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Thread: When you wanna go low grit... How low should you go?

  1. #1

    When you wanna go low grit... How low should you go?


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    Everyone always talks about polishing and honing on super fine abrasives... I want to get a really gnarly, toothy edge, the kind that makes slicing through meat or fibrous materials seem like child's play.

    I know a few members here have played around with sharpening on lower grits so I don't think this topic should be too esoteric...

    The lowest grit I have personally is a 220 JIS waterstone. I've played around with edges fresh off this before... It can be difficult to remove a burr and get it really refined, but I've gotten edges sharp enough to shave my arm hair--if my skin can bare it. So for that reason I've still wound up finishing on a relatively higher grit. Usually 1000 JIS waterstone or 25 micron DMT, and I find myself liking the edges I get from the coarser DMT a little more but that's just for everyday carry kind of stuff.

    I think that if I were going to be cutting something with a lot of abrasive qualities

  2. #2
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    I frequently carry a knife with a 120 grit DMT finish. I absolutely love it, and it shaves hair off my arm without bothering my skin at all. I always finish with edge leading strokes, that helps minimize burr formation. I also finish doing one stroke per side maybe 10-15 times each to make sure it's even. I think the 120 grit scratch pattern is really attractive


  3. #3
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    there is no need to go above 400 grit on any edge. you can strop with a medium grit white compound but its a waste of time to go any finer. a lot of members have tested this out and found it to work just fine. i sharpened a spyderco with h1 steel on 80 grit and buffed it on the slotted paper wheel and had the owner call and tell me that he was treetopping hairs on his arm with it.
    I offer professional knife sharpening 40 years of experience, 22 with the paper wheels. $1. per inch for a v edge, $2 for a convex. I sharpen all edges & "Ti" knives, serrations. plus i do regrinds. Check out my website.http://sites.google.com/site/richardjsknives/Home

  4. #4
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    bpeezer, i see that you are in ohio. send me an email if you would. i'm just west of columbus.
    I offer professional knife sharpening 40 years of experience, 22 with the paper wheels. $1. per inch for a v edge, $2 for a convex. I sharpen all edges & "Ti" knives, serrations. plus i do regrinds. Check out my website.http://sites.google.com/site/richardjsknives/Home

  5. #5
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    That treetopping buffed 80 grit edge is something I managed to do once by accident. I really wish I could do it on a consistent basis as it's one of the best performing edges I've ever used.

  6. #6
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    yoda4561. i'm going to make a test blade and see how a 24 grit edge will do. i can do it consistently with the wheels i use. i did use a belt sander to work up the burr but i finished the edge on the slotted paper wheel. have you checked out my sticky on the wheels?
    I offer professional knife sharpening 40 years of experience, 22 with the paper wheels. $1. per inch for a v edge, $2 for a convex. I sharpen all edges & "Ti" knives, serrations. plus i do regrinds. Check out my website.http://sites.google.com/site/richardjsknives/Home

  7. #7
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    I have, paper wheels are something I've been wanting to try out ever since I saw them at a gunshow years ago. They just seem like a really good idea where powered sharpening is concerned.

  8. #8
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    i had a member come down and he brought his wicked edge. he was sold on the wheels once he seen what they could do. he came down and brought a knife he had trouble sharpening with the wicked edge and i let him use my wheels and he was amazed. you cant beat them, not even by hand sharpening.
    I offer professional knife sharpening 40 years of experience, 22 with the paper wheels. $1. per inch for a v edge, $2 for a convex. I sharpen all edges & "Ti" knives, serrations. plus i do regrinds. Check out my website.http://sites.google.com/site/richardjsknives/Home

  9. #9
    Richard, why did this thread have to be turned into an advertisement for your products and services? The OP asked about low grit stones and toothy edges. What does that have to do with paper wheels? There are plenty of sharpeners here who sell their services (I am not one of them), but they don't feel the need to hijack threads.


