The Bernardo STG 20 tap grinding machine sharpens taps from M5 – M20 with 2, 3 and 4 flutes, adjustable point angle 5° – 30°, speed 4,400 rpm, single-phase 230V 0.16 kW motor. Weight 14 kg. Distributed in Italy by Krollit as an official Bernardo distributor since 2007.
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Working range (taps): M5 – M20
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Number of flutes: 2, 3 and 4
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Point angle: 5° – 30°
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Rotor speed: 4,400 rpm
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Motor power: 0.16 kW – 230V single-phase
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Weight: 14 kg
Who uses the STG 20 and for what
The Bernardo STG 20 grinding machine restores HSS and carbide taps with 2, 3 and 4 flutes in the M5 – M20 range: instead of replacing a worn tap, it is resharpened in a few minutes, restoring the cutting edge profile with precision. An M20 HSS tap costs 20–80 euros; sharpening it with the STG 20 takes 5–10 minutes and a trained operator. With 14 kg and single-phase 230V, it can be used on any workshop bench. In Krollit customers' workshops, it is used by mechanical workshops, mould makers and CNC machining centres that regularly use taps.
Who is the Bernardo STG 20 for
| Profile |
Compatibility |
Reason |
| Hobbyist |
Suitable |
For hobby use, taps wear out rarely — the ROI on the grinding machine is long. Useful if frequent drilling is done. |
| Professional mechanical workshop |
Ideal |
M5 – M20 range: restores the most commonly used taps in mechanical workshops without frequent replacement costs. |
| Industrial production |
Ideal |
In production with high tap consumption, the grinding machine pays for itself in a few months. |
Not suitable for: taps outside the M5 – M20 range; taps with 6+ flutes (check compatibility); drill bit sharpening (consider DG 13 MD or DG 32).
Technical specifications
| Specification |
Value |
| Working range |
M5 – M20 |
| Number of flutes |
2, 3 and 4 |
| Point angle |
5° – 30° |
| Rotor speed |
4,400 rpm |
| Motor power |
0.16 kW |
| Power supply |
230V – single-phase |
| Dimensions (L × W × H) |
320 × 235 × 265 mm |
| Weight |
14 kg |
Compliance and safety
| Specification |
Value |
| Marking |
CE |
| Directive |
Machinery 2006/42/CE |
Logistics
Bernardo shipping: 5–9 working days (7 days to the South). Original spare parts available with 3–5 working days shipping. Customer assistance available in Italian.
Frequently asked questions
Does the STG 20 sharpen carbide taps?
Yes. The STG 20 is compatible with HSS, carbide (tungsten carbide) and TiN coated taps. For carbide taps, check that the supplied grinding wheel is suitable — diamond or CBN wheels are typically used for carbide. Contact Krollit for details on the specific grinding wheel for carbide.
What is the difference between STG 20 and STG 42?
The STG 20 covers taps from M5 to M20 with a 0.16 kW motor (14 kg). The STG 42 covers taps from M16 to M42 with a 0.25 kW motor (24 kg) — for larger taps that require more sharpening power. For workshops that mainly work on M16 and below, the STG 20 is sufficient; for taps up to M42, the STG 42 is needed.
Is specific training required to use it?
Yes, more than for drill bit sharpeners. Tap sharpening requires an understanding of cutting edge geometry (point angle, clearance surface). An inexperienced operator can damage the tap. It is advisable to follow the manual in Italian and practice on already worn taps before sharpening new ones. Krollit provides comprehensive documentation.
Are replacement grinding wheels available?
Yes. Original Bernardo replacement grinding wheels available with 3–5 working days shipping.
Does the STG 20 also sharpen right-hand and left-hand taps?
Yes. The grinding machine handles both right-hand and left-hand taps with the same basic setting, varying the feed direction during sharpening. The Italian manual illustrates the procedure for both orientations.
