Parent page is Machining
There are really only a few tapers in common use even with all the names for milling machine tapers. Quite a few manual milling machines use the "R-8" taper, but most CNC and large machines use something else. A tool-holder consists of 2 sections separated by the gage line (the gage line is an imaginary line marking the portion of the tool-holder that matches the bottom edge of the machine spindle). The taper fits into the spindle allowing the machine spindle to transfer rotary motion to the tool holder which holds the tool.
A toolholder has a 2 part specification, taper and tool. This page covers the machine-to-toolholder standard and not the holder-to-tool standard. and example might help. A NMTB #30 collet chuck and an NMTB 1/2" endmill holder fit the same machine, but hold different tools.
The NMTB refers to the taper standard family - the #30 the shank size (if they leave off the #30 part it is assumed to be the small one.) At the end of the tool-holder name is the name of the tool type - 1/2" end-mill holder or
Conversely, a NMTB 1/2" end-mill tool-holder and a Universal Kwik-Switch 200 1/2" end-mill tool-holder will hold the same tool, but fit different machines. The drawings below show only the taper portion of the tool-holder.
The ANSI standard size is determined by the machine size; Larger machines use larger shanks.
Spindle size to Machine size | |
---|---|
Taper Shank No. | Machine Size |
#60 | Very large machines |
#50 | Medium size machines (20 to 50 HPs) |
#40 | Small size machines |
#30 | Very small machines |
All of the major tapers, except the Universal Kwik-Switch family, use the 3 1/2" in 12" model of the NMTB or 7:24. A 3/8" end-mill #50 NMTB tool-holder is about a serious 9 pounds of metal compared to dainty 3/4 of a pound for a #30 NMTB 1/4" end-mill tool-holder.
A Tool-Holders with Ears!
This taper style is also made by Collis who call it Rapid-Switch. The Kwik-Switch is supplied as alternative tooling in Bridgeport, Wells index, and other machines. The 200 series is pretty much equivalent to the NMTB #30, but has more mass and a more positive lock.
|
,
![]()
|
The single collar taper is the most popular, as evidenced by the
numerous names it has. Most often NMTB or Erickson Quick Change. NMTB (from National Machine Tool Builders' Association, 1927. and also known as DIN 2080 / IS 2340 SHANK)
You'll see it called Quick Change, NMTB, MM, National Standard, American Standard Machine Taper, ISOXX, & QCXX... The American Standard Steep Machine Taper (ASA B5.10-1963) defines 12 tapers: #5, #10, #15, #20, #25, #30, #35, #40, #45, #50, #55, #60. Those numbers in bold are the "Preferred Series" while the others are in the "Intermediate Series". ANSI mentions six taper shank sizes including #30, #35, #40, #45, #50, and #60. For all the sizes the taper is 3 1/2" per foot. The taper is 3.500 inches per foot and is also referred to as "7 in 24" or 7/24 or better yet 7:34; the computed angle is 16.5943 degrees
|
|
There are two common dual flange types: V-flange (often referred to as Caterpillar V-flanges) and BT-flange.
BT-flange holders are widely used in Japanese and European made
machining centers and have metric threads for the retention knob, but
their adapters can be designed to accommodate a wide range of
inch-dimensioned cutting tools.
The BT Flange is also known as
|
|
Caterpillar V-flanges use inch threads for the retention knob and are used to hold inch-dimensioned cutting tools.
