Page 3 of 4 FirstFirst 1234 LastLast
Results 31 to 45 of 50

Thread: Flattening chisel backs with waterstones

  1. #31
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119
    Quote Originally Posted by Robert Hazelwood View Post
    Partly. On the JIS scale that waterstones use, 1000 grit is indeed coarser than 1000 grit on the P scale.
    This is completely backwards. 1000 on FEPA P-scale is 18 micron average particle size. Current "1000#" waterstones are between 10 and 15 um. IIRC the King is on the high side of that range.

    EDIT: The King 1000# stone is 16 microns, so just a hair finer than FEPA P1000.

    The current JIS-1998 spec calls out 11.5 um for a 1000# waterstone, so considerably finer than P1000. Similarly, the old JIS-1973 spec called out 15.5 um for 1000#, which is *still* finer than P1000.

    Perhaps you've confused CAMI (which *is* finer than JIS at high grit #s) and FEPA P-scale here?

    Quote Originally Posted by Robert Hazelwood View Post
    But I think the haziness from the King is due to the scratch direction being more randomized than you get with sandpaper- this is due to the mud coming off the stone and creating loose abrasive slurry. On sandpaper the scratches are aligned, which seems to gives a more reflective surface for a given grit- even fairly coarse grits can give a reflection amidst the scratches.
    This part is right. The dull finish is caused by the presence of the loose grit (in slurry) on the surface of the waterstone. To achieve a mirror finish at such a low grit the scratches need to all be oriented the same way. That's true for sandpaper (assuming you lap in one direction), but the loose abrasive in a waterstone's slurry moves around fairly randomly, leading to a dull surface finish . This is also why Veritas tools come with very smooth but also very dull finishes - the lapping machine that they use moves the tool randomly over the abrasive.

    As many people have said many time, a mirror finish tells you absolutely nothing whatsoever about surface smoothness or the quality of adjacent edges. The only thing you can infer from it is how the tool was sharpened. It's possible to get mirror finishes with unacceptably rough surfaces, and it's possible to get matte finishes with pristine ones (as with Veritas' fancy lapping machines).

    IMO the "mirror finish myth" is one of the more harmful bits of disinformation that circulates amongst woodworkers.

    Quote Originally Posted by Robert Hazelwood View Post
    Also, sandpaper particles, especially if Silicon Carbide, break down in use and become smaller and/or duller, which makes the paper effectively finer. Waterstones constantly release new grit so they cut at a more consistent rate.

    There are two obvious problems with this argument. First, it depends on the hardness of the stone's binder. The King that the OP used is fairly hard, and tends to retain abrasive after it has started to break down and glaze. Second, the released abrasive sticks around in the form of a slurry (unless the user flushes it) and refines the cutting action a bit. There are some advanced waterstone techniques that exploit this to get the finest possible surface from polishing stones.
    Last edited by Patrick Chase; 09-07-2017 at 6:04 PM.

  2. #32
    Join Date
    Apr 2013
    Location
    Stone Mountain, GA
    Posts
    751
    Well I stand corrected on the grit ratings. It could be that I have confused the scales...I was thinking of the typical black wet dry sandpaper which I don't believe is actually P scale? Not sure, really, and as you pointed out the loose abrasive is the dominant aspect here.

    The 1000 King stone I had was super soft, and consistently created a heavy slurry without particular effort, resulting in a "bead blasted" finish. My impression is that this is pretty typical of Kings. In contrast my Shapton 1000 doesn't slurry much at all and leaves an aligned scratch pattern similar to sandpaper. I was assuming a soft binder in my comment.
    Last edited by Robert Hazelwood; 09-07-2017 at 10:09 PM.

  3. #33
    Join Date
    Apr 2013
    Location
    Stone Mountain, GA
    Posts
    751
    Quote Originally Posted by David Ragan View Post
    Hi Brian,

    I understand what you are saying-sort of.

