Chosera Angles versus Diamond Angles?
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This topic contains 15 replies, has 8 voices, and was last updated by Edwin Lurvey 11/23/2011 at 9:08 am.

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10/28/2011 at 1:29 am #753
Does anyone know the exact implications of the thicker Chosera stones in terms of bevel angles?
In other words if you set the angle guide to say 20 degrees, does the thicker Chosera stone produce a 19 degree bevel or an 18 degree bevel or a 17 degree bevel, or what?
Thanks!
10/28/2011 at 2:05 am #758Does anyone know the exact implications of the thicker Chosera stones in terms of bevel angles?
In other words if you set the angle guide to say 20 degrees, does the thicker Chosera stone produce a 19 degree bevel or an 18 degree bevel or a 17 degree bevel, or what?
Thanks!
I believe Clay uses a 3 degree offset, so 17 degrees sounds right for the above example…but I may have to stand corrected.
Cheers
Leo10/28/2011 at 2:10 am #760Does anyone know the exact implications of the thicker Chosera stones in terms of bevel angles?
In other words if you set the angle guide to say 20 degrees, does the thicker Chosera stone produce a 19 degree bevel or an 18 degree bevel or a 17 degree bevel, or what?
Thanks!
I believe Clay uses a 3 degree offset, so 17 degrees sounds right for the above example…but I may have to stand corrected.
Cheers
Leo[/quote]Thanks Leo, much appreciated!
10/29/2011 at 11:38 am #773There will be a diminishing difference over time as the Choseras wear. Initially, there is a ~2.5 degree average difference – so if the Diamonds read 20 degrees, the Choseras will read about 17.5.
If you read this[/url], Question 3 shows a chart of how my WEPS stock diamonds lined up with the Choseras in the same position.
10/29/2011 at 11:57 pm #775Thanks, that’s very clear.
11/11/2011 at 6:34 am #840The best way to do it is to buy an “angle cube” from Amazon or one of the other online dealers. This way you can get an exact angle of attack for each stone and adjust as necessary.
I have the iguaging cube from Amazon:
http://www.amazon.com/iGagingDigitalMagneticLevelProtractor/dp/B002LL0BIC/ref=sr_1_1?ie=UTF8&qid=1320953566&sr=81TedP
11/11/2011 at 2:10 pm #844just ordered my angle cube. I am sold!
11/11/2011 at 3:29 pm #845The angle cube method is good. If you are more analytically inclined its a simple trig problem to work out the angle difference.Here is a table of results that applies when the stones are vertical, in line with the clamp.
Similar results can be calculated over the entire swing of the arms by considering how the blade edge intersects spheres
but I haven’t done that so far.15.9415 15 r =0.6 h =0.25
21.2627 20 r =0.6 h =0.25
23.29 22 r =0.6 h =0.25
26.2572 25 r =0.6 h =0.25
31.3605 30 r =0.6 h =0.25
Here is an example of how to read this table.
r=.6 means half the thickness in unches of the hone. this is about .6″ fordiamond stones and .8 ” for shaptons.
h is the height of the sharp edge of the blade above the end of the clamp(not above the setting gauge). The six digit numbers are the calculated angle and the 2 digit numbers are the angle you set the rods to. so for example the calculated angle is 15.9415 degrees when the set angle is 15 degrees. (dont take the six digits seriously the accuracy of my measurements of the numbers is such that 3 digits at most are good.the next table shows that the wicked edge sharpener is in fact calibrated for h=0.5 inch blade extension beyond the clamp since the calculated and set angles are quite close.
15.0572 15 r =0.6 h =0.5
20.141 20 r =0.6 h =0.5
22.0883 22 r =0.6 h =0.5
24.9499 25 r =0.6 h =0.5
29.9055 30 r =0.6 h =0.5
more blade extension tables :
Do[
14.2625 15 r= 0.6 h =0.75
19.1252 20 r= 0.6 h =0.75
20.9966 22 r= 0.6 h =0.75
23.7562 25 r= 0.6 h =0.75
28.5649 30 r= 0.6 h =0.75
13.5447 15 r =0.6 h =1.
18.2017 20 r =0.6 h =1.
20.0013 22 r =0.6 h =1.
22.6633 25 r =0.6 h =1.
27.3274 30 r =0.6 h =1.
