Lubricating screw thread so resistance not increased

Graphite powder?

Graphite powder? E.G.

That also works a treat on the thread of Edison Screw light bulbs/spots so that when you come to take them out they don't jam up and break in your hands. But then I'll bet all the D-I-Yers have been doing that for some time.

Graphite or MoS2 - both are black powders.

Big fan of moly myself on screws (especially things like lead screws), but I didn't think it was a conductor like graphite.

The other thing I would suggest is one of the "Copaslip" type greases often used on disk brakes. These contain copper powder. Anti-seize thread lubricants used in other more difficult environments contain finely powdered nickel, but not worth looking for unless you can blag a smear from an existing user.

I'd personally suggest a mineral oil product rather than a dry lubricant on aluminium because it will help to prevent corrosion if it is a torch which regularly gets wet.

Moly grease needs to be used very sparingly, it doesn't come out of clothes. DAMHIK.

Surely (going back to OP) the 'right' thing to use would be one of the specialist contact lubricants. I'm not at all convinced that graphite is going to help the connection much.

Graphite? The problem is probably the oxide in any case. Some torches have a little finger on the bottom spring that rubs on the inside of the case to help in this respect. Brian

I doubt if using any old oil will make any difference to the brightness of the LED.

They will have some sort of voltage booster to run a LED off a single cell so that will take care of any voltage drop that might occur.

I'm not sure what contact lubricants contain, but I don't believe they work by being conductive, rather by providing a cleaning function. Also reduced friction means that contaminants get removed automatically by a "wiping" contact. I've never seen any particular evidence in torches of a problem with contact resistance at threaded joints (except where they have become severely corroded, and this is obvious by inspection).

Yes, I don't think they *are* conductive, that's not how they're meant to work. What they do is ensure that the contact surfaces are clean and make good contact, much more effective than trying to add an extra layer of something conductive.

But usually they are meant to hang around on surfaces which move, each time they are actuated.

Vaseline seems to work just fine, although my flashlights are higher voltage than yours (1 x 18650 lithium cell @ 3.7V). If the contact is poor just screw it tight then undo and redo a quarter turn, a few times to bed it in?

Some Brasso or similar on the threads to lap them in then clean off?