Minimum grit or micron - hair splitting

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ALittleHigher

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The title says it all:
What have you found to be the minimum grit or micron abrasive required to achieve hair splitting sharpness? This is my next goal. If you have an example of a grit and micron size (example of both would be fantastic) of media you've used please post since I'm weighing my options. Budget friendly would be a plus.

And by "minimum" I actually mean coarsest that you can get away with.
 
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ALittleHigher said:
The title says it all:
What have you found to be the minimum grit or micron abrasive required to achieve hair splitting sharpness? This is my next goal. If you have an example of a grit and micron size (example of both would be fantastic) of media you've used please post since I'm weighing my options. Budget friendly would be a plus.

And by "minimum" I actually mean coarsest that you can get away with.
Click to expand...
I don't think it's an issue of "grit and micron size"... as much as it is finishing with a good clean edge.

I seldom "whittle hair" anymore (mostly due to lack of availability)... but have been so impressed by the edges coming off of HeavyHanded's Washboard strop, that I tried it the other day with success. Don't know what the grit rating was, but it was after finishing on a XF WorkSharp diamond stone, with a bit of stropping on the Washboard... so, far from a "mirror edge".

What do you have now, and what level 'sharp' are you getting? Might just try refining your technique a bit (good clean edge, light strokes to refine, etc.), and see if that improves your sharpness. (If not, try the Washboard). :)
 
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Hi CBW,

I have another thread going asking about what is the next step finer than red rouge on cardboard- which is the closest thing to a strop I have now. It turns out red rouge is for very soft metals like gold. It is indeed very slow and requires lots of pressure and speed especially on anything other than 8Cr13. I sometimes use paper wheels with white buffing compound.

So I do think I need something with a bit more "bite" and I was considering green buffing compound as its Chromium Oxide would cut Steel better than the red buffing compound (iron oxide). Also considering diamond paste and a leather strop but not sure what micron required. But I would like to know what it takes to get hair whittling sharp. If I do not get something that makes it possible (like red rouge on an S30v blade) I think I'd get pretty discouraged or frustrated.

I've been able to push cut phone book paper with the grain (vertically) on a good day, but not horizontally across the page. I don't think I could push cut receipt paper.
 
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I don't think I can give you a "micron required"... what I was referring to before. I personally don't like the green compound, for me, it seems to 'kill' an edge more often than improving it. I've had good success with "Flexcut Gold" and now with the compound that comes with the Washboard strop I mentioned (from what I understand, it's a mixture of Heavyhanded's own creation... he has a lot of experience and it shows).

The white buffing compound from the paper wheels also leaves an excellent edge that should "whittle hair"... I think some of this might just be practice? My .02.
 
When I was into extreme levels of sharpness I found it was 50% the steel you are sharpening and 50% edge cleanliness. I've split hairs after just a fine DMT no stropping.

As mentioned, how clean the apex is will be one of the biggest factors.
 
I was going to say about what Jason said except I am not near talented enough to come off a fine DMT and split hairs. Then I was going to make a specific recommendation.

But first what alloys are you working with ?
 
I've got a variety of alloys But the ones that actually could use some fixing up would be an s30v and a 14c28n.

I might look into a fine diamond DMT. The diamond I have is one of those Walmart yellow and orange Smith's paddle sharpeners and I am unable to push cut after the fine side. I feel like the fine is actually still pretty coarse. Makes a mean slicer though.
 
Any steel with high Vanadium is worthless to polish, IMO. The wear resistance of the steel is meant for rough cutting and this matches well with a coarse edge.

I can tell you from experience that S30V with a polished edge performs about as well as AUS8.
 
From the StraightRazorPlace.
http://straightrazorplace.com/srpwiki/index.php/Hanging_Hair_Test,_from_trick_to_probing_method

"Serrated versus smooth edges
Edges that carry a microscopic sawtooth pattern have a performance advantage for severing hairs. Unfortunately such edges also have an advantage for blemishing skin, while used for the purpose of shaving. Per consequence, we aim for smooth, toothless edges while honing a razor. However, during the early stages of razor sharpening, sawtooth patterns are present at the edge, and this has a big influence on the performance of the HHT. On a sawtooth edge, only a limited number of minuscule spear-like points try to penetrate the hair. Those points, when freshly cut on a relatively coarse hone, have a high chance of being quite acute. More acute than the overall keenness of the entire edge. In addition to that, the entire weight of the hair is pushing down on only a few teeth, instead of being distributed evenly. Both principles make the serrated edge a very effective one. Even an edge coming off a DMT 325 can pop hairs surprisingly well. Serrated edges do not show all the fine nuances from the aforementioned scale. The hair tends to pop or not."


Miso
 
Miso2, thank you! I will read your reply over again more carefully.

