Thursday, June 5, 2014

Tighten Table Lamp Body

A patient came in the other day and was really wobbly. Not just loose the poor thing was constantly leaning in one direction.
The cause of the problem was obvious: a plastic neck on the top of the lamp, just below the harp base, was broken and cracked. Like most plastics over time, this one had become brittle and busted. No need to worry. A little tweak here and there and this lamp would be good as new.
The first thing we need to do is remove the socket. This lamp is held together with one threaded rod from base to socket. We need to remove the socket to replace the broken neck and get access to the top nut. Removing the socket is easy. With a flat head screw driver, pry the shell (top metal of the socket) from the cap (bottom of the socket). Most sockets have a place marked "To remove, press here." That would be the right place to pry the cap from the shell. If you are planning to use this socket again, please be careful not to bend the cap or shell.
When the socket is out take me a moment to inspect the sockets insulator. This is the cardboard insert between the socket shell and socket interior. If this insulator is crunchy, burned or looks decrepit it should be replaced. This patient's insulator was in good shape, so it will stay in service. Now I untie the UL knot, pull the cord through the body, and remove the socket cap. You can see the top nut.
I have to remove the nut (9/16 inch socket or wrench), the harp base, and the seating ring to get to the old broken neck piece. With all the pieces off the lamp I took the lamp body off to show the threaded rod in this lamp.
I am going to replace the broken plastic neck with a stamped steel neck (in brass plated color for matching). This item is very inexpensive.
The new neck will last longer and allow me to tighten the lamp more without worrying about breaking a plastic piece. The new neck is slightly shorter than the old piece so I will need to make an adjustment to the bottom nut and pull in some of the new space.
I tighten the bottom nut by about 3/8 inch and start putting everything back in place. I put the lamp body back on the threaded rod, then the new neck, the harp base, a locking washer and the top nut. Using the 9/16" socket, I tighten everything so the lamp is strong and tight. After looking at the cord, I decide it is time to replace the old one. The old cord is smashed in a section like it has been under a chair for a while and the prongs are not polarized. The cord is polarized with one smooth line and one ribbed, but if prongs are the same width there is no guidance for what way is top and bottom. I decide to use an 8 foot brown SPT-1 lamp cord.
I push the new cord through the center pipe, tie the UL knot so it won't slip through the socket cap and attach it to the socket interior.
The socket interior on this lamp is a little old, but still in good condition. To wire this socket correctly, I need to make sure I get the right wires on the correct socket screws. Newer sockets have a brass screw and a nickel screw. The smooth wire attaches to the brass screw and the ribbed wire to the nickel screw.
With the interior wired, I pull the slack from the wire back through the base of the lamp and lock the socket shell onto the socket cap. The shell locks with two clicks into the socket cap. I place a bulb in the socket and plug in the cord. I turn on the lamp and make sure everything works as it should.
This lamp is ready for its harp and many more years of good service. Total time < 30 minutes total cost of lamp parts < $5.00.