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

Ben,
I am the same as you with the hobbies. Lots as my friends say. What I would do if you have an access to a lathe is chuck it up as close as you can get for centre. On my 10" I use sometimes a strip of folder on one jaw if needed and I also use a tight fitting brass tube over the bolt. This helps with the indicator as the threads are impossible to get a reading on. Set your tool at centre line and put a little nick at centre. I then drill with my tail stock under size a few thou and then ream to size. Most bolts have a lip on the end from the threads and you might have to machine it smooth.
As an amature I hope this is some help. The big boys can comment.
John