1-11/16 inch-12 UN HSS tap: thread and tool checks
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1-11/16 inch-12 UN right-hand HSS tap
The listed tool is a right-hand HSS straight-flute tap for a 1-11/16 inch, 12 threads-per-inch UN thread. In this designation, 12 is the thread count per inch. Confirm the required thread class and tool dimensions from the job drawing before ordering.
Read the thread designation correctly
| Item | What to check |
|---|---|
| Nominal diameter | 1-11/16 inch = 1.6875 inch = 42.8625 mm |
| Pitch | 12 TPI; calculated pitch is 25.4 ÷ 12 ≈ 2.1167 mm |
| Thread family | UN; retain the complete drawing callout and tolerance class. |
| Direction and material | Right-hand, high-speed steel (HSS), as stated in the listing. |
| Flute form | Straight flute; request the actual chamfer and tool dimensions. |
The conversions above are arithmetic from the listing designation. They are not measured dimensions of the delivered tool. A drill description such as "1-11/16 x 12" can describe diameter and length, so it must not be treated as the same product as a 12 TPI tap.
Give the supplier the machining conditions
Send the material grade, required full-thread depth and whether the hole is blind or through. Include the thread class from the drawing, the holder interface and any reach restriction. Ask for overall length, threaded length, shank diameter and square dimensions before approving the tool.
Tap geometry is application-dependent. YAMAWA’s manufacturer reference separates spiral-flute, spiral-point, hand and other tap types. Use it as background when discussing chip evacuation; it does not identify the maker or approve the KOEED-listed tool for a particular material.
Source: YAMAWA tap type reference. Match the document to the full model and revision on your unit.
Select the pre-hole from the actual job requirements
Obtain the tap-drill recommendation for the required thread class, material and engagement from the tool supplier or the approved process sheet. Do not choose a production drill size solely from the approximate diameter-minus-pitch rule.
For a blind hole, distinguish the usable full-thread depth from the drilled depth and the tap lead. Ask the machinist to check the available clearance and chip space before setting the tool.
Put the drawing requirements into the inquiry
- 1-11/16 inch-12 UN, right-hand, with the required thread class.
- Work material, blind or through hole and full-thread depth.
- Required chamfer, shank dimensions and holder compatibility.
- Quantity, tool markings and any inspection or gauging requirement.
Check the listed part
Review the straight-flute HSS tap listing and send the complete thread drawing callout and machining details.
Manufacturer references
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