You'll see the CAT flange referred to as DIN69871 I've seen them most often referred to as CAT-30, CAT-40, CAT-45, and CAT-50 and CAT-40 seems to be the most common. |
,
![]()
[Inches] |
Need information on this one... |
,
![]()
|
This is not truly a taper as defined by Machinery's Handbook, since it is held in place by a drawbar. Picture a long 7/16"NF bolt leading down through the spindle, threading onto the R-8 tool-holder. The included angle is 8.25°1 OD of 1.25" 18.85/2 degrees or 8.25?? Taper = 16 Deg 51 Min.Included End Dia. .9495 +0 -.0003 Overall from front dia. of 1 1/4"is 4" Undercut dia. 15/16" The "arctan(3.5/12)" solution by definition implies a right triangle with a 3.5" short side and 12" long side. Thus, the hypotenuse is 1.25". |
,
![]() |
Taper Name | Large End Diameter |
Taper/ft | Taper/in | Angle in degrees From Center |
Small End Diameter |
Length |
#0 Morse | 0.356 | 0.625 | 0.052 | 1.491 | 0.252 | 2.000 |
#1 Morse | 0.475 | 0.599 | 0.050 | 1.429 | 0.369 | 2.130 |
#2 Morse | 0.700 | 0.599 | 0.050 | 1.431 | 0.572 | 2.560 |
#3 Morse | 0.938 | 0.602 | 0.050 | 1.438 | 0.778 | 3.190 |
#4 Morse | 1.231 | 0.623 | 0.052 | 1.488 | 1.020 | 4.060 |
#4-1/2 Morse | 1.500 | 0.624 | 0.052 | 1.489 | 1.266 | 4.500 |
#5 Morse | 1.748 | 0.632 | 0.053 | 1.507 | 1.475 | 5.190 |
#6 Morse | 2.494 | 0.626 | 0.052 | 1.493 | 2.116 | 7.250 |
#7 Morse | 3.270 | 0.624 | 0.052 | 1.489 | 2.750 | 10.000 |
#1 Brown & Sharpe | 0.239 | 0.502 | 0.042 | 1.198 | 0.200 | 0.940 |
#2 Brown & Sharpe | 0.300 | 0.502 | 0.042 | 1.198 | 0.250 | 1.190 |
#3 Brown & Sharpe | 0.375 | 0.502 | 0.042 | 1.198 | 0.313 | 1.500 |
#4 Brown & Sharpe | 0.421 | 0.502 | 0.042 | 1.199 | 0.350 | 1.690 |
#5 Brown & Sharpe | 0.539 | 0.502 | 0.042 | 1.197 | 0.450 | 2.130 |
#6 Brown & Sharpe | 0.600 | 0.503 | 0.042 | 1.201 | 0.500 | 2.380 |
#7 Brown & Sharpe | 0.720 | 0.502 | 0.042 | 1.197 | 0.600 | 2.880 |
#8 Brown & Sharpe | 0.899 | 0.501 | 0.042 | 1.196 | 0.750 | 3.560 |
#9 Brown & Sharpe | 1.078 | 0.501 | 0.042 | 1.196 | 0.900 | 4.250 |
#10 Brown & Sharpe | 1.260 | 0.516 | 0.043 | 1.232 | 1.045 | 5.000 |
#11 Brown & Sharpe | 1.498 | 0.501 | 0.042 | 1.196 | 1.250 | 5.940 |
#12 Brown & Sharpe | 1.797 | 0.500 | 0.042 | 1.193 | 1.500 | 7.130 |
#13 Brown & Sharpe | 2.073 | 0.500 | 0.042 | 1.194 | 1.750 | 7.750 |
#14 Brown & Sharpe | 2.344 | 0.500 | 0.042 | 1.194 | 2.000 | 8.250 |
#15 Brown & Sharpe | 2.615 | 0.500 | 0.042 | 1.194 | 2.250 | 8.750 |
#16 Brown & Sharpe | 2.885 | 0.500 | 0.042 | 1.194 | 2.500 | 9.250 |
