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V-Stick Sharpening Angle Formula

Posted by jasonstone20 
V-Stick Sharpening Angle Formula
November 11, 2017 11:56AM
This formula is on the Spyderco Forum:
[www.spyderco.com]

COS (R) = SIN (D) / SIN (A)

D is the desired angle, A is the V Stick Angle, R is the rotation angle need to achieve D.

I haven't been able to get the formula to work.
I have written a program in C++ to use the formula so you can just enter the angles and get the rotaion angle that you need. Can anyone help me sovle for R? My understanding of trigonometry is that you use arc cos to do it, but it isn't working, and I am getting angles larger than 90, negative angles, and nan (not a number).

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
November 11, 2017 02:28PM
Quote
jasonstone20
This formula is on the Spyderco Forum:
[www.spyderco.com]

COS (R) = SIN (D) / SIN (A)

D is the desired angle, A is the V Stick Angle, R is the rotation angle need to achieve D.

I haven't been able to get the formula to work.
I have written a program in C++ to use the formula so you can just enter the angles and get the rotaion angle that you need. Can anyone help me sovle for R? My understanding of trigonometry is that you use arc cos to do it, but it isn't working, and I am getting angles larger than 90, negative angles, and nan (not a number).

Hi,
I think you forgot to convert degrees to radians, whatever sin/cos functions you're using probably work with radians
function deg2rad( deg ){
    return deg*Math.PI/180;
}

function rad2deg( deg ){
    return deg/(Math.PI/180);
}
WolframAlpha COS (R) = SIN (D) / SIN (A)
Says Solutions:
Approximate forms
sin(A)!=0, R = 2 π n - cos^(-1)(csc(A) sin(D)), n element Z
Open code
sin(A)!=0, R = cos^(-1)(csc(A) sin(D)) + 2 π n, n element Z

Hmm,
after writing this up, I think a physical model, paper (or 3d sketchup) might be more informative smiling smiley
result http://jsfiddle.net/fmorzf07/1/show/
code http://jsfiddle.net/fmorzf07/1

Maybe you can take a crack at translating the WolframAlpha solution to javascript
reference https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/acos
https://en.wikipedia.org/wiki/Trigonometric_functions#csc

____
Thanks
I don't mow smiling smiley
Re: V-Stick Sharpening Angle Formula
November 11, 2017 04:08PM
Well
i tweaked it up to 4
http://jsfiddle.net/fmorzf07/4/show
I think results indicate turn ~4 degrees to change up / down 1 degree


VaDeRo(A=15, D=0) = Rotate = 90
VaDeRo(A=15, D=1) = Rotate = 86.13355899461966
VaDeRo(A=15, D=2) = Rotate = 82.25055681627654
VaDeRo(A=15, D=3) = Rotate = 78.33374082922751
VaDeRo(A=15, D=4) = Rotate = 74.36439400572287
VaDeRo(A=15, D=5) = Rotate = 70.3213795496262
VaDeRo(A=15, D=6) = Rotate = 66.17985494241171
VaDeRo(A=15, D=7) = Rotate = 61.90941087186531
VaDeRo(A=15, D=8) = Rotate = 57.47119354834923
VaDeRo(A=15, D=9) = Rotate = 52.81314475766226
VaDeRo(A=15, D=10) = Rotate = 47.86150012004939
VaDeRo(A=15, D=11) = Rotate = 42.50406986235892
VaDeRo(A=15, D=12) = Rotate = 36.55273102568923
VaDeRo(A=15, D=13) = Rotate = 29.6406660416851
VaDeRo(A=15, D=14) = Rotate = 20.81794236658335
VaDeRo(A=15, D=15) = Rotate = 0


code revisions
http://jsfiddle.net/fmorzf07/4/
http://jsfiddle.net/fmorzf07/3/
http://jsfiddle.net/fmorzf07/2/
http://jsfiddle.net/fmorzf07/1/
http://jsfiddle.net/fmorzf07/

