Contact vs Spaced Coils

[GOMuniEsq]

I've recently switched to Framed Staple contact coils and I've been having issues getting my builds to last. As beautiful as they were, I was getting burnt hits on longer pulls and the resistance became erratic. I was changing the cotton (Cotton Bacon Prime) every single day and seeing scorches on it.

I ran this 3.5mm one at 150W:

Saddle Horse Blues 0.11Ω ⌀3.5 Staggered Framed Staple Build on Zeus X

• GOMuniEsq
• Mar 28, 2019
• staple coils

0.21ohm per coil \
26gN80 Frames \
36g/38gN80 - 3.5mm \
0.5mm K1 Ribbon x4

And this 3mm one at 110W:

Geekvape Framed Staple Contact 0.12Ω Dual Coil Build Side View

• GOMuniEsq
• Mar 25, 2019
• coil geekvape zeus rta

Geekvape F202 Framed Staple Fused Clapton Coil 4-wrap 0.25Ω x2 on Zeus X

So I decided to stretch one into a spaced coil and it made a big difference. I run this 3mm one at 120W:

Geekvape Framed Staple Spaced 0.1Ω Dual Coil Build Side View

• GOMuniEsq
• Mar 28, 2019

Geekvape F202 Framed Staple Twisted Coil 4-wrap 0.2Ω x2 on Zeus X

Notice the cotton visible between gaps.

Geekvape Framed Staple Spaced 0.1Ω Dual Coil Build Top View

• GOMuniEsq
• Mar 28, 2019

Geekvape F202 Framed Staple Twisted Coil 4-wrap 0.2Ω x2 on Zeus X

The spaced coil build has so far outlasted the others with no noticeable performance degradation after 24 hours, and most importantly no dry hits (although the wick is a slightly discolored). The wick doesn't seem to burn easily when there are spaces between the wraps. I'm guessing that it doesn't dry out as severely due to extra juice in the gaps, which also serves to cool down the coils faster. And I can pack a bit more cotton in there too since it has room to expand.

I speculate that the resistance is more stable because there is no contact between wraps for electricity to bridge across.

You don't see a lot of talk about larger spaced coils. I only found one detailed comparison video (Youtube, 41min) discussing the topic. I'm curious to know what the community thinks about them.

 

[Flavored]

There's a term for it, called "heat flux," or more simply "heat per volume of wick." Even simpler if you've built the contact and the spaced coils on the same diameter rod/mandrel, just consider the length of wick within the "heating zone" of the coil. With a spaced coil, the heat is spread over a longer section of wick, and the difference can be significant. You don't have a great deal of space between those wraps, but I bet it more than makes up for the small bump in watts you have between the two.
Back in the day that contact coils and "micro coils" (less than 2mm diameter and tight contact between wraps), we all marveled at how efficient and flavorful they were. They required less watts for the same performance, but they still got pretty hot in the center of the coil, and the coils would gunk up quicker than a spaced coil. The trade off was either charging batteries more often or cleaning and rewicking coils. Good times.
I went to rayon as a wick (way better wicking, doubled the time between coil gunks), spaced the coils, and just bumped the watts up until I got the same vape as before with the contact coils.
Your wire is quite wide, and it is going to get very hot in the center of that coil, long drags and chain vaping will not be something you'll be able to do, even with perfect wicking. You gave targets of wattage, but I can't help but wonder how you got to those numbers. The fanciest wire I ever vaped was a straight clapton, and I started out at a lower wattage and bumped up until I got the flavor I wanted and stopped. How did you arrive at your wattage for the builds that were burning through wicks?

 

[Punk In Drublic]

Shane over at SaddlehourseBlues makes some very nice coils, dude is a craftsman. But they are massive coils that require a boat load of power heat up and even more airflow to cool down.

I also own the same Geekvape coils – was given to me by a local store to try out. And again, these are massive coils that are difficult to control. Even when spaced.

The more mass a coil employs, the more power is required to heat it up and the more time is needed to cool it down. If ample enough time is not given, the coil just keeps getting hotter, and hotter. Their heat also effects their surroundings which could also have an adverse effect on the quality of the vape.

You can get lower mass Clapton type coils with higher surface area but perform much more efficient at lower wattages.

 

[greek mule]

Imho too much mass for a rta.Tank must get too hot at 150w.
If you like massive build I would suggest a rda.

 

[GOMuniEsq]

How did you arrive at your wattage for the builds that were burning through wicks?

They way I choose the wattage is by intuitive trial and error. If I hold down the fire button and don't get a quick, satisfying response I bump it up higher. If I start getting bad hits I drop it.

That 0.10Ω spaced one I made above ended up being far from ideal, only lasting for 2 days before the flavor went off. The wick was scorched (or possibly just stained) when I removed it. I also found that the entire tank got too warm when I reefed on it repeatedly, as you predicted.
So this morning I took the 0.12Ω build and spaced it, set it to 100W and am finding it better. The tank doesn't overheat when I chain vape and it's wicking like a beast. What a fine balance there is to strike!

First spaced attempt vs 2nd spaced attempt

0.10Ω@120W left, 0.12Ω @100W right, spaced

• GOMuniEsq
• Mar 30, 2019

Same coil build, before and after spacing:

Identical 0.12Ω dual build, contact 110W (left), spaced 100W (right)

• GOMuniEsq
• Mar 30, 2019

Thanks for the explanation of "heat flux". I'd seen it before but never really understood what it meant. I've been reading about rayon as wicking and it sounds like it'd be ideal for my use case, so I went ahead and ordered a bunch of this Graham Cellucotton off Amazon which should arrive in a couple weeks.

 

[GOMuniEsq]

I went to rayon as a wick (way better wicking, doubled the time between coil gunks), spaced the coils, and just bumped the watts up until I got the same vape as before with the contact coils.

