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nichrome wire terminations

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Oznog

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I am trying to build a small 12V heater with nichrome wire, the wire being a ribbon from a toaster. I need to make air in the realm of 500F so the heater will need to be hotter than that, also there's going to be difficulties regulating that air temp so excursions substantially higher seem likely.

Well for one end I can use the original welded termination, but the other termination will have to be custom. Since the wire will be far above the melting point of lead solder ordinary solder cannot be used.

I'd like to weld it, but I do not know what method I might be able to carry out. I don't have a spot welder. There wouldn't be any odd tricks I could carry out with a car battery or anything is there?

I have silver jewelry solder and an oxyacetylene TinyTorch. So far that seems like the best plan, it has a flow temp of 1450F. Any flaws I'm not aware of, or am I missing a better way to do this?
 
Can you braze it? Like with a blowtorch? Rather than a spot welder?

I found this:
"Filler Metal name: Braze 051
Typical Applications: Brazing nichrome resistance elements, or simultaneous brazing and heat treating of steels.
Solidus: 1545'F/840'C
Liquidus: 1615'F/880'C
Max. Recom. Brazing Temp. 'F: 1700
Nominal Composition,%: 5Ag 58Cu 16Zn 37Cd
Joint Color as Brazed: Brass Yellow
Density Troy oz/cu in: 4.47
Electrical Characteristics
Conduct. % IACS: 24.4
Resistivity microhm-cm: 7.06 "

"SILVER 5
(Cd Free)
Brazing nichrome resistance elements, or simultaneous brazing and heat treatig of steels "
 
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In toasters I've seen the round wire wrapped once around a rivet and riveted. Clamping or crimping it might be the easiest solution.
 
When I needed a nichrome wire for a polystyrene cutter, I crushed a wirewound resistor and inside is a nichrome wire already terminated. If you know the voltage & current you will be operating at, then the right resistor may be a ready made element.

Mike.
 
Why solder or braze at all? kchristie is right, a simple steel screw terminal is probably the best sollution. Just make it a heavy duty one so what heat is transfered at the termination point is distributed over as large an area as possible. High power/heat electronics almost always use screw terminals. Ideally you'd want to use a terminal that didn't transfer heat very well, but did transfer electricity well. In a pinch you could probably use generic standoffs (like from a PC) and some appropriate screws with a couple of washers for surface area.
 
An alternative might be a crimped connector - possibly one you'd fashion yourself if you have the means. I'd prefer welding but have the same limitations as you. Next preference would be brazing as already suggested.

With the nichrome wire I have (maybe 28 ga) I'd try drilling out a short length of 1/8" brass rod in the lathe then try crimping it in a press. The cutting edge of wire cutters allows application of considerable force - may be sufficient if done carefully. Steel (possibly from a nail) might also be a good choice. I wouldn't say that this is preferable - it's just another way.
 
Simple Nicrome Splicing

We use stainless steel screws, nuts & washers washers to splice wires on 10KW heaters. Works fine for years. Example: #16 wire use #6 screws. Not handsome but it works.
 
Hi,

I've used bolts and nuts, and washers. The washers hold the wire nicely, and you can use three washers to tie the end in with a regular wire. The nichrome wire goes between two of the three washers (one center and one outer) and the copper wire goes between the center washer and the other outer washer. Use lock washers too, and tighten securely.
 
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