Folks, if you have not read the article I wrote with Jon Broida's help which is on Knifeplanet, you should. It covers a lot of very useful information, but I will discuss some points here as well.
Novices often get frustrated when starting with Angles. There are two elements to this, one is actual SHARPENING ANGLE and the other is the ability to stabilise that chosen angle, to hold it constant while you sharpen.
Let's deal with the easy one, the choice of a Sharpening Angle.
These are the pictures from the Knifeplanet article.
Your choice of angle should be determined by the knife you are sharpening and to some extent, to what you are cutting but for now, let's make that choice based on the knife, i.e. the steel used to make it. The useful pictures above will tell you that all knives are sharpened between 10 and 20 degrees per side, you can choose any angle you want. The guideline illustrated above are designed to enhance the cutting performance of a knife and edge retention. For example, if I am going to sharpen a dull knife that is relatively soft, i.e. 54 on the hardness scale, my SA (Sharpening Angle) will be 20 degrees per side, or as close to that as I can manage. Remember, we are freehand sharpening so these angles are not precise, but they can be very close and exact precision is unnecessary.
I choose this angle (20 deg) because it is "safe" angle in terms of the steels ability to keep that primary edge in place, to prevent it from failing for as long as possible. This angle will provide the necessary support to the edge. It will still fail and roll over eventually but we can't stop that, if we are using the knife. I could sharpen that same knife at 12 deg if I wanted to, however, the period of edge retention, the time it takes to go from extremely sharp to useless would be much shorter as the supporting steel behind the edge is thinner, there is not much there to keep that edge in place.
Now, you can always try sharpening at different angles once you have built up muscle memory in an effort to gain as much cutting performance from your knife as possible. If you typically sharpen at 20 deg per side, try 17, see how the knife holds up, you can always go back to 20 deg. Gain muscle memory first though, you can do this down the road a little.
You can find the angle, i.e. what the 20 deg angle looks like, i.e. how high the spine of the knife off of the stone is by various means. You can wing it, you can hold the knife at 90 deg to the stone, i.e. straight up and down and just lower it until you get to what you think is 20 deg or whatever your SA is. You could create a little guide, a stack of quarters for example as a visual clue. There are angle guides available and there is an Angle Meter in your iPhone in the Compass App. Just swipe left.
Just do a little experimenting to see how it works, if the screen turns red, just tap the screen to get it back to black. It is very accurate. Remember however, this just shows you what your chosen SA looks like, you'll be on your own once you start sharpening and there is much to take in.
In the video shown on Lesson #2, I describe a four level pressure system, this has proved to be an excellent system for me in terms of burr removal which of course leads to a clean edge and sharpness.
However, when you are just learning, if this is confusing, i.e. trying to hold and angle and manipulate pressure at the same time, just use a couple of pressure variances. One moderate and one light. You need some pressure to form the burr. Why not call these two levels of pressure:
BURR FORMING PRESSURE
BURR REMOVAL PRESSURE
Use whatever level of pressure is necessary to form the burr but keep it at a level that enables you to work at that same level, i.e. it is not so hard or soft that it becomes difficult to maintain.
HOLDING AN ANGLE
This is the more difficult part but there is good news: This is the difficult part for all of use when we are learning, this is nothing new, this is your body getting accustomed to a different motion. It will get used to it and in time, with PRACTICE, you will be amazed at how well you will be able to keep your wrist steady and you will see a difference in your edges and bevels, your consistency will grow as your muscles adapt.
Since we are not using an Edge Pro which removes angle issues, we need to build SM.
HOW TO GET THEM
Here is another easy part to learn, building muscle memory is easy. There is no quick fix, holding an angle steady while you sharpen, any angle is a skill that can only develop with practice. However, you an expedite the process, you can speed things up a little but it takes effort. The only way that I know of to increase sharpening muscle memory is to sharpen. You need to sharpen many knives before it starts kicking in, before your body figures out what it is you are forcing it to learn.
Get a good Chef Knife that is undamaged, its 8' (203 mm) in length and consider this as your new best friend. Paint the edge with a sharpie and remove it by sharpening at very very light pressure, you are not actually sharpening the knife you are working at holding the angle, this is exercise. Now, repeat the process on the other side, concentrating on holding that angle, there is nothing else going on around you, just you doing some exercise.
Now when you have done that, and it may take a minute or less, do it again. Do this ten times per side and put the knife down. You should do this about twenty times and you will see an improvement for sure in your ability to hold that particular angle. At the same time, you are also developing your ability to manipulate pressure and hold it steady, sharpening and pressure holding skills are being developed.
This is going to be boring perhaps so just do it for five minutes and give it a rest but don't give up on it, it will work. Your muscles adapt quickly and in no time you will notice it getting much easier to hold that angle.
This SM growth will have the added benefits of improving your confidence, solidifying your technique and making everything you are doing in regards to sharpening easier, more effective and a heck of a lot of fun.
|Coarse, Medium, Fine (L-R)|
The four pillars to successful sharpening.