12.8937 15 r =0.6 h =1.25
17.3593 20 r =0.6 h =1.25
19.0911 22 r =0.6 h =1.25
21.6599 25 r =0.6 h =1.25
26.1829 30 r =0.6 h =1.25
12.8937 15 r =0.6 h =1.5
17.3593 20 r =0.6 h =1.5
19.0911 22 r =0.6 h =1.5
21.6599 25 r =0.6 h =1.5
26.1829 30 r =0.6 h =1.5
11.7587 15 r =0.6 h =1.75
15.8798 20 r =0.6 h =1.75
17.4877 22 r =0.6 h =1.75
19.8836 25 r =0.6 h =1.75
24.1376 30 r =0.6 h =1.75
11.2613 15 r= 0.6 h =2.
15.2275 20 r= 0.6 h =2.
16.7787 22 r= 0.6 h =2.
19.0948 25 r= 0.6 h =2.
23.2216 30 r= 0.6 h =2.
the same tables for the shapton stones have r=0.8:
13.2112 15 r =0.8 h =0.25
18.6513 20 r =0.8 h =0.25
20.7288 22 r =0.8 h =0.25
23.7739 25 r =0.8 h =0.25
29.0233 30 r =0.8 h =0.25
12.4702 15 r =0.8 h =0.5
17.6558 20 r =0.8 h =0.5
19.6465 22 r =0.8 h =0.5
22.5759 25 r =0.8 h =0.5
27.6601 30 r =0.8 h =0.5
11.8054 15 r= 0.8 h =0.75
16.7559 20 r= 0.8 h =0.75
18.665 22 r= 0.8 h =0.75
21.4839 25 r= 0.8 h =0.75
26.4061 30 r= 0.8 h =0.75
11.2059 15 r =0.8 h =1.
15.939 20 r =0.8 h =1.
17.7715 22 r =0.8 h =1.
20.4855 25 r =0.8 h =1.
25.2501 30 r =0.8 h =1.
10.6629 15 r =0.8 h =1.25
15.1948 20 r =0.8 h =1.25
16.9554 22 r =0.8 h =1.25
19.5701 25 r =0.8 h =1.25
24.1823 30 r =0.8 h =1.25
10.6629 15 r =0.8 h =1.5
15.1948 20 r =0.8 h =1.5
16.9554 22 r =0.8 h =1.5
19.5701 25 r =0.8 h =1.5
24.1823 30 r =0.8 h =1.5
9.71766 15 r =0.8 h =1.75
13.89 20 r =0.8 h =1.75
15.5203 22 r =0.8 h =1.75
17.9523 25 r =0.8 h =1.75
22.2773 30 r =0.8 h =1.75
9.30401 15 r= 0.8 h =2.
13.3155 20 r= 0.8 h =2.
14.8866 22 r= 0.8 h =2.
17.2348 25 r= 0.8 h =2.
21.4254 30 r= 0.8 h =2.
For the gadget freaks consider using adjustable parallels to accurately set up the swing arms in a repeatable manner:
use calipers to repeatably set the adjustable paralles
to a precise width. Then use the adjustable parallel between the edge of the wicked edge base and the adjustable pivot.A good usb microscpe is the ProScope HR2 withe the 30x lens.
11/11/2011 at 3:48 pm #846I just cant do things right the first time. The tables for
h=1.5 should be as follows.I suppose I have created enough confusion for now.
10.1689 15 r =0.8 h =1.5
14.5143 20 r =0.8 h =1.5
16.2076 22 r =0.8 h =1.5
18.7283 25 r =0.8 h =1.5
23.194 30 r =0.8 h =1.5
12.3008 15 r =0.6 h =1.5
16.5881 20 r =0.6 h =1.5
18.256 22 r =0.6 h =1.5
20.7362 25 r =0.6 h =1.5
25.1223 30 r =0.6 h =1.5
11/11/2011 at 4:22 pm #847Congratulations StJohn! It’s not every day I glaze over! :silly: :silly: :silly:
I must not have enough spin on my propeller head hat today. 🙁
+1 on the angle cube. But not to be completely propellerless 😉 , one thing I have noticed is that you really do need to place the stone/arm in the same place on the knife when using the cube, otherwise there is variation in the reading, which is what stjohn’s post relates to (hey, I said not enough spin, not no spin! B) )
One thing more to throw at you stjohn – I’ve been wondering of the variables on the Chosera and Shapton stones in regards to flipping the paddles. What I mean is that when you use a freshly flattened stone, say the 2K of a 2K/5K combo, you get an accurate reading because the stone is theoretically consistently flat. But when you flip that paddle over to use the 5K side, you arguably have a degree of dishing (although not anywhere big enough for regular nonpropellerheads to care) which I think can change the reading.
