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Superglue to build air coil?

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ricko_uk:
Hi,
planning to build a few air core coils with 0.2mm enameled magnet wire. Because of the dimensions (40mm length, 15mm ID and 20 layers) and the thin wire (and preferably no supporting core) I need the wire itself to provide structure/strength to maintain its shape.

What is the best/easiest way to make them?

Also what is the best way to keep the wires in place as I wind them? I was thinking about a line of superglue every few mm (along the solenoid length). But not sure if it chemically melts or affect the enamel?

There will be almost no current through it so operating temperature is not an issue.

I know I can buy wire with glue that can be heated but not sure I could keep the heat constant without damaging the wire (I remember that happened when I tried once years ago).

Thank you

T3sl4co1l:
Superglue is fine. I haven't seen it affect enamel, myself.

I would suggest, use just enough that it wicks into the turns, but leaves lots of free space to later get varnish or something in there to more permanently secure it.

You may find it useful to use tape anyway, if nothing else just to hold the former and cheeks in place, and secure layers, before soaking the whole thing in something, or using self-bonding wire (if resistive heating isn't well enough controlled, just stick it in the oven).  Jig parts made of Teflon or PP, or something shiny and non-stick anyway, will be helpful.  Preferably with some way to release the form, like a few wraps of sheet around a cylinder, maybe even a split cylinder held in with shims.

For example, I have some PET film that epoxy doesn't stick worth a damn to, it peels off very easily.  That would make a nice form, or wrapped around one, and then some way to anchor the cheeks.  End plates like washers, with a bolt through the stack to hold it together, is a good way to make a winding arbor.  Helps greatly to have a machine shop to make custom sized parts, but some adjustability can still be had while using relatively few parts.

Epoxy by the way, can be used like varnish if it's thinned -- it might not soak in well otherwise, but with a little solvent, or I would say preferably just by heating it -- the slower-cure types get pretty flowable, and for more than long enough to soak into things and for bubbles to move out. (Vacuum impregnation is always best though.)

Tim

KE5FX:
I'm sure you can't get it in the UK anymore, and probably not here either, but there used to be a cement made just for this purpose called "Q Dope."  It was basically polystyrene dissolved in toluene IIRC.

Nowadays I use UV glue with a blue laser pointer and/or UV flashlight.  The stuff sold by JB Weld is absolutely superb.  It has some cyanoacrylate mixed in to allow it to set eventually in areas not reached by the light, a big drawback of other UV-cured glues.  You will not mess with traditional "super glue" after trying this.

coppice:

--- Quote from: KE5FX on June 19, 2024, 09:12:45 pm ---Nowadays I use UV glue with a blue laser pointer and/or UV flashlight.  The stuff sold by JB Weld is absolutely superb.  It has some cyanoacrylate mixed in to allow it to set eventually in areas not reached by the light, a big drawback of other UV-cured glues.  You will not mess with traditional "super glue" after trying this.

--- End quote ---
UV glue has been the go to approach for things like this since it was launched. Watch out for the cyanoacrylate types, though. They usually have a very low melting point.

TimFox:
“Q Dope”, made by GC Electronics, is readily available in the US in 2 fl oz bottles.
The solvent is listed on the MSDS as MEK, which may well be banned elsewhere.
I found a statement that it is banned in parts of California, but I don’t know its status in UK and EU.
It certainly requires care with ventilation, etc.
It is a traditional material to make RF inductors due to the very low dielectric loss of the solute polystyrene; the solvent is very volatile and disappears quickly (perhaps up your nose—be careful).

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