The most significant part of this conversion is the finial. As you can see, it lets the shade offset to the rear. (More about this later.) This allowed me to use an existing hole in the shade and offered additional clearance for the bulb. Ideally I would have liked the shade to be perfectly centered but the small offset was a small price to pay for ease of construction.
Taking the iMac apart takes about a half-hour to an hour and requires a full set of star drives. Be sure to have some small containers handy to keep the zillions of screws and small parts in. And don't try to save the many cables you'll encounter. Just cut them out. You won't need them.
Once
I ripped all the guts out of the central support
and installed the new wiring I simply
used some bolts, washers, and wing nuts to secure it vertically. It will
still twist 180 degrees but that's not a problem.
Note that the top swivel has an inner part that will need to be filed
down to allow room for the threaded shaft (that the harp will bolt
onto)
to
be bolted
in place, using a pair of flat nuts.
For the shade support
I used a 4-inch harp. This allowed the shade to be lowered enough to
hide
all the fiddly bits from view. I got this one off eBay for a couple
of bucks.
The support for the lamp socket was
made from a piece of 3/4-inch aluminum slat, available at your local
big box hardware store. These aluminum slats are dead-simple to cut,
shape, and drill but plenty sturdy enough for this job. By shifting the
angle 90-degrees in this way I didn't have
to
worry about
the height of the bulb.
The metal part that attaches to the top of the harp, the one the finial screws down on, can be adjusted to different angles. By angling it back a bit it let the shade sit level. Sweet! This finial is brass but I spray-painted it chrome.
The base was held in place in the iMac by six little screws on the outer edges but using three of the screws, upside-down, made easy-peasy self-leveling feet. To keep the wiring secure I cut a 6" round of matt-board and used the three screws to attach it to the bottom.
As you can see there are six leg-holes and five cord-slots. I didn't consider this when I drilled the hole for the switch. If I had it to do over I would have drilled the switch-hole another 60-degrees clockwise. That way the switch and cord holes would have matched up perfectly.
That's about it. If you have any questions, let me know.
