A Thread Thread.

[sosemot728]

What is a standard metric, relatively fine pitch internal (and corresponding matching external) thread size that is used in flashlights?

Or is there no 'standard'....

 

[Th232]

From what I've seen, most flashlights use imperial rather than metric, and I've personally never known any that use metric. That kind of data is hardly ever given in reviews though.

That said, standard metric threads can be found here:

http://www.tribology-abc.com/calculators/metric-iso.htm

And there's a link at the bottom for fine threads, bearing in mind that tap and die sets for the fine threads will be rarer and more expensive.

If you're making your own light, I'd say go for whatever fits, and if you've got choices after that, go for the coarser option in general, but a twisty light may need some further thought.

 

[gadget_lover]

To amplfy on Th232's statement....
"If you're making your own light, I'd say go for whatever fits"...

There is no single standard thread. There are lots of them. The one you choose for a flashlight is based on two major questions:

1) How deep can the threads be? A finer thread is shallower, so can be used in a thinner part. A coarse thread is deeper, so the part has to be thicker.

2) How many turns do you want to user to have to make? A very fine pitch (0.25) may be fine for the reflector holder, since that makes fine adjustments easy. The reflector will move .25 mm per revolution. Use that 0.25 pitch on a 20 mm long tailcap thread and the poor guy will have to turn it 100 times to change the battery.


If you look at the chart at http://www.tribology-abc.com/calculators/metric-fine-iso.htm you will note that there are acually several different pitches that can be selected for various diameters and still be considered "standard".

BTW, the standard only applies to fasteners. When making parts you can choose any pitch that work for you.

Daniel

 

[Geir68]

I dont think there is standard, but many of the cheap Chinese lights that are sold where I live(europe) are using 1mm metric threads.

Surefire E series are using 20TPI for both the head and tail. This is very close to 0.8mm metric pitch.

I'm working on a series of light components that are interchangeable. All tailcaps, battery tubes and heads use the same thread. These are lights made for small litium cells like 18650 and 16350. All of these are threaded 22x1mm.

Make your own standard, and stick with it.

 

[precisionworks]

Make your own standard, and stick with it.

L. S. Starrett used to do that with all their precision measuring tools ... but the pitch & size were so unusual that any replacement part had to be purchased from Starrett. Not only did they get 99% of all the parts business, they also got to repair the tools that someone cobbled up trying to make or use a "standard" thread size.