a constant and very specific short.

[Lance_Wallen]

I hear people talk about hotspots and shorts all the time. I'm getting a very specific hotspot/short. It's ALWAYS the top of my coil and more specifically the little bit of wire between the positive post and the wick. That section lights up immediately everytime, regardless of how many wraps, how I oxidize the coil, etc.

I'm using 36awg nichrome, 400 mesh SS, a MOV DID knock off on a provari. I've tried a wide number of wraps and oxidizing methods and gotten almost identical results everytime. Throw me a bone!

-Lance

 

[TomCatt]

I'm far from an expert with SS wicks . On one of my builds when I couldn't get rid of that, I stuck a small piece of cotton on the leg. It wicked juice over from the SS wick and no more glow.

 

[BuzzKilla]

I may be wrong, but i have my own theory as to why this happens...

I was able to prevent this by wrapping coil around a drill bit, installing it, removing drill bit from coil & tank, then sliding coil through coil and into tank... i cant recall who came up with this, but there is a post about it linking to a video. credit goes to them.

What i think i kept doing wrong, was while wrapping that last coil or just tightening it down, i would be pulling on the wire too hard and rubbing off the non conductive layer on the wick. Thus causing a short.

I have a coil that is on its second day, using the drill bit method. not one hotspot, ever!
positive and negative legs of the coil arent even discoloured, still silver.... cant say the same for the rest of the coil lol

 

[Lance_Wallen]

I'll try the drillbit method tonight if I can. I'm debating drilling out the wick hole on my DUD anyway.

 

[troncellot]

You have probably tried this, but you could slightly bend the wick towards the negative post or bring the coils down more on the wick. Good luck to ya!

 

[spraintz]

2 reasons I see for the "top coil" hot spot to show up:

1. If the coil is shorting on the wick, even a very slight short anywhere in the coil, the bulk of the current gets forced to the first available "non-shorted" part of the wire..........the leg of wire coming from the positive post.

2. coil not getting wet. whether you are using the drill bit method or any other method, one needs to be sure that that each coil is pulled closely to the wick. The top coil wrap can be tedious to get it to stay in contact with the wick. if any part of the top coil is slightly away from the wick then that part of the wick will dry out faster and the coil doesn't stay wet and bam, hot spot.

The drill bit method is great for getting a very even and almost perfectly round set of coils but it is only a good method if yer wick is nicely oxidized and rolled to a near perfect diameter compared to the coils. when inserting a wick there is a good amount of tension between the wick and coil and the oxidized layer can be easily disturbed if the wick is over oxidized. Also with the drill bit method, the coils can slightly move around on ya when inserting a wick and create the space between the top/bottom coils and the wick as described in issue #2 above. Point is you just need to take extra care when inserting the wick.....go slow and don't rush it.

 

[P1NkY]

I've seen people make this mistake on genesis videos where they wrap the center conductor in the same direction as the coil wrap. It creates an open air gap for the top "leg" of the coil which becomes a hot spot, as there is nowhere to dissipate the heat from the wire.
Sorry for the crude mspaint drawing; it is supposed to be a look from above between the screw terminal and the SS mesh wick.
The blue line is supposed to indicate the wire:
View attachment 143440
Sorry if this is common knowledge, but it may help a noobie!

 

[junkman]

I had the same problem with my last coil and had to mess with it for a long time to get it to quit lighting up the top coil and leg. It finally settled down, but I ended up having to move all the coils a bit, not just the top one - so Spraintz's comment #1 may be the reason.

I've heard of people wrapping the wick back on the legs to make it 2x thereby reducing resistance on the legs. I haven't tried it and don't know if it will help, but maybe worth a try.

 

[spraintz]

I used to do the wrap around back on itself (top coil/POS post) when I first started but later found that it was just a band-aid and not a solution to the underlying problem.