How to Sharpen a Chisel with Sandpaper

Chisel bevel with honed to a mirror finish.

Chisel bevel with honed to a mirror finish.

I like to buy used chisels at antique stores and flea markets. You can get a quality chisel for a few bucks, and with a little elbow grease turn that rusted dull tool into something you can shave with. You can use water stones, oil stones, or … sandpaper. Yup, sandpaper. This article will show you how to use sandpaper to sharpen your chisels and plane irons to a razor sharp edge that your oil and water stone buddies will be jealous of. All you need is sandpaper in a variety of grits, a flat surface like a piece of glass, some 3M adhesive spray, and some acetone to clean the adhesive spray off the glass when changing the sandpaper.

The use of sandpaper to sharpen edge tools is really nothing new. The idea has been around for about as long as sandpaper. Sharpening is all about removing small amounts of metal by rubbing the blade against an abrasive. Water stones, oil stones, ceramic stones, and sandpaper come in different grits (from course to fine and everything in between) that indicate the size of the abrasive. Fine stones and sandpaper have high grit numbers which correspond to small abrasive size. The opposite is true for course stones (low grit number, large abrasive size).

Why do I use sandpaper instead of stones? There are a lot of good reasons why I like to use sandpaper instead of stones. Here are some of the reasons why I choose sandpaper over water or oil stones.

  1. It’s cheaper to get started. You don’t have to invest in buying new stones. A minimum of 2 stones and a flattening stone are needed to get decent results, but more grit steps in between will get you to a much sharper edge faster than skipping 1000’s of grits. Norton Waterstones, an industry favorite, offer stones in 220, 1000, 4000, and 8000 grit. So, that’s 4 stones plus a flattening stone… you’re easily looking at a few hundred bucks. With sandpaper, you can get all your supplies for around $25. In the long run you may end up spending more on sandpaper but I’m more of a “get the job done right on a shoe-string budget” type of guy.
  2. You don’t have to worry about concave areas on your stones. If you grind your blade too long on a waterstone you’ll create a hollow area on the stone.  You’ll have to use a flattening stone to work the stone flat again. I find this to be a nuisance as I constantly have to adjust my blade across the stone so I don’t create a hollow area. With sandpaper and glass, you never have to worry about creating convave spots. The glass is perfectly flat and doesn’t get worn down since the sandpaper takes the brunt of it. You can’t mess up sandpaper on glass, and you don’t need a diamond plate to get back to flat.
  3. You get a really, really, really sharp edge. The back of my chisels are so shiny they’d pass for a mirror. My chisels are so sharp they could be used to shave in the morning. No joke, check out the video below at the 3:30 mark. I’ve gotten good results with waterstones but nothing like the sandpaper method. I think I get a better edge because the sandpaper method involves going through 6 different grits, progressively getting smoothing the surface of the two cutting surfaces. With stones you might have a 2 or 3 grit progression.
  4. All grits are not created equal. 2000 grit sandpaper puts a finer polish on a blade than a 4000 grit waterstone.
  5. It’s not messy. Waterstones can be a mess in the workshop; water and slurry everywhere. And water rusts your tools so make sure you wipe and oil your tools immediately after sharpening or else suffer the consequences! Oil stones aren’t much better and in my opinion, are inferior to water stones in their ability to produce a finely honed edge. I seem to get oil everywhere when I’m using oil stones and oil isn’t easy to remove from clothing, your workbench, your projects… I use sandpaper dry, you just have to brush off the metal filings every once in awhile. No mess.

Tools and Materials

  1. Sandpaper – Go to an automotive store like AutoZone and look in the body finishing section for sandpaper designed to sand metal. For resurrecting old chisels, or anything other than touch ups, use 80 grit. They also sell an “Assorted Grit” packs. 3M makes a 220, 400, 800, 1000 grit pack. If you want to go even higher, and get your chisel to shine like a mirror, pick up a pack of 1500 or 2000 grit sandpaper.
    80 grit sandpaper.

    80 grit sandpaper.

