Hey Mac,
I'm not understanding this, I understand the half wrap/full wrap difference. The point at which it leaves the coil is where it leaves the coil? Are we subtracting half wraps?
Vape On My Friends!
The author calculates the difference. There is a selection box below the "target resistance" field entitled...
Use neutral axis for wrap circumference. The coil calculation is absolute. The real variable here is lead length which may vary for every wind and substantially. But you're right. The value that matters is contact to the pin. I've used a variety of deductions over the past year. There are things we can't see like grommet deflection. Pin length varies slightly.
When
measuring for a practical average you measure from the point the lead stops bending and is straightened by compression of the grommet. You may find after you measure a few that it is a point beneath the uppermost extension of the pin slightly and
it changes
based on the angle of your set, how deeply the wire cuts into the grommet (tension applied on the leads). In reality it varies for each wind and winder. So you're going to have to find your own happy medium based on your own practical experience what to discount from your calculation. Some days depending on how you're winding you may decide differently than others.
My tendency is to use the high side of any such calculation making the resistance target somewhat higher than actual. If I'm lower I'm tending to suspect the wind as shorted and frankly that's just fine by me. This would happen when it's wonky anyway. And I'm ok with rejecting a perfectly good wind under those circumstances rather than suffering a bad vape.
Now despite our theoretical look ups. We often end up with a result that doesn't quite approach the wire length. I was wrapping quite loose for some time because of silicone. In recent months I'm
trying to get back to tighter. We need more table contributions correlated to steam-engine now that it's turned out to be such a formidable machine
and most of you guys probably have better hands than I do. On really good days I can hit precise wire lengths using the deduction. Most often I'm pleased if I'm within o.o5.
I'm using 12mm as a practical rule of thumb for my RDA builds since I do a lot of outboard stuff for airflow. Everyone's always said Protank leads are longer. Well they aren't but you'll have to see exactly how much if at all by taking your own measurements. Then you'll be able to close in tighter on resistance targets. But
not using any deductions might have you as much as roughly o.12Ω or maybe more off target. Y'all will have to decide what's useful to you.
Consider that there are
many variables like hand strength applied in set and wind, how consistent you were, inconsistencies in the wire, etc. I'm not going to enumerate them all but to say that our brains are an amazing tool. And we can detect these small variations in astounding detail. Adjust from wind to wind if we do enough of them or close together enough. I have come to the conclusion that it would take quite some instrument to be able to accomplish what we can in a few minutes with a simple tool, our hands and our amazing on board calculator.
The leads at the end of the day have played a big part all along on the broad range of results we all get. I'm pleased to see some interest in this. Precision improves greatly as you gain tension consistency and you build more often
especially if you also are consistent with your termination strategy. If not you can go way off every time and not know why. So
lead angle is the important first step. No strategy and all the calculation in the world won't mean a thing.
Good luck all.
Let me know buddy.
