What happens when HA-insulated threads wear out?

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schuster

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The most common barrel design seems to use HA-treated threads in the barrel and head of the flashlight, thus using the HA as an insulator to allow the real contact to be made when the top of the barrel fully contacts the inside of the head.
When anodization is used as an insulator between metal-on-metal threads, what happens when the HA wears away from repeated use?
Will the flash light be stuck "on"? Will some designs present a dead short?
Some of my cheapies (e.g. that Ultrafire single-AAA) are already showing wear on the threads, with black stuff coming off on my fingers and bits of metal visible through the sharpest point of the threads.
 
McGizmo

McGizmo

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Other than "counting on" the anodize film as an electrical isolator for keeping a LED slug out of the circuit, I think it is a real mistake to design with the need for the film to keep parts electrically isolated; especially threaded parts or parts that move with contact of plated area needing to remain plated.

Some of the lights you mention may not in fact require this electrical isolation. I hope not!!
 
Daniel_sk

Daniel_sk

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I was concerned about the same thing, could someone please enlighten me if this would be an issue for Fenix flashlights? (like L1D)
 
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zipplet

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Look at the PCB on the bottom of a head on most fenix lights - for example the L0P. You'll notice a contact ring on the bottom of the PCB which touches the top of the body. This is the only place current can actually flow! The threads on the heads of most fenix lights are not connected to the circuitry in the head - with the exception of the "2 control" UI such as that in the L2D.
 

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