Lumberman,
I make a lot of arrow shafts from various hardwoods such as whuite and black ash, spruce, white and yellow birch etc. I used to use a sander and turn the "squares" into octagons and then hand sand them round. Another way is to glue coarse sandpaper inside various (descending) sized tube and "spin" the squares through them with a drill motor (use a 1/2" drive socket extension).....but the easiest way (and most cost effective) is a Veritas dowel and tennon cutter that costs about $20 and comes with extra blades. you can make thousands of shafts with that 20 dollar "pencil sharpener".
Being on a small fixed income I thought the 20 bucks was a big deal at the time....but turned out to be a good idea cause it paid for itself, and is still working great.
Hope that helps ya some....they do get easier after making a few
rich