Hi, I'm trying to think of a good way to make a solid coupler between my stepper motor and lead screw. I know several designs just use a piece of rubber hose, but I need a solid coupler since the opposite end of my lead screw is not going to be supported (no thrust bearing because my cnc is for lightweight hotwire cutting only).
Anyway..my lead screw is 1/4 inch thread rod and the motor shaft is 3/16". So currently I took a 1/4 coupler (like a really long nut) and just drilled a set screw hole in it for the motor shaft. Of course even the I.D. of the coupler is still a small bit bigger than 3/16, so if I tighten the set screw down too much the coupler becomes "off center" or tilted just a bit. But over the length of 2 feet of rod, it's a lot!
I'm trying to think of a way to make a coupler for 3/16 to 1/4 - the 1/4 inch part I would tap out so it just screws unto the lead screw.
Really, I'm thinking a lathe is the only real way to be able to do this..
At first the thought of using a drill press, but it's hard to keep the bit centered properly - for example, if you drilled the hole for the 3/16, and then switched bits to drill out the 1/4 (Drill all the way thru with the 3/16 so you don't have to move the part when you switch bits). I know in the past I've tried this before and it still didn't really have concentric holes.
I also have found one post in the forum about this sort of thing but I don't remember what they suggested to the fellow.
Is there any other technique I can use?
-niko