various sizes you use to build a new coil around? Not sure how to find these because I don't know what to call them.
Material to build the formers out of?
Is there anything I need to be aware of when buying magnet wire, other than gauge?
What do I use to hold the windings together? Epoxy? Varnish? Youtube videos showed epoxy. Slow cure?
I can replace voice coil assemblies and do reconing and refoaming already.
You need proper diameter copper enamelled wire.
Enamel must stand 130C or higher.
Epoxy is slow industrial type, curing overnight. Not 5 minute home type.
Main former is polished turned or you won't be able to remove paper former die
Former base is 0.1mm kapton aluminum Nomex Kraft paper paper.
Epoxy has 1 drop of toluene or acetone added to become more liquid (brush able) and delay curing.
Ampletos has a very good diy explanation..
Enamel must stand 130C or higher.
Epoxy is slow industrial type, curing overnight. Not 5 minute home type.
Main former is polished turned or you won't be able to remove paper former die
Former base is 0.1mm kapton aluminum Nomex Kraft paper paper.
Epoxy has 1 drop of toluene or acetone added to become more liquid (brush able) and delay curing.
Ampletos has a very good diy explanation..
Now (watching the rest of the video) I remember seeing that DMM displaying 8 before ... that video was posted a few years ago and I mentioned the 8 ohm DCR thing back then:
https://www.diyaudio.com/community/threads/custom-diy-8-fullrange-driver.308447/page-6#post-6121441
https://www.diyaudio.com/community/threads/custom-diy-8-fullrange-driver.308447/page-6#post-6121441
What do you mean by this?
For the former he uses "X-ray plastic, 1145 aluminum foil, and craft paper"
Do you know a good source for those?
I see a few packages of X-ray film on amazon, would cost me around $100CND for a package that would be as much as I'd ever need.Though I'd start with a smaller quantity if possible. Maybe my local art supplies store would have something close enough?
No idea where to find the right aluminum foil.
What sort of paper is the craft paper? Construction paper?
Is this epoxy suitable?
https://www.amazon.ca/gp/product/B0166FFFS4
English is a crude-ish language.
Here "former" is used for 2 very different parts:
* The polished metal cylinder around which everything is wound.
Polished so it's easier to slide away the finished voice coil.
and
The paper-aluminum-plastic-nomex tube around which wire is wound and glued to with epoxy.
Kapton and Nomex are typically 0.1mm thick.
Kraft paper is that strong brown paper used for flour and Portland cement.
All those insulating sheets can be bought at a transformer or motor rewinding shop.
Aluminum: again 0.1mm thick, you can get it at a hobby shop.
You must-degrease-wash your hands regularly, I use ethyl alcohol, any sweat or grease spot on clean metal or kapton will weaken adhesion.
It is very doable and practice makes perfect.
Yes, the Ampletos method is crude but works, will save you more than once. I
Here "former" is used for 2 very different parts:
* The polished metal cylinder around which everything is wound.
Polished so it's easier to slide away the finished voice coil.
and
The paper-aluminum-plastic-nomex tube around which wire is wound and glued to with epoxy.
Kapton and Nomex are typically 0.1mm thick.
Kraft paper is that strong brown paper used for flour and Portland cement.
All those insulating sheets can be bought at a transformer or motor rewinding shop.
Aluminum: again 0.1mm thick, you can get it at a hobby shop.
You must-degrease-wash your hands regularly, I use ethyl alcohol, any sweat or grease spot on clean metal or kapton will weaken adhesion.
It is very doable and practice makes perfect.
Yes, the Ampletos method is crude but works, will save you more than once. I
Finding a transformer/motor supply place that sells consumer level quantities seems a bit tricky. Is there one you use?
What holds the layers of the former together? Epoxy?
Where can I get a metal cylinder like the one he uses as a form for the coil? One like his that fits in the drill? I can find no leads on a source for those at all.
I found a local place with Kraft paper. So that's one thing off the list. I'll call some hobby shops to try to track down the aluminum.
Is the epoxy I linked in my previous post suitable?
It seems this isn't something a large number of people do. There's a speaker tech local to me who works on speakers including building his own voice coils and rewinding old ones. He can rewind tweeters too. I go to him sometimes. He's the kind who doesn't really share much knowledge though. Especially to another tech like myself who'd use that knowledge to compete with him. When I was at his place, I saw he had a bin of metal cylinders of various sizes to use as voice coil forms.
I've got a couple projects to get me started. A Tannoy Cheviot voice coil that is a good candidate for rewinding because the former is not damaged. For that all I need is the wire and epoxy. And I figured out what wire I need. And a later tannoy dual concentric model with a flat wire coil I cannot source. This might be tricky. But Bridgeport Magnetics has flat wire. I might be stuck with these unless I can fix them. I'll have to build full new coil assemblies for those.
Many thanks for your help!
What holds the layers of the former together? Epoxy?
Where can I get a metal cylinder like the one he uses as a form for the coil? One like his that fits in the drill? I can find no leads on a source for those at all.
I found a local place with Kraft paper. So that's one thing off the list. I'll call some hobby shops to try to track down the aluminum.
Is the epoxy I linked in my previous post suitable?
