Modelling - Winding length bigger than Gap Length ?

Hello,

I want to model a voice coil and use a voice coil calculator to help. The gap length is determined in the calculator using the magnet thickness and top plate thickness. Now I have the case that I have twice as long a winding length as the gap length.. can that be right?
 
Hello,

I want to model a voice coil and use a voice coil calculator to help. The gap length is determined in the calculator using the magnet thickness and top plate thickness.
No: gap length here is plate thickness plus an assumed (unless you can accurately measure it) extra fringe magnetism, say 10% plate thickness, maybe 15%

Magnet thickness has no relation to that.
Now I have the case that I have twice as long a winding length as the gap length.. can that be right?
It´s common in woofers.

FWIW I use 9mm winding length for my Guitar speakers (if I want them fat sounding) or 7-8 mm for normal sound, and 11 mm for Bass Guitar voice coils, all on nominal 6mm-1/4" plates.

As you see, almost twice plate thickness.
 
Off topic, but @JMFahey: do you machine the polepiece/motor parts yourself?
Yes, of course.
Turn pole pieces out of cold rolled 12L14 steel bar which is quick and easy to machine and plates out of punched or oxygen cut (depending on diameter and thickness) SAE1008-1010 plate if available; sometimes can only find 1018

Making/machining as much as possible in-house is the only way to be competitive, specially given the Chinese onslaught who sets low reference prices for everything.
We also have very low Customs protection, maximum tariff allowed on anything is meager 20% (d*mn GATT, WTO and all free trade associations, all destroy local Industry and kill jobs), useless if original product is made for 1/4 our cost.

Some free samples, 10" - 12" Guitar/Bass speaker frames and 4" cone tweeter parts:

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Excuse the omnipresent dust 🙁

Oh, I send them out for galvanizing (Gold or "Blue")

I had set up a galvanizing tanks, rotors and 6000 Ampere power supply but after 2 batches I disassembled and sold everything, terrorized because all baths contain cyanide and many very nasty heavy metals salts; I don´t want to die with cavernous holes in my lungs.

In fact I carry raw stamped or turned parts, only covered in some light oil to zinc plater and leave them at their door, then ask them to load finished parts back into my truck, I don´t want to breath air inside for 5 minutes, go figure.
 
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