Objections to David Charlesworth’s ‘Ruler Trick’ - Popular Woodworking Magazine

Objections to David Charlesworth’s ‘Ruler Trick’

 In Chris Schwarz Blog, Woodworking Blogs

Place the steel ruler on one long edge of the stone – friction from the water will hold it in place. Place the blade on the stone with the cutting edge off the stone. With light pressure bring the blade about 5⁄8″ onto the stone. This short stroke removes the wire edge and polishes the back of the blade.

The first time I used David Charlesworth’s “ruler trick” on the backside of a plane iron it took an act of sheer will to do it. I had watched David’s groundbreaking 2004 video with Lie-Nielsen Toolworks “Hand Tool Techniques Part 1: Plane Sharpening” and had thought about the ruler trick for a few weeks before I could muster the courage to try it myself.

I couldn’t come up with any reasonable objection to using the ruler trick on a plane iron. So I sharpened my block plane iron. First the bevel. And then I put the thin ruler on my finishing stone and looked at it for a bit.

The only thought going through my mind was: I’ve spent hours and hours polishing the back of that iron. Why would I want to undo all of that work with a ruler?

And then I realized I had answered my own question. With the ruler trick, you don’t need to spend “hours and hours” dressing the backside of an iron. So I ruler tricked the snot out of that plane blade and have never looked back.

What About the Resistance?
When in mixed company, some people sneer at the ruler trick. When I ask their specific objections, they become vague.

“You don’t need it.”

“It’s bad for the plane iron.”

“It’s sloppy work.”

“It creates a back bevel, which is a problem.”

These are all false or silly reasons to avoid the ruler trick. And so I am asking – honestly and sincerely – for you to post your objections in the comments below. Not someone else’s objections – your objections.

Note: People get emotional about this topic. Don’t fall into that trap. One famous woodworker, who shall remain nameless, got so mad about the ruler trick that he exclaimed: “I would not sell that…. To a Monkey!!!!”

This is just a woodworking technique, not something important (like putting mayonnaise on French fries). Give me a sentence that explains why the ruler trick is not a good idea for you (not for others, for you).

Once I understand your objections, I think I’ll be able to sleep better at night. It has been bugging me.

— Christopher Schwarz

The Last Word on SharpeningThe Last Word on Sharpening
By Christopher Schwarz

Grind, Hone & Get Back to Work

– Learn how to grind straight & curved edges
– Hone perfect micro-bevels
– Pick the right stones for you
– Achieve polished edges like a professional the first time out
– Dispelling the Myths

Sharpening an edge has one purpose – allowing you to quickly get back to work. Christopher Schwarz has devised a system of sharpening that is simple and intuitive. By following his clear instructions, you will be able to sharpen your edges quickly and get back to your bench.

What is Sharp? Understanding the answer to this simple question will clarify a lot of the misinformation about sharpening. Chris walks you through the life cycle of an edge, and teaches you the techniques of sharpening so you achieve excellent and consistent results. You’ll learn the different types of systems for grinding, honing and polishing so you can choose the best system for your needs and budget. Plus, you’ll learn how to sharpen both curved and straight edges, and the best angles for grinding your edges for woodworking.

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Showing 65 comments
  • amoscalie

    About a week before I read this article, I spent about 3 hours one afternoon sharpening and flattening the backs of my irons and chisels. However, on this “sharpening day”, I used my Worksharp 3000 and spent only a matter of a minute or so flattening the back of each iron and chisel. The must difficult iron was that of a late 18th century coffin smoother with a rusted, but still relatively sharp iron. I probably spent at least 10 minutes, not hours, just flattening the back. I might have tried the ruler trick if I not already spent minutes flattening the backs. However since everything is now a near mirror finish on the bottom 1/2” to 3/4”, I may not get another opportunity to give it a try.

    • zirconia

      I guess my main objection is that I use laminated hollow-back Japanese blades that only have about a millimeter or two of flat at the edge to start with. Traditionally the back iron is set a “hair’s breadth” (for me in practice about 1/3) mm from the blade edge, so the ruler trick just might work—but since the entire back doesn’t need to be flattened it seems unnecessary.
      That said, I do sometimes use a similar but rather ancient traditional “trick” on both planes and chisels that doesn’t result in any perceptible back bevel. It is to lightly rub a block of tree/insect/Chinese wax (secreted by the insect Ericerus pela) on one edge of the stone, lay the blade as one would when doing the ruler trick, and apply light pressure only on the edge side. The wax stripe is narrow enough to not really affect the sharpening action should I need to work on other blades, and flattening the stones afterwards removes it.
      Perhaps I should call it the “Japanese Wax Trick”…
      The caveat is that the stones must be flat for this to work. Also, I have no Western planes or chisels so I don’t know whether it would work on those as well.

