Hello!

I am an amatuer machinist/hobbist. I have never worked professionally doing metal work, and therefore have never had any training. Actually im a software engineer. I have been tinkering with building a CNC PCB router for the last year or so. I am trying to get my router up and running. Currently I am working on the Y axis, Im going with the Y axis on the base/table and the X axis suspended just above. The major problem that I am having is trying to couple my lead screws to my stepper motor. I am using very small motors (4mm shaft) and I am using threaded rod for lead screws (about 3.5mm). I have tried making my own shaft couplers, but I can't seem to get a hole directly in the center of the cylindrical shaft. Is there any good techniques to put a hole dead center in the end of a bolt? My latest attempt to couple the shafts is to adapt a small dremel chuck to the end of my motor and just clamp the lead screw into the chuck. The dremel chuck is threaded on the shaft side and requires some sort of bolt with a hole in the center to close the chuck. Any ideas?

Thanks!
Ben