NMTB tool holders (National Machine Tool Builders Association) are single-flanged tool holders and are often referred to as Quick Change.
NMTB tool holders come in different Imperial sizes: NMTB30, NMTB40, and NMTB50. The number designates the size of the taper: the higher the number, the bigger the taper.
The NMTB shank was developed for use in the NMTB spindle, which uses a drawbar to pull the shank up into the spindle. NMTB designs are relatively old, but they do fit modern machines.
What sets NMTB tool holders apart from other tooling is the drawbar: on the small end of the taper, there is a cylindrical extension. Also, NMTB tool holders come single-flanged with a simple flange with two flat keyways.
The flange diameter, flange thickness, and distance from the gage line of the taper to the outward face of the flange are not critical dimensions for NMTB tool holders. Therefore, they can vary in products made by different manufacturers.
Quick Change tooling is used on CNC machines and uses a pull stud on each of the tools and a claw device that locks on the stud and pulls it into the spindle. Most (but not all) NMTB shanks are compatible with the corresponding size of Erickson Quick Change Spindles. It depends on the manufacturer of the NMTB tool holder, but all tool holders made by Erickson that are marked Quick Change will work fine.
In most cases, other brands will also work fine, but you may want to find additional information on sizes of some parts of tool holders as they might be slightly different and may not fit in your quick change spindle.
If you are using machinery made in the middle of 20th century, most likely you are looking for NMTB tooling (or R8). Though being relatively old, they provide high stability and reliability.
NMTB Tool Holders (Quick Change) Shank
ANSI B5.18, National Machine Tool Builders’ Association, 1927. DIN 2080 / IS 2340, ISO R 290-2583
Also called Quick Change, NMTB, MM, National Standard, American Standard Machine Taper, etc.
Below you can find the table of sizes:
|
ANSI B5.18 (from Kennametal catalog 7060) |
||||||||||||
|
Size |
D–1 |
D–2 |
D–3 |
D–4 max |
D–5* |
L–1 |
L–2 |
L–3 |
L–4 |
L–5 |
L–6 |
G |
|
30 |
1.250 |
0.655 |
0.673 |
1.380 |
1.812 |
2.690 |
0.810 |
0.125 |
0.076 |
0.344 |
0.359 |
1/2-13 |
|
40 |
1.750 |
0.935 |
0.984 |
1.890 |
2.500 |
3.690 |
1.180 |
0.188 |
0.076 |
0.313 |
? |
5/8-11 |
|
50 |
2.750 |
1.495 |
1.545 |
2.760 |
3.500 |
5.000 |
1.000 |
0.188 |
0.141 |
0.453 |
? |
1-8 |
* These are Kennametal dimensions. D5 varies with different mfgs.
|
ISO R 297-2583 and DIN 2080 |
||||||||||||
|
Size |
D–1 |
~ |
D–3 |
D–4 max |
D–5 |
L–1 |
L–2 |
~ |
L–4 |
L–5 |
L–6 min |
G |
|
30 |
31.75 |
~ |
? |
? |
50 |
68.39 |
? |
~ |
1.62 |
8 |
? |
M12 |
|
DO40 |
44.45 |
~ |
22.63 |
50 |
63 |
93.40 |
? |
~ |
1.6 |
10 |
11.0 |
M16 |
|
45 |
57.15 |
~ |
? |
? |
80 |
106.8 |
? |
~ |
3.2 |
12 |
? |
M20 |
|
DT50 |
69.85 |
~ |
34.25 |
78 |
97.5 |
126.8 |
25 |
~ |
3.2 |
12 |
16.0 |
M24 |
Tool holders built in those two types are usually interchangeable, but there are few differences. Keep this in mind when choosing the right one.
CAT, BT & NMBT Tool Holders
NOTE: They are NOT the same – same taper, different flanging, different key lugs.
Sometimes people rework their CAT spindle to hold BT tool holders (or vice versa), depending on what tool holders are available. If you change the holders, you have to also change the tool holder fingers in the ATC.
Bottom Line
Depending on the application and machine that you are using, as well as what you want to accomplish as far as performance, capabilities, and precision, Tool Holder Exchange can help you to find the perfect NMBT tool holder.
We offer a large selection of NMBT tooling and have an experienced staff who will point you in the right direction and give you the best prices on the name-brand machine tooling you need.