Aside from lapping the 2K stone before flipping, is it me, or am I just OCDing this? :whistle: :unsure: :dry:
11/12/2011 at 2:59 pm #855Not sure that the gist of the tables is understood after seeing Tom’s comments.
The calculated angle in the tables is the actual angle you wll get when the set angle on the crossbar is as indicated
in the tables. Thus for the half width of the hone, r=.6 inch,
the angle set on the crossbar is about right only if the blade extension above the clamp is about 1/2 inch. The higher the blade extension the more the true angle deviates from the set angle. For the extreme case of 2 inch blade extension and a set angle of 22 deg (h= 2 inch, r=0.6)the actual angle will be about 16.7 deg for example. For the thicker hones,like the Shaptons this same setting yields a true angle of (r=0.8 inch, h=2inch ) 14.9 deg. you should be able to roughly confirm this using the angle cube (the accuracy of the angle cube setup is such that its difficult to get better than 1 deg resolution in my experience. NOTE: ITS MY SETUP, NOT THE ANGLE CUBE,THATCAUSES THIS 1 DEG INNACCURACY)you can see the effect of stone dishing by recognizing that for any fixed set angle on the crossbar the true angle will be more for the thinner section of the hone. In effect a dished stone will convex the edge slightly. The effect is really too small to capture in the tables since it would only be a difference of r=0.800 inch at the end of the hone and r=0.795 inch at the lowest dished point. the measurements required to construct the tables are certainly not accurate enough to do this.
Conclusion: thicker stones(r> .6 inch) give less of an angle than is set on the crossbar. Hence unless you increase the set angle you will not reach the edge with the thicker stones on an knife initially sharpened with the thin stones. The tables are intended to give you an indication of how large the variation is.
Again keep in mind that the tables are for the stones centered on the clamp,with no swing forward or backward.
11/12/2011 at 7:43 pm #856Well, I guess the ‘ol propeller is spinning in the wrong direction today! :blink: :blush:
😆 😆 😆
11/15/2011 at 7:31 am #863Not sure that the gist of the tables is understood after seeing Tom’s comments.
The calculated angle in the tables is the actual angle you wll get when the set angle on the crossbar is as indicated
in the tables. Thus for the half width of the hone, r=.6 inch,
the angle set on the crossbar is about right only if the blade extension above the clamp is about 1/2 inch. The higher the blade extension the more the true angle deviates from the set angle. For the extreme case of 2 inch blade extension and a set angle of 22 deg (h= 2 inch, r=0.6)the actual angle will be about 16.7 deg for example. For the thicker hones,like the Shaptons this same setting yields a true angle of (r=0.8 inch, h=2inch ) 14.9 deg. you should be able to roughly confirm this using the angle cube (the accuracy of the angle cube setup is such that its difficult to get better than 1 deg resolution in my experience. NOTE: ITS MY SETUP, NOT THE ANGLE CUBE,THATCAUSES THIS 1 DEG INNACCURACY)you can see the effect of stone dishing by recognizing that for any fixed set angle on the crossbar the true angle will be more for the thinner section of the hone. In effect a dished stone will convex the edge slightly. The effect is really too small to capture in the tables since it would only be a difference of r=0.800 inch at the end of the hone and r=0.795 inch at the lowest dished point. the measurements required to construct the tables are certainly not accurate enough to do this.
Conclusion: thicker stones(r> .6 inch) give less of an angle than is set on the crossbar. Hence unless you increase the set angle you will not reach the edge with the thicker stones on an knife initially sharpened with the thin stones. The tables are intended to give you an indication of how large the variation is.
Again keep in mind that the tables are for the stones centered on the clamp,with no swing forward or backward.
Correct. FWIW, the angle remains the same along the straight portion of the blade and only changes with varying heights of blade or curvature. It’s most noticeable along the curve of the belly because the stone is rotating on the rod as it sweeps through the curve and constantly entering a new plane of contact. Had we gone with square guide rods and square holes in the handles, that effect would be eliminated but we’d lose some of the flexibility with different knife designs.
Clay
11/22/2011 at 12:33 pm #902I also notice a difference from the diamonds to the ceramics. THe ceramics are thinner than the diamonds.Angle cube for the win!!
11/23/2011 at 3:19 am #906So are you saying that we should move our ceramics in one degree to keep the same angle as the diamonds? I dont have an angle cube so any help is appreciated.
Lucky

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