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THREADING | Solid Carbide and Indexable Thread Mills

Thread Mill Calculations and Recommended Passes

A

Thread Mill Drill Calculation Based on nominal tap drill diameter. Based on 0.075 mm or 0.003" probable mean oversize. To calculate the percent of full thread for a given hole diameter:

DRILLING

Major Thread Diameter for # Drills Drill #

Thread Diameter

# 2 # 3 # 4 # 5 # 6 # 8

0.086 0.099 0.112 0.125 0.132 0.164 0.190 0.216

76.96 Pitch (mm)

% of thread =

• [ Basic major diameter of thread - Drill hole size ]

METRIC:

Basic major diameter of thread - Drill hole size 0.0130

% of thread = # of threads per inch •

IMPERIAL:

B

# 10 # 12

BORING

Recommended Passes

NPT / NPTF / BSPT / API

Recommen ISO ded Passes

UN / UNJ / BSPP / BSW / NPS / NPSF

Machinability

Machinability

Machinability

C

Pitch Size

Pitch Size

Pitch Size 0.40 0.45 0.50 0.70 0.75 0.80 1.00 1.25 1.50 1.75 2.00 2.50 3.00 3.50 4.00 4.50 5.00 6.00

Easy

Average Difficult

Easy

Average Difficult

Easy

Average Difficult

REAMING

64 56 48 44 40 36 32 28 24 20 19 18 16 14 13 12 11 10

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2

1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3 3 3 3 3

2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 4 4 4 4 4 4

28 27 19 18 14

1 1 1 1 1 1 1 1 2

1 1 1 1 2 2 2 2 3

2 2 2 2 3 3 3 3 4

1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2

1 1 1 1 1 1 1 2 2 2 2 3 3 3 3 3 3 3

2 2 2 2 2 2 2 3 3 3 3 4 4 4 4 4 4 4

11.5

11 10

D

8

BURNISHING

1 Pass 2 Passes 3 Passes 4 Passes

E

9 8 7 6

THREADING

X

SPECIALS

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