#17 Brown & Sharpe | 3.156 | 0.500 | 0.042 | 1.194 | 2.750 | 9.750 |
#18 Brown & Sharpe | 3.427 | 0.500 | 0.042 | 1.194 | 3.000 | 10.250 |
#2 Jarno | 0.250 | 0.600 | 0.050 | 1.432 | 0.200 | 1.000 |
#3 Jarno | 0.375 | 0.600 | 0.050 | 1.432 | 0.300 | 1.500 |
#4 Jarno | 0.500 | 0.600 | 0.050 | 1.432 | 0.400 | 2.000 |
#5 Jarno | 0.625 | 0.600 | 0.050 | 1.432 | 0.500 | 2.500 |
#6 Jarno | 0.750 | 0.600 | 0.050 | 1.432 | 0.600 | 3.000 |
#7 Jarno | 0.875 | 0.600 | 0.050 | 1.432 | 0.700 | 3.500 |
#8 Jarno | 1.000 | 0.600 | 0.050 | 1.432 | 0.800 | 4.000 |
#9 Jarno | 1.125 | 0.600 | 0.050 | 1.432 | 0.900 | 4.500 |
#10 Jarno | 1.250 | 0.600 | 0.050 | 1.432 | 1.000 | 5.000 |
#11 Jarno | 1.375 | 0.600 | 0.050 | 1.432 | 1.100 | 5.500 |
#12 Jarno | 1.500 | 0.600 | 0.050 | 1.432 | 1.200 | 6.000 |
#13 Jarno | 1.625 | 0.600 | 0.050 | 1.432 | 1.300 | 6.500 |
#14 Jarno | 1.750 | 0.600 | 0.050 | 1.432 | 1.400 | 7.000 |
#15 Jarno | 1.875 | 0.600 | 0.050 | 1.432 | 1.500 | 7.500 |
#16 Jarno | 2.000 | 0.600 | 0.050 | 1.432 | 1.600 | 8.000 |
#17 Jarno | 2.125 | 0.600 | 0.050 | 1.432 | 1.700 | 8.500 |
#18 Jarno | 2.250 | 0.600 | 0.050 | 1.432 | 1.800 | 9.000 |
#19 Jarno | 2.375 | 0.600 | 0.050 | 1.432 | 1.900 | 9.500 |
#20 Jarno | 2.500 | 0.600 | 0.050 | 1.432 | 2.000 | 10.000 |
#0 Jacobs | 0.250 | 0.592 | 0.049 | 1.412 | 0.228 | 0.440 |
#1 Jacobs | 0.384 | 0.925 | 0.077 | 2.207 | 0.333 | 0.660 |
#2 Jacobs | 0.559 | 0.979 | 0.082 | 2.335 | 0.488 | 0.880 |
#2 Short Jacobs | 0.549 | 0.979 | 0.082 | 2.335 | 0.488 | 0.750 |
#3 Jacobs | 0.811 | 0.639 | 0.053 | 1.525 | 0.746 | 1.220 |
#4 Jacobs | 1.124 | 0.629 | 0.052 | 1.501 | 1.037 | 1.660 |
#5 Jacobs | 1.413 | 0.620 | 0.052 | 1.480 | 1.316 | 1.880 |
#6 Jacobs | 0.676 | 0.623 | 0.052 | 1.487 | 0.624 | 1.000 |
#33 Jacobs | 0.624 | 0.762 | 0.064 | 1.818 | 0.561 | 1.000 |
Parent page is Machining
Need information about origin of standard and metric standards..
Key | Size | Comments - Chucks |
---|---|---|
K0 | 1/8" 0.125" |
|
K2 | 1/4" 0.250" |
|
K3 (K3C?) | 5/16" 0.312 5" |
|
K4 | 3/8 0.375" | (#9) |
K5 | 7/16 0.437 5" | (#26) |
K7 | 7/32" 0.218 75" |
|
?? | 21/64 0.328 125 |
|
K30 | 15/64" 0.234 375 |
|
K32 | 1/4" 0.250" |
|
KG | 1/4" 0.250" |
|
KI | 5/32" 0.156 25" |
|
KK | 9/32" 0.281 25" |
|
K30 | 15/64" 0.234 375" | (#13) |
(C) Copyright 1994-2017, Transtronics, Inc. All rights reserved
Transtronics® is a registered trademark of Transtronics, Inc.
All trademarks are the property of their respective owners.