BUILDING A SLITTING SAW ARBOR
Since we last left off, we were making a end mill bit arbor or holder so I thought we should continue to use these nifty little blank arbors and machine a slitting saw arbor, but first, a little info about the blades themselves. Slitting saw blades are basically milling tools and are very different from the common saw blades used in wood working. The body of the blade can be high speed steel of solid carbide. I personally have never truly had a need for a solid carbide slitting blade. They are primarily intended from industrial applications and high production situations. High speed steel machining blades have teeth with a flat chisel edge as opposed to wood working blades which come with teeth edges at many other angles for different purposes. There is no set to the teeth of machining blades and they do not alternate to the right and left to produce a kerf that is wider than the blade body as in common blades. To provide the needed clearance for the blade body, they are hollow ground so the blade is not really flat and parallel but instead, it is somewhat dished out on both faces. The periphery is a few thousands thicker, gradually becoming thinner toward the central arbor hole. It is because of the hollow ground design, that they tend to produce such smooth finished cuts. The sizes we normally use in small equipment range from 1-1/2" to around 2-2/2" diameters with arbor holes from 1/2" to 5/8" in diameter. Many of the commercially available blade arbors have multiple steps to accept several diameter arbor blades, but I prefer to make individual arbors for each type blade as they can be made more accurately this way. TAIG Tools offers a pre cut blank arbor intended to be made into a saw arbor. It has had the front center drilled and threaded and the front 1/8" parted off to create the washer that will ultimately hold the blade against the arbor body. It is sold for $2.50 which as far as I am concerned is about a fifth of was it should really go for. There is very little machining to do, with the first step being to screw the arbor onto the spindle and taking some light turning and facing cuts to true up and expose a fresh surface. At the end face, we will need a shouldered step the diameter of the arbor hole of the intended blade. It needs to be about 1/16" thick. Begin by partially facing toward the center until you are about 1/32" from reaching the proper diameter. Begin to reduce the diameter a few thousands at a time and checking the central step with an actual blade, stopping when it fits snug. Deepen the step by removing material with a facing cut from the step toward the edge of the arbor. When it is about 1/16" deep, you can stop. The washer now needs to be chucked squarely, faced and the central area corresponding to the arbor's step machined away to create a negative step. This should leave the washer with a ring around its perimeter that will bear against the blade as it is screwed to the arbor. The blade is placed over the central arbor step or flange so if you look at it directly, the teeth will cut on the counter clockwise direction. Place the washer with the negative step so it overlaps the positive step of the arbor and insert a 1/2" long 10-32 cap screw and tighten to secure the whole assembly. Screw the arbor and blade to the spindle to use. Slitting blades are mostly used on milling machines but they can easily be used on the lathe if the work pieces are held in a vertical milling vice / slide. More on that later.