    OP, the low grit question is a good one and has been discussed in several recent threads and videos. Crimson Tide Shooter (JDavis882 on YouTube) made a vid fairly recently where he finishes with a DMT Coarse stone and diamond spray on leather and praised this combo as a great general-use edge. awestib talked about it recently, too, and made a video. knifenut (MrEdgy81) made a video about doing all stone work with a Norton India stone and finishing with light stropping (also diamond spray on leather). I recently also discovered the value of stopping at DMT Coarse and stropping to finish (I used green compound on leather). I think that's as low as I'd want to stop for a general purpose edge. There is value in refinement, depending on what you want to do, though. A 6k or 8k finish can be desirable, depending on the steel and the use, and I finish high end kitchen knives at 6k. That's not too refined to remove all bite. But yes, a relatively low grit finish can make a great utility edge.
    Last edited by Magnaminous_G; 06-18-2013 at 10:51 AM.

  10. #10
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    I'm well aware of the dangers of overheating an edge on power equipment, but thousands of knifemakers (including high end factory production) do it on a daily basis with no harm, it's just a matter of keeping the edge moving and using fresh abrasive. That buffed 80 grit edge I managed by accident was on a cold steel Twistmaster Carbon V, and it held that edge at least as long as any hand sharpened edge I've put on a knife, I'm attributing most of that to the level of cutting agression it had, it took a long time to dull because it cut through things so fast. I also happen to believe that the temper at the very apex of the edge is inevitably damaged by power sharpening, the question is, how much does this actually impact edge holding? I haven't seen any hard data on it, and my personal experience implies that when done properly a power sharpened edge can match or exceed what you can do with hand sharpening in a few cases, like the very coarse grits.

  11. #11
    I'm not here to further hijack the OP's thread, so I'm not going to get into a debate about the merits of paper wheels here. That's a topic for another day (and another thread!), so I removed the reference. The main point I want to make is about thread hijacking, and that should really stop.

  12. #12
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    Quote Originally Posted by Magnaminous_G View Post
    Richard, why did this thread have to be turned into an advertisement for your products and services? The OP asked about low grit stones and toothy edges. What does that have to do with paper wheels? There are plenty of sharpeners here who sell their services (I am not one of them), but they don't feel the need to hijack threads.


    OP, the low grit question is a good one and has been discussed in several recent threads and videos. Crimson Tide Shooter (JDavis882 on YouTube) made a vid fairly recently where he finishes with a DMT Coarse stone and diamond spray on leather and praised this combo as a great general-use edge. awestib talked about it recently, too, and made a video. knifenut (MrEdgy81) made a video about doing all stone work with a Norton India stone and finishing with light stropping (also diamond spray on leather). I recently also discovered the value of stopping at DMT Coarse and stropping to finish (I used green compound on leather). I think that's as low as I'd want to stop for a general purpose edge. There is value in refinement, depending on what you want to do, though. A 6k or 8k finish can be desirable, depending on the steel and the use, and I finish high end kitchen knives at 6k. That's not too refined to remove all bite. But yes, a relatively low grit finish can make a great utility edge.
    Richardj's mentioning of the paper wheels is no different than you mentioning DMT stones or the like.
    Stop your trolling.
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  13. #13
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    I have been using DMT's 600grit stone but I'm going to be trying a DMT 325grit edge.
    I have some concerns of the little serrations being weak and causing premature dulling. Anybody know anything about potential problems with going too low?
    If I were to guess, different steels will work better with ultra coarse edges than others. I hear D2 takes a great coarse edge. I am working with CPM154 currently.

    Any thoughts?

  14. #14
    I've brought this up with another mod and think a conversation needs to happen at the administrative level. Respectfully, I was not trolling, neither intentionally nor unintentionally.

  15. #15
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    Quote Originally Posted by Nullity View Post
    I have been using DMT's 600grit stone but I'm going to be trying a DMT 325grit edge.
    I have some concerns of the little serrations being weak and causing premature dulling. Anybody know anything about potential problems with going too low?
    If I were to guess, different steels will work better with ultra coarse edges than others. I hear D2 takes a great coarse edge. I am working with CPM154 currently.

