How do I sharpen a chisel/plane blade?

Question

I'm getting started with woodworking and am looking to refine my technique for sharpening chisel/plane blades. Currently, I just have a cheap double-sided water stone, but am now looking to get a "proper" setup which will hold me moving forward and then also refining my technique. Any suggestions?

Edit: Specifically, what type of water stones and diamond stone do I need, should I get a honing guide, what else is must have vs a nice to have, etc. Then what process do I go through to "correctly" use these tools.

Answer 1

Sharpening is a lot trickier than one would expect. In order to have a sharp blade you need to have two polished sides meeting one another: the back of the plane iron (or chisel) and the bevel. A couple of tips really helped me as I was sharpening.

1. Sharpen up to 8000 grit. I used to have harbor freight stones and they only went up to 1000 grit--not nearly enough.
2. Keep the back flat and the bevel at 25 degrees (or whatever degree it uses). A honing guide usually helps maintain the bevel, but if you don't have one, rock the plane iron until the bevel snaps level, then drag across the stone.
3. You know you're sharp when you can pare away at end grain on a soft wood (e.g., pine or alder).
4. Continually check the "reflectivity" of the meeting edges (i.e., the back and the bevel) to make sure the surfaces are polished. Look at @Peter Grace's image toward the meeting edges--that's what you're looking for is a window-like reflectivity at the meeting edges.

Good luck!

Answer 2

You mention that you have a sharpening stone. One improvement might also be to make an angled guard that you run atop the stone that helps to impart the proper chisel angle. Something like the below might help to ensure you get a razor-sharp edge at the proper angle.

Answer 3

In trade school we sharpened tools on a fine sanding wheel, like a 16 in grindstone. I leaves a slightly concave surface on the angled side, and left a tiny burr on the flat side. Using a fine oil stone and honing only the angled side until the burr came off as a shiny thread, and we were done. We then checked to see if we could shave some hair off our wrist. about 99% of the time we could. Two very important things the edge of the blade has to be straight and square, and sharpen slowly enough so the metal does not overheat and turn blue.

Answer 4

I would recommend reading the book "The Razor Edge Book of Sharpening" by John Juranitch. This book is the simplest path to understanding the basic principles.

You do not necessarily need a stone, just two gritted surfaces of about 80 grit and 400 grit. Gluing sand paper to a square of plate glass with rubber cement is good enough, believe it or not. A guide of some kind is critical and you need a way to set the angle on the guide. One advantage of using a grinding wheel is that you do not a movable guide, just a fixture to hold the blade at the right angle.

There are three basic steps:

1. grind the relief angle
2. grind the cutting edge
3. remove the burr

You really need to read a book such as the one I cited above to get the details right.