Step 7: Flattening the Back

All of that sharpening you've done so far has created a little burr on the back of the blade edge. If you run your finger up the back of the chisel, you'll feel it when you get to the edge.

To get rid of that burr, you'll need to flatten the back of the chisel. To do this, start with the 800-grit stone. Lay the back of the chisel against the stone and make several passes on it. The chisel must lie completely flat against the stone.

It doesn't matter how much of the back you place on the stone. You only really need the very end flattened, but the more you have on the stone, the easier it will be to keep the chisel flat.

Do several sets of passes as you did with the blade, moving up through the 4000-grit stone.

There. You now have a finely-honed and powerfully useful tool. Now go to this instructable to see what you can do with it!
<p>An excellent Instructable! I read this a couple of years ago and printed in and the comments for reference. I still have it hanging over my chisels and sharpening station. The best reference on the topic I have found to date.</p>
Thanks so much! Glad it helps. :)
Firstly, A very nice guide to get people started in sharpening. Glad to see that you went with the water sharpening, IMHO a more precise method of sharpening, less messy and you can more easily get rid of the &quot;metal dust&quot; left on the stone.<br> <br> &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; One small item that you forgot to go over that makes all the difference. Being a fine woodworker I am looking for the cleanest cut and the fastest sharpening time. Because of this I flatten the back and sharpen up to the final 8000 grit to a mirror finish before I do anything else. This sets me up for success in my sharpening. Yes, it may take a while but if it is VERY uneven you can even do just 1cm to 1/2 cm near the tip if needs be. Doing an inch or so will save you time in the future and will most likely last a good decade or more. Sharpening any edge too is reducing the material to an infinitely small edge by sharpening or &quot;polishing&quot;. Any visible scratches are groves that will leave a serrated edge. The smaller the scratches the finer the sharpening possible. A mirror finish gives us microscopic scratches and a leg up in keeping a sharp tool.<br> &nbsp;&nbsp; &nbsp; &nbsp; After sharpening the back up to the 8000, I start on the bevel. 500 (or 800 or whatever) I run it over this level to establish a flat edge, create the geometry of the chisel and get a nice burr going. I then turn it over and with the flattened back I go to the 8000 (eight thousand) stone to &quot;cut off&quot; the burr. You will see it as a darker line on the stone until it disappears and evens out. Then back to the bevel next stone up. Same process and finally when I reach 8000 I have a chisel sharp enough to shave with.<br> &nbsp;&nbsp; &nbsp; &nbsp; This seems time consuming but with a little practice it won't take more than 5-10 minutes and leave you with a consistent result. Thanks again for the good Instructable!
Thanks very much for this outstanding comment. Since creating this Instructable, I have come to appreciate the importance of properly flattening the back. When I looked at all of my chisels and plane blades that were sharpened as in this Instructable, I was dismayed to see how little of the backs were mirror-shiny.<br><br>I've since gone through all of them and given all of them a good resharpening, starting with the backs. I figured the backs would likely be a one-time endeavor, with me only needing to pay attention to the microbevel (and from time to time, the primary bevel as well).
&nbsp;I have found that sharpening with progressively finer wetordry sandpaper over glass is both very practical and comparatively inexpensive. &nbsp;A flat thick glass piece and the required 3M sandpapers are way cheaper than a set of stones; and you don't need to flatten them. &nbsp;Only the worst cases of badly dented chisels will benefit from a complete treatment on a set of 3 to 4 stones.<br /> <br /> <br /> In my case, I bought a somewhat similar adjustable angle guide from &quot;General&quot; brand of tools that uses two small wheels that can roll freely at both sides of the sandpaper strip if you cut it a little wider than the blade to be sharpened, so that they don't have to roll over the sandpaper. &nbsp;Cutting the sandpaper in those widths gives several strips from every sandpaper sheet, which means even more savings!<br /> <br /> <br /> To sharpen the narrow chisel blades, I made a wooden base with a lateral guide rail, so that the sharpening guide can roll straight and paralell to the sandpaper strip.<br /> <br /> <br /> The glass plate is 3/8&quot; (9 mm) thick, which is very rigid and ensures flatness even with some heavy down pressure; and was not expensive since the size is not large.<br /> <br /> For me, the glass and wetordry sandpaper is the way to go.<br /> <br /> amclaussen, Mexico City.
