This easy sliding lamp uses tension to be easily repositioned vertically along a steel cable. The design was inspired by the Parentesi Lamp which I saw in the book Nomadic Furniture 2. While the design is very similar, my version uses easy-to-find parts such as a bike handlebar, exercise weights, and a bolt-on adjustable work light. As such, this take on the lamp can be made for significantly cheaper than the $550 list price of the Parentesi Lamp.
The nice thing about this lamp is how customizeable it is. Aside from being easily positioned, it can also be expanded to include multiple lamps on the same steel cable. With a bit of redesign, it could potentially be mounted horizontally or - really - so long as the cable is kept tensioned, at any angle you would like. Any which way you decide to go, this is a cheap, easy, and stylish weekend project.
Step 1: Lamp Materials
You will need:
(x1) Adjustable Mini Arm Light
(x1) Bike handlebar
(x3) 5 pound round weights
(x1) 3D Printed Lamp Bracket***
(x1) 4" steel cover plate
(x1) 1/4-20 turnbuckle
(x1) 10' x 3/16" plastic coated steel cable
(x2) 3/16 compression sleeves
(x2) 3/16 wire rope thimble
(x1) 6" x 3/4" spring (or similar)
(x1) 1/4-20 x 1" bolt
(x4) 1/4-20 x 3/4 hex head bolt
(x4) 1/4-20 nut
(x1) Threaded bolt hook
(x1) Light bulb
(x1) 15' 2-wire black fabric cord (optional)
(x1) 2-prong power plug (optional)
(x2) 1" sections of heat shrink tubing (optional)
***See the next step for more information and alternate solutions.
Step 2: 3D Lamp Printed Bracket
3D print a lamp bracket using the attached STL file. This bracket will hold the lamp to the bike handlebars (assuming the handlebars have a 1" diameter).
If you don't have a 3D printer, you can use a service such as Shapeways to print the file for you.
If you don't have a 3D printer or want to pay for a 3D printing service, you can likely replace this part with zip ties. Two standard black zip ties should be enough to firmly fasten the lamp to the bike handlebars. However, to be on the safe side, you may want to consider getting some steel zip ties.
Alternately, steel hanger strap and some bolts may work.
Step 3: Bend the Handlebars
When this step is completed the handlebars should lie flatly on the table roughly in the shape of shrugging guy's arms (i.e. ¯\_(ツ)_/¯ like this).
The trick is to find handlebars already bent roughly in that shape. However, none will be perfect and require some modification. Typically the handles are bent back towards the rider and need to be bent in the opposite direction to make it flat.
The easiest way to do this without entirely destroying them is to clamp it in a table vise. It is also advisable to put clean work rags over the jaws of the vise to keep the paint job from getting scratched and scuffed up.
Next, find a metal bar - preferably a square steel tube - to insert into the end of the handlebar as a lever. Gently - or not so gently - wrench back on the lever until you bend the handles into position.
Check your handlebar against a flat surface once completed and make any necessary adjustments.
Step 4: Base Hook
Remove the eyebolt from the 1/4-20 turnbuckle that has standard threading.
Fasten the turnbuckle to the 4" cover plate using the 1/4-20 x 1" bolt.
Once completed, the plate should be able to lie flat on a table with the remaining hook of the turnbuckle pointing up in the air.
Step 5: Weights
Neatly stack the three weights atop the cover plate such that the hook from the turnbuckle is protroduing out the center hole.
Step 6: Insert the Cable
Insert the steel cable through the handlebar.
Step 7: Rewire (optional)
The cord that comes with the mini arm light is not exactly the most aesthetically pleasing and potentially not long enough for some applications. While not entirely necessary, it is probably best to replace it with a longer more aesthetically pleasing cord.
To do this, simply disconnect the existing lamp cord, and solder in place a 15' black fabric cord. Make sure to insulate any exposed solver joints with heat shrink tubing.
Step 8: Wire a Lamp Plug (optional)
After replacing the lamp cord, the cable is going to need a new plug. Simply connect a wire from to each of the plug's prongs and close it up.
Step 9: Clamp Together
Affix the adjustable mini arm light to the center of the handlebars using the 3D printed lamp bracket and 1/4-20 nuts and bolts.
Step 10: Modify the Spring
Make sure that one side of the spring has an opening large enough to hook through the base's eyebolt.
If it is not wide enough, bend or cut it so that it is.
Step 11: Loop the Spring
Slide a compression sleeve onto the end of the steel steel cable.
Pass the end of the steel cable through the closed hook on the spring (assuming one side is closed).
Next, pass the end of the cable back through the compression sleeve and insert the rope thimble in the middle of the loop.
Pull the cable tight around the thimble. Use the proper diameter compression tool to compress the compression sleeve and lock the cable in place.
Without the proper diameter compression tool, the sleeve can still be compressed using a hammer, chisel and very hard surface. Simply bang the heck out of the compression sleeve with the hammer and chisel until the cable is locked in place.
Step 12: Top Cable Loop
On the other end of the cable, use the remaining compression sleeve and thimble to make another loop.
Step 13: Attach the Hook
Anchor the anchor hook firmly into a wooden ceiling beam.
Step 14: Hook the Cable
Insert the ceiling hook through the top cable loop.
Step 15: Hook the Base
Hook the open end of the spring into the eyebolt in the base.
There should now be tension on the wire, and the handlebar should be locked into its current position.
However, there should not be so much tension that the weights are floating off the ground. If they are, adjust the height of the eyebolt until they are not.
Step 16: Light Bulb
Insert the light bulb into the lamp.
Step 17: Using the Sliding Lamp
Plug it in, and turn it on
The lamp can easily be repositioned by lifting the weights off the ground, sliding the handlebar, and lowering the weights once more.