I took your advice. It's the same 0.12Ω dual spaced build but since switching to Rayon I was able to bump it up from 100W to 120W. The cloud density is noticeably improved, the wicking stays saturated for the entire firing duration (no bad hits), and no sign of singeing. Thanks @Flavored!

 

[Skunk!]

I agree with the earlier posts. Those coils would do well in an RDA with massive airflow. For a similar RTA cloud build I would suggest Quad core FC with 28 or 30 core wires and 38 or 40 wrap. That will give you just about the same amount of surface area but are very flat. This will cut the mass of your build significantly. It should ramp up and cool down much quicker and give you the same clouds and flavor at a lower wattage.

 

[Flavored]

I took your advice. It's the same 0.12Ω dual spaced build but since switching to Rayon I was able to bump it up from 100W to 120W. The cloud density is noticeably improved, the wicking stays saturated for the entire firing duration (no bad hits), and no sign of singeing. Thanks @Flavored!

You're welcome, glad it worked!

 

[00jim2]

I was having this problem on my simple single coil builds. The contact coils stay hot too long. I could hear the coil still sizzling away after I already completed my drag. The coils would gunk too quickly. I started spacing them which helped quite a bit but I still think it stayed too hot. I cured this by using a custom Wattage curve that tappers down in power as I draw. My coils last much longer and I am achieving a consistent vape. I have been wondering if others have the same problem with simple coils - contact vs. spaced.

 

[GOMuniEsq]

Damn this Rayon is good. I haven't had to rewick it in a week despite putting 2 bottles of juice through it, and it's showing no signs of degradation. I can even blot it upside down on tissue paper to draw out any impurities that collect. No wonder commercial coil assemblies never use it—sales would plummet!

 

[MacTechVpr]

I was having this problem on my simple single coil builds. The contact coils stay hot too long. I could hear the coil still sizzling away after I already completed my drag. The coils would gunk too quickly. I started spacing them which helped quite a bit but I still think it stayed too hot. I cured this by using a custom Wattage curve that tappers down in power as I draw. My coils last much longer and I am achieving a consistent vape. I have been wondering if others have the same problem with simple coils - contact vs. spaced.

Contact coils were intended to be oxidized (Kanthal). If not oxidized Kanthal and any other comp wire may go exceedingly hot. If done well, properly burned in Kanthal contact coils can be very productive and stable. That's what contributed in great measure to the explosion of open systems vaping.

I've written a few things on this topic.

Good luck.

 

[00jim2]

Contact coils were intended to be oxidized (Kanthal). If not oxidized Kanthal and any other comp wire may go exceedingly hot. If done well, properly burned in Kanthal contact coils can be very productive and stable. That's what contributed in great measure to the explosion of open systems vaping.

I've written a few things on this topic.

Good luck.

Much to learn, I have! Can you explain oxidized Kanthol? I use Kanthol A-1 and pulse it before wicking.

Sent from my VS835 using Tapatalk

 

[GOMuniEsq]

Can you explain oxidized Kanthol?

I've been curious about this for a while now but am not sure I completely understand.

@MacTechVpr seems to be famous for his documentation of tensioned micro coils, specially wrapped contact coils where the wire is in close contact with itself along the entire length. (forgive a noob)

I used to ask myself, "What stops the electricity from taking the shortest path through a contact coil, since all the wraps are touching? Seems like a terrible idea to use one!"

Well, we know it's not, but how does it work? One of the unique things about Kanthal is that the surface oxides when heated, becoming non-conductive so the only path for the electricity to follow is the long way around all of the wraps, even though they're touching. That's why we burn in our coils.

I believe he's saying that other metals like, say, Ni80 and Stainless Steel don't share this property, so it's best to space the wraps.

 

[MacTechVpr]

Much to learn, I have! Can you explain oxidized Kanthol? I use Kanthol A-1 and pulse it before wicking.

Sent from my VS835 using Tapatalk

I've been curious about this for a while now but am not sure I completely understand.

@MacTechVpr seems to be famous for his documentation of tensioned micro coils, specially wrapped contact coils where the wire is in close contact with itself along the entire length. (forgive a noob)

I used to ask myself, "What stops the electricity from taking the shortest path through a contact coil, since all the wraps are touching? Seems like a terrible idea to use one!"

Well, we know it's not, but how does it work? One of the unique things about Kanthal is that the surface oxides when heated, becoming non-conductive so the only path for the electricity to follow is the long way around all of the wraps, even though they're touching. That's why we burn in our coils.

I believe he's saying that other metals like, say, Ni80 and Stainless Steel don't share this property, so it's best to space the wraps.

Pretty much. Kanthal builds an alumina oxidation layer (essentially ceramic) which insulates the turns electrically constraining randomness. Turns still share thermally turn-to-turn which gives contact coils their distinctive concentration in part along with their compact size.

It used to be done by torching the wire. However this deposits carbon on the surface of the wire unevenly inhibiting the effective evolution of oxidation for our purposes. If not done right you never see the full potential even distribution of heat that's possible with Kanthal. That's what allows you to throw more power in a given wind and keep it cool (actually vaporize more). Also if oxidation is inadequate they can get quite hot which was the original criticism of m.c.'s way back.

I should add it's not possible to do with multi-wire effectively except parallels and with some degree of success with twisted-pair. The goal obviously is uniformity of contact to ensure oxidation as evenly as possible.

Used and tested all types of winds and varieties of wire. There's a means and a way to enjoy them all if it can be done effectively and repeatably. That's my concern. Particularly for new vapers. If you find your spot you def want to get there again. Why I've been so dedicated to the notion that users learn how to strain-wind single wire. Once there a great many things start to make sense as we observe these winds. Then they're a great tool for comparing results otherwise.

Good luck.