Sharpening Your Tools
Sharpening your tools is not difficult. Once you learn how and do it a few times you will be surprised at how easy it is. After a while you realize that sharpening is really about feel and touch. I have never used or owned any sharpening jigs o diamond stones. They are not really necessary if you know what you are doing. Sharpening can be quickly learned. You just need a few things and know how to use them.
You will never do really fine work if your tools are not razor sharp. I’m sure you have seen photos of exquisitely made furniture with crisply executed joinery, pristine surfaces and gently rounded edges. This was not done with dull tools. If, and only if your tools are sharp, can you cut as cleanly as the wood permits.
Guitar building utilizes a lot of softwood. The tops, braces and neck are all typically made out of softwood. To work softwoods such as spruce and cedar your tools need to be extra sharp to get good results. If your tools are not sharp when attempting to cut softwood the tool will crush the fibers, not cut them.
Everything I use to sharpen my tools is described below. If these tools are used and cared for properly it won’t take long to put a razor sharp edge on your tools, and maintain it.
How to Sharpen Plane Blades
It doesn’t matter whether you use oil or water stones. They all work the same. Water stones are messy but the dirt comes off easily. Not so much with oil stones. Water stones have become very popular and are now used by a large number of woodworkers.
Types of Stones
You only need three grits of stones, coarse, medium and fine. Flat stones are used to sharpen plane blades, chisels, gouges and scrapers. And slip stones which come in a variety of sizes and shapes are for sharpening certain types of carving tools as well as part of the gouge sharpening process.
Your Stones Need to be Flat
In order to put a fine edge on your tools your stones need to be flat. Over time the surface of your stones will get dips in them from going over the same places while sharpening. Before these dips get too deep you need to flatten the stones. If you wait until they are really deep flattening them is not going to be quick. On the other hand if there is only a slight dip it will just be a few passes and you will be flat.
Flattening surfaces are discussed further down the page.
Many guitar builders and woodworkers use all kinds of gadgets to keep the tool at a certain angle. Some people flat grind their tools. Frankly, it is time consuming and not necessary to producing a sharp edge. Gadgets are not necessary to sharpen your tools if you know what you are doing.
I hollow grind all my cutting tools. Hollow grinding refers to the crescent shape of your blade after sharpening on a round stone. Regardless of what anyone tells you this is a great way to sharpen and its quick.
Hand Crank Grinders
At the woodworking school we all learned to use hand crank grinders like the one on the left. The stone spins only as fast as you crank. It takes some getting use to but once you get it its a breeze. As Jim used to say “its sort of like tapping your head while rubbing your belly”. You control the speed of the wheel so you can keep your tool cool as you grind. This will prevent changing the temper the edge of the blade. we have all seen blades that are a kind of blue at the end. This changes the hardness of the steel and has to be completely removed. Hand crank grinders are relatively inexpensive but you have to build a tool rest for it like the one in the photo. There are plans for this tool rest in the members section.
Most people are familiar with electric grinders. These things work but most spin too fast to sharpen the kind of tools you will be using in guitar building. The slower the stone spins the less chance you have of overheating the blade and ruining the temper of the tools edge.
There is a use for electric grinders. They cut fast so if you are sharpening on the go as you do in wood turning this is the best way to go. Years ago I did quite a bit of turning and used an electric grinder to put an edge on my gouges. It will only take a few seconds but again, you need to be very careful not to overheat the edge. So its a good idea to have some water handy to dunk the tool in and cool it off. But for chisels and plane blades they are not very suitable.
In order to sharpen your tools the surface of your sharpening stones needs to be flat. When the dips in the surface of your stones gets too deep it will be impossible to sharpen your tools properly. So your stones will need to be flattened regularly. To do this you will need a flat surface to flatten your sharpening stones on.
A Piece of Glass
The cheapest solution for this is a 1/4″ thick piece of glass. Glass is dead flat and the surface is hard. This is ideal for flattening your stones. You don’t want to be using a soft surface. To flatten just put some wet/dry sandpaper on the glass, spritz with some water and rub the surface of your stone on it until it is completely flat. Its flat when the entire surface of the stone show signs of being sanded.
A Granite Flattening Surface
Since I have other uses for a flat surface I have a granite slab which is produced to be flat within .001″ over its entire surface. These granite surfaces are typically used in machining. I use mine for flattening by stones, accurately measuring the thickness of my tops, making tools and flattening hand plane bottoms. These things are heavy and they take up some space. So unless you really need one you can get by with just a piece of glass.