    Am familiar w wear bevel. It does seem like a lot of work to have to re-flatten the back of a chisel periodically. This is where the David Charlesworth ruler trick comes in?

    Then, you say to strop the back w clean material (cloth/leather/wood,etc) only. I'm not getting the connection of why stropping w compound would make for more trouble.

    Thanks, David
    You wouldn't normally remove the wear bevel by re-flattening the back. The wear bevel is just a very shallow worn, rounded area at the tip on the back side. It will show up as a shiny line near the tip, and is usually more pronounced on plane irons than on chisels. You can remove it by working the bevel side sufficiently to move the edge back past the wear bevel. Often, this means you have to sharpen a bit past the point where you begin to feel a burr, which is where the standard sharpening advice tells you to stop. If you stop before completely removing the wear bevel, you can still get a fairly sharp edge, but it won't be the best edge and won't last as long. This is because there is still a tiny radius on the back at the edge, and so you can't actually get to the very edge when you are honing the back. So the burr cannot be totally removed even if it is too small to feel.

    This is a tip I've picked up from reading Brian's posts and it has been extremely helpful.

    I don't use it, but the ruler trick makes a lot of sense for dealing with the wear bevel on plane irons. It wouldn't be a good idea on most chisels though, since the flat back is so often used as a reference.

    As for stropping, with a soft stop loaded with compound, even if you place the back flat on the strop the material will compress to some extent and kind of curl around the edge, putting a slight radius at the tip. Basically you would be stropping a wear bevel onto the back. You'd get a sharp edge, but the next sharpening will be more difficult because there will be an even larger wear bevel to remove. A bare leather strop removes the burr remnants without being abrasive enough to create any wear.

    With a hardwood or mdf strop you can probably get away with using compound if you are careful.

  4. #34
    Join Date
    Aug 2013
    Location
    Princeton, NJ
    Posts
    7,254
    Blog Entries
    7
    Thanks Robert, glad to hear that you have found that useful!

    David,
    Exactly as Robert says, I don't rework the back and what I'm driving at is a goal of not reworking the back ever. The only thing that happens with the back is that I will take a few strokes on the final finish stone to remove any hint of burr. The burr being untouched during this process will actually wear to a very very small amount on a good finish stone.
    Using compound on a strop on the back of the blade makes this process more difficult, if not impossible, because it rounds the back ever so slightly. Doing so makes it so that the back won't contact the stone at the extreme edge.

    So long as the wear pattern remains consistent on the back of my irons and chisels it tells me two things; one that they're flat to the degree that my final stone is capable of, and that my final stone is very flat. If you get an inconsistent pattern on the backs of your irons/chisels it means that either the back isn't flat, the stone isn't flat or both.

    On western tools I use a plain strop to work the blade lightly before putting it back to work, on Japanese tools I won't do that.
    Bumbling forward into the unknown.

  5. #35
    Join Date
    Feb 2007
    Location
    Hiawatha KS
    Posts
    66
    Quote Originally Posted by Brian Holcombe View Post
    Thanks Robert, glad to hear that you have found that useful!



    On western tools I use a plain strop to work the blade lightly before putting it back to work, on Japanese tools I won't do that.
    Brian, what are your thoughts on why you do this?

  6. #36
    Join Date
    Aug 2013
    Location
    Princeton, NJ
    Posts
    7,254
    Blog Entries
    7
    Why I strop one and not the other? Western tools have a big surface of hard steel, the smallest rounding and they won't clean off the burr on the finish stone. Japanese tools have a hollow, they can contact right up to the extreme edge.
    Bumbling forward into the unknown.

  7. #37
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119
    Quote Originally Posted by Paul Bent View Post
    Brian, what are your thoughts on why you do this?
    The Japanese tools are harder and more brittle near the edge, and probably don't form wire edges to the same degree.

    Now let's see if I got it right :-).

  8. #38
    waterstones are just about useless for flattening. The coarser they are the quicker they cut AND go out of flat. This is where diamond plates rule.

