Page 723 - Yamawa_European_Catalogue_YEU21

24. Drill size and recommended hole size for cutting taps

Intro

Taper Internal Pipe Threads - Rc(BSPT)-PT (refer to JIS B 0203 or ISO 7-1) Unit: mm

Thread Standards Minor Diameter Recommended Bored Hole Sizes Reference SP
When Threads (reference)
When Threads Tap
Basic Eff ective Thread Length do not have
Basic Diameter (Minimum) Pipe End have non-Full the non-Full Maximum Size of Straight Bored Basic Diameter Position.
Diameter (Workpiece Threads Threads Hole ℓg
Size
Pipe End Face)
When When Threads (Basic Diamater) Position away Position away When Threads SL
Tolerance Tolerance in axial Threads have do not have the from Pipe End from Pipe End When Threads do not have Long Short
by ℓ
by t
in radial direction non-Full Threads non-Full Threads have non-Full the non-Full Thread Thread Rc
direction c ℓ t Threads Threads Type Type
Basic Size Basic Size Basic Size
1 2 3 4 5 6 7 8 9 0 ! " £
PT 1/16 - 28 ±0.071 ±1.13 6.2 4.4 6.561 6.174 6.286 6.1 6.2 13.0 10.5 10.1
PO
PT 1/8 - 28 ±0.071 ±1.13 6.2 4.4 8.566 8.179 8.291 8.1 8.2 13.0 10.5 10.1
PT 1/4 - 19 ±0.104 ±1.67 9.4 6.7 11.445 10.858 11.026 10.7 10.9 21.0 12.5 15.0
PT 3/8 - 19 ±0.104 ±1.67 9.7 7.0 14.950 14.344 14.513 14.2 14.4 21.0 14.0 15.4
PT 1/2 - 14 ±0.142 ±2.27 12.7 9.1 18.631 17.837 18.062 17.6 17.9 25.0 17.0 20.5
ST
PT 5/8 - 14 ±0.142 ±2.27 (13.4) (9.65) 20.587 19.750 19.984 19.6 19.8 25.0 - -
PT 3/4 - 14 ±0.142 ±2.27 14.1 10.2 24.117 23.236 23.480 23.0 23.3 25.0 19.0 21.8
PT 7/8 - 14 ±0.142 ±2.27 (15.2) (10.9) 27.877 26.930 27.196 26.7 27.0 28.0 - -
PT 1 - 11 ±0.181 ±2.89 16.2 11.6 30.291 29.279 29.566 29.0 29.3 32.0 22.0 26.0
ROLL
PT 1 1/8 - 11 ±0.181 ±2.89 (17.4) (12.5) 34.939 33.855 34.158 33.6 33.9 32.0 - -
PT 1 1/4 - 11 ±0.181 ±2.89 18.5 13.4 38.952 37.796 38.115 37.6 37.9 32.0 24.5 28.3
PT 1 1/2 - 11 ±0.181 ±2.89 18.5 13.4 44.845 43.689 44.008 43.5 43.8 32.0 25.5 28.3
PT 1 3/4 - 11 ±0.181 ±2.89 (18.5) (13.4) 50.788 49.632 49.951 49.4 49.7 32.0 - -
PT 2 - 11 ±0.181 ±2.89 22.8 16.9 56.656 55.231 55.600 55.0 55.4 35.0 27.5 32.7 CARBIDE
PT 2 1/4 - 11 ±0.216 ±3.46 (26.7) (18.6) 65.710 64.041 64.548 63.8 64.3 50.0 - -
PT 2 1/2 - 11 ±0.216 ±3.46 26.7 18.6 72.226 70.557 71.064 70.3 70.8 50.0 32.0 37.1
PT 3 - 11 ±0.216 ±3.46 29.8 21.1 84.926 83.064 83.607 82.8 83.3 52.0 36.0 40.2
PT 3 1/2 - 11 ±0.216 ±3.46 31.4 22.4 97.372 95.410 95.972 95.1 95.7 52.0 - 46.2 LONG
PT 4 - 11 ±0.216 ±3.46 35.8 25.9 110.072 107.835 108.453 107.6 108.2 55.0 - 46.2
Note: Length toward End of Smaller Diameter from Basic Diameter Position
HAND
TAPS
REMARKS DURING TAPPING
1. PT internal threads have R design on their crests. The tap should cut threads with their thread rot.
2. On thread drawing non-full threads. If you are going to cut effective thread length ℓ., use the tap of long type.
EG (STI)

When Threads have When Threads do not have
non-Full Threads the non-Full Threads
SPECIAL
Basic Diameter Position
Remarks 1. Opening of Internal Thread (Face of workpiece) is Basic THREADS,
Diameter Position. GAUGES
Remarks 2. Effective Thread Length has 2 types: with non-Full Thread
Type and without non-Full Thread Type.
Remarks 3. Concerning bored hole shape, considering load on taps,
taper bored hole is recommended. THREAD
Remarks 4. Use the machines that has synchronized feed system in the MILLS
case of taper bored hole.
Remarks 5. When applying taper bored hole, by referring to values
shown in columns 258, prepare the taper hole by using
pipe reamer (1/16 taper). By referring to values shown in DIES
columns 9 and 0, select the drill diameter before reaming
by taking reamer’s margin into account.
Remarks 6. When preparing straight bored hole, by referring to values
shown in columns 9 and 0, select drill diameter.
CENTER
DRILLS

Technical
info

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