How to Sharpen a Plane Blade Part2: How to sharpen the front side.
How to Sharpen a Plane Blade Part2: How to sharpen the front side (bevel) of a new blade using a honing guide, and how to manage the stone surface.
After the ura-oshi process, we are ready to sharpen the bevel of the blade. New plane blade's angle of the blade is always too acute. I have heard that this is because of two reasons. One is that the blade looks more appealing with more ji-gane showing, and another is that, for more expensive blades, when the professional sharpeners (Sui-ken-ya: Water-sharpener) perform uradashi before uraoshi, it is easier when the bevel is wider.
This is my way, but basically for brand new blades, I don’t start hand sharpening in the beginning. I need to use a honing guide to aid the angle. Until there is enough bevel area created to maintain the flat with freehand on the stone, I need to keep using the honing guide. Since I prefer hand sharpening, it is quite frustrating to set the jig every time when I sharpen, but otherwise I’d have to waste 3mm worth of steel by grinding off the tip and make the angle less acute, and I don’t want to do that. I can talk about pros and cons of various honing guides, but I’ll keep that discussion for later article.
So, first of all let me explain how to sharpen using a honing guide. You might think that there is nothing to it to honing guide sharpening, oh, but yes there is! Let us assume that the blade has reasonable edge on already done by the Sui-ken-ya, but the bevel is rounded (this is always the case), and you want to fix that and sharpen the edge using a finer stone to make it sharper. I will explain how to make the edge reasonably sharp using up to med fine natural stones. Unless you are after single digit micron thin shaves, this will make the edge sharp enough for ANY kind of job.
I will list the grit and the brand of the stone for reference, but it doesn’t have to be these particular ones. But it is worth noting that better stones cut far better thus easier to work with, so I recommend not to be stingy when choosing the brand. When it comes to sharpening alloys, cheapest stones won’t cut at all! The steel will glide on the surface of the stone as if you were trying to sharpen a piece of glass on the concrete block.
1. Coarse synthetic stone. #220 Shapton Professional Series.
2. Coarse synthetic stone. Norton super cheap stone from local hardware store. I prefer this stone to fix other stones, since these are basically all glue and super hard. Which means, less cutting strength so cannot be used for sharpening, but retains the flat longer.
3. Med coarse synthetic stone. #1000 Shapton Professional Series.
4. Med coarse synthetic stone. #2000 Bester.
5. Med coarse natural stone or #4000. Aoto(Blue stone).
6. Fine synthetic stone. #8000 Kitayama.
7. Med fine finishing natural stone. Oohira Namito.
8. Straight edge rule to check the condition of the surface.
9. Honing guide.
Now let us begin!
1. Flattening the stone surface.
This is the most important step when sharpening. Unless the stones are absolutely flat, there is no way you can sharpen the blade to a super keen edge. You start off by submerging the stones (1&2) in the water until there are no bubbles coming out from the stones. When both stones are wet enough, you place one stone on the bench and another on top of it so that both stones’ sharpening surface face each other. Then you move the top stone as shown in the drawing rubbing against the one below, and this will create the flat surface for both stones. Ultimately if you can prepare three stones, and do the same process it will be even flatter, but I personally don’t feel this necessary.
http://www.geocities.com/soatoz/phot...ing/flate1.jpg
2. Checking the surface with a straight edge rule.
Until you are used to managing the flat of the stone, it is better to constantly check the surface with a rule. It is important to use an accurately straight edged rule, because normal rules are not so straight as you might expect. There is a straight edge specifically used to check the condition of the sole of the plane block, and these are very accurate. Check the flat in various directions as shown.
http://www.geocities.com/soatoz/phot...ning/check.jpg
3. Start sharpening.
Set the blade onto the honing guide to your preferred angle of the blade. Since the roller will drop from the stone if you go too far down, you need to rotate the stone and start from the other side of the stone to use the entire surface of the stone. It is very important to press the tip of the blade as much as possible. I sometimes even scrape my tip of the finger without noticing because my fingers get to close to the tip. If it is the very first time you sharpen the blade, you will only need to sharpen until the whole width of the blade touches the stone. Only about 1mm to 2mm from the tip needs to be sharpened, as if you are making a second bevel. But I will explain how to sharpen after certain amount of bevel has been created.
As the roller’s axis cannot be "accurately" positioned in the center, you will feel this very slight rocking motion if you pay enough attention. When it is tilted to the steel side of the bevel, you feel less resistance moving the honing guide, and when it is tilted toward the iron side, you feel the stone biting on the iron thus gives you more resistance. If you keep the numbers of repetition the same between these two, you would end up grinding more iron than the steel, so what you need to do is spend extra repetitions when you are grinding the steel side.
You should divide the stone into perhaps 6 sections, and repeat about 30 laps for the steel part and 20 laps for the iron part for each section. You keep repeating this for maybe 3 sets on #1 stone, and then use the #2 stone to fix the surface. Keep repeating this until the mark on the bevel become uniform. For the last couple of laps, decrease the pressure you apply to the blade, and try to erase the coarse marks as much as possible. This will decrease the time and effort spent on the next step. Do this at the end of each stone.
http://www.geocities.com/soatoz/phot...ng/honing1.jpg
