Keeping a Keen Edge
Ways and Equipment to Sharpen Woodturning Tools
For any woodturner, the difference between frustration and fluid artistry often comes down to one critical factor: the sharpness of their tools. A dull tool tears and scrapes, leaving a ragged finish and demanding excessive force. A sharp tool, on the other hand, glides through wood, creating clean shavings, smooth surfaces, and a more enjoyable turning experience. Understanding the various methods and equipment for sharpening is fundamental to successful woodturning.
Why Sharpness Matters
Before diving into the “how,” it’s crucial to reiterate the “why.” A sharp edge:
Produces Cleaner Cuts: Leads to smoother surfaces, reducing the need for extensive sanding.
Requires Less Force: Reduces fatigue and improves control, minimising the risk of accidents.
Extends Tool Life: Less pressure means less wear and tear on the tool itself.
Enhances Safety: A tool that cuts effectively is less likely to slip or grab.
The Fundamentals of Sharpening
Regardless of the method, the core principles of sharpening remain the same:
Grinding/Abrasive: Removing material to create a new, sharp edge.
Angle Consistency: Maintaining the correct bevel angle for the tool’s function.
Cooling: Preventing the tool from overheating, which can compromise the steel’s hardness (known as “bluing”).
Burr Removal: Eliminating the tiny wire edge created during grinding for a truly sharp edge.
Sharpening Methods and Equipment
There are several popular methods and pieces of equipment used by woodturners to achieve a razor-sharp edge:
1. Bench Grinders
The ubiquitous bench grinder is the workhorse of many woodturning workshops.
Equipment:
Grinder: Typically a 6-inch or 8-inch model with two wheels.
Grinding Wheels:
Aluminium Oxide Wheels: Common for general sharpening. Available in various grits (e.g., 60-grit for shaping, 120-grit for refining).
CBN (Cubic Boron Nitride) Wheels: A premium option. These wheels are incredibly durable, run cool, don’t need dressing, and maintain their shape, making them ideal for consistent angles. They are more expensive upfront but offer excellent long-term value.
Grinding Jigs/Sharpening Systems: Essential for consistency. These systems (e.g., Wolverine Grinding System, Oneway Sharpening System) typically include a V-arm support and a platform to hold the tool at the desired angle.
Dressing Stone: For traditional abrasive wheels, a dressing stone is used to clean and true the wheel’s surface, removing clogged material and restoring its cutting efficiency.
Water Trough/Cup: For cooling the tool to prevent overheating.
Method:
Set Up: Secure the grinder and attach the appropriate sharpening jig.
Adjust Angle: Set the jig to the desired bevel angle for your tool (e.g., 35-40 degrees for gouges, 20-25 degrees for skew chisels).
Grind: Lightly touch the tool to the spinning wheel, moving it consistently across the width of the edge. Apply light pressure and keep the tool moving to prevent localised heating.
Cool: Frequently dip the tool in water to dissipate heat.
Check Burr: Feel for a burr (a tiny wire edge) on the back of the bevel, indicating you’ve reached the edge.
Hone (Optional): Some turners will then move to a finer grit wheel or strop for a polished edge.
2. Wet Grinders (Slow-Speed Grinders)
These grinders operate at much lower RPMs and use a water bath to keep the grinding stone cool, eliminating the risk of overheating the tool.
Equipment:
Wet Grinder: Brands like Tormek are popular. They feature a large, slow-spinning grinding wheel that runs through a water trough.
Honing Wheel: Typically a leather honing wheel charged with honing compound for deburring and polishing.
Specialised Jigs: Many wet grinder systems come with a wide array of specific jigs for different turning tools, ensuring precise and repeatable angles.
Method:
Fill Water Trough: Ensure the water level is correct.
Set Up Jig: Select the appropriate jig for your tool and set the desired angle.
Grind: Gently hold the tool in the jig against the wet grinding wheel. The slow speed and water bath prevent heat build-up.
De-burr/Hone: Once the edge is formed, move to the leather honing wheel with compound to remove the burr and create a highly polished, sharp edge.
3. Belt sharpeners
These use a 50 x780 mm belt and the bed can be tilted to suit your preferred stance and location within the workshop. They have a table that can be set very quickly to the preferred bevel angle and also have guides for different types of tool. They are probably the least hassle of all of the sharpening methods and give a very consistent grind or just a light touch up. They are a superb solution for anyone who has a problem getting to grips with a bench wheel grinder however they are not a cheap option. The two main players in the market are the Robert Sorby Pro-Edge and the Axminster Ultimate Edge. The Pro Edge has been around for a lot longer and so you may be able to pick one up second hand.
4. Diamond Plates and Honing Guides
While not for major reshaping, diamond plates are excellent for touch-ups and maintaining an edge between grindings, especially for tools like scrapers.
Equipment:
Diamond Plates: Available in various grits (e.g., fine, extra-fine, super-fine).
Honing Guide (Optional): Can help maintain a consistent angle for straight-edged tools.
Method:
Secure Plate: Place the diamond plate on a non-slip surface.
Hone: With light pressure, rub the bevel of the tool across the diamond plate at the correct angle.
De-burr: Flip the tool over and gently rub the flat back to remove any burr.
Progressive Grits: Work through progressively finer grits for a sharper, more polished edge.
5. Honing and Stropping
These techniques are for refining an already ground edge, not for initial shaping. They remove the microscopic burr and polish the cutting edge, leading to superior sharpness.
Equipment:
Leather Strop: A piece of leather, often mounted on wood.
Honing Compound: Abrasive paste (e.g., chromium oxide, jeweler’s rouge) applied to the strop.
Slip Stones/Arkansas Stones: Small, shaped stones used for honing curved edges (like the inside of gouges).
Method:
Apply Compound: Rub honing compound onto the leather strop.
Strop: With light pressure, pull the tool away from the cutting edge along the strop. Never push into the edge, as this can embed the edge into the leather.
Repeat: Strop both the bevel and the back of the tool until the burr is gone and the edge is polished.
Slip Stones: For gouges, use a slip stone to hone the inside flute, ensuring a complete cutting edge.
6. Maintaining your edges
Frequent Touch-Ups: Don’t wait until your tool is completely dull. Frequent, light touch-ups on a finer grit wheel or strop will keep your tools performing optimally and reduce the need for aggressive grinding.
Listen to the Wood: A sharp tool will produce continuous, fine shavings. If you’re getting dust or torn fibres, it’s time to sharpen.
Storage: Protect your sharpened edges from nicks and bumps during storage. Tool rolls or racks are excellent for this.
Sharpening woodturning tools is a skill that develops with practice. By understanding the principles and utilising the right equipment, you’ll ensure your tools are always ready to transform raw wood into beautiful creations, making your turning journey more efficient, enjoyable, and ultimately, more rewarding.