TwinBox Short machine tap Form C + reamer HSS-G NPT 1/4 x 18

The decisive advantage of a conical core hole is the significant reduction in the chip volume that the tap has to handle during the subsequent thread cutting. This considerably relieves the tap, extends its tool life, and leads to a much better surface quality of the cut thread.

• For general use in easily machinable materials up to 900 N/mm².
• Ideal for unalloyed and low-alloy steels.
• Can be used for both manual and machine thread cutting.
• Suitable for through and blind holes.
• The kit contains a tap and a reamer for optimal results.

1. Step 1: Drill the Core Hole
   First, drill a cylindrical core hole into the material. The diameter should correspond to the smallest diameter of the conical core hole.
2. Step 2: Ream the Core Hole Conically
   Use the NPT reamer from the TwinBox and ream the core hole to the exact taper ratio of 1:16. This ensures an ideal fit for the tap.
3. Step 3: Cut the Thread
   Now you can use the NPT single-pass tap. Thanks to the conical core hole, the tool is only subjected to a minimal load, as only a small chip volume needs to be removed.
4. Step 4: Check and Clean
   After cutting, remove all chips and check the quality of the finished thread. The TwinBox ensures a clean and precise surface.

• Thread Type: American conical pipe thread NPT, Taper 1:16
• Form: Form C
• Material: HSS-G (Ground High-Speed Steel)
• Nominal Size: NPT 1/4 x 18
• Overall Length (L1): 70 mm
• Thread Length (L2): 25 mm
• Shank Diameter (D2): 11 mm
• Drive: Square 9 mm
• EAN: 4022835635925
• Item Number: 63592

Q: What is an NPT thread and why is it conical?

A: NPT stands for "National Pipe Taper" and is an American standard for pipe threads. It is conical (taper 1:16) to create a pressure-tight connection, which is especially important for piping. The thread seals by flank pressure as the two parts are screwed together.

Q: Why should I use a conical core hole for NPT threads?

A: A conical core hole significantly reduces the chip volume that the tap has to handle. This protects the tool, reduces the risk of chip accumulation, and leads to higher thread quality and longer tool life.

Q: Can I cut the thread without a reamer?

A: While it is generally possible to cut an NPT thread into a cylindrical core hole, it is not recommended. The tap will be subjected to extreme stress, which increases the risk of tool breakage and a poor thread surface.

Q: What is the advantage of the TwinBox?

A: The VÖLKEL TwinBox is a matched kit that contains both the tap and the appropriate NPT reamer. This ensures you always have the optimal tools at hand to create an ideal conical core hole and a high-quality thread.

Q: What does the designation HSS-G stand for?

A: HSS-G stands for "High-Speed Steel" where the "G" means "ground." This means that the tap was manufactured using a complex grinding process, which leads to higher dimensional accuracy, better tool life, and cutting quality.