Taper shank twist drills to DIN 345 are driven by friction inside a Morse taper sleeve - no chuck, no slipping, and a much stronger grip for large diameters. The reference below collects the MT 1 to MT 6 dimensions a buyer or machine fitter needs when matching drills, sleeves and spindle sockets.
How a Morse taper holds
The half taper angle is only about one and a half degrees, so the shank locks into the sleeve by friction alone - a self-holding fit. The tang at the end of the shank does not transmit torque; it exists for extraction with a drift. Always seat the shank firmly, with a light tap of a soft mallet, before drilling.
MT 1 - MT 6 dimension table (mm)
Ref: A = large end diameter of the taper, a/2 = half taper angle. Other letters follow the DIN 228 taper shank drawing.
No. 1: A 12.065 / B 9 / C 5.2 / D 12.2 / E 62 / F 13.5 / G 3.5 / H 8.7 / a/2 = 1 degree 25'43"
No. 2: A 17.780 / B 14 / C 6.3 / D 18.0 / E 75 / F 16 / G 5 / H 13.5 / a/2 = 1 degree 25'50"
No. 3: A 23.825 / B 19.1 / C 7.9 / D 24.1 / E 94 / F 20 / G 5 / H 18.5 / a/2 = 1 degree 26'16"
No. 4: A 31.267 / B 25.2 / C 11.9 / D 31.6 / E 117.5 / F 24 / G 6.5 / H 24.5 / a/2 = 1 degree 29'15"
No. 5: A 44.399 / B 36.5 / C 15.9 / D 44.7 / E 149.5 / F 29 / G 6.5 / H 35.7 / a/2 = 1 degree 30'26"
No. 6: A 63.348 / B 52.4 / C 19 / D 63.8 / E 210 / F 40 / G 8 / H 51 / a/2 = 1 degree 29'36"
Which Morse taper fits which drill
Typical DIN 345 catalog mapping: MT1 for twist drills up to about 14 mm diameter, MT2 for 14 to 23 mm, MT3 for 23 to 31.5 mm, MT4 for 31.5 to 50 mm, MT5 for 50 to 76 mm. Larger diameters, and most diamond core drills, move to MT5 or MT6. Always match the sleeve to the machine spindle first - the drill follows the spindle.
Sleeves, sockets and removal
Reduction sleeves let a smaller taper run in a larger spindle, for example an MT3 drill in an MT4 socket. A drift knocks the taper out of the sleeve through the drift slot. Keep drift slots clean and never grind the tang shorter unless the machine maker specifies it.
Buyer checklist
Confirm the spindle taper of the drilling machine, the drill diameter range you need, and whether you want a standard DIN tang or a shortened shank for CNC holders. FANXI Tools supplies taper shank twist drills to DIN 345 in M2, M35, M42 and 9341 grades, milled or fully ground, with Morse tapers MT1 to MT6.