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designing and building with wood channels my creativity and challenges my mind.
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Friday, September 23, 2011

How to sharpen chisels and planes with sand paper

As I get better at furniture making, I am beginning to use chisels and hand planes more often.  Why?  It's not only because I'm trying to learn expert techniques (like hand-chopping mortises or flattening a panel with hand planes).  I'm also reaching for these woodworking mainstays more often because they're sharp.

One thing I've noticed about chisels and planes: almost everybody has one (or more), but few people use them.  The reason is that, unlike many other tools, chisels and planes simply do not work if they're not sharp.  Take a new hand plane out of the box and try to take a shaving, and you'll likely end up frustrated, wondering what the damn things are good for, anyway.

But if your chisels and planes are sharp, they become go-to tools that get used nearly every day.  Sharp chisels and planes have taken my furniture to another level of quality, and fitting snug joints has become a lot easier.
But I didn't go out an buy a Tormek wet grinder to sharpen my blades, and once I "discovered" sand paper sharpening, I didn't spend spend a long time sharpening, either.

Using sand paper you don't get the hollow grind of a wheel.  But the speed of sand paper makes up for any time lost sharpening the "entire" bevel of a straight-ground blade.

Here's how I sharpen with sand paper: 

First off, I use a bevel guide for the initial steps in the sharpening process, especially if I'll be grinding the entire bevel, which I sometimes do on the first sharpening.  So once I put the blade in the bevel guide, I do the following:
  1. load an 80 grit belt into my belt sander.  I use a 6x48" stationary sander, but even a small belt sander, held upside-down in a bench vise, works fine.  
  2. turn on the sander and lower the blade onto the abrasive, following the bevel guide's instructions.  I make sure to use light pressure, and I sand in 5 second sessions to avoid burning the steel of the blade.  
  3. Dip the blade in water or oil between sessions on the belt.
  4. Repeat these steps with 100, 120, 150, 180, 220, and 320 grit belts. 
  5. use spray adhesive to stick sheets of abrasive to a piece of 1/4" glass: 400, 600, 800, 1200, 1500, and 3000 grit.  
  6. By hand, sharpen the blade on these grits.  
  7. finally, move to your fine stone, and then leather strop.
This method starts with 80 grit abrasive to quickly re-define the bevel angle on the blade to match the bevel guide.  This is the big time saver.  But sand paper in general cuts faster than stones, so the whole process takes only 10-15 minutes per blade.

Finally, if you want, you can put a steeper "micro bevel" on the tip of the blade.

I know that some of you out there will insist this method is too crude for fine steel.  But I assure you it is not!  the end result is the same, especially if you finish the job with your choice of stone, honing compound, or whatever.

And for those who swear by the hollow grind of a wheel: keep on keeping on.  When I can afford a Tormek, I will likely join your ranks.  Until then, I'll use sand paper to keep my blades sharp, and my chisels & planes in the rotation.

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