| Clamping Down Your Wheel |
| I fashioned my clamps after CH's Flight Yoke system which is very reliable and easy to use. Using 3" corner braces from the hardware store, I attached them to the wheel base allowing one of the legs to extend downward as the arm hinge. After cutting out the hardwood arms, I drilled a 1/4" hole at one end for the hinge and a 3/8"wide X 3/4"long slot for the 1/4"x 5" hex bolt. This allows the arm to pivot up and down without binding on the bolt. You have to rock the 3/8" drill bit back and forth several times to ream out the slot well enough for the bolt to fit loosely. Next, attach the arm to the bottom hole of the braces with a 1/4"x2" bolt. Make sure that the arm pivots easily; the idea being that it will drop down when loosened from your desk top. Drill a hole through the wheel base and insert a Tee-Nut, or a threaded insert, that accepts a 1/4" bolt. Fit a knob to the end of the hex bolt and slip it through the slot in the arm, threading it into the Tee-Nut. My desk has a 1 5/8" thick top, which the clamp accommodates. If your top is of a different dimension, use a longer or shorter bolt to fit your needs. This system allows for quick attachment or removal of your wheel, while tightly securing it to your desk without worrying. In the illustration at right, you can see how the tightening knob works. These can be found in some hardware departments, but you can also construct them yourself from two pieces of wood, plastic, or other dense material. Basically, it's two disks about 3/8" thick; one has a 1/4" hole in the center, the other is cut out to accommodate the hex head. Glue them together and slip the bolt through the knob, so the hex part of the bolt fits snugly into the cutout. The knob acts as a wrench of sorts, while tightening the bolt into the Tee-Nut. An even simpler solution to this would be a radio knob fitted with a set screw. Just cut off the hexhead end of the bolt and file a flat side on the shaft. This will accept the setscrew, and prevent the knob from slipping. I've seen some in Radio Shack that would do the trick. Although slightly smaller in diameter (aprox. 1"), it would provide you with enough torque to secure the wheel down tightly. |
| Cross section of clamp setup |