    Any thoughts?
    Absolutely different steels take better to different edges. Generally speaking the harder and less tough the steel, the finer you want the edge to be. On the other end of the spectrum (of quality steel) you get the really tough materials that seem to do better the coarser you go to a point. Too soft and the teeth will flop over and round, too hard and they'll break off quickly and dull. I know that Carbon V will take a very coarse edge nicely, and Spyderco H-1 for example is known to be phenomenal with a fully serrated edge, and I suspect this may carry over to very coarse but refined plain edges.

  16. #16
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    I've been thinking that stropping is even more important when using coarse edges. With a coarse edge you are going to have more weak material at the edge and stropping (with an abrasive) will help remove the weakest parts of the tiny micro-serrations.

    I'm only guessing though.

  17. #17
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    Quote Originally Posted by Nullity View Post
    I've been thinking that stropping is even more important when using coarse edges. With a coarse edge you are going to have more weak material at the edge and stropping (with an abrasive) will help remove the weakest parts of the tiny micro-serrations.

    I'm only guessing though.
    The timing of your comment here has me smiling. I was sitting here reading this thread and thinking the same thing.

    I've settled into simpler steels like 1095, 420HC, etc., and was thinking about how I prefer to sharpen them. I have often started out using something like 320/400 grit to establish new edges, which have some delicious 'bite' in them with these steels, and from then on, I maintain them by stropping on SiC or green compound (mostly green & bare leather for daily touch-ups). Over a little time, with repeated stropping using the compound, the toothy nature of the edge will become somewhat less-so. But at the same time, as the edge becomes somewhat more refined, the slicing also becomes smoother and smoother (and smoother). The 'teeth' eventually go away, but the additional refinement of the apex sort of picks up where the toothy cutting left off. I think this is a big part of why I like these particular steels as much as I do, because they perform very well in that wide middle ground from 320 - 2000 grit, between ultra-coarse and super-refined. Very easy to get along with, in that range.

    I do agree that, in very general terms, softer and 'lower quality' steels seem to respond better to a coarse edge. I have an old, cheap Japanese-made paring knife in 'mystery stainless' that cuts beautifully with a newly-applied and probably sub-320-grit edge. I actually used a coarse black emery board (for filing fingernails) to apply that edge (thin convex), and it's the best-cutting edge I've put on that knife so far. BUT, because it's a relatively coarse-grained and soft steel, the teeth seem to go away pretty fast, especially when stropped as described above. Needs frequent touching up on the emery board to keep that bite, but the performance at that grit is enough justification for doing so.

    And the thought of putting a very coarse edge on uber-hard steels (high RC, like ZDP-189) makes me cringe. I recently managed to break the very-pointy tip off of a Kershaw Leek, in ZDP-189, while STROPPING it on thin cardboard over glass. I had just finished making the edge on that knife very thin (on DMT Coarse/Fine Duo-Sharp bench hone). When the steel is that hard and thin (and therefore very brittle), I shudder to think how fast some coarse micro-teeth might chip away from the edge under normal use. So a more refined edge seems very sensible, in that case.


    David
    Last edited by Obsessed with Edges; 06-19-2013 at 03:13 PM.

  18. #18
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    Quote Originally Posted by Nullity View Post
    I hear D2 takes a great coarse edge. I am working with CPM154 currently.
    Your comparison is a little bit backwards; it's not that some steels "work better with coarser edges", it's just that some steels are coarser in structure to begin with.