____
Thanks
I don't mow smiling smiley
Re: V-Stick Sharpening Angle Formula
November 11, 2017 06:36PM
Thanks for the help. I wasn't converting the radians to degrees until after I divided sin D/sin A. Your code helped a lot.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
me2
Re: V-Stick Sharpening Angle Formula
November 23, 2017 04:13PM
Huh. Here I was just doing it by doing it proportionally. 90 degrees gives the angle the V is set at. Zero degrees equals zero. 45 equals half the set angle. I haven't tried it, but I figured I could get 10 degrees per side by putting the knife at 45 degrees to the Sharpmaker rods in the 20 dps slot. That formula may work that way too, but I haven't worked it out myself.
Re: V-Stick Sharpening Angle Formula
November 23, 2017 05:47PM
Chris,
That's what I was doing also, before I tried this formula. If you want half the angle:
15DPS=59* (7.5 desired degree per side)
20DPS=59* (10 desired degree per side)
25DPS=59* (12.5 desired degree per side)

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
December 12, 2017 12:17PM
Interesting that if you have a Spyderco Sharpmaker, and you put the rods with the corners in the sharpening position, if you rotate the Sharpmaker up until the flats are aligned, it is about 60*, which is close to the 59* needed to halve the angle, so you would have 10* per side, 20* inclusive for the 40* setting, and 7.5* per side and 15* inclusive for the 30* setting.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
January 11, 2018 12:40PM
I was thinking of adding a function to this program where you can adjust the angle but tilting or shimming the Sharpmaker: [youtu.be]

Because the stones are triangle rods vs round rods, the rotating formula doesn't really allow you to use the flats fully. At a rotation of 60*, you basically half the normal angle and can use the flats of the triangle rods, but for smaller adjustments you end up on the corners or partially on the flats. Discussion: [www.spyderco.com]

Just using a ruler and an angle measuring app on my phone, 0.5" lift on the opposite side of whichever rods you are using is a +- 4* angle change.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges



Edited 2 time(s). Last edit at 01/11/2018 01:07PM by jasonstone20.
Re: V-Stick Sharpening Angle Formula
January 11, 2018 01:51PM
Still working on it. I just need to brush up on my 90* triangle math.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges



Edited 5 time(s). Last edit at 01/11/2018 02:22PM by jasonstone20.
Re: V-Stick Sharpening Angle Formula
January 11, 2018 03:31PM
Ok, got the formula:

[www.csgnetwork.com]

SIN A = a (opp. length) / c (hyp. length)

To find c, you need the to solve a^2 + b^2 = c^2

So for raising the Sharpmaker 1", and it is about 7.5" long, you have:

1^2 + 7.5^2 = c^2

sqr(58.25) = c

7.63 = c

SIN A = 1 / 7.63

A = 7.53

Only thing is that I can't use this method for heights less than 1".

I don't think I am doing something right.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges



Edited 4 time(s). Last edit at 01/11/2018 03:47PM by jasonstone20.
Re: V-Stick Sharpening Angle Formula
January 11, 2018 08:06PM
Quote
jasonstone20
So for raising the Sharpmaker 1", and it is about 7.5" long, you have:
...
I don't think I am doing something right.
Well smiling smiley
1) you're not sharing no jsfiddle
2) you're not using no shortcuts

I'd just use the 1-in-60/1:60 rule , ex rise 15 / run 60 is approx 15 degrees (give or take no more than 0.1 of a degree)
So if sharpmaker base is 7.5" long, 7.5/60 is 0.125inch , so 1/8inch (2/16 inch ) is your 1 degree increment, 1/16inch is half degree
So if sharpmaker base is 190.5mm long, 190.5mm/60 is 3.175mm, so ~3mm is your 1 degree increment, ~1.6mm is half degree

You can use !wa to verify arctangent( rise / run )
atan(1/8 / 7.5 is 0.9548 degrees
atan( 3 / 190 ) is 0.9046 degrees
atan( 3.175 / 190.5 ) is 0.9548 degrees
atan( 3.2 / 191 ) is 0.9598 degrees

FWIW, most of this is not off the top of my head, its from my notes / my programs,

Mentioned in Spyderco Sharpmaker Cubic Boron Nitride Rods : first look - CliffStamp
for 1/2 degree, a Toonie is 1.75mm thick
so
atan( 1.75 / 191 ) is 0.5249 degrees
times two is
atan( 3.5 / 191 ) is 1.05 degrees


Speaking of stacking coins to use as sharpening angle guide,
like the kitchen/chef/culinary knife sharpening angle tip,
instead of merely stacking the coins on your stone,
YOU CAN TAPE THE COINS TO YOUR BLADE WITH TAPE AS SHARPENING ANGLE GUIDE
clips/clamps I've tried but it never quite occured to be to just tape stuff to the blade
so I recognize the genius smiling smiley
Alberta Ed : If sharpening freehand you can tape a coin (dime, nickel, penny, etc.) to the back to establish the angle you want. Works the same as an angle guide, tho' not as elegant.

