Question about dual-coil rebuilds

[rickylford]

I am waiting for my first true mech mod as well as my Omega clone to come in, and before I build it for the first time, I have a question... If I'm going to do a dual-coil build, do both of the coils have to match exactly in wraps, kanthal gauge, etc? Such as, if I were to build a coil that is micro and has 8 wraps, would it be a horrible idea to have the second coil be a regular build with the turns spaced out with only something, like say, 4 wraps?

Not that I'd ever have a need to do something like that, but I'd hate to build something that was slightly off and have it short out and destroy my battery or something else. If I were to ever get off in the wraps, I would imagine maybe being off by 1 wrap on one of the coils, but I don't see myself building a micro coil and a regular coil. I just wanted to ask before risking my health.

Also, on these Omegas/Omega Clones, for those of you that have them, is the negative post the center post? I thought I heard somewhere that it was, and that both of the coils from a dual-coil build need to at least be sharing the center post.

Thanks!
Ricky

 

[suspectK]

Always wrap your coils the same.. it won't cause a short, but it will cause one to lead/be hotter... won't vape well.. it's pretty easy to get side tracked wrapping multiple coils..I use my cell phone camera to check how many wraps I've done.

Positive post is the center post/connects directly with firing pin. .common/negative with atomizer body.. with an atomizer that doesn't have a center post, the post with an insulator separating it from body of atomizer is the positive post.

37, ph0n3 h0m3.

 

[rickylford]

Always wrap your coils the same.. it won't cause a short, but it will cause one to lead/be hotter... won't vape well.. it's pretty easy to get side tracked wrapping multiple coils..I use my cell phone camera to check how many wraps I've done.

Positive post is the center post/connects directly with firing pin. .common/negative with atomizer body.. with an atomizer that doesn't have a center post, the post with an insulator separating it from body of atomizer is the positive post.

37, ph0n3 h0m3.

Ahhh gotcha. The whole positive post thing makes a lot more sense now that you say it that way. Thanks for the info!

 

[State O' Flux]

I have a question... If I'm going to do a dual-coil build, do both of the coils have to match exactly in wraps, kanthal gauge, etc? Such as, if I were to build a coil that is micro and has 8 wraps, would it be a horrible idea to have the second coil be a regular build with the turns spaced out with only something, like say, 4 wraps?

Obviously, the resistance values of differing wire gauge and length will, as stated by suspectK, cause the lower resistance coil to "lead", or heat fastest and first. The second, higher resistance coil will heat, but depending on the resistance, may not heat enough to vaporize juice. It's the rough equivalent of having a poor connection on one coil of a dual coil atomizer.

Although I've never felt the need to test the theory... you can build coils (wired in parallel) that are different in design with the same resistance, but must use 2 different gauges of wire. The lengths (terminal to terminal) must be exact for heating to occur fairly equally.
Due to varying leg length power loss values, as well as wrap count, coils may require fine tuning for truly equal heating to occur. I speak theoretically... again, I've not tested this.

For example (leg lengths and ID being equal), a 28 gauge Kanthal A1 wire, 55.8mm in (terminal to terminal) length will provide 1.0Ω. To obtain 1.0Ω with 30 gauge wire, the length will need to be 35.1mm.
The math for this was calculated using "Steam Engine"... a coil build calculator that can be found via my first sig line hyperlink.

 

[rickylford]

Obviously, the resistance values of differing wire gauge and length will, as stated by suspectK, cause the lower resistance coil to "lead", or heat fastest and first. The second, higher resistance coil will heat, but depending on the resistance, may not heat enough to vaporize juice. It's the rough equivalent of having a poor connection on one coil of a dual coil atomizer.

Although I've never felt the need to test the theory... you can build coils (wired in parallel) that are different in design with the same resistance, but must use 2 different gauges of wire. The lengths (terminal to terminal) must be exact for heating to occur fairly equally.
Due to varying leg length power loss values, as well as wrap count, coils may require fine tuning for truly equal heating to occur. I speak theoretically... again, I've not tested this.

For example (leg lengths and ID being equal), a 28 gauge Kanthal A1 wire, 55.8mm in (terminal to terminal) length will provide 1.0Ω. To obtain 1.0Ω with 30 gauge wire, the length will need to be 35.1mm.
The math for this was calculated using "Steam Engine"... a coil build calculator that can be found via my first sig line hyperlink.

Thanks a bunch for your reply! Your Steam Engine website is quite amazing, and looks as if I'll be using it quite a bit! The only issue I see is not being able to add flavoring in the e-juice recipe, unless I'm missing something? I just woke up, so that's entirely possible.

