The threads reverse at the center section. There is a smooth section in the
middle of the threaded rods that ride in a bearing in the center part of the
jig, so the center piece never moves on the threaded rods. Since the
threads to either side of the center section are revered from each other,
both side either move in towards the center or out, as the threads rotate,
if that makes sense.


"igor" wrote in message
...
How does a self-centering doweling jig work? That is, how does the
centering set-up actually function? There is the center and then the two
sides. I assume it is all in the threading, but what is the setup? I
DAGS
and all I could find was how-to-use info. TIA. -- Igor