Jason B, In the meantime just wanted to mention that if S30v isn't a good candidate, I have 154cm, D2, s110v, and a ZDP (actually Cowry X) full flat grind as alternate candidates.
 
Hi,
After doing it accidentally on purpose randomly in 2016
I've finally done it intentionally on purpose in 2017
using harbor freight diamond 600 grit (? around 25-30 micron)
and even harbor freight diamond 200 grit side (? around 65-75 micron)
and even the dollar tree tool bench double sided sharpening stone
which is similarly coarse (?might be around P240 on fine side (around 60 micron)

Its funny but I didn't really put it all together
until I bought buffing compound and tried stropping and failed
and was disappointed that it wasn't like magic and I could just wing it and whittle :)

things that help, keys to success
  • - low angles, like under 10 degrees per side (20 degrees inclusive) or 7dps (14 degrees)
  • - using light force in shaping / raising a burr ( under 1lb, under 1/2 lb )
  • - not raising a giant bur, esp using the coarsest grits
  • - not raising a tiny burr, not even using the finer grit
  • - not raising a tiny tiny burr but only raising a barely teeny teeny tiny tiny tiny burr on the finishing
  • - flat stones
  • - clean stones , no slurry on stones when finishing ( deburr/microbevel )
  • - edge leading for final strokes
  • - short strokes for final strokes, like 1inch of travel on the stone
  • - cross the scratch pattern, cross hatch the grits
  • - using lighter than light force on finishing strokes and deburring (under ~4oz or ~100 grams , as close to 10-20 grams as possible), this is harder to do with worn abrasive (200 diamond)
  • - guided freehand, put a wedge/triangle on stone for angle reference/control, or put the stone at an angle (like sharpmaker)
 
ALittleHigher said:
Miso2, thank you! I will read your reply over again more carefully.

Jason B, In the meantime just wanted to mention that if S30v isn't a good candidate, I have 154cm, D2, s110v, and a ZDP (actually Cowry X) full flat grind as alternate candidates.
Click to expand...

D2 and ZDP work pretty well with a polished edge, the others I wouldn't take past a Fine DMT.
 
Whittling hairs and other extreme polish tests are kinda worthless. Perhaps fun to get to, but it's really sharpening masturbation. It doesn't get any real work done.

It's very humbling to realize that the major knife manufacturers' sharpening process really does produce a very good working edge when done right: Somewhere between 180 and 360 grit for sharpening and deburring on a high speed buffing wheel. Nice and toothy. Can be scary sharp if done with the right touch.

You don't need extreme polish for actual cutting. Just a clean edge bevel.

Brian.
 
Very obviously you have gotten all the great advice you need to have success with getting a hair splitting edge off coarser stones. Heck, perhaps I too, in time could even achieve it.

Though I simply love and use all the time edges that are very shallow angle, ten degrees per side (20 inclusive) or there a bouts . . . and since every one knows I enjoy getting a little "obtuse" about all this sharpening theory / facts / theory / facts / theo . . . .
I just want to add for perspective here :
The blades bellow are single bevel edges all in A2. The edge angle for each is written in marker so I know where to set the jig as well as how the edge will react with problem wood grain.

Note the blade marked 54°. That would be the equivalent of 27° per side on a knife.
and yet
the edge ALWAYS comes off the sharpener very easily hair whittling sharp let alone hair splitting.

My point ? As long as control of the blade and the sharpening media are maintained I'm thinking hair splitting edges should be possible with fine, as apposed to super fine, stones at wider angles.

Finally, being a person that just detests edge leading strokes, at least for the finer stones, ALL of the strokes were edge trailing on these plane blades. Perhaps a time waster and counter productive. Chalk it up to obsessive compulsive character deficit disorder.

I tend to sharpen my pocket knives the same way . . . again probably not the fastest or best way. You will be proud of me though . . . today I finished my UK PK with S110V going edge leading. That was on my 8000 diamond plate though so I'm still a chicken at this juncture.
:)

 
I use cheap smith's ceramic stones, rated at 1000 grit (US rating). I have a feeling they wear in with use though and get smoother. Hair splitting is possible, but improves alot with just a couple of passes on a chromium oxide coated leather strop.
 
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I just wanted to say thanks to you all for your input. You've given me a lot to work on and your responses are much appreciated.

I can say that I currently have NOT been paying attention to a few things while sharpening like: clean stones, light pressure, only raising a tiny burr. I am very encouraged that hair whittling sharpness is possible with rather ordinary abrasives. At the same time it's a tiny bit daunting too. But it's good to know there's more for me to improve on. I have a little green chromium oxide compound on the way but now I'll be sure not to use it as a substitute for actually making a clean apex.

I'm a crossover hobbyist from the pistol world. I gather that in part, this is like when folks will regularly stop by the forums and say "what's wrong with my sights / trigger/ pistol, it always shoots low and to the left". So thank you for your tactfulness and willingness to share.
 
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