Hi All-
After lurking for some time, finally had reason to join and post a question or two.... well maybe more.
Just picked up a pair of Rectilinear Mini III speakers for my office, with a non-functional woofer. Paper bobbin voice coil had separated from the cone, so I'm ready to wade into a voice coil winding project. Maybe due to air leak or just age...
After a lot of time spent watching videos and reading posts, I think I have what I need, less a few critical pieces of info.
As these are low power speakers, I had considered winding on a paper bobbin, but most info on the web speaks to nomex or kapton, and I'm not finding much in the way of suppliers of paper bobbin stock. So, path of least resistance, I'm considering kapton. The original paper bobbin was ~0.004" thick, so Question 1: would 0.003 or 0.005 kapton sheet be an acceptable/appropriate substitute for original bobbin?
Question 2: I assume sheet kapton (no adhesive) is preferred over the kapton tapes I see available?
Question 3: I'll be using non-adhesive coated wire to wind the coil, and understand that a long-cure time, high temperature epoxy is best for a home wound voice coil. Any recommendations on brand/product and supplier willing to supply hobbyist (I'm in US).
And I guess, while I'm at it, I understand getting a good bond on kapton can be tricky. thoughts on using nomex paper for a bobbin?
Thanks in advance for any advise.
After lurking for some time, finally had reason to join and post a question or two.... well maybe more.
Just picked up a pair of Rectilinear Mini III speakers for my office, with a non-functional woofer. Paper bobbin voice coil had separated from the cone, so I'm ready to wade into a voice coil winding project. Maybe due to air leak or just age...
After a lot of time spent watching videos and reading posts, I think I have what I need, less a few critical pieces of info.
As these are low power speakers, I had considered winding on a paper bobbin, but most info on the web speaks to nomex or kapton, and I'm not finding much in the way of suppliers of paper bobbin stock. So, path of least resistance, I'm considering kapton. The original paper bobbin was ~0.004" thick, so Question 1: would 0.003 or 0.005 kapton sheet be an acceptable/appropriate substitute for original bobbin?
Question 2: I assume sheet kapton (no adhesive) is preferred over the kapton tapes I see available?
Question 3: I'll be using non-adhesive coated wire to wind the coil, and understand that a long-cure time, high temperature epoxy is best for a home wound voice coil. Any recommendations on brand/product and supplier willing to supply hobbyist (I'm in US).
And I guess, while I'm at it, I understand getting a good bond on kapton can be tricky. thoughts on using nomex paper for a bobbin?
Thanks in advance for any advise.
If anyone can professionally answer this interesting question, then it's our good member JM Fahey from Buenos Aires, the veteran of (re)building drive units.
The kapton I always used had a treatment and was coated in an adhesive on one side, but not the same stuff that is on kapton tape. It worked with the adhesive that came on the wire I was using. For paper, I think you want kraft paper. That's easy to find anywhere online - amazon, ebay, etc. You could also try aluminum sheet (try McMaster-Carr) or fiberglass sheet (https://store.acpsales.com/products/2342/fiberglass-sheets-natural). I imagine you will have to do some experimenting with any of these materials. I think we wrapped our voicecoils above the wire coil with something like Nomex 410 (ebay).
With an epoxy to glue the wire to the former, I imagine you will be fighting weight. Maybe not so much on a woofer, but if you're too far off from the original you'll start shifting the driver's parameters and it will no longer work the same way. The glue used to coat wire is very good at bonding the wire together without adding a bunch of weight. However you might give something like this a try: 832HT-375ML MG Chemicals | Mouser
With an epoxy to glue the wire to the former, I imagine you will be fighting weight. Maybe not so much on a woofer, but if you're too far off from the original you'll start shifting the driver's parameters and it will no longer work the same way. The glue used to coat wire is very good at bonding the wire together without adding a bunch of weight. However you might give something like this a try: 832HT-375ML MG Chemicals | Mouser
Thank you John...your response is helpful. I see some overseas suppliers that carry kapton sheet with SV glue, but haven't found small supplies. Not sure about the "SV" glue either.
I kinda like the idea of the fiberglass sheet- seems like good temperature characteristics, and getting a good bond with epoxy shouldn't be an issue.
I kinda like the idea of the fiberglass sheet- seems like good temperature characteristics, and getting a good bond with epoxy shouldn't be an issue.
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