renatoa wrote:

Do you have any overheat protection due to low airflow ?
A bimetal on hot air exit should be enough to protect your element for overheating.

renatoa wrote:

Melting in the contact areas, and not the wire, is a different story... the culprit was the imperfect contact, an issue that develop in time.
If the two contact surfaces aren't perfectly flat and tightened, you can see the contact area as hills and valleys, making contact only in some microscopic points.
In these points you will have first a local temperature increase, that led to oxidation, that finally led to complete contact rust.
The oxides having increased resistance, in the contact area you will have a significant power drop in a very small volume, that means heat (in excess) => finally melting.

Thank you for the detailed explanation. So, the element that is still working, I've attached as good a picture as I could get to show the sandwich. Is there a different configuration that I could use to mitigate melting?

allenb wrote:



One thing that can create issues with varying contact quality is using an incorrectly sized eyelet diameter. Using too large eyelet diameter will cause contact to occur only on one small area of the ring and depending on how things line up, it will sometimes appear to have a good solid contact but in reality does not and voltage drop/overheating can occur.

allenb wrote:

I've found large wire gauge in small screw size (stainless steel or something high temp) in the past at one of the resistive wire heater suppliers but this was quite a while ago and can't remember who. I'll do some digging and let you know what I find. Hopefully someone else here with more current build can chime in as well (help

allenb wrote:

Did the nichrome wire melt through or just arc across to the washer?

allenb wrote:

I haven't found anything smaller than that. I would go for the #6 eyelet and step through a couple of washer sizes to get good full contact with that one.

renatoa wrote:

Never trash it, even melt in the middle.
I have one with two wires of different diameters, just wrapped together and inserted inside of a brass tube, then the tube pinch each side with a wire clamp tool. Working ok for some years.

CK wrote:

R&D at its finest... sorry for your temporary set backs. Any idea of the amperage you're putting through that connection? I'm reading about dissimilar metal connections and negative effects of high current at the connection point.