Heating coil as clean method - pics and a new discovery

[kinabaloo]

I have been investigating temperature control of the atty coil. This involves having the heater coil out of the atty casing and on a breadboard; so I can see the coil clearly and visually see it get hot - and mostly I'm running it red-hot and yellow hot - approaching white hot at times. Perhaps 15-20 seconds at longest.

Was not investigating cleaning, but ...

Then, taking some pictures to illustrate the temperature control experiments, lo and behold I see that the coil is really very clean - especially the inner wick; this never cleaned with any liquid, always remained black.

You'll notice that the coil is not shiny, but it has no deposit other than a very thin oxide (presumably); which is quite normal.

I am quite stunned by this.

Then I noticed something else - that the solder blobs have a hole where the nichrome enters the blob. And it seems to be that the hot wire has caused the solder to recede.

This might sometimes lead to atty failure but in the under 2 months use bracket, most failures seem to be due to wire snap due to deposit buildup; I still think that this is the majority case.

As far as tin getting into the deposit, I dont't think this is because of the solder melting around the nichrome alone, but also some electro-chemical action - because only tin was found in the deposit - no copper or silver.

The tin component of the deposit (about 3%) is not likely to be burned off and may be part of the reason why the coil is not shiny. Whether this tin coating might affect the resistance of the coil over time is unknown, but quite possible.

 

[breakfastchef]

You findings make a good argument against all of those who claimed the cleaning cycle of an e-cig is a bad thing. The designers and manufacturers knew what they were doing. This may significantly simplify our atomizer maintenance. While soaking attys in various beverages may help to clear out flavors of vaping past, coil cleaning really is best performed with heating. Great stuff!!

 

[kinabaloo]

ps: I don't think the solder blob melting is a concern for the heating coil to clean it approach - as this probably occurs during normal operation many times a day though briefly (that the coil will get red-hot or hotter when the coil becomes dry).

pps: Although in the most recent testing I was feeding the coil with a square wave at around 200Hz, I don't think the frequency of heating has anything to do with the cleaning - just the heating itself (feasibly might make it a little more effective though?).

 

[kinabaloo]

You findings make a good argument against all of those who claimed the cleaning cycle of an e-cig is a bad thing. The designers and manufacturers knew what they were doing. This may significantly simplify our atomizer maintenance. While soaking attys in various beverages may help to clear out flavors of vaping past, coil cleaning really is best performed with heating. Great stuff!!

I have seen merit in this approach for some time, but was nevertheless surprised to see the effect close up - especially as that was not my aim!

Dry residues from juices burn and harden on the coil but also settle elsewhere (particularly the metal foam) diminishing juice flow and even air flow when dry in the hole behind the atty; so a simple wash out with warm distilled water soak now and then can still be useful.

As to the 'in built cleaning cycle', what we are finding (and SurbitonPete's the main man on this) is that it needs to be done roughly daily; any less and when it is done the deposit is already too thick, heat insulating the coil and possibly causing wire melt (failure).

So as a cleaning method it is best only used with a new atty, daily; for about 10 seconds, with battery and not a passthrough. There are lots of variables; might kill off an atty, especially one that has been used for some time already.

The main thread discussing this effect as a cleaning method is: http://www.e-cigarette-forum.com/fo...ed-effective-method-prolonging-atomisers.html

 

[emus]

Extensive thermal cycling will cause embrittlement.

Do the failed coils break easily when bent?

 

[HockerMagnum]

I have had 2 atomizers fail and in both I found the coil wire to be very brittle. Both coils had opened away from the solder joint.

I don't know what solder formula is used in these but I was able to desolder one joint with a 135W soldering pen.

 

[kinabaloo]

I have had 2 atomizers fail and in both I found the coil wire to be very brittle. Both coils had opened away from the solder joint.

I don't know what solder formula is used in these but I was able to desolder one joint with a 135W soldering pen.

Probably standard lead-free solder; tin with a little copper.

 

[crazyhorse]

So as a cleaning method it is best only used with a new atty, daily; for about 10 seconds, with battery and not a passthrough.

Would you recommend a lower voltage battery for this cleaning. By lower voltage, I mean one that is drained below 3.5v.

 

[Closet Toker]

I clean burn the coil on my 901's. I do this several times per week. I can tell when I need to do it, 'cause the atty. gets very hot, but produces little vapor. It works great for me. I have a manual switch, I blow out any excess liquid, and burn the coil for about 8 secs. with the coil being cherry red.
The voltage is around 3.7 volts.

Vapor production is back to normal.

 

[Vaporer]

Nice demonstration.

When heated above normal the wire should swell a bit, then shrink as it cools.
This would allow deposits to crack away and any cleaning, blowing should remove the debris.

As far as the solder receding...normally it would have air passing by it in a juice cup. Looking at your pic the solder joint and connecting wire , being larger, will act as a heat sink and I doubt it melts when drawing a puff.

Yes, nichrome wire will lightly oxidize on the surface and long term high heat and cooling will make the wire more brittle than new over time and cycles. As the cleaning occurs the carbon will pull some of the oxide off making a thinner weak spot as a new oxide layer forms.

You can buy 6% silver solder, lead free, at Radio Shack and other places.
It does have a higher temp rating.

Your test is a good one but I think its cooler than that when being used due to the airflow across it.

Tony

 

[kinabaloo]

Would you recommend a lower voltage battery for this cleaning. By lower voltage, I mean one that is drained below 3.5v.

