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Just a few thoughts on this subject, as I have used a preliminary mill for a few years now and am currently in the process of the design and building of a true two spindle beveler. For a preliminary mill, the average rodmaker can save a tremendous amount of time by using this type of device to mill the initial 60 degree angle on strips. I converted an old Delta Rockwell wood shaper to do just this. I designed a mechanism that bolted down on the top of the shaper that utilized hold down shoes on either side of the cutters, so that the bamboo strips are rigidly held as they are fed through the cutters (I use a lift cut as opposed to a climb cut - primarily for safety). I use double angle milling cutters, and stack two of them together to get the perfect 60 degree internal angle. They are High Speed Steel, made by Dolfa of Poland, and Cost about 58 dollars a pair. The beveled edges stay sharp for about 5 rods worth of strips, and then I need to reverse stack them for another 5 rods worth. I generally just buy new cutters instead of resharpening, as I have been quoted 45 dollars the pair to resharpen, so I just bite the bullet and get new ones. I soak my strips overnight before milling, as I have found that this gives me a cleaner cut. My strips need additional attention to straightening, squaring up, and sanding the enamel side flat, before I run them through the mill. This may sound like heresy, but when you add machining of any type to bamboo preparation, expect to add heresy to the process. My shaper turns at 10,000 RPM and gives a nice clean finish after two passes, the second pass done after the fence assembly has been moved closer to the cutters, allowing the second pass removal of about 35 thousandths. I will resoak briefly for the second pass. At this point I like to bind the six strips by hand and allow to dry for a few days before preliminary planing. After preliminary planing to a taper that is 40 thousandths over final dimension, I then bind and heat treat, and follow with final planing. This method, although sounding more complicated than the traditional method, lends itself well if you want to make more than one rod at a time. The stacked milling cutters act as a self centering device that keeps the cut straight and true through the entire pass. The cutters just cut through those nasty jumps that seem to occur at nodes. I never find any tear out at the nodes when I start to plane. This type of mill is fairly cost effective (I've spent about $500 on the machine and bar stock aluminum for the mill - I wouldn't use wood due to the wetting of the strips). I can let it sit unused for months and then ready it in about 5 minutes time for use again. The best attribute of this type of mill over a final mill or beveler is that the tolerances don't need to be so razor thin. Anyone contemplating the use of a device to cut to final taper dimension in one or two passes, get ready to do a hell of a lot research about metal machining in general, and about spindles, cutting tools, linear motion control systems, and motor control systems in specific detail. You will need the services of a fully equipped machine shop and a critical eye for running such complicated machinery. Also, a fat checkbook or wallet is an absolute necessity. Hope I've added some light to what promises to be a stimulating topic. (Tom McDonnell)
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