Page 1 of 7 12345 ... LastLast
Results 1 to 15 of 104

Thread: Ruler trick example

  1. #1
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119

    Ruler trick example

    This is a tangent from Stewie's "stone flattening" thread, particularly the assertion that ruler-tricking is used as a substitute for flattening the back of an iron. Here's an example of ruler-tricking done as Charlesworth recommends (a quickie snap of the iron from my L-N 8). Note the mirror-finished strip immediately behind the edge:



    The back of the iron is dead flat, though not mirror-polished. I worked it to 3 um, or about #4000. The edge was then "ruler-tricked" on 0.5 um diamond paste (#20000-30000) using a 1/4 mm strip of shim stock set about 60 mm back from the edge. The result is a 1/4-deg back bevel, extending a few tenths of an mm back from the edge.

    It's probably worth noting that the edge is only recessed from the back by a couple microns at most (~0.5*sin(1/4) millimeters), so the back has to be very flat for this variation of the ruler trick to work. Higher back-bevel angles (from thicker shims or shims positioned closer to the edge) and/or bevels extending further back from the edge will be more tolerant of imprecise flattening.
    Last edited by Patrick Chase; 11-20-2016 at 4:29 PM.

  2. #2
    Join Date
    Aug 2010
    Location
    USA
    Posts
    5,582
    Nice job! Thanks for the snapshot

  3. #3
    Now I understand what this trick thing is.

    My only question is, why?

  4. #4
    Join Date
    Sep 2007
    Location
    Longview WA
    Posts
    27,312
    Blog Entries
    1
    The back of the iron is dead flat
    To my thinking there is not a good reason to bother with 'ruler tricking' if the back is dead flat.

    My blades are usually taken to the stones before enough of a wear bevel builds up to not be removed by honing the bevel.

    Of course my methods are clearly different, as are those of others. Like so many my efforts are used on ways found to work for me in my environment.

    Little time is spent flattening stones, making secondary bevels, ruler tricks or even hollow grinding. Hollow grinding works for me, but I do not have an electric grinder. A flat bevel is no big deal to sharpen.

    Out of a desire to get into the shop before my doctors have cleared me for woodworking some time today was spent working on a pair of type 6 #4s. I am swapping some parts around that got switched between the two. (One has a new paint job the other doesn't. The frogs got mixed when they were reassembled.)

    The first one was put back together with as many of the original type 6 parts that I have. The blade was inspected and though it was fairly sharp it wasn't as sharp as can be. A few strokes on a 4000 stone and the back was cleaned up of any residue. The bevel was also touched up on the 4000 stone. Then a bit more time was spent on an 8000 stone to get as close to a mirror on the back as could be obtained and the bevel was worked until it could shave hair. Then some swiping on the strop.

    After all of this the plane was reassembled and the blade was adjusted to take as fine a shaving as it could without the wood turning to dust. With a little bit of careful adjustment my best shaving was 0.0005".

    Now that isn't something that is going to do much good in most situations, but is there really any reason to change my approach?

    Maybe a better, more to the point question would be; what advantage would be gained by using the ruler trick?

    I came in for a spot of lunch. One more plane to put back together and get working. I'll try to remember to bring the camera out to the shop.

    jtk
    Last edited by Jim Koepke; 11-20-2016 at 4:50 PM. Reason: wording
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  5. #5
    Join Date
    Aug 2010
    Location
    USA
    Posts
    5,582
    Quote Originally Posted by Jim Koepke View Post
    To my thinking there is not a good reason to bother with 'ruler tricking' if the back is dead flat..

    A few strokes on a 4000 stone and the back was cleaned up of any residue. The bevel was also touched up on the 4000 stone. Then a bit more time was spent on an 8000 stone to get as close to a mirror on the back as could be obtained and the bevel was worked until it could shave hair.
    The entire reason for the ruler trick, er shim stock trick, is to save you from all the work needed to get a mirror / dead flat back. Sometimes its worth it to try a different approach.

  6. #6
    Join Date
    Sep 2007
    Location
    Longview WA
    Posts
    27,312
    Blog Entries
    1
    Quote Originally Posted by Pat Barry View Post
    The entire reason for the ruler trick, er shim stock trick, is to save you from all the work needed to get a mirror / dead flat back. Sometimes its worth it to try a different approach.
    I have tried the ruler trick.

    Once a back is flat, unless one wears it to the point of not being able to cut, it shouldn't need flattening again.

    Now days, once a blade's back is flat, the most their backs get to the stones is to remove any pitch that builds up where the chip breaker meets the blade or to remove a burr.

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

  7. #7
    Join Date
    Aug 2003
    Location
    Seattle, WA
    Posts
    21
    Patrick's method is similar to mine for bench plane blades. The advantage of flattening the back is that it allows the microbevel to remain very narrow. This means only a tiny amount of steel needs to be removed each time the blade is honed.

    Jim's method of using a strop for final honing has an effect similar to a narrow, very shallow microbevel. Because the strop is somewhat resilient it takes a little more off the edges.

    In my experience it is much more difficult to get a large surface like the back of a blade to a highly polished state. Using either a microbevel or a strop puts the sharpness right where it is needed--at the cutting edge.