It seems this isn't something a large number of people do. There's a speaker tech local to me who works on speakers including building his own voice coils and rewinding old ones. He can rewind tweeters too. I go to him sometimes. He's the kind who doesn't really share much knowledge though. Especially to another tech like myself who'd use that knowledge to compete with him. When I was at his place, I saw he had a bin of metal cylinders of various sizes to use as voice coil forms.
I've got a couple projects to get me started. A Tannoy Cheviot voice coil that is a good candidate for rewinding because the former is not damaged. For that all I need is the wire and epoxy. And I figured out what wire I need. And a later tannoy dual concentric model with a flat wire coil I cannot source. This might be tricky. But Bridgeport Magnetics has flat wire. I might be stuck with these unless I can fix them. I'll have to build full new coil assemblies for those.
Many thanks for your help!
Coil winding is a science of its own. As the video shows it requires very special tools and knowledge.
The last coil winder I worked with in my region (Northern Germany) ceased operation some 15 yrs ago.
Nowadays the next coil winder might be found in poland for me.
This may be different in Argentina - but in Canada? Good luck!
The last coil winder I worked with in my region (Northern Germany) ceased operation some 15 yrs ago.
Nowadays the next coil winder might be found in poland for me.
This may be different in Argentina - but in Canada? Good luck!
You need something similar:
What's shown in video.
Wire is glued to former paper.
Start with paper which is classic specially for vintage speakers.
You won't "find" it, have one turned as needed.
Yes.
You bet 😄
A former employee learnt the trade and has been living out of it for decades now.
He has cylinder formers in all sizes turned out of hardwood. and repairs tons of car and DJ speakers.
Looks like they have the Kapton and Nomex in 0.13mm. Assuming that is close enough since you linked it.
I imagine every coil won't need all 4 layers? Not everything will be an 800W subwoofer.
I'll be going by the composition of the original coil I guess.
Maybe I could get this, and have a machine shop turn me some forms that would fit on it. There is a wood lathe at my parents but I might have a bear of a time getting wood forms accurate enough.
https://www.amazon.ca/gp/product/B00LHQLWLC/
I imagine every coil won't need all 4 layers? Not everything will be an 800W subwoofer.
I'll be going by the composition of the original coil I guess.
Maybe I could get this, and have a machine shop turn me some forms that would fit on it. There is a wood lathe at my parents but I might have a bear of a time getting wood forms accurate enough.
https://www.amazon.ca/gp/product/B00LHQLWLC/
Got the winder I ordered off amazon today! Trying a couple test coils to get the feel for it. Not using proper former material yet.
For the first attempt, I used the hand crank. This was awkward and I didn't get the wire tight enough.
For the second attempt I stuck the power drill on. Better.
The hardest part is starting the next layer of the coil without just pushing the last wire in the previous layer out of the way. Do I need to let the epoxy of the first layer start to harden more? Or is it about getting the wire tight enough? Any tips and tricks for this?
For the first attempt, I used the hand crank. This was awkward and I didn't get the wire tight enough.
For the second attempt I stuck the power drill on. Better.
The hardest part is starting the next layer of the coil without just pushing the last wire in the previous layer out of the way. Do I need to let the epoxy of the first layer start to harden more? Or is it about getting the wire tight enough? Any tips and tricks for this?
Attachments
Not needed or desirable to let epoxy harden, not even partially.
With practice you will find the slight angle needed for wire to lie just by the previous turn without pushing it away, same with wire tension.
There is an old guy from India who winds voice coils "in the air", no winder or drill involved, and he tensions wire by passing it around his naked (or sandal clad) foot thumb, go figure! 😱😱😱😱
We Humans can learn to do almost anything 😲
With practice you will find the slight angle needed for wire to lie just by the previous turn without pushing it away, same with wire tension.
There is an old guy from India who winds voice coils "in the air", no winder or drill involved, and he tensions wire by passing it around his naked (or sandal clad) foot thumb, go figure! 😱😱😱😱
We Humans can learn to do almost anything 😲
I have seen a few videos on winding guitar pickups, and it seems like those don't require well-aligned windings; these speaker coils are another level entirely, IMHO. 😬
This has been a very interesting and informative thread, indeed!
Many thanks, @JMFahey for the insights!
Kind regards,
Drew
This has been a very interesting and informative thread, indeed!
Many thanks, @JMFahey for the insights!
Kind regards,
Drew
I tried rewinding a tweeter tonight. I have lots of blown ones around because I don't like throwing that sort of stuff out.
It was a two layer coil which was tricky. I don't think I got the second layer as good as it could be. Might be short a few winds. But it seems to work.
I need one of those headsets jewellers use. The biggest obstacle here was I couldn't see well enough.
I've got another tweeter here that is just a single layer coil. This one shouldn't be hard.
Will have another go at a woofer coil too.
It was a two layer coil which was tricky. I don't think I got the second layer as good as it could be. Might be short a few winds. But it seems to work.
I need one of those headsets jewellers use. The biggest obstacle here was I couldn't see well enough.
I've got another tweeter here that is just a single layer coil. This one shouldn't be hard.
Will have another go at a woofer coil too.
So called flat wire actually is genuine circular one that has been milled/flattened by a pair of drums. So it's cross section isn't exactly rectangular. And I have no clue how one manages to wind it edgewise, as it JBL e.g. does/did.
Best regards!