Definitely battery and not direct usb/mains powered adaptor. Probably best to keep to the standard 3.7 or less for the dry-burn. Perhaps higher in some cases, depending on the atty.

 

[kinabaloo]

Nice demonstration.

When heated above normal the wire should swell a bit, then shrink as it cools.
This would allow deposits to crack away and any cleaning, blowing should remove the debris.

As far as the solder receding...normally it would have air passing by it in a juice cup. Looking at your pic the solder joint and connecting wire , being larger, will act as a heat sink and I doubt it melts when drawing a puff.

Yes, nichrome wire will lightly oxidize on the surface and long term high heat and cooling will make the wire more brittle than new over time and cycles. As the cleaning occurs the carbon will pull some of the oxide off making a thinner weak spot as a new oxide layer forms.

You can buy 6% silver solder, lead free, at Radio Shack and other places.
It does have a higher temp rating.

Your test is a good one but I think its cooler than that when being used due to the airflow across it.

Tony

Air flow cooling - yes, but not always and not particularly where the solder blobs are. The connector leads i used are the standard 901 type, enamelled copper.

The dry burn is not designed to crack deposits (more likely to crack itself) but burn off a fine layer of deposit (such as just 1 day's use); carbon to carbon dioxide.

The dry burn is more likely to thicken the oxide layer than 'pull it off' (in best use practice, daily).

I think the solder blob does recede from the nichrome wire; though this does not seem to be a life-limiting factor; rather thermal stress is (plus deposit mechanical stress and thermal insulation leading to overheating if the deposit is allowed to build up.

 

[Taelon]

I've come back to burn-cleaning because of lazyness to use the steam-cleaner, too. But be careful with SLB DSE103 atomizers, they've got the heater cable standard electronics lead temperature soldered to the atomizer anode, not high temp soldered (brazed?), so it can get off after too much time under 4,5 V power, I had to repair one.

I use 5x 3 sec at 4,5V- / 20 sec air cooling duty cycle to clean a DSE103 atomizer and put it into 70% ethanol after that, then suck it dry with vacuum cleaner.

Has anyone found out about the heater element material? Is it PTC or classic?

 

[Vaporer]

In pic #4 you can see the heat sink effect. The hottest part of the coil will naturally be the middle. I compare the cleaning cycle to an ovens. These little coils arent nearly as durable. Some have stated using 6v to do a burn off. I'd consider that rough on it.
The max the battery can charge is 4.2v . I've cleaned my tough ones with 4 AA NiMH (5v) rechargeables by just touching the wires to the atty till I get a good bright red glow for maybe 2 seconds. Then let it cool. Thats hotter than a normal 5 sec puff will be. I may do this 3 times max then do my liquid cleaning. The gunk has formed because there wasnt enough heat to vaporize it, low battery , flooding..... Home recipies have oils and sugars in them and that just promotes trouble.
I don't think a drained battery would do much to clean it.
The oxide layer can only form as thick as O2 can touch the actual metal surface.

Good maint. is a good habit and should give the coil it best longivity. The more build up thats allowed to form takes more to remove.

 

[kinabaloo]

In pic #4 you can see the heat sink effect. The hottest part of the coil will naturally be the middle.

That's only true when the coil is dry. When the coil is wet, the hottest places are between the solder blobs and the wet coil, nearer to the blobs as the wet coil is the greater heat sink. And that is exactly where most often the nichrome will eventually 'break' - in one of the legs nearer to the solder blob that to the coil/wick.

If I took another picture with a wet coil, you'd see what i mean.

 

[Vaporer]

kinabaloo,

No need to take another pic. A wet wick with air being passed by would be cooler than the drop legs.

I clean when the atty feels hot and no or little vapor is being produced. Its right back to normal. If done regularly, a dip cleaning usually works well and no burn off is needed. I burn as a last resort.

In another thread it was discussed abt making a plug in coil. I just got some nichrome and will be working on that. I have a cold heat pen and am going to try to weld the connector or copper wire to the nichrome wire solderless.

I have a couple coils in a mini that have no wick and work fine.

 

[Vaporer]

Double post....sorry

 

[crazyhorse]

In another thread it was discussed abt making a plug in coil. I just got some nichrome and will be working on that. I have a cold heat pen and am going to try to weld the connector or copper wire to the nichrome wire solderless.

Very good! I'm awaiting delivery of supplies to begin my tinkering.

 

[Vaporer]

crazyhorse,

I just got the nichrome yesterday. I've designed/built micro rc planes/helis with circuit mods for yrs. They use lithium polymer batteries. Same max charge and min cutoff specs. I even have a simple charger that can be built low cost I plan to post soon.
I have the connector ends, even in gold plated. They are cheap and easy to obtain. Crimping the gold to the coil may eliminate any soldering.
I cant post a pic or links yet and I dont have any dud attys to actually mount it. The one I tried to take apart (my 1st) I busted the juice cup beyond repair.

I posted the place I got my wire from in the other thread. 10ft for $2 free S&H. I bought the 36ga (.005 dia) 20ohms/ft. 1 1/2" would be 3.37ohms.
I have a Blu and Janty Mini Fogger. The Blu atty is 3.4ohms and the Janty is 2.5 -2.7ohms (2 diff coils) so a 1mm core wrap ....length is good and resistance is in the right range.

I'm all for learning to make our own parts. Cheap, simple so most can do it.
Then we can maintain and design our own custom units.

 

[crazyhorse]

Sounds great Vaporer. If you don't mind, I would like to move this conversation over to the Attn: atomizer rebuilders thread. We can compare notes on this shared goal. I'll reply to you there later today.