      • zirconia

        Or better yet, let’s make it “The Awld Japanese Wax Trick…”

  • Billy's Little Bench

    I don’t use the ruler trick because I just don’t need to.

    Out of all my tools that I need to sharpen the only few tools I can actually use this on are a few hand planes.
    Which like you observed, once the backs are flat, they are flat, polished and nothing ever needs to be done to them after that. I stroke the back on my polishing stone and strop them and that’s it, for the rest of the blades life.
    At this point the ruler trick would just be an unnecessary step.

    Hand planes make up a small part of my sharpening compared to chisel, carving tools, joinery planes, etc. . .

    With all that said I do understand the merits of it. Conceptually it is the same thing I do to my carving gouges. Almost all my gouges have an inside bevel on them of around 5-10 degrees, outside bevel at 20 degrees. Though the reasons for the inside bevel serve more of a functional purpose on my carving tools. Working an edge from two directions makes the process much faster, less metal is removed, and you can produce a more work hardy edge life with the very slight bevel angle increase.

  • Kris

    If you have already spent the time and energy in getting your plane blades flat and polished, you shouldn’t use the “ruler trick”. It is technique to avoid having to spend that time or do that work. If do this to a flat polished blade, you have been “ruler tricked”.

  • Zvuv

    Having spent far too much time flattening the backs of my irons, I am very tempted. Like Chris, I have hesitated. I have two concerns. First this changes the cutting/attack angle on bevel down planes. Second, this is hard to reverse.

  • MikeV

    The fact that this topic spurs so much passion and debate is further evidence that woodworkers need to get out of their shops and spend some quality naked time with the significant others in their lives….

  • sdergar

    Have you ever tried Newfie fries?

    Also I dont think it can be repeated with any consistency. Ruler trick sharpening I mean, not the fries.

  • pearlsb4swine

    54 “thoughts” in response to Mr. Schwartz’s invitation so far and no non-specious objections in sight so hopefully he can get some well deserved sleep. Now I’m losing sleep wondering if the “famous woodworker who shall remain nameless” has the initials M D.

  • Capntools

    The answer to your question is that there is no practical objection to the Ruler Trick.

    It’s correct name is The Ruler Trick because that’s what it’s inventor called it.

    It simply polishes the extreme edge of a previously flattened plane blade. Never a chisel blade. The flattening is a once only procedure, carried out on the 800 (or thereabouts) stone. Flattening is not polishing. It is unnecessary to polish the whole back of a plane blade. Only a fraction of a millimetre on both sides needs a polish.

    The time required to do it properly is 30 seconds.

    It works on all blade profiles.

    I learned all this on David’s course in Devon. I’ve watched all the other methods on YouTube and only freehand is simpler. But that needs a lot of practice and I could never get an edge as even as I could with a jig and a ruler.

    The most important thing here is not whether or not to do the ruler trick; it’s to avoid criticism of anyone’s method, in the interests of peace and harmony amongst people who love woodwork.

  • charlie

    I have considered using the ruler trick many times. So far I haven’t tried it because if I decided to stop using the approach I would have made myself some work to grind the edge back and return to my old ways. I realize that isn’t a monumental objection.

    It is more tempting for me to try the ruler trick on bevel up plane irons as I’ve read that the back of the bevel up blade accumulates a wear bevel and this approach would seem to address that particular issue well. However, on bevel down irons, it doesn’t seem like it has much to offer if the iron backs are already flat and polished. I would appreciate any thoughts related to that.

    I would very much like to hear a bit more from Christopher Schwartz regarding his experience. It seems that he has found this approach beneficial because he continues to use it. I presume that his block plane was well sharpened before he employed the ruler trick but it would be interesting to know if Chris got a sharper result or a comparable result with less time/effort. Also, some other posts suggest that once the back of the plane iron is flat and polished that the ruler trick is not a time saver. Once again I presume that the iron Chris was using in his block plane already had a flat and polished back, so it would be interesting to hear what benefit Chris observed by employing the ruler trick. Some of the posts also question the effectiveness of the ruler trick when using a cambered plane iron. Once again, I would like to know what Chris experienced because it seems very likely that many of his plane irons are cambered.

