Dual coil newb, help

[BreilaRose]

Hi all, after having done pretty well with several single coils, I decided to give setting up a dual coil a try on my Troll. It...did not go well.

I know it was only my first try and that these things take patience, but I feel like my problem was that I couldn't figure out what the problem was.

I built two identical coils with the coil master, double and triple checked them for equality before mounting them. Got them mounted, resistance read well (.7 ohm, right where I was aiming), so I mounted them on the rda deck. I centered them to the very best of my ability, checked to see if they were even, and tightened everything down.

One glowed before the other. I tried to center it more, no change. I moved one up just a nudge, now it glowed first. I moved the other one up a nudge, nothing. I moved them both down, now the other glowed first. Repeat. Well, you get the idea.

I guess what I'm trying to say is that I was definitely changing things, but I was never sure if I was making it better or worse. After an hour and a half, I gave up.

 

[sos2001]

If you used the coil master, they should have been fairly tight. After you get them positioned where you want them, use your tweezers or flat head mini screw driver and give them a light "strum" like strumming guitar strings...not while firing btw. After a few strums, they should sync up nicely if the screws are tightened properly. Every so often, even with a coil jig, you may have to do some pinching. Never use metal when pulsing....pulse, then pinch. If you have ceramic tweezers, you can pinch and pulse at the same time.

Hope that helps.

edit...here is a Grimm Green vid on dual coils and strumming and pinching....

 

[BreilaRose]

I pinched and strummed the snot out of those coils!!!!

 

[puffon]

re-tighten the posts?

 

[BreilaRose]

re-tighten the posts?

So so so many times!

 

[sos2001]

Getting any ohm jumping, any shorts, how close to your target resistance are you???? Obvious hot spots???

 

[BreilaRose]

No ohm jumping, other than when a screw came loose, I fixed that

Target resistance is spot on, .7 ohm

No obv. hot spots after a bit of strumming, just one coil turning red before the other ever even started to glow.

 

[BreilaRose]

Ultimately, I'm just trying to figure out if there is knowledge that I don't have yet. For example, if I build a dual coil and one heats up before the other, what is the likely cause?

Or maybe it is just "try all the tricks and hope one of them works."

FWIW, I finally did get the coils to heat at the same time, but they did so so very slowly, that was when I gave up.

 

[BreilaRose]

Tonight, I built two perfectly identical coils, and put them in two different RBAs. Both worked perfectly without issue from the start.

I was too chicken to brave dual coils again tonight, but I'll try again soon.