- Joined
- Apr 29, 2002
- Messages
- 1,273
Previously, I thought about getting a sharpening system that allowed me to sharpen at arbitrary angles. My Sharpmaker, with its limited selection of angles (30/40 degs included), just wasn't flexible enough. I've heard of other people sharpening at arbitrary angles by using lots of magic marker and "eyeballing" it. I've tried this, but for the very same reason that I can't freehand sharpen on a stone, it didn't turn out too well.
Now I use a special setup to allow my Sharpmaker to sharpen at arbitrary angles. It's made my sharpening time much more enjoyable, since now I don't need to estimate angles. It's also faster now, since every pass down the rod is made at exactly the right angle (unlike when I'm freehanding).
I can take pictures of the setup, if necessary. I know my writing isn't too clear:
To change the angle, you need to slip something under one end of the Sharpmaker, to change the angle. I use sheets of paper, since you can add or subtract from the height easily. With a handy ruler, I figured out the correct height to use, and slipped it under the Sharpmaker (without lid attached to base).
For repeatable results, I always put the rods in the 40 degree side. Then I align the other side, through the two holes in the base, by having half of the holes showing through. Err... by that I mean that the stack of paper underneath the base supports the Sharpmaker at the line where the center of the two holes meet.
The length from the holes to the edge of the Sharpmaker, which should be in contact with the table, is 17.4cm. This measurement, when combined with the height of the stack of the paper (which we'll call H), can give us the angle.
Then, from simple trigonometry, the following formula tells us the angle we have:
sin(angle) = H/17.4
which can be converted to:
angle = inverse sin(H/17.4)
Note that to get the true angle, you need to add 20 (half of 40) to the angle from the formula. So if you want a 30 degree angle (per side, not inclusive), you would put:
sin(10) = H / 17.4
which can be converted to:
H = 17.4 * sin (10)
That tells you the height of the stack of paper you should use. You could also use a trial and error method with magic marker, to figure out the original angle on a blade, if you just add/subtract paper as needed.
You can calculate inverse sin with Calculator (duh!
) in Windows. But for the people that are sick of high school/college math (I am!), I've calculated some commonly seen angles:
Per side angle (in degrees).......Height of stack of paper (in cm)
20.......................................0
21.......................................0.3
22.......................................0.6
23.......................................0.9
24.......................................1.2
25.......................................1.5
26.......................................1.8
27.......................................2.1
28.......................................2.4
29.......................................2.7
30.......................................3.0
31.......................................3.3
32.......................................3.6
33.......................................3.9
34.......................................4.2
35.......................................4.5
36.......................................4.8
37.......................................5.1
38.......................................5.4
39.......................................5.7
40.......................................6.0
Note that the angle above is just a per-side angle. So the overall, included angle would be 80 degrees for the last entry.
Be sure to account for compression of the paper when you measure the height of the stack. You need to hold the Sharpmaker down on the paper, so you'll need to add a few more mm of paper for there to be room for squashing.
Also, when you need to do the other side of the blade, you need to flip the whole Sharpmaker around. You need to sharpen with arms somewhat crossed, to support the Sharpmaker. Be careful in this position, sharpening is an inherently dangerous activity. Once again, I can take pictures if my writing isn't too clear.
Now I use a special setup to allow my Sharpmaker to sharpen at arbitrary angles. It's made my sharpening time much more enjoyable, since now I don't need to estimate angles. It's also faster now, since every pass down the rod is made at exactly the right angle (unlike when I'm freehanding).
I can take pictures of the setup, if necessary. I know my writing isn't too clear:
To change the angle, you need to slip something under one end of the Sharpmaker, to change the angle. I use sheets of paper, since you can add or subtract from the height easily. With a handy ruler, I figured out the correct height to use, and slipped it under the Sharpmaker (without lid attached to base).
For repeatable results, I always put the rods in the 40 degree side. Then I align the other side, through the two holes in the base, by having half of the holes showing through. Err... by that I mean that the stack of paper underneath the base supports the Sharpmaker at the line where the center of the two holes meet.
The length from the holes to the edge of the Sharpmaker, which should be in contact with the table, is 17.4cm. This measurement, when combined with the height of the stack of the paper (which we'll call H), can give us the angle.
Then, from simple trigonometry, the following formula tells us the angle we have:
sin(angle) = H/17.4
which can be converted to:
angle = inverse sin(H/17.4)
Note that to get the true angle, you need to add 20 (half of 40) to the angle from the formula. So if you want a 30 degree angle (per side, not inclusive), you would put:
sin(10) = H / 17.4
which can be converted to:
H = 17.4 * sin (10)
That tells you the height of the stack of paper you should use. You could also use a trial and error method with magic marker, to figure out the original angle on a blade, if you just add/subtract paper as needed.
You can calculate inverse sin with Calculator (duh!
) in Windows. But for the people that are sick of high school/college math (I am!), I've calculated some commonly seen angles:Per side angle (in degrees).......Height of stack of paper (in cm)
20.......................................0
21.......................................0.3
22.......................................0.6
23.......................................0.9
24.......................................1.2
25.......................................1.5
26.......................................1.8
27.......................................2.1
28.......................................2.4
29.......................................2.7
30.......................................3.0
31.......................................3.3
32.......................................3.6
33.......................................3.9
34.......................................4.2
35.......................................4.5
36.......................................4.8
37.......................................5.1
38.......................................5.4
39.......................................5.7
40.......................................6.0
Note that the angle above is just a per-side angle. So the overall, included angle would be 80 degrees for the last entry.
Be sure to account for compression of the paper when you measure the height of the stack. You need to hold the Sharpmaker down on the paper, so you'll need to add a few more mm of paper for there to be room for squashing.
Also, when you need to do the other side of the blade, you need to flip the whole Sharpmaker around. You need to sharpen with arms somewhat crossed, to support the Sharpmaker. Be careful in this position, sharpening is an inherently dangerous activity. Once again, I can take pictures if my writing isn't too clear.
.
,but I hope you can understand me.