I'm experimenting with a design of my own. PVC pipe fittings are cheap, abundant, and some are even threaded.
Basically, take a PVC cap and plug, and thread them together. Drill a hole through both ends, and tap them. Epoxy on some metal nuts -- I don't think PVC this thin would stand up to much use.
Now, since the thread pitch of the lead screw and the PVC fittings is different, you can screw or unscrew the PVC parts together/apart, and in doing so, dial out the backlash between the metal nuts.
A side benefit (if it works) is that the nut would be hollow, and I will try using this as a grease reservoir, to help reduce friction. I'm hoping that the PVC portion of the thead will be tight fitting, and act to keep contamination down to a minimum.
I'm going to make one of these tomorrow -- finally got the right size drill bit and tap. :-) We'll see if theory works in reality.
-- Chuck Knight |