Tool Tip: How to Sharpen a Chisel
Intro: Tool Tip: How to Sharpen a Chisel
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!
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!
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.
STEP 2: They're Called Waterstones for a Reason
Put your stones in water and let them sit there a while. The few articles I've read about it suggest that only 5-10 minutes is needed. You may also choose to store your stones in water (like in a tupperware container); I know some who do, and some who caution against it.
STEP 3: Setting the Honing Guide
Insert your chisel into the honing guide with the bevel facing down. Tighten the honing guide just enough to hold the chisel, but leave it loose enough so that you can still adjust it. Ideally, the entire bevel will be touching the stone at the same time, but the front part is (obviously) more important.
Don't worry too much about getting it micron-level accurate at this point. Just get it to where you think the bevel is lying flat against the stone, and tighten the honing guide screw to lock the chisel in place.
Don't worry too much about getting it micron-level accurate at this point. Just get it to where you think the bevel is lying flat against the stone, and tighten the honing guide screw to lock the chisel in place.
STEP 4: First Passes at 800 Grit
Take your stone out of the water and put it somewhere where it won't slide all over the place. You may want to make a little setup like mine on Step 1. Another option is to place the stone on a piece of fine-grit sandpaper which has been secured to your workbench. You can see in the picture below that I had neither at the time, but merely used the lid of a plastic storage tub.
Set your chisel (in the honing guide) onto the stone. Applying even pressure on the back of the chisel blade, and with your thumbs on the jig, give it about five or six passes, forward and back. Try to distribute your passes over as much of the stone as you can, so you don't end up with a big groove right down the middle of your stone. Grooves are bad.
Wipe the blade clean and take a look at it. You'll now be able to see where the blade is making contact with the stone, because the grind marks will be worn away there. If you need to adjust the chisel's position in the honing guide, do so. You want the chisel blade to be contacting the stone at least for the first 1/8". The more the better, but the first 1/8" is the most important.
Do this step a few times. In between each set of passes, do three things: wipe the blade clean, inspect your progress, and rinse the stone of the residue that accumulated on it.
Now move up to the 1200-grit stone, and then the 4000-grit stone. Once you start making some passes with the 4000-grit stone, you'll notice the blade really starting to shine.
Set your chisel (in the honing guide) onto the stone. Applying even pressure on the back of the chisel blade, and with your thumbs on the jig, give it about five or six passes, forward and back. Try to distribute your passes over as much of the stone as you can, so you don't end up with a big groove right down the middle of your stone. Grooves are bad.
Wipe the blade clean and take a look at it. You'll now be able to see where the blade is making contact with the stone, because the grind marks will be worn away there. If you need to adjust the chisel's position in the honing guide, do so. You want the chisel blade to be contacting the stone at least for the first 1/8". The more the better, but the first 1/8" is the most important.
Do this step a few times. In between each set of passes, do three things: wipe the blade clean, inspect your progress, and rinse the stone of the residue that accumulated on it.
Now move up to the 1200-grit stone, and then the 4000-grit stone. Once you start making some passes with the 4000-grit stone, you'll notice the blade really starting to shine.
STEP 5: Using the Nagura Stone
The finer grits of waterstones (6000 and above) need a little help to produce the slurry needed to actually sharpen the chisels. Enter the nagura stone. You're now ready for the 8000-grit sharpening.
Take your wet nagura stone (which should have been submerged along with the other stones) and rub the top of your 8000-grit stone in a circular motion. You'll see the slurry starting to form on the top of the stone.
After each set of passes, rinse the stone like you did with the others, and reapply the nagura stone.
You're almost done. It's time to add a microbevel.
Take your wet nagura stone (which should have been submerged along with the other stones) and rub the top of your 8000-grit stone in a circular motion. You'll see the slurry starting to form on the top of the stone.
After each set of passes, rinse the stone like you did with the others, and reapply the nagura stone.
You're almost done. It's time to add a microbevel.
STEP 6: Adding a Microbevel
You've now gone through the four grits of waterstones, and you should have a chisel blade so shiny and sharp that it will put a smile on your face. But there's still one more thing you can do to help your chisel out: add a microbevel.
A microbevel (or second bevel) is just what it sounds like: a very small bevel at the end of your already-beveled edge. The primary purpose of this microbevel is to save you time. When your chisel dulls, you merely need to sharpen the microbevel instead of going through all of these steps from scratch. It will take several sharpenings before the microbevel has been ground more or less flat with the rest of the bevel; at that point, you will go through all of these steps again.
To put a microbevel on your blade, slurry up your 8000-grit stone with the nagura stone and put your chisel/honing guide onto the stone. Raise the handle of the chisel a tiny bit, and with a nice steady stroke, push forward to the other side of the stone. Pick up the chisel (don't draw it back on the stone), place it again on the near side, and repeat a handful of times. Each time, try to raise the chisel handle by the same very small angle.
After several sets of passes, you'll see a thin line on the end of your chisel blade. Job well done.
But wait! There's one more important step before you can pack your stones up and start hacking away at wood.
A microbevel (or second bevel) is just what it sounds like: a very small bevel at the end of your already-beveled edge. The primary purpose of this microbevel is to save you time. When your chisel dulls, you merely need to sharpen the microbevel instead of going through all of these steps from scratch. It will take several sharpenings before the microbevel has been ground more or less flat with the rest of the bevel; at that point, you will go through all of these steps again.
To put a microbevel on your blade, slurry up your 8000-grit stone with the nagura stone and put your chisel/honing guide onto the stone. Raise the handle of the chisel a tiny bit, and with a nice steady stroke, push forward to the other side of the stone. Pick up the chisel (don't draw it back on the stone), place it again on the near side, and repeat a handful of times. Each time, try to raise the chisel handle by the same very small angle.
After several sets of passes, you'll see a thin line on the end of your chisel blade. Job well done.
But wait! There's one more important step before you can pack your stones up and start hacking away at wood.
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!
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!
83 Comments
OldGuy52 8 years ago
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.
offseid 8 years ago
DoubleTrouble 13 years ago
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 13 years ago
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).
Evocatorum. 7 years ago
Love the article and reminded me that I needed to pick up stones (I keep forgetting).
You mention in the write-up storage of stones in water. Some can be stored in water (which, I can't be certain), there are those that can't. For instance, the Naniwa Chosera line of Magnesia bonded stones. The water breaks down the bonding material and will lead to the stone crumbling in ones hands... and at $140 for a #5000 grit stone, it would be horrible. It should go without saying that one should really consult the manufacturer for tool storage and maintenance.
offseid 7 years ago
amclaussen 14 years ago
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.
oilitright 8 years ago
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.
Broom 13 years ago
lcrookston 8 years ago
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.
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.
escher7 8 years ago
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.
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.
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!
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.
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.
Groaker 8 years ago
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.
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.
CJStephens 8 years ago
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!
see spot run 15 years ago
curbowman 9 years ago
Someone told me a granite or marble countertop could be used for truing stones. What do you think?
jessevans67 9 years ago
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 "dial in" 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 "Surface Plates" 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
see spot run 9 years ago
offseid 15 years ago
mauriceh 14 years ago
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 13 years ago