Straight flutes are fairly easy with a laminate trimmer mounted on a sled and sliding along a table mounted on the ways of the lathe. Spirals take a drive/indexing wheel on the outboard spindle and a system of pulleys to pull the sled while the piece rotates (thus producing a spiral). I've described in more detail regarding the piece entitled Left, right 5160 and 5161 in my album as well as in comments on some of my pieces on another album of mine on the AAW site. My setup is a modification of one described on the WoW website.