<p>I was wondering if someone would mention using glass to sharpen on with sand paper. Stones are great but I truly believe a scary sharp type system works better for beginning sharpeners. I supplement my retirement by going to farmer's markets and swap meets and sharpening different items for people. I use several different methods and equipment from an expensive Tormek system to glass and sand paper and many others. I always tell people to start cheap and see how they like sharpening and then if they like it spend a little more and try different methods until they find the right one for them.</p>
<p>You posted at just the right time for me. I decided to improve a small project I am working on today, requiring my chisels. Mine are horribly dull, and I realized I had just seen an instructable on this, and here I am. Very handy.</p><p>I haven't sharpened them in a few years. We learned how to do it by hand in art school, but I think it would be worth it to purchase a honing guide.</p>
<p>Water stones sharpen great, but as noted, narrow blades (like chisels) will wear a grove no matter how careful you are. Given the price of good water stones, it might be better to use oil stones for the first few stages and finish with a 4000/8000 grit water stone. Then dress the stone with the nagura to remove any groves. I mostly use abrasive (sand) paper on a tempered glass surface up to 1200 grit and then buff on a felt wheel with green compound.</p><p>For the micro edge, marking the back of the chisel with a line and then moving it up slightly in the jig is more accurate than lifting the handle.</p><p>The wire edge on the back is better removed as you go through the grits with a light rub on the back by laying the chisel flat. To do it all at the end may ruin the fine edge or even put a rough wire edge on the front!</p><p>Finally, buffing with a felt or hard cloth wheel and green buffing compound on your bench grinder will give the sharpest edge. Of course an edge this sharp is best for hand paring wood, not hammering away. It should leave a shiny surface on the wood itself if truly sharp. My neighbour often brings me nail-dented dull chisels, used for everything but cutting wood, and I never sharpen it beyond a 400 grit, (too dangerous and a waste of good steel). I used to have several sets from dull to razor sharp in a fine wooden boxed set, but now just keep a basic set for cabinetry and a few sharp but not razor-edged chisels for general household work.</p><p>The best test for sharpness is to cut a small corner off a scrap piece of wood and feel that nice, no resistance slice that leaves the wood shiny, but if you must test on your finger, use a thumb nail and see how low of an angle it will bite. If sharp, it should catch the nail when almost flat.</p>
<p>Another good way to sharpen is to use first flatten the back of the chisel, progressively going through grits until you can see yourself as in a mirror. This is most easily done with sandpaper on a flat granite surface.</p><p>Then with a 6 or 10 inch grinder put a curve into the bevel of the chisel until it reaches the tip. Because you can now sharpen the chisel with the removal of a small amount of material, it goes very quickly, and using 6000 grit sandpaper is quite feasible. Let the edge do the cutting, not your muscles.</p>
<p>Amazing write up! You did a great job not very many people know how much work needs to go into getting your blades Sharp, and as you said not just sharp that it will cut skin but truly sharp. Great job! </p>
nice Instructable-- couple things for other people to remember -- sharpen early; sharpen often; 1. in step six you say to look for the thin line on the chisel edge. this line is on the bevelled side of the chisel. The back needs to be dead flat. If you see a thin line on the back of the chisel, then it's time to flatten the back again and sharpen. 2. another thing that took a little while for me to figure out is that the stones need to be flattened periodically to keep them flat too. when using a honing guide the center of the stone tends to get dished out because as from the metal rubbing on the stone. the back of the chisel is only going to get as flat as the stone. To "dress" the stones, I rub the wetstone back and forth on a thick piece of glass (3/16" min for me) with some wet/dry sandpaper spray-mounted to it, sprinkled with some water. Typically the ends of the stone rub when first dressing. After a few minutes of work the whole surface of the stone shows wear equally. At this point I know the stone is flat (or at least as flat as the glass.) I got my current piece of glass for free from an architect friend as a 12"x12" left-over sample. my previous piece was a scratched up glass tabletop.
