Lately I’ve wanted to use dowels with a flat edge on them for handles and pulls or as decorative moldings on my projects. But how would I mill that flat edge safely? Here’s one way: at the router table using parallel bar clamp. Position the dowel inside the clamp so its bottom edge and the bottom faces of the clamp are flush against the router table top. Tighten the dowel in the clamp. Then, use the clamp as a carrier to slide the dowel along the router table fence. Make the cut with a straight bit extending just beyond the fence faces.
The dowel must be several inches longer than necessary: you need to leave a round portion on the infeed and outfeed ends to serve as bearing surfaces against the fence. Make the flat profile wider and deeper by resetting the fence a little further back from the bit with each pass. Limit these depth-of-cut changes to not more than about 1/16″ with each pass. When you’re done routing, just cut off the round, un-flattened ends.