Brass lamp cap repairable?

[ivaldes1]

I picked up a lamp at Chickasha but then tried to get the brass cap off and the underside bolt disintegrated. Is this salvageable somehow?

[Allan]

That's a really nice brass cap well worth saving. Attached to that badly rusted piece was a 3/16" coarse thread stud that screws into the lamp chimney. This is what holds the lamp pieces together, so you need to find a way to replace. It may mean silver soldering a metal thread to a steel disc and then silver soldering that disc onto inner edge of the steel under the brass cap.

Or you could just buy a repop.

Hope this helps.
Allan from down under.

[Wayne Sheldon]

With the brass top, you need to be very careful not to get anything too hot! However, it is not that difficult to do. Since much of the steel is rotted away, you will need to replace a bunch of that. I have simply brazed common bolts in place of the broken studs IF the base steel was good (yours isn't). The plus side to this is that what I usually do has to be carefully done so as to not cause the cap to sit too high!
In this case, I would carefully cut a piece of sheet steel (about 18 gauge, almost any scrap body steel will do fine) to fit down inside the dimpled offset near the outer edge. Using a hammer, dish the piece only slightly, drill a hole for the bolt to go through, then braze the bolt on through the backside of the dished piece.
Now, for the tricky part. VERY carefully, using a small tip, but fairly high heat, and ALWAYS aiming the heat from the outside toward the middle, braze the dished piece into the low dimpled area. Be VERY careful and pay close attention to your heat near the brass top!. Brass goes from okay to a puddle in a heartbeat! You might want to put the brass top in a jar lid with a bit of water to keep it cool, however, that also causes tricky issues. The water can evaporate and you with a false sense of security may not notice the brass suddenly getting too hot until too late! You cannot allow the brass top to float because you will be chasing it all around the pool! So the pool cannot be large or deep. (Need I go on?)
I have done that successfully, and with no disasters so far.
However (I sure do use that word a lot!), if you are concerned? You could simply make the steel piece to fit, braze the bolt onto it, and then J B Weld glue the thing in place. With some simple finish work and the underside painted, it will look great! And if anybody ever wanted to? The J B Weld can be carefully burned away and it can be better repaired at any time later. No harm. No foul.

Clarification. Do not dish the replacement steel very much. Just barely enough to sit nearly flat inside the dimpled area which is itself slightly dished. You want the outer dimple to be nearly full depth! It surrounds and clamps down on the outer chimney when the lamp is assembled.

[MWalker]

What I would do, which doesn't involve any heat, is to clean it up a bit and fill that void with JB Weld, then imbed a bolt into it. Quick and easy, and plenty strong enough for this application.

[George House]

I’m with Mike. I’ve done this before. Lightly sandblast the underside then continue with Mike’s advice. No heat !!

[ivaldes1]

Would have to finally spring for that blasting cabinet I've wanted for years... Don't tempt me Frodo!

I’m with Mike. I’ve done this before. Lightly sandblast the underside then continue with Mike’s advice. No heat !!

[Allan]

I have no experience with JB Weld. Sounds like marvelous stuff. If it will allow you to screw the top cap down tight enough to hold the inner chimney in place as it locates the reflector, a diffuser ring, and will hold the top outer chimney assembly in place as well, then it must be good.

I'd go down Wayne's path, but use silver solder so you don't have the same heat problems with the brass bit so close. I guess that could be the next step if the JB Weld doesn't hold up.

Allan from down under.

[Scott_Conger]

I see a very easily fabricated sheet metal piece, cut into 3 pieces, inserted and then tack welded together again with a carriage bolt captured in the center. No big deal.