  8. #8
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119
    Quote Originally Posted by Pat Barry View Post
    The entire reason for the ruler trick, er shim stock trick, is to save you from all the work needed to get a mirror / dead flat back. Sometimes its worth it to try a different approach.
    That's right - In the blade in the photo the back-bevelled part is fully polished (i.e. all striations from preceding, more coarse grits removed) to the equivalent of #20000-30000. Doing that without the help of the shim is a pain in the a**, because you end up spending tons of effort polishing metal that will never see wood. I've done it, and it's a massive waste of time.

  9. #9
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119
    Quote Originally Posted by Jim Koepke View Post
    I have tried the ruler trick.

    Once a back is flat, unless one wears it to the point of not being able to cut, it shouldn't need flattening again.
    No, the back has to be flat AND POLISHED. Getting it flat is the easy part. Getting it polished to the point of removing *all* scratches/striations is much more time-consuming unless you use a very slight back-bevel to "focus" your polishing efforts on the portion of the back adjacent to the edge. As several people including David Charlesworth himself have said several times, the ruler trick is a polishing aid, not an alternative to or replacement for flattening.

    Also, if you plane abrasive wood then it can screw up your polish immediately behind the edge long before it degrades to the point of "not being able to cut". This is particularly true of BU planes in my experience.
    Last edited by Patrick Chase; 11-20-2016 at 5:42 PM.

  10. #10
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119
    Quote Originally Posted by Steve Elliott View Post
    Patrick's method is similar to mine for bench plane blades.
    Indeed. I'd previously used one of your pictures to illustrate this. For that matter I also use diamond paste on cast iron (or mild steel), though I haven't taken my "honing guidance" to quite your level of refinement :-).

    You bring up a good implied point: This is only valid for tools that cut with a fair amount of clearance. It doesn't make sense for chisels (zero clearance when paring) or for low-angle spokeshaves (very low clearance) for example.
    Last edited by Patrick Chase; 11-20-2016 at 5:34 PM.

  11. #11
    Join Date
    Aug 2007
    Location
    Dickinson, Texas
    Posts
    7,655
    Blog Entries
    1
    Quote Originally Posted by Glen Canaday View Post
    Now I understand what this trick thing is.

    My only question is, why?
    Because you can hone an edge on the bevel and the ruler trick puts a micro-bevel on the back. It is down, dirty and very fast.
    I find it to be effective, so I use it. I do hone the back of my irons on the first sharpening, but not subsequent sharpening's.
    I use it. I would rather spend my time working the wood.
    Last edited by lowell holmes; 11-20-2016 at 6:13 PM.

  12. #12
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119
    I should have remembered to say...

    Quote Originally Posted by Jim Koepke View Post
    Out of a desire to get into the shop before my doctors have cleared me for woodworking some time today was spent working on a pair of type 6 #4s. I am swapping some parts around that got switched between the two. (One has a new paint job the other doesn't. The frogs got mixed when they were reassembled.)

    The first one was put back together with as many of the original type 6 parts that I have. The blade was inspected and though it was fairly sharp it wasn't as sharp as can be. A few strokes on a 4000 stone and the back was cleaned up of any residue. The bevel was also touched up on the 4000 stone. Then a bit more time was spent on an 8000 stone to get as close to a mirror on the back as could be obtained and the bevel was worked until it could shave hair. Then some swiping on the strop.

    After all of this the plane was reassembled and the blade was adjusted to take as fine a shaving as it could without the wood turning to dust. With a little bit of careful adjustment my best shaving was 0.0005".
    Welcome back to the land of the (woodworking) living! Glad to hear you've been able to get some work in.

    Quote Originally Posted by Jim Koepke View Post
    Now that isn't something that is going to do much good in most situations, but is there really any reason to change my approach?
    Heavens no. I was trying to clear up some misconceptions (in other threads) about what the ruler trick is and why it's used, not arguing that everybody should do it.

    Quote Originally Posted by Jim Koepke View Post
    Maybe a better, more to the point question would be; what advantage would be gained by using the ruler trick?
    Faster polishing, particularly if you're going to very fine grits and trying to remove all striations.

  13. #13
    Join Date
    Oct 2010
    Location
    Australia
    Posts
    2,534
    To my thinking there is not a good reason to bother with 'ruler tricking' if the back is dead flat.
    Thanks Jim; that's a very pertinent question.


    Patrick; excellent to see your using a camera for a change.


    Stewie;

  14. #14
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    4,119
    Quote Originally Posted by Stewie Simpson View Post
    Thanks Jim; that's a very pertinent question.
    No, it's completely irrelevant and grounded in confusion about what the bevel trick is trying to accomplish (as was your similar comment in the other thread).

    The bevel trick is about polishing, not flatness.

    Quote Originally Posted by Stewie Simpson View Post
    Patrick; excellent to see your using a camera for a change.
    Yeah, as with the needle file thing your nonsense finally motivated me to break it out.

  15. #15
    Join Date
    Oct 2010
    Location
    Australia
    Posts
    2,534
    My personal take on micro back bevels; is that it reinforces laze of technique in preparing the back of your plane iron. Its not as though we are discussing the full back of the iron. An area within a range of 1/2 to 1 inch is ideal target to aim for. I made mention of the fact that it encourages laze of technique for good reason, as what generally occurs is that practice soon migrates to being used on the backs of chisels, and that is a well entrenched no no.

    Stewie;
    Last edited by Stewie Simpson; 11-20-2016 at 7:40 PM.

Posting Permissions

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