Hand Tap set of 2 pieces DIN 2181 HSS-G - BSF 3/16 x 32

Specific applications

Typical tasks include small fastening threads in components with a specified BSF-3/16 requirement. The component drawing must specify the thread designation BSF 3/16″ × 32 threads/inch; check the material against the suitability information below.

Existing threads can be recut if their size, pitch and condition allow it. This does not restore missing material or severely damaged threads.

Suitable materials

HSS-G is intended for general use and readily machinable materials up to approximately 900 N/mm². These include unalloyed and low-alloy steels, structural steels, carbon steels, case-hardening steels, free-cutting steels, spheroidal graphite cast iron and malleable cast iron, as well as selected non-ferrous metals.

The following table shows example materials and represents only a selection of the suitable materials.

Close section

Cutting diameter D	4.7625 mm
Shank diameter D2	6 mm
Overall length L1	50 mm
Thread length L2	14 mm
Square drive	4.9 mm

Close section

• Standard: DIN 2181
• Tool material: HSS-G – ground high-speed steel
• Product type: Hand tap set
• Design: 2-piece set
• Thread type: British Whitworth fine thread
• Thread standard: BS 84
• Thread size: BSF 3/16″ × 32 threads/inch
• Thread tolerance: medium
• Thread direction: Right-hand thread
• Flute form: N (straight flutes)

Chamfer of the two cutting stages

The chamfer is the front cutting section in which the thread profile is built up gradually.

1. Secure the workpiece
   Clamp the workpiece securely so that it cannot rotate. The hole must be readily accessible so that the tap can be started squarely and guided in line with the hole axis throughout the operation.
2. Prepare the tapping drill hole
   Drill the tapping drill hole for BSF 3/16″ × 32 threads/inch to the recommended diameter of 4 mm. You can find a clear overview of selection and calculation in the VÖLKEL article Calculating the tapping drill hole size for taps. Blind holes must also be drilled sufficiently deeper.
3. Deburr and clean the hole
   Remove the burr at the hole entrance and clear away loose drilling chips. A clean, lightly chamfered hole makes it easier to start the taper tap squarely and prevents damage to the first thread.
4. Tapping with the taper tap
   Clamp the taper tap in a suitable tool holder and align it precisely with the hole axis. Apply sufficient cutting lubricant for tapping to the tool and hole. Turn the taper tap into the workpiece with steady pressure.
5. Tapping with the bottoming tap
   Finally, insert the bottoming tap and apply sufficient cutting lubricant again. The bottoming tap produces the complete internal thread profile. Work with steady movements and avoid excessive force, particularly when the bottoming tap reaches the bottom of a blind hole.
6. Check the thread
   Remove chips and residual cutting lubricant from the finished thread. Then check the thread size and ease of engagement using a suitable inspection tool, such as a GO/NO-GO thread plug gauge if compliance with the required tolerance must be demonstrated.

Further guidance is available in the VÖLKEL blog article Cutting clean threads: how to produce internal and external threads .

• Hand Tap Rougher DIN 2181 HSS-G - BSF 3/16 x 32 (22710-1)
• Hand Tap Finisher DIN 2181 HSS-G - BSF 3/16 x 32 (22710-3)

Which combination defines the small BSF-3/16 thread?

For this item, the 3/16 inch nominal size is combined with 32 threads per inch. Only the complete combination of BSF, nominal size and thread count determines the correct tool.

Which tapping drill do I need for BSF 3/16″ × 32 threads/inch?

For BSF 3/16″ × 32 threads/inch, the recommended tap drill diameter is 4 mm. Guidance on preparing the tapping drill hole. The simplified metric tapping drill hole formula is not applied indiscriminately to this thread designation.

How do I avoid sideways loading when starting in a small hole?

Clamp the workpiece securely, align the tap with the hole axis and guide the holder evenly. Do not overcome increased resistance with sideways pressure or excessive force.

What is the correct sequence for the 2-piece set?

Taper tap followed by bottoming tap. The matched cutting stages build up the profile gradually. The bottoming tap produces the complete internal thread. Tapping step by step.

Is BSF 3/16 inch equivalent to a metric M5 thread?

No. The converted nominal size is 4.7625 mm; this does not create a metric thread designation. The profile and thread count remain matched to BSF 3/16 inch with 32 threads per inch.

Which materials is HSS-G intended for?

HSS-G is intended for general use in readily machinable materials up to 900 N/mm², particularly unalloyed and low-alloy steels. The material overview in the first section shows the assigned example materials. Comparing tool materials for hand taps.

Can I tap a new BSF-3/16 hole using the bottoming tap alone?

This classic set is designed for the sequence of taper tap followed by bottoming tap. Do not routinely skip the taper tap when producing a new thread; the matched tools share the cutting work.

Which tap wrench fits this hand tap?

The holder must securely grip the 4.9 mm square drive. Compare this value with the specified clamping range of the tap wrench or tool holder. Choosing the right tap wrench.