Bernardo Leather Honing Wheel for NTS 250 Pro / NTS 250 Pro Vario – Ø 200 × 30 mm, center Ø 12 mm
Leather honing wheels represent a technical investment for workshops that require constant precision during intense work cycles. Unlike grinding wheels, leather allows for a mirror finish and controlled application of fine abrasive paste for high-speed steel tools.
In the context of the NTS 250 Pro lathe (and the Vario version with automatic speed change), this wheel is used for the final stages of sharpening HSS tools and for restoring them after long working periods. The 200 mm diameter maintains a constant peripheral speed even on high-power spindles.
Difference compared to NTS 200: NTS 250 Pro lathes operate at higher spindle speeds and more intense loads. The Ø 200 mm wheel ensures optimal peripheral speed (1,500-2,200 rpm on 250 Pro) without altering the abrasive paste-leather adhesion ratio.
Distinctive features of the Bernardo product:
- Adhesive natural leather, professional quality
- Prepared for fine abrasive paste (aluminum oxide grit 240-400)
- Quick M12 thread mounting compatible with NTS 250 Pro spindles
- Competitive price for high-frequency sharpening cycles
Who is the Bernardo NTS 250 Pro sharpening system with leather wheel suitable for?
| Profile |
Suitable? |
Reason |
| Craftsman / small workshop (parallel metal lathes) |
Adequate |
NTS 250 Pro is a professional machine, often oversized for pure craftsmanship. Useful if regular workloads and frequent sharpening are required. |
| Industrial maintenance and spare parts |
Ideal |
NTS 250 Pro is the gold standard for reconditioning HSS tools under continuous loads. Higher spindle speed guarantees sharpening cycles 40% faster than on NTS 200. |
| Professional job-shop workshop (diversified machining) |
Ideal |
The Vario version with automatic speed change allows for rapid switching between roughing and finishing sharpening without manual intervention. Requires an experienced operator. |
| Series production (small repetitive batches) |
Adequate |
Sharpening during a series is feasible, but long cycle times suggest evaluating integrated carbide CNC systems if the series is >500 pieces. |
Not suitable for:
- Hobbyists and small workshops without regular sharpening cycles — NTS 250 Pro machine investment not justified without continuous use
- Operations on non-ferrous materials (aluminum, copper) — leather if damaged, requires dedicated equipment
Technical specifications
Dimensions and mounting
| Parameter |
Value |
| Outer diameter |
200 mm |
| Width |
30 mm |
| Hole diameter / center (thread) |
Ø 12 mm (M12 × 1.75 mm) |
| Net weight |
10 kg |
| Form tolerance |
According to EN ISO 1302 (natural leather, ±1 mm permissible) |
Material and composition
| Parameter |
Value |
| Material |
Vegetable-tanned natural leather, professional quality |
| Adhesion to backing |
Permanent bonding to phenolic core |
| Surface grit |
Fine, prepared for abrasive paste (grit 240-400) |
Compatibility with Bernardo machines
| Machine |
Compatible? |
Notes |
| NTS 250 Pro |
Yes |
Direct M12 mounting, speed 350-2,200 rpm |
| NTS 250 Pro Vario |
Yes |
Compatible, automatic speed change not affected |
| NTS 200 |
Yes, but not recommended |
Geometry suitable but 200 mm diameter redundant for smaller machine |
| Other Bernardo machines |
Check manual |
If M12 × 1.75 mm spindle is present, mounting is possible |
Compliance and markings
| Parameter |
Value |
| Manufacturer |
Bernardo GmbH, Linz (Austria) |
| Bernardo item code |
05-20610 |
| Compliance |
Not subject to Machinery Directive 2006/42/EC (accessory component) |
| Country of origin |
Austria |
Standard equipment
- Leather wheel Ø 200 × 30 mm mounted on phenolic core
- M12 × 1.75 mm thread (center compatible with NTS 250 Pro / NTS 250 Pro Vario spindles)
Frequently asked questions
What is the difference between a fine and coarse wheel for NTS 250 Pro?
The fine wheel (this product, Ø 200 × 30 mm) is for the final sharpening stages and produces a mirror finish, 30-60 seconds per tool at 1,500-1,800 rpm. The coarse wheel is used for roughing heavily worn tools, 15-30 seconds at 800-1,200 rpm. Recommendation: have both in stock for complete reconditioning cycles.
Does the NTS 250 Pro Vario have any incompatibility with the 05-20610 leather wheel?
No. The automatic speed change system (Vario feature) is independent of the spindle. M12 thread mounting is identical to the standard NTS 250 Pro. The only adaptation: check the recommended plexiglass guard for speeds >2,000 rpm on Vario (higher maximum speed compared to the basic 250 Pro).
How do I choose between the Ø 200 × 30 mm (05-20610) wheel and other Bernardo sizes for NTS 250 Pro?
Bernardo offers few diameters for NTS 250 Pro (mainly Ø 200 mm). The 200 mm diameter is standardized for peripheral speeds of 1,500-2,200 rpm on this machine. If you are looking for other sizes, contact Krollit to check availability and compatibility.
Is the 05-20610 wheel suitable for sharpening solid carbide or only HSS?
A: Recommended for HSS. Solid carbide is too hard and damages natural leather. Bernardo offers alternative solutions for carbide (synthetic wheels or CBN systems) — consult Krollit for options.
What is the life cycle of this wheel for NTS 250 Pro under intense use?
With frequent sharpening and daily cycles, durability is 2-3 years. Typical deterioration: leather hardens, loses paste adhesion, no longer achieves a mirror finish. With maintenance (regular brushing, paste activation), life can be extended up to 4 years.
How do I activate a new 05-20610 wheel before first use?
Brush at low speed (600-800 rpm) with a rotating wire brush for 1-2 minutes. This raises the leather grain and prepares the surface for paste adhesion. Then apply fine Bernardo abrasive paste 05-20602 in powder form, increase speed to 1,500-1,800 rpm, and test on a trial tool.
What maintenance does this wheel require between sharpening cycles?
After each sharpening session (every 5-8 tools): light brushing with a dry cloth to remove paste residue. Every 100 hours of use: mechanical brushing with a wire brush + application of new paste. Every 6 months: check leather adhesion (it must not detach from the phenolic core).
Is the 05-20610 wheel included in the Bernardo warranty or the Krollit machine warranty?
Bernardo 24-month warranty on manufacturing defects (leather delamination, core fractures, defective thread). Does not cover natural wear and tear. If purchased as part of a Krollit maintenance contract for the machine, check with the sales office for inclusion in the terms.
Can I mount the 05-20610 vertically (like grinding) instead of horizontally (like sharpening)?
No. The leather design and the NTS 250 Pro spindle assume a horizontal setup for operator safety and uniform paste adhesion. Vertical mounting causes uneven compression of the leather.