<p>Someone told me a granite or marble countertop could be used for truing stones. What do you think?</p>
<p>granite tops are used by every tool and die shop in the world to show flatness, and are also used for measurements and to set or &quot;dial in&quot; precision measuring equipment(height gauges, etc...). In manufacturing and mechanical engineering, flatness is an important geometric condition for any workpiece or tool., they're called &quot;Surface Plates&quot; and tolerances can be + or - .0000035. its tolerance of flatness is measured in microinches, and theres 3 grades AA(35 microinches), A(60), B(110). so a surface plate is so far out and costly i would recommend a sturdy piece of glass thick enough to withstand minor deflection on a solid flat surface, (like birch plywood)(any inconsistencies with the the ups and downs of the plywood, if the wood is fastened really well, a piece of thick glass would span it. people use 1/4-3/8 inch plate glass to roll around their office chairs on, just saying...woodworking does not have the same tolerances(most of the time) as metalworking, and a piece of glass is your answer, if set up right, its as accurate as you will ever need, unless your building a swiss watch</p>
Sure. It is hard and flat and won't deflect when you press hard which is one of the important things. <br>
Hey thanks for the comment! Yes, thanks for the clarification if it wasn't clear enough in my post - the thin line (microbevel) should be on the bevel edge. And yes, a flat back is essential and should only really need to be done once for the life of the chisel. And thanks also for the tips about flattening the stones. I didn't get to that (seemed a bit tangential) but it is really important so I appreciate what you said. I have a sanding screen (180 grit) glued to a piece of glass to flatten my lowest grit stone, and I flatten the other ones with the next lower grit stone. I've also heard that polished granite makes a good dead-flat surface if you don't want to go with glass.
OK, I *KNOW* you will laugh at this, but please think about it:<br /> One of the very best ways to &quot;true' your stones ( making them flat again is called &quot;True'ing&quot; them) is to pour some water on a flat concrete sidewalk, and work the stone on this surface.<br /> I find a &quot;figure 8&quot; pattern is best.<br /> This cuts the stone to flat very quickly and effectively.<br /> Once it is flat, I then finish it with sandpaper, wet, on glass, as you described above. That is just to take out any scratches on the stone.<br /> <br />
Should work, if you vary the path of the stone a good bit (to avoid an area of cement with locallized wave).
wow , thanks thats good info ....
<p>ive always been taught the best angle for a sharp edge was 30&deg;, but in reading a few posts i have seen 25&deg; used by some people, i'm no expert or novice, i actually worked tool and die for a decade or so and the standard was 60&deg;(30&deg; per side)(except a drill bit which is 118&deg;, 59&deg; included angle). but that was for metals. please put this conflict to bed a tell me the optimal angle for wood working chisels, not what the book says but what experience proves to be correct</p>
<p>Thanks for the instructable, I've picked up some of this info here and there, but its nice to get it all in a cohesive, complete set of instructions. I would note that, at least on some honing guides, they list the distance the chisel should stick out from the front to achieve a certain angle. My honing guide looks identical to yours, except for these measurements on the sides, so the same measurements may work for honing guides of that type. I don't have it with me right now, but offhand I know that the chisel should stick out 4 cm for a 25 degree bevel.</p>
Nice guide, as I try to improve my skills I keep finding so much more information. One of the tips I found along the way to a sharper chisel in the polishing end of the scale, is to put down some polishing compound on a hard surface like a piece of glass and moisten it a bit to form a slurry. Working the chisel back and forth in the slurry on the glass will further sharpen and polish the cutting edge. Using course through finer polishing compounds is very helpful in getting that keen edge and much less expensive that a fine stone and the glass is easily replaceable. It would work like a fine grinding compound.
Barbers and knife makers take off the burs by rubbing it against a strip off taught leather, maybe that may be better for keeping the bottom flat and removing just the burs
I made a jig for sharpening chisels out of a wedge of wood and some wooden toy wheels. I used an incra jig protractor to get the right angle so that I could lay the chisel on the top of the wheeled edge and roll the whole thing over some sandpaper, and get a wicked sharp edge.
Excellent Tip!<br><br>Thanks for the suggestion.
Man alive that looks sharp. My chisels are all chipped and need an expert like you. I'm a plumber so I put them through a lot of nails etc!
You need one of these:<br> <br> <a href="http://a.imageshack.us/img838/5759/sideo.jpg">http://a.imageshack.us/img838/5759/sideo.jpg</a><br> <br> Skip the stones!<br>
If you're putting chisels through nails you should use what's called a 'cold chisel'. Cold chisels are designed for that sort of thing and look almost nothing like wood chisels. You can find them at Lowes or Home Depot. They are beveled on both sides, each at about 35 degrees from the long axis (about 70 degrees total).<br />
Hey, I'm no Yoda. Anyone can do this! But if your chisels are all chipped then you might need to grind them down on a grinder first to establish a flat edge and a starting bevel. I don't cover that here (I don't even have a grinder) but you could probably find tips (and video) on this elsewhere. Once you've done that, start with this Instructable and you'll be set!
