Screw Thread Instert (STI) Taps

Source high-performance STI taps designed to cut precision oversize threads for secure screw insert installations across demanding assembly environments.

Whether you need standard hand plug styles for general tapping or specialized spiral flute taps for blind-hole chip evacuation, AMTOIND provides the complete range of inch and metric sizes with flexible volume pricing, strict quality compliance, and same-day dispatch support for US manufacturing operations.

Product Variations & Sizes

STI Taps

Hand Tap Plug Style

Plug Style: (4-Thread Chamfer) Easy starting for through-holes and blind holes.

 Size  T.P.I  Number Of Flutes Thread Class Drill Bit Size OAL Part Number  Product Name
2 56 3 2B 41 Ga. 1.88 D77P001 HIGH SPEED STEEL STI HAND TAP, PLUG
3 48 3 2B 7/64″ 1.94 D77P002 HIGH SPEED STEEL STI HAND TAP, PLUG
3 56 3 2B 36 Ga. 1.94 D77P003 HIGH SPEED STEEL STI HAND TAP, PLUG
4 40 3 2B 31 Ga. 2.00 D77P004 HIGH SPEED STEEL STI HAND TAP, PLUG
4 48 3 2B 31 Ga. 2.00 D77P005 HIGH SPEED STEEL STI HAND TAP, PLUG
5 40 3 2B 29 Ga. 2.13 D77P006 HIGH SPEED STEEL STI HAND TAP, PLUG
6 32 3 2B 25 Ga. 2.38 D77P007 HIGH SPEED STEEL STI HAND TAP, PLUG
6 40 3 2B 25 Ga. 2.38 D77P008 HIGH SPEED STEEL STI HAND TAP, PLUG
8 32 3 2B 16 Ga. 2.38 D77P009 HIGH SPEED STEEL STI HAND TAP, PLUG
8 36 3 2B 16 Ga. 2.38 D77P010 HIGH SPEED STEEL STI HAND TAP, PLUG
10 24 3 2B 5 Ga. 2.5 D77P011 HIGH SPEED STEEL STI HAND TAP, PLUG
10 32 3 2B 13/64″ 2.5 D77P012 HIGH SPEED STEEL STI HAND TAP, PLUG
12 24 3 2B 1 Ga. 2.72 D77P013 HIGH SPEED STEEL STI HAND TAP, PLUG
1/4 28 3 2B 6.7 mm 2.72 D77P014 HIGH SPEED STEEL STI HAND TAP, PLUG
1/4 20 3 2B H 2.72 D77P015 HIGH SPEED STEEL STI HAND TAP, PLUG
5/16 24 4 2B 21/64″ 2.94 D77P016 HIGH SPEED STEEL STI HAND TAP, PLUG
5/16 18 4 2B Q 2.94 D77P017 HIGH SPEED STEEL STI HAND TAP, PLUG
3/8 24 4 2B 25/64″ 3.38 D77P018 HIGH SPEED STEEL STI HAND TAP, PLUG
3/8 16 4 2B X 3.38 D77P019 HIGH SPEED STEEL STI HAND TAP, PLUG
7/16 20 4 2B 29/64″ 3.59 D77P020 HIGH SPEED STEEL STI HAND TAP, PLUG
7/16 14 4 2B 29/64″ 3.59 D77P021 HIGH SPEED STEEL STI HAND TAP, PLUG
1/2 20 4 2B 33/64″ 3.81 D77P022 HIGH SPEED STEEL STI HAND TAP, PLUG
1/2 13 4 2B 17/32″ 3.81 D77P023 HIGH SPEED STEEL STI HAND TAP, PLUG
9/16 12 4 2B 19/32″ 4.03 D77P024 HIGH SPEED STEEL STI HAND TAP, PLUG
9/16 18 4 2B 37/64″ 4.03 D77P025 HIGH SPEED STEEL STI HAND TAP, PLUG
5/8 11 4 2B 21/32″ 4.25 D77P026 HIGH SPEED STEEL STI HAND TAP, PLUG
5/8 18 4 2B 41/64″ 4.25 D77P027 HIGH SPEED STEEL STI HAND TAP, PLUG
3/4 10 4 2B 25/32″ 4.69 D77P028 HIGH SPEED STEEL STI HAND TAP, PLUG
3/4 16 4 2B 49/64″ 4.69 D77P029 HIGH SPEED STEEL STI HAND TAP, PLUG
7/8 14 4 2B 57/64″ 5.13 D77P030 HIGH SPEED STEEL STI HAND TAP, PLUG
7/8 9 4 2B 29/32″ 5.13 D77P031 HIGH SPEED STEEL STI HAND TAP, PLUG
1 14 4 2B 1 1/32″ 5.75 D77P032 HIGH SPEED STEEL STI HAND TAP, PLUG
1 12 4 2B 1 1/32″ 5.75 D77P033 HIGH SPEED STEEL STI HAND TAP, PLUG
1 8 4 2B 1 1/32″ 5.75 D77P034 HIGH SPEED STEEL STI HAND TAP, PLUG
1-1/8 7 4 2B 1 11/64″ 6.06 D77P035 HIGH SPEED STEEL STI HAND TAP, PLUG
1-1/4 12 4 2B 1 9/32″ 6.38 D77P036 HIGH SPEED STEEL STI HAND TAP, PLUG

