Shropshire Association of Woodturners

This article is written primarily to advise our newer and less experienced members of the importance of this often overlooked but vital piece of  equipment.  If your gouges or chisels aren’t sharp, you can not expect to  cut your piece of wood effectively and likewise, if your grinding wheel  isn’t “sharp” you can not expect to cut the steel of your tools  effectively when sharpening them, it is as simple as that.

If you magnify the surface of a grinding wheel you see millions of minute  carborundum particles with very sharp edges all stuck together and  having equally minute gaps between each one.  It is these sharp edges  of carborundum that grind or cut the steel of your tools away and leave  you with a cutting edge. The steel that is removed during sharpening is seen as red sparks and the majority of it shows as black dust underneath the wheel. The rest of it however gets stuck in the gaps between the carborundum particles and hides  their sharp edges, and also, some of these sharp edges are blunted or  worn smooth.  The end result of this is patches of black or silver seen on the surface of the wheel, and a wheel that rubs the tool instead of cutting it so the tool gets hot and turns a lovely shade of blue.  This is the time to re sharpen or dress your wheel and it is very simple providing that you have the means to do  it.

Most turners use a long square stick of carborundum called a Devil Stone, they are easily obtained from tool suppliers and cost about 6.00.  You  simply switch on the grinder, rest the stone on the tool rest, touch it  on one edge and move it across the front of the wheel. The surface of  the wheel is removed taking with it the embedded metal and the blunt  particles and leaves a new surface of clean, sharp edges that cut again.  Don’t overdo it though, just enough to get rid of the black or  silver patches because obviously, every time you sharpen or dress the  wheel you make it slightly smaller and the more you do it the sooner you will have to buy a new one.  The other important thing is to make sure that you move the devil stone in a straight line so that the front of  the wheel ends up flat, and not concave or convex, most important when  you come to sharpen a tool such as a skew that requires a straight  edge.  It is also very important to protect your eyes when dressing the  wheel because the dust that comes off it will do serious damage to your  eyes if it gets in there, so please remember to wear goggles.

A lot is written in adverts about grinding wheels, extolling the virtues  of each one but remember, the writers of the adverts also sell the wheel so they would wouldn’t they.  Claims are made that “our wheel keeps the tool cooler and cuts cleaner” but in my long experience, all  wheels will cut almost as well as each other providing that they are dressed and the way to keep  the tool cool is to grind slowly and gently.  I have a grinder that was  sold with a grey wheel on one end and a white wheel on the other and I use both wheels equally, some tools I grind on one and some on the  other.  I can honestly say that I find no difference in the sharpness of tools ground on one wheel or the other and the only time they turn  mildly blue is when I press too hard or the wheel needs dressing.   Others may have different views but those  are mine, so why pay much more for a white or red or a ruby  wheel than a common grey one when they will all cut well if treated  well. Also, after 5 years of moderate usage, my wheels have only been  reduced by dressing them from 6 to 5 1/2 inches diameter so don’t get  sucked in by all of this hype and change them un-necessarily.

  Fred Harris.