    Many thanks to Christopher Schwartz for starting this line of discussion.

  • jlaviolette

    Simplification. That’s why I don’t use it. I generally only use new tools from reputable makers. They come ground flat. Polishing the back is minimal effort.

    I have one unified repeatable process for all my edges. Bench planes, joinery planes, chisels, etc. Just hands and stones.

    If I had to go to extreme measures to flatten a vintage plane iron back, well, I’d rather just throw Ron Hock a few bucks and save some trouble (and waterstone slurry)

    • Zvuv

      I have no problem with LN’s prices in terms of value, but many of us can’t afford them.

      Part of the attraction of hand tools, by no means the only one, is that they are much more affordable. After spending $200 on ebay for a suit of 3 Stanley planes and restoring them, I can do all my surfacing. Machine tools, joiner, planer, belt sander, palm sander and dust collection and PPE is about $1500+

  • charles543

    Many people seem to be missing the point here. The only surfaces that matter are right at the edge. The rest of the iron does not do anything except support the edge in its proper position. We’re not talking about spending time getting the back flat. and then adding the ruler trick. We’re talking about ignoring the rest of the back, and making it flat right at the edge. We’re talking about saving time by not flattening the whole back and just a little bit of time for the ruler trick which makes the back flat where it is needed, right at the edge.

  • IrritableBadger

    The only problem is that the ruler lacks the sophistication people like to associate with hand tools. I think that’s too bad, because it’s simply wrong. Hand tools are refined, not at all sophisticated. The fact you can do this with a ruler is proof the tools have been so well thought through over the years (though not necessarily always well made) that it’s really hard to screw them up and very easy for people to maintain and use to the fullest extent of their abilities. But marketing has confused the vocabulary and the end user.

    The handplane is a working tool, designed by tradespeople for thousands of years with a common basic design being reached by everyone. The body of knowledge with that kind of thing is always going to be full of practical ideas that are accessible to everyone. The further you get from that, the more specialized something is, means there’s still refinement left to be defined. Using a ruler, another extremely refined tool, like this is the essence of refinement.

    If somebody makes a tool for this and calls it anything but a ruler people will buy it. But it’ll still be a ruler, just less functional.

  • curiousdork

    I was a nay sayer myself until I finally convinced myself when I saw Tom Fidgen do it. I used my ‘other’ block plane first and within 5 minutes I had a deadly sharp blade (I actually cut my hand on my plane blade it was so sharp). I didn’t spend hours upon hours dressing the back, when my new block plane arrived the ceremony of sharpening took all 5 minutes.

    I honestly don’t know why I didn’t take this advice earlier. I could have saved myself hundreds of hours dressing the back of my plane blades with this technique (which I prefer over the term ‘trick’). I should have listened to experts and not a bunch of YouTube “experts”.

  • DCMurphy

    I guess I don’t have any strong objections to the ruler trick, but I don’t use it myself.

    I think you could argue that it’s a great trick that came on the scene a couple decades too late. We are absolutely blessed by the abrasives available today: they’re fast, cheap and available in a huge range of (very consistently graded) grits. There are several fast and reliable ways to keep your water/oil stones nice and flat. Getting the backs of your chisels and plane irons flat and polished (and then keeping them that way) just isn’t that hard anymore.

    If I remember David’s method correctly, you still have to get the back of the tool flat and free of any coarse grinding marks, working up to the level of, say, a 800-1000x waterstone. In my experience, that’s the time-consuming part of lapping. After that, you’re just creating a polish, which shouldn’t take more than 20-25 minutes (even on the widest A2-steel blade).

    Now, the ruler trick isn’t a huge hassle, but it does add a couple seconds to your sharpening routine. So, would you rather invest 20-25 minutes once and just be done with it forever, or make every single resharpening a little bit more work than it needs to be?

  • afullerton

    Are you crazy? Never ever put mayonnaise on French fries!

    • CrazyDave

      I have always used the same method learned years ago at Highland Woodworking for both plane irons and chisels… mirror shiny back, done once, hone bevel edge to sharpen, strop off wire edge. But, this method for plane irons seems worthy of a try. However. It just makes my skin crawl to think of placing a steel scale onto a block of abrasive material (in another parallel life I am a machinist). Then it occurs to me. A piece of brass shim stock can do the same job and I don’t care about scratching it. I’m going out to the shop to try it. My block plane irons need sharpening. Thanks for making me aware of this idea.

