6" vs 8" grinder advice
Dear Fellow woodturners:
If you took two identical tools and sharpened one on a 6" wheel and the other on an 8" wheel
at identical angles, due to the different radii of the wheels, the hollow grinds produced are different. As a result, the point where the bevel meets the cutting edge will be more accute on the tool ground on the 6" wheel. The problems with this are:
1) because it is more accute on the tool sharpened on a 6" wheel
2) the edge will wear more quickly
3) the tool will be more aggresive
4) it will vibrate more on the wood.
While neither speed will ruin the temper of high speed steel tools, I recommend a grinder speed of
1800 RPM instead of 3,600 RPM. The reasons are:
1) at 1,800 rpm you will remove 1/2 the amount of metal from your tool than
you will with a 3,600
2) if you make a mistake, it's 1/2 as bad.
I also recommend a 1" wide wheel. Often you will see inexpensive grinders offered in home stores etc. and they will have a 1/2" wide wheels. If you are using a 1" wide wheel, you are less likely to allow your tool to slide off the side of the wheel.
As far as wheels are concerned, the most-effective improvement you make to any wheel is to make it truly concentric to the axle of the grinder and perform this as they are mounted on the axle and at operating speed. This will significantly reduce grinder vibration, tool bounce and will improve the smoothness of the bevel and the edge of your tools. It also eliminates the need to balance your wheels. "Geiger's Wheel Truing and Dressing Solution" does an excellent job of truing the wheels, leveling the aggregate to produce smoother bevels on your tools and it de-glazes the wheels. Using it also eliminates the need for a wheel balancer. If you want to learn more go to:
www.geigerssolutions.com.
Don Geiger