MTFCA Forum

who knows how to take the brass top off of a 1915 sidelamp?

There is a nut on the bottom side. If you take the font and burner out you should be able to look up the inside of the chimney and see it/access it with a socket and extension.

If the sidelamp is rusty, about nine times out of ten, just turning the brass cap will break the long stud that holds it to the rest of the lamp, and in turn holds the top half of everything together.
Usually, that stud can be replaced by very careful brazing (put the brass cover into water to keep it from getting too hot and disappearing!), however, better to NOT break it in the first place.

Soaking in good penetrating oil might do the trick? Or not.
I usually use a small tip torch, carefully aimed in through the vent holes below the cap (either brass or steel caps) to heat the stud itself or the nut which should be captive in the chimney's inner piece. A bit tricky to do without getting some things too hot and damaging them. And it may not work the first time. Several times, being careful to not get something too hot, I had to heat and allow to cool several times before the stud would turn. I had one that I tried several times and it kept refusing to come loose. I finally said enough, got my small strap wrench to grab the brass cap and applied pressure until it broke off. Then I brazed a correct size machine screw into the underside of the cap. Looks and works perfect!

does that mean that the inner sheet metal part turns with the nut? because the nut is sitting in a hex pocket in that sheet metal...

The lamps I have taken apart, the nut does not turn, the lamp top turns. A blue wrench or a long soak in penetrating oil is recommended first to keep the stud from breaking.

sorry, what is a blue wrench? and yes, it does look to me like the top would unscrew from the nut, but I did not want to force it not knowing so.

A "blue wrench" is an oxy acetylene torch. Like Wayne described, just heat the stud from inside the chimney to get a faint dull red color and let air cool. once cool it should unscrew by hand.

Piece of cake ! thanks Humble J and everyone else .