I looked at a small Fray mill last night that uses tool holders. Does any one have a nice link to standard tool holder specs? Or ID the one's on there? These are 2" long, 1.25" at the fat end, .75' at the small end, looked like 1/2" ?? taped hole.
According to RoyJ :
Sounds like a #30 NMTB taper. Also ANSI B5.18-1972, R1991. (Page 920 of the 25th edition of _Machinery's Handbook_.)
Diameter at gauge: 1.250" Diameter of neck: 0.66" or 0.65"
Diameter of pilot: 0.670" or 0.670"
Length of pilot: 0.81"
Distance from rear of flange to end of arbor: 2.75" (Subtract length of pilot to get approximate length of taper.)
Drawbar Thread: 0.0500-13
Taper: 3.500" per foot
It has a flange beyond the gauge line with a pair of notches opposed by 180 degrees which engage two keys on the spindle nose.
There are several other variations which have the same taper, with differences in the flange to accommodate automatic toolchanger mechanisms -- and these tend to have a ball screwed into the drawbar thread which is gripped by a special motorized drawbar assembly.
But for anything which uses a plain drawbar, just about any one of them can work For some, such as the quick-change nose on the Bridgeport Series-1 CNC machine which I have, it requires the NMTB flange, not one of the others.
But -- my old Nichols horizontal mill uses the 40-taper (more of the same), and I've adapted a lot of different ones to it -- some , such as the CAT-40 need a pilot turned and threaded in to accept the drawbar threads, as they end at the taper. If you do such a conversion, be sure to use a good solid Loctite to hold it in, so you don't wind up with the adaptor pilot unscrewing from the taper and remaining on the drawbar. :-)
Enjoy, DoN.
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