Machine Tap DIN 371 Form C 35° Spiral Flute HSSE 7G - M 3 x 0.5

• Wide Range of Applications: Ideal for general use in well-machinable materials up to 900 N/mm².
• Steel and More: Particularly well-suited for unalloyed and low-alloy steels.
• Long-Chipping Materials: Thanks to its special geometry, it is also suitable for materials that form long chips.
• Blind Hole Specialist: The Form C with 35° spiral point (SP) is perfectly tailored to the challenges of blind holes. The spiral-shaped flutes efficiently push chips backward (towards the shank) and out of the hole. This prevents chip clogging and ensures a clean thread profile all the way to the bottom.

This tap cuts a metric ISO thread M 3 x 0.5 according to DIN 13. With an overall length of 56 mm, a thread length of 6 mm, a shank diameter of 3.5 mm, and a 2.7 mm square drive, it is compact and precise for fine threads.

The 7G tolerance is a special tolerance class for internal threads (nut threads). It is less common than the standard 6H tolerance but has its specific areas of application.

• The "7" stands for the tolerance grade. A higher number (like 7) means a larger tolerance field compared to a lower number (e.g., 6). The finished thread therefore has a slightly larger range in its dimensions.
• The "G" stands for the tolerance position and means that the tolerance field is above the zero line (the nominal dimension) with a positive fundamental deviation. Compared to "H," where the tolerance field begins directly at the zero line, "G" shifts the entire tolerance field slightly upward, so the thread tends to be slightly larger.

When to choose 7G? A 7G tolerance is typically used for loose fits. This can be advantageous when:

• You are cutting threads that will be coated later (e.g., galvanized or painted). The larger tolerance provides space for the coating without the thread becoming too tight.
• You want a very easy assembly, even under less-than-ideal conditions.
• A backlash-free connection is less important than ease of assembly or when a certain amount of play is desired.

DIN 371 is an important German industrial standard that specifies the dimensions and requirements for machine taps with a reinforced shank.

• The "reinforced shank" means that the shank diameter (D2) of these taps is essentially equal to or only slightly smaller than the nominal thread diameter (D) up to the square.
• This design gives the tap higher stability and break resistance compared to taps with a reduced shank (e.g., according to DIN 376).

For you, this means more security at high cutting forces and better tool guidance in the machine, which is especially important for smaller diameters and in tough materials.

With this VÖLKEL machine tap, you get a specialized tool that serves you reliably and precisely even under demanding conditions.

1. What is the main difference between HSS and HSSE?

The main difference is in the material. HSSE is a further development of HSS and contains a cobalt content (usually 5% or 8%). This additive significantly increases heat resistance, wear resistance, and cutting performance, making the tap more suitable for demanding materials and higher cutting speeds.

2. Why does this tap have a spiral point?

The spiral point (SP) with 35° is specifically designed for cutting threads in blind holes. The spiral shape of the flutes effectively pushes the chips backward, out of the hole. This prevents chips from clogging at the bottom of the blind hole, which could block or damage the tool.

3. What does the 7G tolerance class mean?

The 7G tolerance class stands for a loose fit of the internal thread. Compared to the standard 6H tolerance, a 7G thread has a slightly larger dimension, which facilitates assembly. It is particularly useful when the thread is to be coated after cutting, as the coating reduces the diameter and the tolerance compensates for this.

4. What is the difference between DIN 371 and DIN 376?

Both are standards for machine taps. DIN 371 refers to taps with a reinforced shank, where the shank diameter matches the nominal thread diameter. They are more robust and break-resistant, especially for smaller threads. DIN 376, on the other hand, describes taps with a reduced shank, where the shank diameter is smaller than the thread diameter. This design is typical for larger threads from M10 and up.

5. Can I also use this machine tap manually?

While theoretically possible, it is not recommended. The geometry of this tap, especially the spiral flutes, is optimized for machine use. Manually, chip evacuation is less effective, and the risk of the tool breaking is significantly higher due to uneven forces. A hand tap set is recommended for manual threading.