Keeping those tools sharp...

7 June 2013, Woodturning in practice, Would you like to leave a comment?

This is something easily overlooked, but an essential part of the turning process. Very dry timber can blunt a gouge in seconds, so understanding the grinding wheel is quite important.

A correctly sharpened gouge will have a perfect bevel, without any flat spots or ridges. The trick is to maintain this profile, even after countless passes over a grinding stone. I used to think that once sharpened, my gouge would be fine for a day or so! However, I soon discovered that wood has a whole load of blunting properties – dirty bark, tough knots and the odd nail or two, soon damage the cutting edge.

Just about all of my tools are sharpened using a Record 6” bench grinder. The only exception is my Rolly Munro, which I will be reviewing shortly. The grinder has a 40mm wide aluminium oxide wheel on one side – a must for sharpening a turning tool. The other wheel is made of a much coarser compound. This can be used for shaping and profiling, but is too rough for sharpening.

I always check the condition of the grinding wheels before using the machine. They can become out of balance quite regularly and need dressing with a specific tool. You can use either a dressing block, or dressing wheel – the photo shows a dressing wheel in use.

Dressing-tool.jpg

When sharpening, I position the gouge at an angle, so that the cutting tip points towards one side. This helps retain a good edge, as I roll the bevel across the wheel. The key is to align the bevel of the gouge with the face of the wheel, so that an even grind is taken off the entire surface, in one pass. However, this is easier said than done and something I have really only just mastered! Parting tools are a lot easier – just start at the heal of the tool and then grind until you can see the tip touching. Repeat this for the other side.

The gouge being sharpened...

Sharpening-a-gouge.jpg

Grinding-a-gouge.jpg

The parting tool is a little easier...

Sharpening-a-parting-tool.jpg

Grinding-a-parting-tool.jpg

Ready for use...

Sharpened-tools.jpg

I have a water butt just outside my workshop and use it for dunking the tools in after a grinding session – I can’t say for certain if it hardens the steel, but it does make them easier to hold!

Jonathan Leech

Written by Jonathan Leech

Jonathan Leech is a woodturner working and living in Cumbria. He specialises in making bowls, dishes and platters from local sustainably sourced timber. Read more or about Jonathan or see a selection of his work.

Your comments

  1. Gravatar of Jonnie
    Jonnie15 October 2014 14:57

    Really helpful advice.

    All I can add is about the quenching/hardening; a design engineer at my work explained how to make my tool edges last longer, and it took two stages:

    1. Heat the cutting end of the tool with a blowtorch until the steel turns light blue, then quench into cold water. This 'resets' the steel.
    2. Rub the surface colour off, then heat the cutting edge again (from cold) but only until it reaches straw colour, then immediately quench. That should harden it, but without it being brittle.

    Not sure I would ever know if it had made a difference. But if you spent days at a time cutting one timber type (e.g. elm salad bowls) you'd perhaps be able to measure the benefit...

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