      • Nipita

        Crazy Dave with your knowledge in the machine trade have you considered a peace of heavier shim stock to mimic the ruler itself. The scale in the picture looks like a flexible style which in turn is thinner gauged material.

    • jbaviera

      Don’t knock it till you’ve tried it! Tarter sauce is better though.

    • Dawsie

      Lol mayonnaise no ice-cream on the other hand yes 🙂 don’t knock it until you tried it.

      On the note of the “The Ruler Trick” as I have been given a cheap set of chisels as a gift I will give this a go after I have cleaned of all the machining marks on the back of them all.

      I have tried different methods for sharpening but then I am still learning ( never stop learning) I have just made a block for polishing for my planes I have found I like doing mine by hand rather than using a grinding wheel I have better control using my oil stone than I did with the grinding wheel that I bought Dad.

      It took me hours to get a straight edge back on my planer blade but now that I have I will keep doing my sharpening by hand. Oddly enough I have found this soothing when my mind is running around with projects that I have on the go. I have a routing of working in the workshop one day doing my woodworking and then the following day I spend it doing my girly things like sewing or beading or what ever I want on that day 🙂 then I spen one morning in the garden and then back to the workshop for the afternoon.
      I am in the middle of building myself a wall unit, I was never able to find the right one in the shops so what the heck I know I can make it so that’s what I am doing out of re-purposed pallets and making my own units for my home designed to keep all my hobbies that I do in order but I first had to work on the storage for Dads workshop so it could accommodate me and my love of woodworking lol Dad is not a woodworker he is a diesel engineer so now I am teaching him the love of woodworking.

  • michaelmouse

    As a rule I don’t use it…

  • rmason

    I think it would be tough on the ruler.

  • apbeelen

    I’ve seen it. I’ve used it. But only on a couple Lie-Nielsen planes I own.

    Then I switched to using all antique wooden planes. I flatten all the iron backs as part of the tuning process on any “new” antique plane I get, so I find no need for the ruler trick once the backs are flat. Also, my jack and fore planes have camber, so it doesn’t work for them. Smooth, miter, and jointer irons are straight, but I’ve learned to get a great edge without jigs or rulers, since they just add time to the process that doesn’t gain me anything anymore.

  • nbreidinger

    Do it. Don’t do it. Try it. Don’t try it. It matters not. For the haters of the method, please at least try it once before you knock it even if you don’t incorporate it into your practice. For the devotees, keep using it if it makes you enjoy your work more. Life has enough division. Let’s not invent another reason. David Charlesworth only recommends this method for plan irons. Use it on chisels at your own risk. I realize this comment is most unhelpful to Chris. I’ve tried it and had varying degrees of success. I don’t currently incorporate it into my sharpening regimen. My attitude is that I only have to flatten the back once and by the time I read about this method they were all flat and I haven’t acquired an iron the needed extensive flattening since. I’d consider it on a vintage iron that would require a lot of flattening. It’s also another tool in the tool box for changing the angle of attack for difficult grain.

  • Kees

    I don’t need it.

    It adds complexity to an otherwise utterly simple process.

    Not usefull for pairing chisels.

    Not usefull for pitted antique blades, the pits need to be removed anyway.

    So why would I use an unnecessary process for those few irons that don’t fit the above categories?

  • zeeboy

    Oh, oh! You’ve done it now! Of course, that was your intent. Stirring up the rabble is what you really enjoy. I enjoy it too – and learn a lot from it.

  • Longfatty

    Slightly different topic but I put 5 or 10 degrees back-bevel on my #4 for smoothing. This works really well but I need to set it for an extremely fine cut in white oak. With 10 degrees it’s noticeably harder to push. I got the idea from a Ron Hock book on sharpening to prevent tear out in wonky grain; it’s a quick, cheap, and easy alternative to a high angle frog.

    In contrast, I could never tell any difference in planing with or without the ruler trick, except that using the trick makes sharpening easier. That’s enough for me, I do it every time now (except on my #4).

  • AlanWS

    I think of the ruler trick as putting on a slightly greater back bevel that you get from simply adding more pressure near the edge while holding the blade flat on the stone.

    I think the objection comes from having worked out a consistent set of rules that if used together allow you to work well, and here’s something that breaks a rule. For some it’s just not worth it to find out where the line is for that rule: it works now so this should go away.

    • AlanWS

      “than” not “that”

  • karlfife

    +1 Marty with regard to getting the chip breaker into the back bevel. This can can cause the chip to drive itself into the space between the blade and chip breaker, making you foul-mouthed because of your fouled-mouth.

    Still, for Bevel up blades and bevel-down jacks, and some other planes this is not a concern, so I say +1 ruler trick in the right application. All else being equal it stands to reason that focusing the polishing work to just the leading edge can result in a better polish-to-effort ratio, and polish begets durability.

  • rwe2156

    With the ever-so-slight back bevel, is burr removal incomplete?

    Does it matter? I’ve always thought it was important to remove the burr before final honing.

  • Mitch Wilson

    First of all, everything I have heard or read (including from Charlesworth) says to not use the ruler trick for chisels. Why is everybody dwelling on this?
    As for my usage, the problem that I have is that I sharpen with abrasive PSA sheets. My final one is 0.3 microns, smooth as silk. And I don’t use water that will adhere/cohere the ruler to the sheet, so the ruler constantly is moving around and gets out of alignment. So what should I do? Use some P150 grit PSA under my ruler in order for it to get some “tooth” on the final honing sheet? I don’t think so. How about spray adhesive? Hhmmm? And most of my planes are low-angle planes, so they are technically block planes and are bevel up. Therefore, the benefits/adversities of the ruler trick are different from most of you who use Stanley bench planes.
    Bit I still keep using the ruler trick anyway. If it’s good enough for David, it’s good enough for me.

  • JesAri415

    I just wanted to thank you Chris for posting this, as I was dreading going home tonight and flattening out the back of a wooden jack plane I just picked up. I’m pretty sure you just saved about 25-30 minutes of my time, as I always forget about this “trick” until after I already flattened the back.

  • Jim Dee

    I have lived on both sides of the fence on this question, so I feel qualified to address both sides.

    My initial objection to the ruler trick was that if I first gently radius the plane iron as David Charlesworth advocates in his video, only the very center of the iron has a tiny, low-angle back bevel when I’m done with the ruler trick. It also seemed to me that if I didn’t get good results with the ruler trick, I would have to grind off a millimeter of plane iron to get back to a flat back.

    But like Chris, I steeled myself, closed my eyes, held my breath, and tried it. And it works, so I (usually) do it.

    I was convinced the ruler trick is okay to do, after the fact, by spending some time looking at Brent Beach’s website. I don’t use his sharpening method, but his photomicrography of how the back of the blade is worn as it planes wood made a little bell ding in my head: the ruler trick addresses almost exactly the area of the blade back which gets eroded by working wood.

    Several responders mention chisels. Much of my chisel work involves registering the flat back of the chisel to a surface, and then trimming something flush to the surface. So since the edge produced by the ruler trick is some microscopic distance above the registration surface once the chisel’s carefully flattened back is against it, the ruler trick is a no-no for flush trimming.

    Fedster mentions Japanese chisels and plane irons, to which I say “Amen!” It seems to me that the Japanese approach builds the ruler trick into the blade itself. Genius! The person I’ve heard object most strongly to the ruler trick uses only Japanese tools, so . . .

    stevenavoigt, as far as I can tell, thinks the ruler trick is done on every grit used in the sharpening process. I may be misunderstanding them. That would indeed be a time waster! But as Charlesworth shows the ruler trick, it’s only done with the finest grit one sharpens with.

    I agree with Marty that we shouldn’t try to put the chip breaker/cap iron on a back bevel. But if the ideal distance between edge and chip breaker is .4mm, the polished area on the back produced by the ruler trick is narrower than that (I think).

    I like stevenavoigt’s “always learning” approach to life, and in their spirit, I suggest anyone who’s unconvinced by either side to try the ruler trick for the sake of learning.

    • stevenavoigt

      I assume Charlesworth is using an eclipse jig or similar? In that case you only need to hit the back once. But if you are freehand sharpening, you need to remove the burr after each step. At least I do-there are some who don’t, I guess.

  • Bob Rozaieski

    Agree John. I’ve experimented with the ruler trick on old chisels as well with no ill effect for either chopping or paring.

  • C. Stanley Plane

    Instead of calling it, David Charlesworth’s “ruler trick”, I suggest renaming it the “elevated burr removal procedure” (as presented by David Charlesworth). A “trick” is great for circus acts or fooling a toddler; most woodworkers envision sharpening as an exact science with no place for tricks. So maybe what’s needed is a name change and PR campaign to shift the public’s perception of this sharpening “trick” (or proceedure).

  • aaronk

    I don’t do the ruler trick exactly because it adds another prop (I do it all freehand). I do however STROP the backside of my plane blades and raise the blade up at an angle which increases for coarser work (smoothing plane gets the shallowest angle, fore plane gets the highest). The effect is probably about the same and is one less gizmo i need to worry about.

    @Fair Woodworking – i hear you, and that’s why i do hand tool woodworking (constantly developing the skill, etc)… but life’s too short to polish the back of plane blades. There’s no reason a plane blade has to be sharpened like a chisel. Put it this way: do you also sharpen ALL plane blades straight across (liek a chisel) without a camber or rounded corners?

    @ marty – put a large enough back bevel on there and you won’t need a chip breaker 😉

    I’d also like to see something about the ruler trick on chisels. I’ve been too afraid to try it myself 🙂

  • Fedster

    Simplest objection: Japanese plane blades and Japanese chisels.

    • John Cashman

      It’s wonderful if your cutting tools come with large hollows in the back, with a very small amount of metal to polish on the periphery. My 2-5/8″ wide A2 blade doesn’t have a hollow, though. There is, I’d bet, 1,000 times more metal to polish.

  • aniakovas

    I have no knowledge really. I have seen expert woodworkers work, and worked alongside them, taking instruction.

    This is not why I have taken the trouble to register.

    Instead I want to say that asking this question, which made it into my news feed somehow, is an enlightened act. It is pedagogically sound, but on the net, brave. Your tone and demeanor have invited mature responses as far as I can see, and added to know my scant knowledge.

    I am impressed and deeply affected by this article. I’m only sorry I had nothing salient to the discussion to contribute.

  • Fair Woodworking

    I feel like I should comment since I know I’ve poked the Bear more than once about this stuff.

    While I have personal theory’s against the ruler trick, I can’t prove any of them so they don’t matter.

    I have a sacred rule for woodworking. Always be learning, and always find ways to make what you learn transferable to other things you want to learn, so that you can learn as much as you can before you die.

    I might be able to learn to hone a plane blade sharper using the ruler trick, and that’s great, but I CAN’T use the ruler trick on my chisels and expect them to work how I want them too. That makes learning to sharpen with the ruler trick NON-transferable to chisels. Not only does it not transfer to chisels, I loose out on the opportunity to practice a mandatory skill needed for sharpening chisels. That does not help in the long run of learning as much as I can before I die. All sharpening a plane blade using the ruler trick gets me, is a plane blade that MIGHT be sharper than I can do if I pretended it was a chisel, and that is wasted time in my book. Especially if the sharpness of my chisels suffers as a result.
    I know this is a very far sighted approach to woodworking. I’m accustom to people looking at me sideways for it, so it clearly is not for everyone, or anyone, anyone that is not me.

  • JumpingJax

    About those hours of polishing the back: you’ve still got to flatten the back or the ruler trick won’t work properly. If there is a hump, the ruler trick hones the middle of the edge, but not the corners. If there is a hollow, it hones the corners but not the middle. So there’s no savings there, but flattening only has to be done once either way. Once flat, the ruler trick will hone across the entire edge. But the edge wears and then the ruler trick has to be repeated and you’ll regret it, maybe not for every honing, but soon and ….

    I”ve tried it on a jack plane and had no big objections or problems, but also didn’t find it worth the bother. OTOH, I’ve been reluctant to use it on any of my smoothers, where the chip breaker is set as close to the edge as possible. My thought there is that the chip breaker will seat on the back best if there is a uniform planar surface at the edge and the ruler trick doesn’t provide that. I know the issue is small, but I’ve not been in a position to test it. And with my experience with the jack, I haven’t found a lot of incentive for testing either.

    • John Cashman

      Flattening a back is one thing. Polishing a back is a whole lot more work.

      And if you flatten the back, but then polish just the bit near the end, it’s been made just as un-flat, if not more so, than one swipe using the ruler trick to remove the burr.

      • Mitch Wilson

        Beware here. Charlesworth, not so long ago, started advocating for a more extended amount of time working on the burr removal with the ruler trick. It is not just one swipe.

  • Fuzzymoose2

    I have no major objection to the use of the ruler trick, as used by other people.
    I don’t use it personally, and have always lapped my backs flat.

    On my smoothing plane, I bought a Veritas custom plane, with two frogs, of different angles. What this demonstrated to me is that changes of angle can make a big difference working in some of the more fractious woods. Now, while the ruler trick may not produce more then a few degrees of a higher effective blade angle, those few degrees can make a difference. I’ve got some very old fir where this is an issue (looks lovely, but it’s not fun to work). Of course, the same holds true in end grain work. Every little bit that angle increases, the more problematic it seems to get.

    Now, another person mentioned the ruler trick with chisels. Here I have had real problems with back bevels of any sort on chisels. I’m a commercial cabinet makers, and do a lot of work with laminates and pvc edge tape. I’ve found a chisel being the quickest and easiest way to trim pvc edge tape flush with a laminate surface, and even occasionally laminate edging, prior to filing. Now if the chisel has a back bevel, this requires me to hold the chisel at a higher angle to bring the cutting surface to bear on the laminate, and it increases the risk that I’ll nosedive into the laminate surface. The same objection would hold true in any sort of paring operation for a chisel.

    *The problem with my method of edge tape trimming is that laminate is very hard on a tool edge. a sharpening that will last a week or more in wooden joint chopping will be undone in a day or two of edge trimming. I keep a pair of 7/8″ chisels for the purpose, and over the last three years, i have reduced their length by easily a half inch, each, in sharpening.

  • Vincent Tai

    My line of thought is a lot like Steve’s. I have no issues with the ruler trick itself. I find that there is a lot of abuse and twisting of the ruler trick, David Charlesworth has some very even and small bevels from his trick; but some people end up taking minutes and minutes to put a polish on something that needs to be flattened first or abraded to get rid of grinding marks. I saw a youtuber use the trick on chisels, I’ve seen another spend a while creating a huge back bevel because they started with a warped iron with a rough surface. A caveat issue for me; Veritas irons. There should be no reason to use a ruler trick on these irons and when I started woodworking with hand tools years ago I was a kid (pretty much still am but can legally drink now) and had not a clue what anything meant. The ruler trick seemed good and very loved by big names and I ended up using it on some old stanley irons. That worked nice, I then started using the trick on my new pristine Veritas irons. I loath having to stretch my hand to keep the ruler from sliding everywhere and carefully avoiding the skewing of the iron while sliding it back and forth on a slippery rail of thin metal. I had no clue what all those micron flatness and roughness per inch leaflets that came with the irons meant and caused myself to use another variable while sharpening that never needed to exist for those certain irons. Perhaps if I was smarter and a little more quick I could’ve avoided this step but with so many youtube demonstrations and write-ups of people using it it was hard for a teenager to avoid the trend. I still use the ruler trick plenty with my bevel up irons and some other vintage irons but honestly with PSA sandpaper and some different grits you can rehab a pitted iron into a fair plane iron in a jiffy. polishing it up to ridiculous levels doesn’t take long either if you really wanted that bling. I think the ruler trick fares well with decently flat blades like Hock, LN, and many Stanley irons but becomes self defeating when you form a big area to polish performing the trick on a warped iron or something like that.

    I don’t have an issue with the ruler trick and still use it just about daily but would like to see more info being put out there like how flat does your iron need to be for this trick, or does your iron need it at all? For me to use the ruler trick on a polished back is just making more work, like using manual fan control on your computer when you aren’t running anything that requires it. Eventually I’ll wean myself off the trick; lets hope I don’t lose my ruler before that happens though.
    Thanks for starting this discussion and braving the inevitable war that comes with it.

  • Marty

    For planes that use a chip breaker, the back bevel constrains how close you can align the chip breaker with the edge of the blade.

    • jeth

      Actually, as a back beveller I would say one of the big advantages is that you can set the chipbreaker right up to the top arris of the bevl, or thereabouts, and the bevel acts to extend the chip breaker to the very cutting edge, guiding the shaving up onto the breaker.
      By any means the bevel is usually very small. I use a bevel between 10 and 15 degrees on my smoother -I live in the tropics and work gnarly wood- It works wonders, making anything planeable to within a quick sniff of sandpaper of done. Even with the bevel I can get my breaker between 1/64″ and 1/32″ of the cutting edge.

    • JesAri415

      You’re telling me you set the chip breaker so close to the edge, that 5-6 strokes on the finest stone/abrasive is going to mess that up? Do you pull out a microscope to get it that close?

      • John Cashman

        I agree. The back bevel is far smaller than the distance the chipbreaker is from the edge.

  • stevenavoigt

    OK, I’ll play, since you asked nicely. I don’t use the ruler trick—and I’ve tried it—because it adds time, complexity, and a prop (the ruler). Compared to working the back of an iron that’s been properly prepared, it is slower. And it’s fussy.
    With the trick, I need to find the ruler, position it, and work the back carefully so as not to dislodge the ruler. And I need to do that 3 times when I sharpen an iron.
    But with a flat back, I just flip the iron over and do a few vigorous back and forths. It’s very fast.
    I get that the ruler trick means you don’t have to put in the initial time to flatten the back, and for an antique plane iron, that time can be significant, maybe an hour or more. But I’m reminded of the saying “you can pay me more, or you can pay me later.” Once I’ve put in that initial time, I don’t ever have to do it again. But with the ruler trick, I’ve got to spend an extra ten seconds and fiddle with the ruler, every time. And we’re talking thousands of times. I expect to keep using my irons til they wear out, which could take a decade or more.
    A reasonable argument is that it’s only 10 seconds. Fair enough. But it’s not about the number, it’s about eliminating every extraneous process and making the process as stripped down as possible. That makes me happy, and it makes the work go faster.
    With all that said, I don’t care if anyone else uses the ruler trick. I won’t tell anyone it’s wrong or bad. It’s just not how I prefer to work.
    Thanks, Chris, for giving us an opportunity to respond in a serious way. You do a great job of taking the religion out of sharpening.

  • aryakho

    No objection, just a question. Is this technique effective with oilstones? Whenever I read about the ruler method, it seems that only waterstones are used.

    • Longfatty

      I have used it with both my black Arkansas oilstone and an 8,000 waterstone. It works with both.

      I have an unheated shop. I got the oilstone so that i could leave it there without having to worry about it freezing.

  • SteveHall

    0.46° would be the objection, assuming a 3″ wide waterstone and a 0.020″ thick ruler 1/2″ wide. That’s the angle from dead flat.

    Which pales in comparison to the 2.40° error induced by an angle setting jig with a flat face that you push the plane/chisel up against to set a honing guide. That’s the error induced with one of these things by the difference of 1/8″ thickness in cutting steels.

    I’ve been designing a honing guide setting jig that solves this problem and have spent hours in CAD just to prove to myself that the fight is real. It is real, but I’m not sure it’s a fight. So I’ll share my drawings if anybody is interested.

  • DGM_Making

    I once heard Vic Tesolin say he would use the ruler trick for an old plane iron, to save hours of lapping, but for new premium irons (Veritas & Lie Nielsen) he doesn’t. I suppose it because the new premium don’t need lapping, just an initial polish, maybe?

    I do the above, but i’m not 100% sure why, i just struggle to “emotionally” to put a bevel on a known good flat surface.

    Q, does it make the edge any more brittle or reduce the durability? I also worry about the repeatability of putting the same angle of the bevel on the back with a ruler – ie what happens if you move to different size stones, change rulers or put the ruler in a slightly different spot?

    Once thing i have notice in doing both, is that it is slightly easier/quicker not doing the ruler trick as i just have to lay the iron flat on the stone to remove the burr, and not get the ruler out.

    I am interested to see other thoughts too.

  • RichTaylor

    I use it. The only change I made is to use a strip cut from one of those thin, flexible cutting mats for the kitchen. The underside has a suction effect to keep it in place on a wet stone, and there’s less friction where the blade rides on it. The thickness is exactly 0.025″ which has worked well for me.

    As for chisels, I think it’s a bad idea.

  • John Cashman

    I have no objection. But honestly, I would like to read a serious discussion of the ruler trick for chisel. Most chisels, at least. I started using it on two older chisels, 1/4 and 1/2 (with average-wonky vintage backs), for dovetails. The back bevel is so slight, I’ve noticed no ill effects.

    I’d love to read your thoughts.

    • rwe2156

      Not applicable to chisels, at least if you plan on paring with it.

      • John Cashman

        Does 1/000th of an inch matter, even on a paring chisel?

        It hasn’t mattered to me.

        • Billinflora

          The only drawback I see is that once you commit you can’t go back. The bevel created cannot easily be reversed.

          • John Cashman

            The back bevel from the ruler trick is so small, the next time you hone the primary bevel, the back bevel is removed — and then some. It’s not an issue.

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