Instructables
Picture of Tool Tip: How to Sharpen a Chisel
chisel1.jpg
For many people, chisels are handy little tools...for prying open cans of paint, that is. But a properly-honed chisel is an extremely useful woodworking tool.

Sharpening a chisel is actually quite easy, especially if you use a honing jig. An initial investment of less than $150 will get you chisels, a honing jig and sharpening stones - all of which will likely last longer than you will.

When I was first starting out in woodworking, I assumed that the "sharp" chisel I brought home from the hardware store was ready to go. But just because something is sharp enough to go through your hand if you're not careful does not mean it's sharp enough to take on wood with nice results.

Chisels go through an elementary grinding when being made which simply gives them a beveled edge. Look at the second picture below, and you can see the grinding marks on the main part of the blade. When we're done, the cutting edge will be glassy smooth.

So let's get started!
 
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Step 1: Items Needed

There are numerous ways to sharpen chisels. Some do it strictly by hand, while others use a jig. Some sharpen with oilstones, others with waterstones, and still others with diamond stones. Some use a strop at the end. This instructable will demonstrate the use of waterstones and a honing guide, and will get your chisel sharpened to 8000 grit with a microbeveled edge. Now here's what you need:

  • Chisels: I recommend Irwin brand chisels (formerly Marples). Woodcraft sells a set of four for $39.99. This instructable will work for any chisel, but you might need to do it more often for the cheaply-made ones.
  • Honing Guide: A honing guide keeps your blade at the right angle for sharpening. Those who are more experienced go by feel, and indeed you may try this, but I use a jig. The one I use costs only $11.99 from Woodcraft.
  • Sharpening Stones: As I just mentioned, this instructable will demonstrate sharpening with waterstones. I use two combination stones (again, from Woodcraft), that take the sharpening through grits of 800, 1200, 4000 and 8000. The 800/4000 stone will set you back $24.99 and the 1200/8000 stone will cost $49.99.
  • Nagura Stone: If you use a waterstone with a grit of 6000 or higher, you will need a nagura stone. The nagura stone creates the "slurry" that helps sharpens the chisel. The same link for sharpening stones above contains a link for the nagura stone, which you can buy for $9.99.

Total Cost (at time of posting): $136.95. Of course, if you only need one chisel you can knock $20 to $30 off of that total, depending on the size of the chisel you get.
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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 "metal dust" left on the stone.

             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 "polishing". 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.
       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 "cut off" 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.
       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!
offseid (author)  DoubleTrouble3 years ago
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.

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).
ssalva29 days ago

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.

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.

Someone told me a granite or marble countertop could be used for truing stones. What do you think?

Sure. It is hard and flat and won't deflect when you press hard which is one of the important things.
offseid (author)  see spot run5 years ago
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:
One of the very best ways to "true' your stones ( making them flat again is called "True'ing" them) is to pour some water on a flat concrete sidewalk, and work the stone on this surface.
I find a "figure 8" pattern is best.
This cuts the stone to flat very quickly and effectively.
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.

Broom mauriceh4 years ago
Should work, if you vary the path of the stone a good bit (to avoid an area of cement with locallized wave).
Thanks!
wow , thanks thats good info ....
Papa_20141 year ago
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.
dent2442 years ago
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
thepelton5 years ago
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!

Thanks for the suggestion.
Danzeyboy5 years ago
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:

http://a.imageshack.us/img838/5759/sideo.jpg

Skip the stones!
gitm Danzeyboy5 years ago
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).
offseid (author)  Danzeyboy5 years ago
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!
wa7jos4 years ago
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.

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.

Once you get your chisel sharp, it is usually only necessary to hit it with a few strokes of the finest grit to "tune it up".

offseid (author)  wa7jos4 years ago
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!
offseid (author)  roflmaozedong6 years ago
It's all good. Why don't you make up for it by giving a plus to a lousy instructable? ;) Just kidding...
Broom offseid4 years ago
Bwahaha!
ezcheese5 years ago
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.
Broom ezcheese4 years ago
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 "biting", and sharp.

Sharper edges will bite on steeper slopes of your nail. But 45-deg is a pretty decent edge.
amclaussen4 years ago
 I have found that sharpening with progressively finer wetordry sandpaper over glass is both very practical and comparatively inexpensive.  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.  Only the worst cases of badly dented chisels will benefit from a complete treatment on a set of 3 to 4 stones.


In my case, I bought a somewhat similar adjustable angle guide from "General" 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.  Cutting the sandpaper in those widths gives several strips from every sandpaper sheet, which means even more savings!


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.


The glass plate is 3/8" (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.

For me, the glass and wetordry sandpaper is the way to go.

amclaussen, Mexico City.
Brilliant.
Rishnai6 years ago
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?
offseid (author)  Rishnai6 years ago
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. :)
Rishnai offseid6 years ago
I don't know either, but I guess that's why I'm not in the razorblade business.
Kavall Rishnai4 years ago
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 :-)
KnexFreek4 years ago
 cool
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)
offseid (author)  Future filmaker5 years ago
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.
offseid (author)  offseid5 years ago
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 : )
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