Hand Tap Bottoming Style

Bottoming Style: (2-Thread Chamfer) Ideal for blind holes that are drilled to a minimum depth.

 Size  T.P.I  Number Of Flutes Thread Class Drill Bit Size OAL Part Number  Product Name
2 56 3 2B 41 Ga. 1.88 D77B001 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
3 48 3 2B 7/64″ 1.94 D77B002 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
3 56 3 2B 36 Ga. 1.94 D77B003 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
4 40 3 2B 31 Ga. 2.00 D77B004 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
4 48 3 2B 31 Ga. 2.00 D77B005 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
5 40 3 2B 29 Ga. 2.13 D77B006 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
6 32 3 2B 25 Ga. 2.38 D77B007 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
6 40 3 2B 25 Ga. 2.38 D77B008 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
8 32 3 2B 16 Ga. 2.38 D77B009 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
8 36 3 2B 16 Ga. 2.38 D77B010 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
10 24 3 2B 5 Ga. 2.5 D77B011 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
10 32 3 2B 13/64″ 2.5 D77B012 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
12 24 3 2B 1 Ga. 2.72 D77B013 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
1/4 28 3 2B 6.7 mm 2.72 D77B014 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
1/4 20 3 2B H 2.72 D77B015 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
5/16 24 4 2B 21/64″ 2.94 D77B016 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
5/16 18 4 2B Q 2.94 D77B017 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
3/8 24 4 2B 25/64″ 3.38 D77B018 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
3/8 16 4 2B X 3.38 D77B019 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
7/16 20 4 2B 29/64″ 3.59 D77B020 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
7/16 14 4 2B 29/64″ 3.59 D77B021 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
1/2 20 4 2B 33/64″ 3.81 D77B022 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
1/2 13 4 2B 17/32″ 3.81 D77B023 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
9/16 12 4 2B 19/32″ 4.03 D77B024 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
9/16 18 4 2B 37/64″ 4.03 D77B025 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
5/8 11 4 2B 21/32″ 4.25 D77B026 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
5/8 18 4 2B 41/64″ 4.25 D77B027 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
3/4 10 4 2B 25/32″ 4.69 D77B028 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
3/4 16 4 2B 49/64″ 4.69 D77B029 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
7/8 14 4 2B 57/64″ 5.13 D77B030 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
7/8 9 4 2B 29/32″ 5.13 D77B031 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
1 14 4 2B 1 1/32″ 5.75 D77B032 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
1 12 4 2B 1 1/32″ 5.75 D77B033 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
1 8 4 2B 1 1/32″ 5.75 D77B034 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
1-1/8 7 4 2B 1 11/64″ 6.06 D77B035 HIGH SPEED STEEL STI HAND TAP, BOTTOMING
1-1/4 12 4 2B 1 9/32″ 6.38 D77B036 HIGH SPEED STEEL STI HAND TAP, BOTTOMING

Spiral Flute Bottoming

Spiral Flute Bottoming Style: (2-Thread Chamfer) Designed to pull chips out of deep or blind holes in soft materials

