Milling cutter holder sleeves ??...

5

56type

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Was poking around on ebay and came across an auction for a milling cutter holder with drawbar & sleeves/adapters that allowed different size cutters to be held in the cutter holder. Having recently purchased the milling attachment, drawbar, and cutter holder for my Atlas 10100 Mk.2 I was missing the spacer (which I have since made) I'm curious about the sizing sleeves for the 1/2" inch cutter holder... which I also don't have

Does anyone know the dimensions of the sleeves and if they are hardened ?? They look fairly simple to make from some 1/2" round stock and mill some slots to allow the set screw in the cutter holder to pass thru, followed by drilling the correct I.D. for the cutter to used. I'm sure I could probably make my own provided they are not hardened but I need to know the range of common endmill shank sizes to get the I.D. of the sleeves correct as well as the overall sleeve length. Or what the original sleeves were sized for as a starting point. Thanks.
 
Atlas originally made/sold two drawbar & cutter holding sets, one in 3MT for the 9", 10" and 12" lathes and one in 2MT for the 6". Model numbers of the sets were 945 and M6-945. They consisted of a handwheel type 3/8"-16 drawbar, taper nosed sleeve for centering the drawbar, and one 3MT or 2MT holder for 1/2" shank diameter cutters. The model No. 563E set of four bushings fit either holder. OD was 1/2". ID was 7/16", 3/8", 5/16" and 1/4". Each of the bushing had a flat cut across them that allowed the set screw in the 1/2" ID holder to grip the cutter shank of one of those four diameters.

Single ended end mills are available three ways. On one type, the shank is the same diameter as the cutter. These require a collet of some sort to hold them.

The second type has a shank that in some cutter diameters is larger than the actual cutter on the in-between sizes. Diameters that I have seen are 1/8" to 1/2" in 1/16" increments. Why the Atlas bushing set stopped at 1/4" ID I don't know.

The third type is known as "Weldon" type or style. These have a flat ground across the shank for a set screw to bottom against. DO NOT under any circumstances put a Weldon style cutter into one of the bushings with the flat turned toward the set screw. It will work fine until you get ready to remove the cutter and discover that you cannot remove it.

Anyway, to answer your original question, the four bushings adapted the 1/2" ID MT holder to hold 7/16", 3/8", 5/16" and 1/4" diameter cutter shanks, whether the cutters are end mills, dove tail or key seat types.
 
Also, on the spacer, I have discovered that one that has the right end turned down to just slip into the spindle bore is much more convenient to use than the taper-nosed one.
 
Thank you sir !!... Just one more clarification please. I seem to always wind up with the Weldon type cutters when I order. I was thinking the bushing with the slot was to be used with that type of cutter ?? is it OK to use the Weldon type cutter in the bushings as long as the slot on the cutter doesn't line up with either the slot on the bushing or the holder ?? Trying to figure out the best way to use the holder other than as a dedicated 1/2 in. only cutter holder. I did just use it with a 11/16" in. Weldon type cutter with 1/2" in. shank for some light milling, but wanted the option of using smaller shank cutters.
 
Using a only a 1/2" shank Weldon style cutter with either of the Atlas holders, align the flat on the shank with the set screw. But with any of the reducing bushings, align the slot in the bushing with the set screw but on the cutter shank, rotate the flat around to about 180 degrees away from the slot and set screw. That is safe. Just do not align the flat on the cutter shank with the set screw.
 
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