Are you saying that the triangular shafts were made cylindrical on a lathe, then triangulated by shaving off the three sides with glass? Not a planer?
~I have an antique mace with a "spoke-shaved" shaft. From a distance it looks smoothly cylindrical but up close you can see the fine shaved lines less than 1mm wide. I believe this technique involves using a planer to cut the sides off square wood stock. You shave 45 degree cuts off the corners of a rectangle- resulting in an octagon. Then you shave down the 8 corners, and so on until you get a nearly perfect round cylinder. That is what I have in mind as "traditional" dowel making. They used to make wagon spokes that way. My mace has an unusual mace head shaped like a pyramid with concavely grooved steps and a big rectangular piece of leather to strike balls. When I researched this I found nothing about using glass to cut the sides, so you have me curious about this. I do remember the triangular shafts, they looked well made in the ads.