 Size  T.P.I  Number Of Flutes Thread Class Drill Bit Size OAL Part Number  Product Name
2 56 2 2B 41 Ga. 1.88 D76SF001 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
3 48 2 2B 7/64″ 1.94 D76SF002 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
3 56 2 2B 36 Ga. 1.94 D76SF003 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
4 40 2 2B 31 Ga. 2.00 D76SF004 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
4 48 2 2B 31 Ga. 2.00 D76SF005 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
5 40 3 2B 29 Ga. 2.13 D76SF006 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
6 32 3 2B 25 Ga. 2.38 D76SF007 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
6 40 3 2B 25 Ga. 2.38 D76SF008 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
8 32 3 2B 16 Ga. 2.38 D76SF009 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
8 36 3 2B 16 Ga. 2.38 D76SF010 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
10 24 3 2B 5 Ga. 2.5 D76SF011 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
10 32 3 2B 13/64″ 2.5 D76SF012 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
12 24 3 2B 1 Ga. 2.72 D76SF013 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
1/4 28 3 2B 6.7 mm 2.72 D76SF014 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
1/4 20 3 2B H 2.72 D76SF015 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
5/16 24 3 2B 21/64″ 2.94 D76SF016 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
5/16 18 3 2B Q 2.94 D76SF017 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
3/8 24 3 2B 25/64″ 3.38 D76SF018 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
3/8 16 3 2B X 3.38 D76SF019 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
7/16 20 3 2B 29/64″ 3.59 D76SF020 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
7/16 14 3 2B 29/64″ 3.59 D76SF021 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
1/2 20 4 2B 33/64″ 3.81 D76SF022 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
1/2 13 4 2B 17/32″ 3.81 D76SF023 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
9/16 12 4 2B 19/32″ 4.03 D76SF024 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
9/16 18 4 2B 37/64″ 4.03 D76SF025 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
5/8 11 4 2B 21/32″ 4.25 D76SF026 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
5/8 18 4 2B 41/64″ 4.25 D76SF027 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
3/4 10 4 2B 25/32″ 4.69 D76SF028 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
3/4 16 4 2B 49/64″ 4.69 D76SF029 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
7/8 14 4 2B 57/64″ 5.13 D76SF030 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
7/8 9 4 2B 29/32″ 5.13 D76SF031 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
1 14 4 2B 1 1/32″ 5.75 D76SF032 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
1 12 4 2B 1 1/32″ 5.75 D76SF033 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
1 8 4 2B 1 1/32″ 5.75 D76SF034 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
1-1/8 7 4 2B 1 11/64″ 6.06 D76SF035 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP
1-1/4 12 4 2B 1 9/32″ 6.38 D76SF036 HIGH SPEED STEEL SPIRAL FLUTE BOTTOMING STI TAP

Spiral Pointed Plug

Spiral Pointed Plug Style: (4-Thread Chamfer) Free-cutting for use in long through-holes and in blind holes with chip clearance.

 Size  T.P.I  Number Of Flutes Thread Class Drill Bit Size OAL Part Number  Product Name
2 56 2 2B 41 Ga. 1.88 D78SP001 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
3 48 2 2B 7/64″ 1.94 D78SP002 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
3 56 2 2B 36 Ga. 1.94 D78SP003 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
4 40 2 2B 31 Ga. 2.00 D78SP004 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
4 48 2 2B 31 Ga. 2.00 D78SP005 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
5 40 2 2B 29 Ga. 2.13 D78SP006 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
6 32 2 2B 25 Ga. 2.38 D78SP007 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
6 40 2 2B 25 Ga. 2.38 D78SP008 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
8 32 2 2B 16 Ga. 2.38 D78SP009 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
8 36 2 2B 16 Ga. 2.38 D78SP010 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
10 24 2 2B 5 Ga. 2.5 D78SP011 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
10 32 2 2B 13/64″ 2.5 D78SP012 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
12 24 2 2B 1 Ga. 2.72 D78SP013 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
1/4 28 2 2B 6.7 mm 2.72 D78SP014 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
1/4 20 2 2B H 2.72 D78SP015 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
5/16 24 3 2B 21/64″ 2.94 D78SP016 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
5/16 18 3 2B Q 2.94 D78SP017 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
3/8 24 3 2B 25/64″ 3.38 D78SP018 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
3/8 16 3 2B X 3.38 D78SP019 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
7/16 20 3 2B 29/64″ 3.59 D78SP020 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
7/16 14 3 2B 29/64″ 3.59 D78SP021 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
1/2 20 3 2B 33/64″ 3.81 D78SP022 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
1/2 13 3 2B 17/32″ 3.81 D78SP023 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
9/16 12 4 2B 19/32″ 4.03 D78SP024 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
9/16 18 4 2B 37/64″ 4.03 D78SP025 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
5/8 11 4 2B 21/32″ 4.25 D78SP026 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
5/8 18 4 2B 41/64″ 4.25 D78SP027 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
3/4 10 4 2B 25/32″ 4.69 D78SP028 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
3/4 16 4 2B 49/64″ 4.69 D78SP029 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
7/8 14 4 2B 57/64″ 5.13 D78SP030 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
7/8 9 4 2B 29/32″ 5.13 D78SP031 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
1 14 4 2B 1 1/32″ 5.75 D78SP032 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
1 12 4 2B 1 1/32″ 5.75 D78SP033 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
1 8 4 2B 1 1/32″ 5.75 D78SP034 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
1-1/8 7 4 2B 1 11/64″ 6.06 D78SP035 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP
1-1/4 12 4 2B 1 9/32″ 6.38 D78SP036 HIGH SPEED STEEL SPIRAL POINTED PLUG STI TAP

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