____
Thanks
I don't mow smiling smiley
Re: V-Stick Sharpening Angle Formula
January 11, 2018 09:25PM
ShaperAndMower,
Thank you for the help. I first started with the 1 and 60 rule and got an answer I wasn't happy with, but looks like you made it work. When you say not sharing, are you meaning posting my code? I wanted to get it running first, then I was going to put it on GitHub.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
January 11, 2018 10:56PM
Ok, so the formula I got to work is:
D = desired angle
A = V-Stick angle
H = Height of shim

H = (D-A) * (0.125)

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
January 13, 2018 05:20AM
a small triangle calc......

yadi.sk

Its only in russian but I was using it long before I could really
read anything.. can define a triangle
1 by coords of the nodes,
2 side lengths
or 3 denfine angle and two sides - most relevent for most..

then it calcs pretty much everything under..

www.instagram.com/jscuttingtools
Re: V-Stick Sharpening Angle Formula
January 14, 2018 11:44AM
Here is a great idea:
[www.spyderco.com]

If you place a Spyderco Rod under the Sharpmaker, you get a change the degrees of the rods by 3* dregrees:
12
17
18
23

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
January 22, 2018 12:29PM
I decided to add a function to calculate the edge bevel angle per side by measuring a knife's edge bevel angle using trigonometry:

[www.mathsisfun.com]

W = Behind the edge width divided by two (so you get a right triangle)

H = Edge bevel height
SIN X = W / H

Example ( my Benchmade 940 in S30V, sharpened freehand)

Behind the edge with is "0.055, divide that by 2 and you get:

W = "0.0275

Height is "0.097

H = "0.097

SIN X = 0.0275 / 0.097

SIN X = 0.2835051546

X = SIN^-1 (0.2835051546)

X = 16.4°

I verified this using the Spyderco Sharpmaker and this technique from Cliff Stamps YouTube video:

[youtu.be]

and also using an angle app on my Smartphone.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
January 25, 2018 11:46AM
I have the code up on GitHub:
[github.com]

Here is how to use the program (same as the README.md file)

VStickAngle
A program written to run in a GNU/Linux Bash Terminal, that helps you adjust and find the angle of V-Stick type knife sharpeners.

This is a program for V-Stick/CrockStick/Spyderco Sharpmaker type knife sharpeners.

This program does four things.

Calculate how to change the angle of the V-Sticks by rotating the base of the sharpener.

Calculate how to change the angle of the V-Sticks by elevation one side of the sharpener.

Display a chart of rotation angles.

Calculate the angle of the edge bevel, per side, of the knife.

Use:

To calculate the rotation angle, when prompted enter the desired angle per side you want, then enter the angle per side of the V-Stick.

To calculate the elevation angle, when prompted enter the desired angle per side you want, then enter the angle per side of the V-Stick. 'Near' for the sticks is defined as the stick nearest to the side being elevated. 'Far' for the sticks is defined as the stick furthest from the side being elevated. For the base of the sharpener, 'Near' is the side closest to the V-Sticks, 'Far' is the side furthest from the sticks. This is assuming the base has the sticks mounted on one side (usully beacause there are two angle settings, or a handhold), and not in the center. It can work if the sticks are in the center also.

To display a chart of the angles and what rotation can be use to achieve a certain angle, type in the angle per-side angle of the V-Stick.

To estimate the edge angle per side of the knife blade, measure the thickness/width right behind the edge bevel. Then measure the height of the edge bevel.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
January 26, 2018 11:33AM
I added my Passes Per Side program, as well as Input Validation.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
January 26, 2018 12:01PM
Jason,

Just cloned the repository and played with your program a bit. Thank you for sharing your work!
Re: V-Stick Sharpening Angle Formula
January 26, 2018 12:04PM
tarantella,
Thank you for your interest. Any suggestions would be most welcome. ShaperAndMower helped me out a lot.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges



Edited 1 time(s). Last edit at 01/26/2018 12:06PM by jasonstone20.
Re: V-Stick Sharpening Angle Formula
January 27, 2018 03:46AM
Quote
jasonstone20
I added my Passes Per Side program, as well as Input Validation.