    Assorted grit sandpaper.

    Assorted grit sandpaper.

    1500 grit sandpaper.

    1500 grit sandpaper.

  2. Plate glass or a surface plate
  3. 3M 77 spray adhesive
  4. Acetone and paper towel or rags
  5. Honing guide (optional but highly recommended)

Instructions

  1. Grinding – (This step is optional if your chisel isn’t in rough shape.) Use a hand or foot powered grinding wheel to grind the tip of the chisel so that it is 90 degrees to the sides. Vintage chisels were sharpened by hand, a process that produces human error resulting in skew and camber on the chisel. We want to remove this and get back to a straight edge. Don’t even think about trying to grind the back of the chisel. The back of the chisel is flat, the grinding wheel is round, it’ll never work. See the next step for dealing with the back of the chisel.

    Hand operated grinding wheel.

    Hand operated grinding wheel.

  2. Honing the back – The back of the chisel must be perfectly flat. Only the last 1/2″ or so needs to be flat, but I usually end up with an inch or two polished. If the back of the chisel has pitting or heavy rust, start with 80 grit sandpaper until you remove all the pits. Then move up through progressive grits until you get to 1000 – 2000 grit, depending on your level of OCD. Cut a strip of sandpaper equal to the length of the chisel you’re going to hone. Spray some 3M adhesive on the back of the strip of sandpaper and place it along the edge of the glass (or surface plate), pressing it flat. Press the back of the chisel against the sandpaper mounted on the glass. Push the chisel back and fourth making sure the chisel stays flat against the surface. As metal filings clog the sandpaper, stop and brush or blow the filings away. Once the sandpaper wears out and is no longer effective, remove the sandpaper by peeling it off the glass and removing the sticky residue with acetone and paper towel.

    Back of chisel honed to a mirror finish.

    Back of chisel honed to a mirror finish.

  3. Honing the primary bevel – If the bevel is pitted, nicked, or has a camber (arc in the cutting edge), start with 80 grit sandpaper. Insert the chisel into the honing guide. Set the honing guide to 30 degrees. You may want to vary the angle to as low as 25 degrees depending on the on the wood and other factors. For most hardwoods, I prefer 30 degree primary bevel. If you’re planning on adding a secondary bevel, you don’t have to work all the way up to 1000 grit. If you’re not doing a secondary bevel, you can go to as high of grit as you feel necessary.

    Chisel bevel with honed to a mirror finish.

    Chisel bevel with honed to a mirror finish.

  4. Honing the secondary bevel – This step is optional, a lot of people don’t add a secondary bevel, so the choice is yours. I prefer to add a secondary bevel that is about 2-3 degrees greater than the primary bevel. So, for example, if my primary bevel is 30 degrees, I might have a secondary bevel of 3 degrees, giving me an effective cutting angle of 33 degrees. My honing guide has a small knob that allows me to set a secondary bevel without adjusting the chisel in the guide. If you’re doing this free-hand, it takes some time to “feel” the correct angle. Practice on your second rate chisels before you feel comfortable doing a secondary bevel on your favorite chisels.

    Primary and secondary bevels visible.

    Primary and secondary bevels visible.

  5. Strop the front and back of the bevel – Honing produces a wire edge that clings to the cutting edge. To remove this, rub the front of the chisel along a leather belt (stropping belt) smeared with buffing compound. After dragging the front of the chisel toward you, flip the chisel over and strop the back of the chisel. You’re bending the wire edge back and forth until it breaks off, leaving a clean sharp cutting edge.
  6. Shave your beard. If you get razor burn, keep practicing!
  7. Make a sheath or covering to protect the edge.

    Making a leather sheath.

    Making a leather sheath.

1 comment for “How to Sharpen a Chisel with Sandpaper

  1. Sophia Liam
    May 20, 2014 at 7:20 pm

    I didn’t realize you could use sandpaper as a sharpener! I’m going to have to try this on my knifes at home. Thanks so much for this article!

    Sophia Liam

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