My woodworking bench has 3/4" dog holes for clamping work. I made an adapter to fit those holes so I could install a swing-arm desk lamp. It's really handy to get light right where I'm working, and I also use it to provide raking light when I'm planing or doing other surface work.
The adapter is simple. I just took a 1/2" PVC schedule 80 threaded nipple, filed the threads off until the end fit snugly into a dog hole, and then cut the end of the nipple off to leave a wide ring around the top. The ring keeps the adapter bushing from falling entirely into the dog hole, and also holds the bottom of the lamp up off the bench so it doesn't drag and scratch. Schedule 80 is usually dark gray, has a thicker wall, and the inside matched the diameter of the desk lamp post pretty closely.
The adapter is simple. I just took a 1/2" PVC schedule 80 threaded nipple, filed the threads off until the end fit snugly into a dog hole, and then cut the end of the nipple off to leave a wide ring around the top. The ring keeps the adapter bushing from falling entirely into the dog hole, and also holds the bottom of the lamp up off the bench so it doesn't drag and scratch. Schedule 80 is usually dark gray, has a thicker wall, and the inside matched the diameter of the desk lamp post pretty closely.