Jason, are You a programmer, respectively would you be able to compile
a source code to run on win 7 or linux ?

www.instagram.com/jscuttingtools
Re: V-Stick Sharpening Angle Formula
January 27, 2018 10:01AM
I just added metric for the height for raising the sharpener.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
January 27, 2018 10:02AM
JSCT,
I program a little. Not professionally. I can compile Linux source code the easiest, I would have to use a virtual machine for Windows.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
January 28, 2018 03:11AM
Quote
jasonstone20
JSCT,
I program a little. Not professionally. I can compile Linux source code the easiest, I would have to use a virtual machine for Windows.

Thanks for answer Jason,
If my friend wont have enough time/be able to do it.
I would ask you for a favor / paid favor dependably
how much time it would be for you.

www.instagram.com/jscuttingtools
Re: V-Stick Sharpening Angle Formula
January 28, 2018 08:05AM
JSCT,
I can give it a shot.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
February 20, 2018 03:40PM
I noticed a problem with the angle calculating formula, due to my latest knife acquisition, the Benchmade 555, because the bevel on each side were not even, so you don't get an accurate angle, just an approximation, which by measurement is what you would get anyway, just not as precise.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
February 20, 2018 05:41PM
Quote
jasonstone20
I noticed a problem with the angle calculating formula, due to my latest knife acquisition, the Benchmade 555, because the bevel on each side were not even, so you don't get an accurate angle, just an approximation, which by measurement is what you would get anyway, just not as precise.
Hi
decent notepad, but,
What are you talking about ?

I'll assume its

4. To estimate the edge angle per side of the knife blade, measure the thickness/width right behind the edge bevel. Then measure the height of the edge bevel.


So the edge bevels are uneven,
left edge bevel is 1mm,
right edge bevel is .8mm,
calipers say thickness is .4 mm, but thickness where?
At the height of the short edge bevel?
At the height of the wider edge bevel?
Diagonally from shoulder to shoulder?

If you got the length of 3 sides you can get some kind of angle out of it

Side 1: 0.8 opposite angle: 75.522°
Side 2: 0.8 opposite angle: 75.522°
Side 3: 0.4 opposite angle: 28.955°
Total Area: 0.1549193338483

14.4775/2 = 14.4775dps

Side 1: 1 opposite angle: 78.463°
Side 2: 1 opposite angle: 78.463°
Side 3: 0.4 opposite angle: 23.074°
Total Area: 0.19595917942265

23.074/2 = 11.537dps

Side 1: 1 opposite angle: 108.21°
Side 2: 0.8 opposite angle: 49.458°
Side 3: 0.4 opposite angle: 22.332°

22.332/2 = 11.116dps


..........................

____
Thanks
I don't mow smiling smiley
Re: V-Stick Sharpening Angle Formula
February 21, 2018 08:19AM
ShaperAndMower,
Yes, that was exactly what I was talking about. Thank you.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
February 21, 2018 12:06PM
I got the updated program up on GitHub.

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges
Re: V-Stick Sharpening Angle Formula
February 22, 2018 09:03AM
I don't think I am doing something right. I am using x = arccos(a^2+b^2-c^2/2ab), and spaced out my code carefully so there is no confusion with the order of operations, but for a triangle of 1, 1, 0.4, I am getting and inclusive of ~60 and per side of ~30:

float SideAngle (float SideA, float SideB, float SideC)
{
float PowA = pow(SideA, 2);
float PowB = pow(SideB, 2);
float PowC = pow(SideC, 2);
float Top (PowA+PowB-PowC);
float Bottom (2*SideA*Sidecool smiley;

float Answer = (Top/Bottom);
float CosAnswer = 1/(cos(Answer));
float Inclusive = rad2deg(CosAnswer);
float PerSide = Inclusive/2;
std::cout << "Inclusive: \n" << Inclusive << "\nPer Side: \n";
return PerSide;
}

------------------------------------------------------------------------------------------------------------------------------------------------------
"Gotta love living in 2019 baby, (63rc too soft on a production knife)"
--Shawn Houston

"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser
------------------------------------------------------------------------------------------------------------------------------------------------------
StoneSharpEdges



Edited 1 time(s). Last edit at 02/22/2018 09:06AM by jasonstone20.
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