I ran into a similar problem in another project making a kanthal wire to copper wire connection that you ran into with your toaster wire (nichrome?).
The best solution I found was not to bother with welding/soldering with metal/alloys. I did a wire wrap, simple as that, I bent one wire in the shape
of a clasp, fed and wrapped the other wire through, and tightened the clasp via pliers.
I do like the variac idea, but when I was experimenting with resistive heating elements I found it very easy to destroy the wire by too much power. I
opted to use a "wall-wart" and a potentiometer, then again, it seems like you are trying to give off a lot of heat.
Great idea though, I remember thinking about needing something like this in the past but never went through with the project.
edit - nevermind the TUBE failed, not the wire contacts. Sorry for misreading!
[Edited on 13-5-2015 by smaerd]Magpie - 20-5-2015 at 13:49
edited:
I have removed this procedure until I can develop a more rugged tube
The non-annealed and annealed sparge tubes failed in testing while using water. The inner tube separated just above the fused joint. The fusion
itself is solid.
I now have access to my neighbor's oxy-acetylene torch. But the fusion is not the failure point. Maybe a thicker walled inner tube will solve this
problem. It is also possible that my testing has been too severe.
[Edited on 20-5-2015 by Magpie]aga - 20-5-2015 at 15:02
Variac ?
Use PWM, please (you should know better smaerd !)
If it's 110VAC or230VAC use a thyristor and an opto-coupler with a zero-crossing detector built in.smaerd - 28-5-2015 at 10:23
Aga - why use PWM for a resistive circuit? Heating wire is essentially a resistor whose resistance remains constant at all temperatures (unless
failure occurs), so why not use a potentiometer to create a super simple voltage divider circuit?aga - 28-5-2015 at 12:51
I just find PWM easier and cheaper is all.
Edit:
Not that it matters much, but resistors are temperature dependent, hence the 5%, 1% rating etc.
[Edited on 28-5-2015 by aga]Magpie - 5-6-2015 at 14:17
The non-annealed and annealed sparge tubes failed in testing while using water. The inner tube separated just above the fused joint. The fusion
itself is solid.
I tried an annealed glass sparge tube with an inner tube of 1.5mm wall thickness. Same result, ie, fracture right at the end of the inner tube. I am
therefore abandoning this effort.