 

[DaveP]

Parallel resistances can be calculated using the formula below. Yes, they need to be close for proper atomization to occur, but you aren't going to blow up your mod if they vary a little. Measure each individually to feed the formula below. Compare the result by clipping the leads together and measuring the two in parallel using a voltmeter before you install them. You need to estimate the proper installed length of the lead tails and clip the leads there to get an accurate reading.

Rt= (R1× R2) / (R1 + R2)
Multiply the two together and then divide by the two added together.

For a neat coil wind, try using a coil winder that's sold for wire art hobbyists. Hobby Lobby or Amazon are both good places to pick up one. You can make coils all the exact diameter and control the number of turns in each very easily.

Amazon.com: Artistic Wire Coiling Gizmo(R) Deluxe Winder for Jewelry Making: Arts, Crafts & Sewing

 

[State O' Flux]

The only issue I see is not being able to add flavoring in the e-juice recipe, unless I'm missing something? I just woke up, so that's entirely possible.

I'm not a DIY juice guy, so I've never even looked at it, let alone used it. Ask "Dampaskin"... he created the site.

 

[Dampmaskin]

Hi. I do my flavors by memory, trial and error. I threw the e-juice calculator together in order to mix my nicotine and PG/VG bases, and haven't added any support for flavoring - yet.

To be honest, mixing percentages with other percentages in order to reach target percentages, seems to be more of a challenge for me, than calculations related to electronics, mechanics or physics. I'm just not used to thinking that way.

So the e-juice calculator is a bit "rudimentary" as it is right now, compared to the other calculators. Maybe I should label it as a "beta version" or something.

 

[dgarci]

I'veseen a few guys who purposeLy buiLd duaL coiLs of different sizes, with the goaL of having an effect on the consistency of their vape/fLavor.. they say it does affect the fLavor in a good way.. since the 2 coiLs wouLd not heat up exactLy at the same time..

I've buiLt my duaL coiLs on a fogger v2 the same way.. that wouLd be 2 horizontaL microcoiLs on top of each other.. with the bottom microcoiL 1 wrap Less than the top coiL.. it's not a huge difference, even when I measure my ohms, but there definiteLy is a difference in terms of the quaLity of vape.. XD Im satisfied though, so that's what counts.. part of the fun In my vaping experience is pLaying around with my coiLs and stuff.. soooo, you shouLd go try it too.. it is fun, and you'LL never know if its going to work for you unLess you try

 

[rickylford]

You're all great. Thanks a ton for all of your responses! I'll be building my coils as exact as I can so as not to get too wonky with my first builds. Hopefully my Nemesis and Omega clones come in today so I can start experimenting. I don't think I've been this excited over getting a mod since picking up my VTR.

 

[State O' Flux]

You're all great. Thanks a ton for all of your responses! I'll be building my coils as exact as I can so as not to get too wonky with my first builds. Hopefully my Nemesis and Omega clones come in today so I can start experimenting. I don't think I've been this excited over getting a mod since picking up my VTR.

Steam Engine is a very handy tool... but solid math, Ohm's Law and battery knowledge are still your bestest of friends when RBA/unregulated mech vaping.
Get a decent grip on those elements - and (if you don't have one) get a DMM and learn how to use it... and you're golden.

Have fun wrappin' and a glowin'. ;-)

 

[scrappy]

If you're using 30g or larger just hold the coils next to each other. As long as you use a lot of tension and there are no gaps between wraps it'll be obvious which coil has an extra wrap or two. It's harder to tell with smaller wire than 30g. (for me at least)

When you have them mounted, fire them up and squeeze em. Ignore any unevenness while you squeezing the coils. Let them cool down for a minute, then fire it up and pay attention to which coil is glowing first. The one glowing first needs a little extra length on one of the legs, or you can take some away from the side lighting up slower.

You can get coils that are uneven to glow at the same time but once they cool they'll light up unevenly again. That's why I like to even them out when they've cooled a bit.

 

[DaveP]

Easy coil count and very neat windings are what make me use the coil winder every time. Turn the handle 10 times from the starting position and you get 10 perfect wraps. Vary the size by changing the rod to a new diameter. Most of the time I use the micro torch and anneal before wrapping and sometimes I torch it after. Either way results in a perfect coil with each wrap touching the next. I just spread it slightly and stuff some cotton in it.

Amazon.com: Artistic Wire Coiling Gizmo(R) Deluxe Winder for Jewelry Making: Arts, Crafts & Sewing

 

[suspectK]

Just use your camera on cell phone if you forget how many wraps you're on... Every time I'm wrapping a multi-coil build, something always happens to throw my attention off of it..

Edit- thought this was another thread.. already said that