  9. #39
    Leveling takes the high spots down to the level of the low spot - it should not result in further removal of abrasive.

  10. #40
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119
    Quote Originally Posted by Warren West View Post
    waterstones are just about useless for flattening. The coarser they are the quicker they cut AND go out of flat. This is where diamond plates rule.
    I would reword this to "waterstones require good technique to be useful for flattening". You need to distribute the flattening workload across the stone (including all 4 edges) so that it wears down uniformly instead of developing hollows. Charlesworth covered one such technique in the FWW article that I linked earlier in this thread, though there are others.

    You also need to know where waterstones do and don't make sense. I think that "one-shot" media (sandpaper, lapping film, compounds) are preferable below about 300#.

    Also if you have a diamond plate then waterstone flattening is a triviality. Swiping the plate over your stone every so often adds maybe 5% to the total effort to flatten the back of a tool, of maybe a bit more if you don't distribute the flattening work across the stone.

    I used diamond plates (DMT and Atoma) for flattening backs before I really figured out how to use waterstones, and while they are unquestionably more forgiving they have their own downsides. They tend to start out cutting very fast, but then they wear in and slow way down. If you replace them often enough to keep them cutting fast then the economics are absolutely awful, and if you don't then they lose all of their performance benefit.

    FWIW my favorite flattening medium these days is diamond compound on steel or iron laps. In terms of performance it's basically equivalent to starting with a brand new diamond plate every time, but for a small fraction of the cost. The plates do have to be maintained (particularly if you allow the abrasive to rub off and form "bare spots", where the tool rubs against the plate itself) but as with waterstones that's a small fraction of the total effort.

    If I were more cost-constrained then I'd go with waterstones.
    Last edited by Patrick Chase; 09-09-2017 at 11:08 PM. Reason: Toned down.

  11. #41
    Join Date
    Aug 2010
    Location
    USA
    Posts
    5,582
    Patrick, you obviously know the ins and outs of sharpening. It would be nice to validate your sharpening expertise for us by showing some of the awesome projects you make with your super sharp and polished edges. Also, please learn how to not offend everyone with your approach to conveying your superior knowledge.

  12. #42
    Join Date
    Aug 2013
    Location
    Princeton, NJ
    Posts
    7,254
    Blog Entries
    7
    Pat, with respect, I don't see anything offensive? Patrick's insights are quite helpful.
    Bumbling forward into the unknown.

  13. #43
    Join Date
    Sep 2010
    Location
    New England
    Posts
    2,474
    Agree. Been scratching my head over this.

  14. #44
    Join Date
    Aug 2010
    Location
    USA
    Posts
    5,582
    Quote Originally Posted by Brian Holcombe View Post
    Pat, with respect, I don't see anything offensive? Patrick's insights are quite helpful.
    I took issue with comment "mentally translate that to "the writer has no idea how to use waterstones"." I see no need to denigrate someone. Perhaps this statement wasn't necessary. I stand by my request for Patrick to show us some actual work as this would validate, to me at least, that he actually does know what he is talking about. Otherwise, I assume he is really just a google bot, regurgitating information that he has gleaned through research without actual practice.

  15. #45
    Join Date
    Sep 2007
    Location
    Longview WA
    Posts
    27,347
    Blog Entries
    1
    Quote Originally Posted by Pat Barry View Post
    I took issue with comment "mentally translate that to "the writer has no idea how to use waterstones"." I see no need to denigrate someone. Perhaps this statement wasn't necessary. I stand by my request for Patrick to show us some actual work as this would validate, to me at least, that he actually does know what he is talking about. Otherwise, I assume he is really just a google bot, regurgitating information that he has gleaned through research without actual practice.
    A Google Bot?

    Pat, are you suggesting Patrick actually may be a beta test of an AI program from a technology company?

    There once was a way such charges were handled:

    https://www.youtube.com/watch?v=zrzMhU_4m-g

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •