David Charlesworth's Ruler Trick

[Phil Harding]

Sharpening plane irons, chisels, and scrapers is not my forte. I rate it right up there with sanding:mad:. This is why I use Festool sanders for sanding and Tormek and Work Sharp for sharpening. I've never felt I was getting truly sharp edges using these techniques so I invested in a set of Norton water stones. I quickly learned that polishing the back of a 2" A2 steel plane blade is a real challenge of my patience. So when I saw David Charlesworth sharpening video (and Rob Cosman's Scraping Wood video) I decided to try using his ruler trick.

Well, I can say it does work. I was able to polish the backs of several plane blades before I ran out of energy. But, keeping the ruler in place on the stone turned out to be a real challenge. It seemed to stay fixed better on some stones than others. I was wondering if anyone here who has experience with this technique has any pointers on how to fix the ruler on the stone so that it doesn't slide around. I suppose that I could use any shim material of similar thickness if it had higher stiction to the stone than a stainless steel ruler.

Thanks, Phil

[Jeff Aldred]

Hi:
I had the same trouble as you. While at a big box store, I found a piece of thin aluminum trim shaped with a right angle - basically thin angle iron. A couple of minutes with a hack saw to take one of the sides down to the appropriate width for my stones, and voila - 4 dollar solution, and enough angle material for generations of wood workers!

[John Broling]

Phil:

I've found that you don't want your polishing stone to be too thick with slurry when you put the ruler down. Charlesworth also advises that the top side of the ruler (where the plane iron rests) should be dry, not wet, for best results. But most importantly, you're not using a great deal of pressure on the iron when you're "ruler tricking", so if the ruler slips, just hold it with one hand, and polish the iron with the other. Charlesworth himself does this in the ruler trick chapter of the video.

J.

[Tri Hoang]

You want to keep the area under the ruler just a little wet, not too wet. When you use the ruler trick, you are polishing the back on a very fine stone...don't use a lot of pressure...just enough to keep the front down. Too much pressure will move the ruler and/or damage the edge.

[Eddie Darby]

Make sure that you stone surface is flat, so that the ruler does not have to bend to make contact, and more importantly, so that you will end up with a sharp edge.

The number one mistake that most people make with waterstones, is that they do not flatten them frequently enough.

Now can anyone help me with my problem, which is how do you get the ruler off the stone?:confused::eek::D:rolleyes:

[Tri Hoang]

Have you tried adding a few drops of water to the edge of the ruler and SLIDE it off the edge of the stone?


Make sure that you stone surface is flat, so that the ruler does not have to bend to make contact, and more importantly, so that you will end up with a sharp edge.

The number one mistake that most people make with waterstones, is that they do not flatten them frequently enough.

Now can anyone help me with my problem, which is how do you get the ruler off the stone?:confused::eek::D:rolleyes:

[Chris Padilla]

Can someone provide the Cliffs Notes on this trick? :)

[John Broling]

Chris:

Here's the executive summary:

1. Get a thin ruler, like one of those stainless steel flexible 6" rulers. DC suggests less than 1mm thick. I've got a cheapie Groz from Woodcraft.

2. On your polishing stone, work up a slurry with the nagura block and rest the ruler, dry, at the edge of the stone.

3. Hone a small back bevel on the plane iron, working crosswise over the stone.

The result should be a very narrow polish on just the very edge of the iron. DC's argument is that you need not polish the back of the iron to a mirror finish; just get it acceptably flat (in DC's case, using an 800 grit Japanese stone). The ruler trick puts a mirror polish on the only part of the iron that needs it, which is the very tip. The back bevel is less than one degree, according to DC.

I've switched to stones from sandpaper, and I'm very happy with the results using DC's methods. As an the absolute beginner in sharpening, DC's video was well worth the money.

Here's a video example (not of me). Go to about 3:20 in the video. http://www.youtube.com/watch?v=__DT-YwGHgc

Hope this helps.

J.

[Mark Roderick]

Personally, I don't find the ruler trick useful. It's not that difficult to get the front half inch of a plane blade flat and honed when you buy it, and you only do it once. Sharpening is fussy enough without having to get the ruler out of the drawer and properly position it on the stone each time. Just my opinion, of course.

[Johnny Kleso]

Good Quality Flex Rulers are very smooth, thin and flat...

I have no issues with them sticking to the stone with some Mineal Sprits on Oil Stones.. I could use Meineral Oil if it was but I think on Water Stones some water and slurry would make a good vacum seal...

You could use some masking tape at the ends if you still have issues with the ruler moving..

[Casey Gooding]

Here's a unique idea.....hold it with your other hand.
Ok, that was a bit flippant, but I think sometimes we WAAAYYYY over-complicate things here.

[george wilson]

Agreed,Casey. I've never used any jigs at all for sharpening.I wouldn't even consider it. I just learned to develop skill.

[Phil Harding]

It looks like I have two problems to resolve. First my ruler isn't totally flat, it's got a little kink in it. I'm sure I can find a low cost replacement. The other is I've got to learn to hold to the ruler with one hand while I slide the blade with the other. I was actually using both hands on the blade. I suspect this resulted in too much pressure on both the blade and the ruler.

I plan another sharpening session in the next few days so I'll spend some time working on my technique.

Thanks for all the pointers.

-- Phil

[Joel Goodman]

In general I was taught to avoid excessive pressure sharpening and "let the stone do the work". Is it possible that you applying too much pressure and that's why the ruler is moving? I don't use the ruler trick so it's just a guess.

[george wilson]

Not having enough pressure is not going to make the stone cut.

[Andrew Homan]

Not having enough pressure is not going to make the stone cut.


George,
Because the ruler is raising the blade, only an extremely narrow strip of the edge is in contact with the stone. It is not necessary to put much pressure on it for this to work. (Speaking from experience of doing this on a 6000 grit stone).
-Andy

[george wilson]

I just raise my blade a tiny bit when doing this. Without these jigs and devices,it only takes a fraction of the time to sharpen a blade,if you train yourself to do it.Roger Barlow ,in Shapton Vs Spyderco thread,mentioned it takes more pressure to use the Spyderco stones,which is what I use,as they stay flat,and aren't as messy and rusting as water stones.

[Chris Friesen]

Personally, I don't find the ruler trick useful. It's not that difficult to get the front half inch of a plane blade flat and honed when you buy it, and you only do it once. Sharpening is fussy enough without having to get the ruler out of the drawer and properly position it on the stone each time. Just my opinion, of course.

Depends how finicky you are. It's been shown that the nominally-flat side of the blade does wear with use (more so with bevel-up planes than bevel-down). In most cases this isn't an issue, but if you want a truly sharp edge (for that super-tuned smoother, for instance), this wear bevel needs to be polished. The simplest and fastest way to do this is via the ruler trick, since it only polishes the area that actually needs it.

You could get the same effect by honing the primary bevel past the wear bevel, or by honing the back side long enough that the wear bevel is gone, but either of those solutions will waste a lot of material.

[Sean Hughto]

As a counterpoint, let me quote a post Larry Williams did on Knots a couple years back. It explains the downsides of the ruler trick very well (at least I think so):

[QUOTING PRIOR POSTER] "Sorry, I don't get it. I don't see a time bomb developing if I use the "ruler trick". The ruler is laid on one side of the stone and the back edge of the blade is hanging about 1/2" off the stone to begin, the blade is pulled about a 1/2" onto to the stone 3-5 times...done. How is that not repeatable? Where is the bomb? Oh, minor detail, It Works..." [END OF QUOTE - WHAT FOLLOWS IS LARRY'S RESPONSE]

Okay BG, let's start here. There's one circumstance in which the ruler trick will improve your edge. That one circumstance would be if you, because of technique or equipment, failed to properly hone the face/back of the iron when sharpening.

If you look at my response to Mike above, you'll get an idea of the effect decreasing angles have on where things end up. At the angle you're talking about very slight changes will greatly effect where you're honing. If any of a previous "ruler trick" back bevel remains it's very easy to end up simply honing the arris between the back bevel and the face of the iron without ever honing to the edge.

There are two ways to avoid this. One is to increase the amount of steel removed each sharpening and the other is to pull the edge closer to the ruler with each sharpening. With the first, pretty soon you'll have a very large flat to try to deal with. The second leaves an ever increasing back bevel angle. Neither of these is a good option and will take considerable time to remove by grinding, both would quickly be bigger than a bad nick in the blade's edge.

There's a third option though. You can completely hone this "ruler trick" back bevel off each sharpening. You know, this bevel will actually be bigger than the wear area you need to hone of at each sharpening. If you can't hone away the wear on the face of the iron, how do you expect to hone away this back bevel? You're opting for more work and the extra step of the ruler trick if you use it. What are you gaining?

Doesn't it make more sense to just learn to hone the face of the iron properly in the first place?

[Roger Barlow]

+1 on learning the skill

[Tim Sgrazzutti]

+1 on Larry Williams' opinion. I've sharpened an iron like this before in a pinch, although by lifting the blade up just a hair - no ruler. Got a great edge with less work than flattening the edge (didn't have the time to), but then you're stuck doing it every time to chase the burr off the back. In the end I regretted it, and found it was easier to grind off the back bevel that was eventually created (it will grow) and flatten the back properly. You only need to initially flatten and polish the first half inch or so - just enough to register solidly on your abrasive of choice. After that it saves you time being able to chase the burr off the back on your fine abrasive after each honing stage without having to diddle with a ruler or any doubt that you're not holding the iron at the same angle as the previous time.

Any time you think you are saving by taking this shortcut will eventually catch up with you, IME. Better to do it right the first time, and then you're done.

[Chris Friesen]

As a counterpoint, let me quote a post Larry Williams did on Knots a couple years back. It explains the downsides of the ruler trick very well (at least I think so):

If any of a previous "ruler trick" back bevel remains it's very easy to end up simply honing the arris between the back bevel and the face of the iron without ever honing to the edge.
<snip>
Doesn't it make more sense to just learn to hone the face of the iron properly in the first place?

Think about the geometry for a minute. The ruler thickness is fixed, as is the distance across the honing stone. You will have honed the bevel somewhat, wearing away metal and thus shortening the bevel caused by the "ruler trick" in the previous sharpening session. If you put the iron on the stone, you will start honing the heel of the micro back bevel. (As indicated above.) However, if you then hone until the back bevel is the same size as it was before (roughly equivalent to the same number of strokes as the last time), you will have reached the edge of the blade and the edge will be sharp.

Also, as I mentioned before, flattening the face of the iron is only useful the first time. After use there will be a wear bevel right at the edge on the flat side of the iron, and successive polishing (unless done for an excessively long time on each sharpening) will not remove this bevel.

[Sean Hughto]

I'm really not one to debate the angels on the head of a pin stuff that some guys get into in sharpening debates. You like the ruler trick, that's great. I've never felt the need to use it. Your assertions about flattening the back do not match my personal experience.

[Allan Froehlich]

I usually place my index fingers near the bevel and use my thumbs to apply lifting pressure to the back of the blade. What I end up with is the last 1/8 to 1/4 inch of the blade getting polished. I can also work at an angle when doing this.

[Richard Dooling]

Sean, "angels on the head of a pin"??!!

The best laugh I've had all day!

[george wilson]

I agree,Sean. Some of these niggling points go on forever,when folks really need to be concentrating on finding good designs and developing good design skills,as well as developing freehand honing skills. Too many crutches!!! To me,the NUMBER 1 skill to develop good design skill,provided you can actually get your tools sharp,and develop basic skills,like sawing straight lines,making decent dovetails,etc..

It does not matter how perfect one's edge is,as long as it is good and sharp. What really matters is making things with those edges. This just seems like nibbling at the edges of woodwork,and not really actually getting into the meat of it.

I am not trying to aggravate anyone here,but the truth is what it is.

[Mark Singer]

George, I agree 100%! I am sure there are great edges out there that never produce a stick of decent furniture.... something designed and executed that "speaks"

[Mark Roderick]

I don't think that's correct. I don't know exactly what you mean by a "wear bevel" on the back of the blade, but I don't think it matters. When you re-sharpen the main bevel, you're cutting away metal. Cutting away that metal until you get a tiny burr on the back of the blade will eliminate any "wear bevel," by definition. Once you've done that, you have a whole new geometry, which will be perfectly flat on the back once again, assuming you flattened the back originally.

To look at it differently, if you've re-ground the main bevel sufficiently to have a slight burr on the back, how could any "wear bevel" on the back remain? I don't think it's physically possible.

[Derek Cohen]

This thread is on WoodNet as well.

It is not easy to be both for and against something at the same time. There is much I like about David Charlesworth - he is a very good teacher. His "Ruler Trick" is very clever and has a place among the tools one might use for sharpening. It will - does - suit some, but it does not suit my style of sharpening.

I believe that it suits those that hone with a honing guide. And it especially suits those that do not strop their blades. I prefer to hone and strop BD and chisel blades freehand, and a micro backbevel just complicates matters. It is even more of a problem (for me) on BU blades.

For those that are interested enough to read my blog on FWW, the article is at http://finewoodworking.taunton.com/item/8521/a-sharpening-strategy-beyond-a-sharp-edge This details the entire issue.

The short version is that one needs to be looking beyond the immeditate honing of a blade - sharpening is the easy part - to that of the resharpening/maintaining of a blade's edge. This is what becomes complicated when you introduce a secondary bevel, especially for BU blades where the bevel angle is all-important.

Note that a microbevel is just a small bevel, and does not indicate a change of angle. A secondary bevel is a change of bevel angle from the primary bevel. You can have a micro secondary bevel. The Ruler Trick is a micro secondary backbevel :)

I maintain a blade by stropping. I do this quite frequently as I work with both chisels and planes. To make this work efficiently and effectively, you need a coplanar surface. This might be a hollow grind or a flat grind, but not a secondary bevel. The RTjust gets in the way.

This is one shortcut that ends up being a detour that takes me the long-way-around.

So for me the Ruler Trick is o-u-t.

Regards from Perth

Derek

[Mark Roderick]

Derek, when you use the term "strop," do you just mean something like freshening up the bevel on a piece of MDF covered with green honing compound? Or does it have a more technical meaning?

[Derek Cohen]

Hi Mark

I use green rouge on a hard leather strop.

http://www.inthewoodshop.com/WoodworkTechniques/Stroppingwithgreenrougeversesdiamondpaste_html_m31 1bfa91.gif

There is a comparison of green rouge and diamond paste, with a pictorial, on my web site:

http://www.inthewoodshop.com/WoodworkTechniques/Stroppingwithgreenrougeversesdiamondpaste.html

Regards from Perth

Derek

[Mark Roderick]

Thanks very much. I thought that's what you meant. I use the same.

When you're planing something like maple, how often do you strop the blade, roughly? And do you just strop, or do you have a rule where maybe every five times you strop you then go back and re-hone on a 4,000 grit stone or something like that?

[Derek Cohen]

Hi again Mark

This is difficult to answer. Maple is a relatively easy wood compared with the average Australian eucalypt. Jarrah, for example, is not only about 50% harder, but it also contains high levels of silica, which blunt edges very rapidly. She-oak is twice as dense as Maple but isnot as abrasive as Jarrah. Planing tends to heat up the steel, which also blunts the edge. My chisels as a result last longer than my plane blades.

I tend to use A2 steel because it is more abrasion resistant. With stropping, I can keep a plane blade going about three times longer than if I did not strop. I begin to strop as soon as I feel and see that the plane is not cutting as easily as expected. The aim is to get to it before it needs to be re-honed.

Can you believe that I have not honed my Blue Spruce chisels (used mainly for paring dovetails) in 12 months?! Theyhave been kept sharp with stropping alone (see the earlier pictorial).

Regards from Perth

Derek

[Mark Roderick]

What you say about your chisels is very interesting. It's so quick to strop the chisel by hand - if you can avoid honing, it not only saves time overall but also saves the chisel blade. I don't want to take more steel off my L-N chisels than I absolutely have to!