General sharpening angles?

O

odp

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Jan 11, 2007
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I have just bought a Lansky Crock Sticks 4 rod sharpener.
It has the option for 20 or 25 degrees.
I cannot figure out which would be best for general sharpening of my everyday pocket knives (Spyderco Dragonfly, William Henry Legacy I and a SAK Soldier).
What angle would you recommend.
Thanks
 
Out of 20 or 25? TWENTY!!! Think about it... the 25 would be a total inclusive angle of 50*, which is quite nearly the 60*, the apex of an equilateral triangle.

Now if it was 20 versus something like 15 (the options on the Spyderco Sharpmaker) or 10, then there'd be some debate... as is, 20 for everything.
 
You actually want more like 15 degrees. 20 degrees is an insult on your presumed lack of determination to sharpen. Put something like a pencil crosswise under the center of the base and tip the base left and right as you hone on the right and left rods. That will subtract about 5 degrees from your honing angles.

I use Spyderco and Idahone ceramic sharpeners and their angles are 20/15 and 22/17 respectively. I put a rod under the base of the spyderco to get 10 degrees.

PS. For the knives that you are talking about I would go for 10 degrees per side of back bevel and 15 degree microbevel.
 
It really depends on the existing bevel of your knives. Most crock sticks come with high bevels that are "perfect" for edc and kitchen knives according to the manufacture. This is usually between 40 and 50 degrees, which is perfect for an ax. The angles are set that high as a catch all for everyone.

With a system like the crock stick, you aren't going to have very much effect on the established primary bevel. It is more for a touch up on the edge. To touch up your edge, you want an angle that is just slightly higher than the established bevel angle. 40 degrees will work, but you can get away with a bit lower than that and your knives will perform better. I use about a 3/4" thick block that I place on either side of my turnbox to change the factory angles. I place one edge of the turnbox on the block(overhanging perhaps 1/2"). This will lower the angle of the rod on that side between 3 and 5 degrees give or take. For the 20 degree holes, this gives me about 31 to 33 degrees inclusive. After a few swipes on that side, I move the turnbox over to the other block. You have to be really careful to remember to move the box to the other block, or you will take a few swipes at a much higher angle.

If your knives have a healthy edge, and the angle you created isn't lower than the established bevel angle. The edge will be shaving sharp in a matter of minutes if not several seconds. One other thing to remember with the 3/8" diameter round rods. You have to be careful to use lighter pressure than you are accustomed to using a flat sharpening surface. The contact area is much smaller with using these rods.

For another option, check this video out on Youtube:
http://youtube.com/watch?v=7beX_EKXkmA

The only thing I don't like about this option is if you don't place the sharpie in exactly the center, then your angles will be different on each side.

Also, I don't agree with the angles that he claims.
 
His claim is that the sharpie pivots the turnbox enough to bring the inclusive angle down 20 degrees inclusive. His exact statement is "the 20 degree holes become 10 and the 25 degree holes become 30 included". Thats from 50 degree inclusive to 30 degree inclusive. I don't have my slide protractor or my turnbox on me at the moment, but I'm almost certain that it is more like 27 degrees and 37 degrees give or take. I have a late night call out job so I'll have axcess to my crock sticks tonight and I'll try to get a more precise measurement with a sharpy. I might be correcting my post on the 3/4 inch block also. I did a quick measurement earlier today and got more like 30 and 40. I was going on my initial quick measurement I got when I first got my sticks.

Incidentally The exact degree change can be pecisely calculated using the pathagoream theorom, but I forgot how to do that several years ago. Any math majors out there?

All you have to do is mearure the lenght of the crock box, and measure the rise on one side of the box and plug it into a right triangle formula and determine the smallest angle on the triangle. This will be the amount per side that you change the angle. This will work on any crock stick holder.
 
So I just took a little more time on my angle measurements for my turnbox. I first used the regular sharpy pivot, and used my slide protractor to get as close a measurement as I could without seeing the results. I locked the results in and came up with a net reduction of almost seven degrees per side. One side measured at 13.5 degrees and the other side measured at 13. The half degree difference could be acredited to a slight offcenter placement of the sharpy.

My 3/4 inch block placed about 1/2 inch in from the edge of the box netted about a 5 to 5 and 1/2 degree change per side.

Incidentally, a larger diameter super sharpie did infact produce a net change of 10 degrees per side.
 
By default you have a horizontal base, a vertical knife, and an angle of X on the stick. Each side of the blade gets the angle of X, so the edge's triangle measures 2X.

Rotate the horizontal base by Y degrees and the stick rotates the same Y degrees, making the stick's angle to the knife X+Y. This is still on both sides of the blade, so the edge's triangle measures 2(X+Y), not 2X+Y.

Another way to think of it...picture your vertical line and the stick rotated X degrees away from vertical. How much would you have to rotate it to have no angle on the blade? You'd want the blade and stick parallel, meaning a vertical stick, meaning you rotated the stick by its initial X degrees (duh...to get it vertical you move it just as far as it was from vertical to begin with).

Since the stick is fixed with respect to the base, you need to rotate your base that same X degrees. So base angle changes 1:1 with stick angle and single-side blade angle (so half of the total edge angle).
 
I found this right triangle calculator and I used it to do a little figuring:

http://www.cleavebooks.co.uk/scol/calrtri.htm

If I raise my 6" turn box exactly one inch on a side, I will have a net lowering of exactly 9.46 degrees.

If I raise it 3/4 of an inch, I will lower the angle 7.13 degrees.

If I raise it 7/8 of an inch(roughly twice the width of a sharpy), I will have a net lowering of exactly 8.3 degrees per side.

I would like to add a disclaimer on my measurements. My 20 degree holes start at about 21.5 degrees when pressed down due to wobble.

This calculator can be used to determine how much any crock style sharpener should be raised on a side to get whatever angle you want. You plug the length of the base and the desired angle change into the formula and it will tell you how much you have to raise one side of the base.

For a 10 degree change I have to raise one side of my turnbox exactly 1.06 inches.

Edit to add: The numbers on this calculator have to be converted to whole numbers. Or decimals there of.
 
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