Optimum grit for steel list

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Temper

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Oct 30, 2002
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Does anyone know of a list that will offer suggestions for the best grit for a specific steel within a certain harndess or just for that steel?

I have read a few conflicting things regarding certain steels and would like a more concise list. Or, is it too job specific depending on the material being cut? If so, how about an optimum grit for push and draw cutting?
 
Temper... said:
how about an optimum grit for push and draw cutting?
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For push cutting, as fine as you can get. For draw cutting, up to 80 grit AO belts work very well, this is much more coarse than the most coarse benchstone.

-Cliff
 
Cliff, I was referring to some steels 'preferring' either highly polished or less polished finishes for longevity of the sharpness, assuming same geometry etc etc. For example, you take a blade and polish it to XXX# and perform a cutting task then re-sharpen it to XXX# and see how long it cuts doing exactly the same job. I know inclusions and other factors play some roles especially with Cardboard and rope but there should be an indication at least that XXX# on XX steel 'seems' to offer the best compromise on sharpness and longevity of said sharpness. I saw mention of this with S30V and today that D2 does not take a polished edge. I have a D2 6" utility from .25 stock that is polished up to #3000 and really slices and dices. I was wondering if there was an official or semi-official train of thought on this matter.
 
Temper said:
Cliff, I was referring to some steels 'preferring' either highly polished or less polished finishes for longevity of the sharpness ...
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This depends on the media being cut and the method, the steel isn't really a factor except in extremes, such as deep hollow ground edges (0.015" thick at 1/4" back) which have very acute sharpening angles, ~3-5 degrees. On the coarse steels it isn't of benefit to go beyond a certain grit as the edge just break apart anyway. However most knives are ground WAY thicker than that. Just sharpen according to the task.

-Cliff
 
What edge finish is optimal is more a function of what material is being cut and by what technique rather than what steel is being used, as Cliff Stamp correctly points out above.

For slicing (pulling the knife back and forth) you want edge aggression, from a courser finish. For push cutting and chopping a finer (as fine as you can manage) is better.


I think for all around use, a medium ceramic ( brown Spyderco stones) are just about the best compromise you can get.
 
I know this guys, pehaps I havent explaind well enough what I am trying to say.

Lets say you had 5 knives made identical.

Lets say 1095, AUS8 ATS-34 S30V & D2

Now, lets sharpen them all with a #600 stone.

We then cut some test medium and miraculoussly it is 100% consistent with no inclusions, we apply the same pressure and the same stroke each time for each blade until it requires xxx of pressure to cut the medium and we deem it 'blunt'

We then resharpen the knives using a #800 and repeat, or we go the other way and use a #400.

What I am trying to find out is, in a perfect word of 100% consistency, what grit suits a certain steel more. For example, cutting hemp rope with S30V is best achieved with a mirror polish of #1000 or more, or only go to #400 the microserrations are large but its tough and or wear resistant enough not to have them snap off. Surely wear resistance and micro serration size and strength are influenced by the grit of the stone used. :confused:
 
I think the diffeence in size between carbides and micro serrations is far too great for it too make such a difference.
 
So I couldn't realistically expect to see a performance difference (Number of cuts before xxx pressure is required) on a steel if I used a 120 Stone or a 600 stone on a softer steel, say AUS6?
 
There will be a difference from one steel to the next, but the same general rules for push/slicing apply. If you run D2 at 80 AO grit vs 420HC at 80 AO then the D2 will slice a lot more rope. If you run them at 600 grit then the D2 will again push cut a lot more rope. The grit effect is so dominant that it can allow less optomized steels to win a rope cutting race. I made a knife out of mild steel with a really coarse edge which would outlast many (probably all) of my high end knives with a polished edge slicing rope.

-Cliff
 
Cliff, thanks for the replies, but this isnt what I am asking. The question is, would I see exactly the same performance on the same steel, cutting the same medium but with the blade sharpened to a different polish each time until its blunt. Blunt being defined as needing xxx amount of pressure to make a complete cut.
 
OK, half way there :D How about the same angle each time on the same medium & same blade material, but different grits. Has anyone been so bored as to have looked into it? :)

for example
With a flat grind with an edge thickness of xxx we found that xxx# performed markedly better than xxxx# and XX# when cutting the same medium, this can be attributed to ......... Conversely we found that XXXXX steel when used on the same medium (we're assuming idential blades here) managed to perform almost twice as many cuts at XX# compared to XXXXXXXX#

Tedious I know, but it is Sunday :p
 
Temper said:
How about the same angle each time on the same medium & same blade material, but different grits.
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The above link does that and compares a fine ceramic to fine DMT (these are two massivly different grits even though they are both called fine) with the same angle on slicing hemp. This was done in many of the older reviews. The difference is huge, 20:1 in that case, it gets even even higher.

-Cliff
 
Thanks Cliff, this is exactly what I wanted to see and suspected to be true. Now, where can I find a big list? :D
 
Aside from the reviews I would suggest you talk to Wilson and Goddard, both of these guys have done a lot of rope cutting with different grits, Swaim's posts on rec.knives contained similar work and Joe has done it as well.

-Cliff
 
Wilson and Goddard you can email, Swaim posted on rec.knives (usenet, can check through google), Joe posted there as well as here.

-Cliff
 
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