    D2 will tend to have a grittier edge than CPM-154 even when you sharpen them with the same gear, because it has big chunks of carbides, whereas CPM-154 has small evenly-spaced carbides. (picture concrete made with lots of 1/2" rocks, compared to concrete made with lots of tiny pebbles and sand) Fine-grained low-alloy steels like 52100 and AEB-L have very few carbides at all, and as such are among the easiest to get really fine edges on. (that's precisely what AEB-L was designed for in the first place, in fact)

    Quote Originally Posted by yoda4561 View Post
    Generally speaking the harder and less tough the steel, the finer you want the edge to be.
    I see what you're getting at, but that's fairly misleading. Hardness has nothing to do with how sharp a blade can get. Dead soft steel will take any sort of edge you want it to - it just won't stay that way very long.

    It is true that if you're using a really hard but fairly fragile steel, you may as well go ahead and polish a real thin edge on it, and use it specifically for delicate cutting and slicing; but very hard steel won't "act" that much noticeably weaker in use because it has a coarse edge on it, unless it's really coarse and completely unrefined.

    High toughness definitely does not work against/preclude using fine edges, or require using only coarse ones as your statement would seem to imply. O1, 1095 and CPM-3V all exhibit very good to excellent toughness, at moderate to quite high hardnesses, and can all take very nice crisp edges - or toothy coarse ones.

    Quote Originally Posted by yoda4561 View Post
    I know that Carbon V will take a very coarse edge nicely, and Spyderco H-1 for example is known to be phenomenal with a fully serrated edge, and I suspect this may carry over to very coarse but refined plain edges.
    Not as much as you might think, in terms of comparing two vastly-different alloys. You're comparing measurements in microns to serrations of fairly large fractions of an inch, and that vast difference brings a whole other set of factors into play, even if you were comparing the same steel.

    Quote Originally Posted by Nullity View Post
    I've been thinking that stropping is even more important when using coarse edges. With a coarse edge you are going to have more weak material at the edge and stropping (with an abrasive) will help remove and/or align the weakest parts of the tiny micro-serrations.
    (bold added by me) That's pretty accurate, which is why a fairly coarse edge that's properly stropped or steeled will still cut pretty dang well.

    I'm over-simplifying all this quite a bit, but you get the idea.
    Last edited by james terrio; 06-18-2013 at 11:43 PM.
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    Quote Originally Posted by Obsessed with Edges View Post
    I've settled into simpler steels like 1095, 420HC, etc., and was thinking about how I like to sharpen them. I have often started out using something like 320/400 grit to establish new edges, which have some delicious 'bite' in them with these steels, and from then on, I maintain them by stropping on SiC or green compound (mostly green & bare leather for daily touch-ups). Over a little time, with repeated stropping using the compound, the toothy nature of the edge will become somewhat less-so. But at the same time, as the edge becomes somewhat more refined, the slicing also becomes smoother and smoother (and smoother). The 'teeth' eventually go away, but the additional refinement of the apex sort of picks up where the toothy cutting left off.
    You could achieve the same result by adding a finer stone (maybe 600) to the regimen, strop less often and skip the break-in period. All you're doing is using the compound to grind the edge - slowly. Nothing wrong with that, it just takes longer.
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    Quote Originally Posted by james terrio View Post
    You could achieve the same result by adding a finer stone (maybe 600) to the regimen, strop less often and skip the break-in period. All you're doing is using the compound to grind the edge - slowly. Nothing wrong with that, it just takes longer.
    That's actually the path I was on, prior to settling into the slightly coarser grit as the jumping-off point for a 'new' edge (not with stones, but wet/dry sandpaper at ~320 grit, give or take). I used to be somewhat fixated (obsessed? ) with a more highly-polished edge finish, but gradually started finishing my working edges lower in the grit range, from 2000 down to 800, then 600, then 400 and down. Then using only stropping to maintain them. A lot of that was just figuring out what methods/abrasives/tools I liked best for the task, and then refining my ability to properly clean up the coarser edges, so they'd perform better for me. So, I don't necessarily want to shy away from the lower grit, because I like how my blades perform through the full range, between 320 and near-mirror (probably similar to 1000-2000 grit).


    David
    Last edited by Obsessed with Edges; 06-19-2013 at 03:06 PM.

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