Braided stainless leader wire for att coils

[vslim]

Hello mods and modesses--

I went to the crafts supply to look for thin stainless wire for making a sturdier atomizer heating coil, and didn't find it. However, when I got home I noticed the nylon coated stainless braided wire fishing leaders in the garage, looked like just the ticket. I'm talking about the ones you can get for a buck, made in China, with the orange beads on them. They seem to be ubiquitous in tackle shops here in the near-coast area. Anyway I shredded one, checked the resistance, it was about 1 ohm/inch. Perfect. I wound a little coil, put it across 3 AA NiMHs, and got a cheery orange glow. It was easier to work with after it had been heated. I am sorry I can't give you an exact part number or size of wire, but if you do coastal fishing I am sure you have seen them and probably have some torn up ones. For sure they are so cheap you can get several and check them out. The only downside is that I couldn't get them to tin or take the lead-free solder, but I solved that by tinning some small wire-wrap wire which I was going to attach them to, crimping over the end of the wire-wrap to hold the stainless and soldering again. I am also going to check a beading supply for tiny crimp beads for this. Sorry again I can't give you an exact wire size, it is somewhat but not a lot larger than the wire on the little coils on my 901 atts, and smaller than bread twist-tie wire. For sure I have found the only coil wire I will need.

[RayJ1]

Couple of thoughts on your choice. Choosing wires with specific resistance is fine, but a couple of other thoughts come to mind. Thickness of wire especially! Voltage and resistance don't cover current draw. If the wire your using is thick... the coil that is created could draw many amps! That would either fry the switches on mods or drain the batteries very quickly. The order of wire thickness in nichrome wire would be in the .0004 to .0005 thickness. This translates to an inductance coil that functions in the voltage range of 3 to 6volts..... desired resistance....and very importantly amperage.

[RayJ1]

Oppss......wire thickness should be between .004 and .005.

[vslim]

Of course voltage and resistance cover current draw- Ohm's Law to the rescue! If the wire has 2 ohms resistance it is going to pull exactly 2.25 amperes from a 4.5 volt source. Ohm's law - Wikipedia, the free encyclopedia
The point is that this wire is readily available, has the right resistance, it is easy to work with, and cheap. Also important, steel doesn't conduct heat very well so it heats up fast, unlike a copper wire which would conduct the generated heat away quickly and would need higher current to get to the same temperature. We already know nicrome doesn't last that long in the toy atomizers that we have now, and I am looking for something more sturdy. I don't know about the lifetime of this wire yet but it looks good so far. Also I have found that micro crimp beads are made that are 1 mm, so maybe I can skip the PIA soldering.

[ISAWHIM]

You don't have to solder directly to the wire. You can make a mini-crimp from another metal if you can feed the wire through the ceramic disk, and crimp it from the back side. You then solder the crimped jumper to the case contacts.

Actually, you would be better with high-temp lead-free solder. But that requires a butane soldering gun, or high wattage gun.

If you can crimp a small enough collar onto it, you might be able to push the crimp into the holes that the wire passes through. (You can use a hammer to flatten the metal collar thinner, and cut it with scissors. The solder would create the thickness required to keep it from burning up.)

[kinabaloo]

Because the wire is greater in volume, you'll use more power to get the same temperature. That might be worthwhile though. Are you intended to use the coil in an existing atomizer or designing a new atty ?

[RayJ1]

There is a reason why they use such small diameter wire and nichrome wire. Practical amperages and battery life.

[Letzin Hale]

Average number of draws per month would probably be around 10,000 so it would be interesting how it and the batteries perform, especially when working in normal (moist/sticky) conditions.
Alan.

[exogenesis]

Also stainless will short across coils windings if they touch,
nichrome forms an insulating thick oxide surface layer.

Was going to try this with tungsten, which is the only other
(commonly available) wire that forms an thick oxide layer.

Thinking it's possible to not need the coil wick if you use a bundle
of tungsten wire (found a supplier):

I calculate that 2 strands of 100mm of 0.05mm diam tungsten has the
same resistance as the 10 mm of 0.1mm diam nichrome used in atomizers.

Could be a bit fiddly tho.

[vslim]

OK, finally some pics. This coil was just for grins, it is 1/8 inch long (3mm). The idea was to find some kind of coil that was up to the high power battery mods we have been making, the 901 is useful but still it is a toy. I think that 1 mm crimp beads would be a good way to attach one. I haven't yet managed to repair an att, I am more inclined to try to design a new one. If I manage either i will post it. The 1.5 ohms was cold coil so the real hot resistance will be higher. It is probably running at about 2 amps current, so in the ballpark. No obvious change in the coil except it got dark. Stainless and nichrome are related, it is just that stainless also has iron in it.


Edit: I checked the resistance of the coil while heating it with a flame, it went up to 2.4 ohms. The battery box voltage went down to 3.2 volts while the coil was energized, so the running current is about 1.3 amperes.