When you get your chisel where you want it in the guide, score a mark across the face of the chisel at the base of the guide. This will allow you to quickly find the right spot the next time you sharpen.<br><br>I use the Veritas sharpening jig. It has a roller on the back with an eccentric cam. Just turn the cam 90 degrees to raise the chisel up 1/2 degree for the micro-bevel step.<br><br>Once you get your chisel sharp, it is usually only necessary to hit it with a few strokes of the finest grit to &quot;tune it up&quot;.<br><br>
Excellent, thanks for your comments making this Instructable even better!
WOOPS im so sorry! i meant to push the plus but accidentally pushed the minus when i was rating! shoot i hope it can get fixed haha. sorry!!! good instructable!
It's all good. Why don't you make up for it by giving a plus to a lousy instructable? ;<sup>) Just kidding...</sup><br/>
The way I was taught was that a chisel was not sharp enough to use until you could shave your arm with it. To this day my left arm is hairless from testing my plane blades and chisels on it. I use water stones up to 6000 grit and then strop using the palm of my hand. You don't need a leather strop & paste. Its got to be done quick or else you cut yourself though.
Easier method (and doesn't deforest your manly arm hair!): rest the edge of your chisel (or knife) against your thumb nail, tilted at a 45-degree angle. Just rest it - don't apply force! If the edge doesn't slide down the nail, it is &quot;biting&quot;, and sharp. <br><br>Sharper edges will bite on steeper slopes of your nail. But 45-deg is a pretty decent edge.
Execellent instructible. I'll have to use this to sharpen my chisels soon, that's for sure. Speaking of sharp chisels, my old woodshop teacher was real anal about keeping sharp chisels, and if you nicked an edge or something, he'd make you stick around and sharpen the dang thing. He had one set he said he kept razor-sharp, which he wouldn't let us touch, but said one could theoretically shave with it if he felt the need. Is it actually possible to get a chisel that sharp, or was he just jiving us?
Well, I think it's definitely possible. I think I heard that razor blades are sharpened to something like 3000 or 4000 grit, and I sharpen my chisels up through 8000 grit. However, woodworking blades are sharpened at a 25-30 degree angle, as that is optimum for wood. I'm not sure what the optimum angle is for skin. :<sup>)</sup><br/>
I don't know either, but I guess that's why I'm not in the razorblade business.
Straight razors are typically sharpened to 8000 grit or above. The primary angle is roughly 15 degrees. I say roughly because when you are honing a straight razor you use the spine of the razor to hold the angle.
you can easily shave the hair from your arm with a well-honed chisel. I don't think I would want to try shaving my whiskers with one, though. It would probably work, but unlike a chunk of wood, when you make a gouge it will hurt more :-)
Now, I have a question, I accidently put a chink in my blade, so it now has a gap right in the middle, If I used this technique, would I be able to sharpen it back into a blade? (the dink is about .5 centimeters long, and is the shape of a half circle)
Let me preface my answer by saying I have never done this myself, I have just read a bit here and there. So if anyone has personal experience with this, I hope they'll share! What I think you'd need to do is run the blade on a grinder until it is flat across the entire blade. Then you have to regrind a bevel (25 degrees or so) on the blade. After that, you start with the steps in this Instructable to hone the blade until it's sharp! Good luck, and if you think of it, post a reply to this after you've solved the problem.
Whoops, let me follow up by saying that if you don't have a grinder (as I don't), you'd have to "grind" that blade down until it's even by using sandpaper or a rough-grit sanding stone (don't use your nice waterstones). I don't know how long that would take. When you're done, then you might consider running it over your coarsest waterstone (maybe 800?) just to be sure that it's a nice straight smooth edge. Then you'd "grind" the bevel in the same way (man, that might take forever!) and after that, get to honing the blade. Hope that made sense!
lol, maybe I should just go and ask for help from a professional at my woodcraft store before I ruin my chisel !
What I did with my plane blades that had some nicks (bought some used planes) is I had my local sharpening guy sharpen them. He ground out all the nicks for me and cost me 10.50 for three blades. Then I'm gonna sharpen'em back up to nice and ready to use. It's a lot easier than trying to do it yourself and possibly screwing it up. :D
Man , I love the store "woodcraft"!! And I figured out there is one about 20 miles from my house : )
Great instructable. I recently had to sharpen one of my chisels and did it with increasingly finer sandpaper. It's good to know that I was at least somewhat on track! Maybe once I own a full set I'll invest in proper stones as well.

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