Cutting Angles

I bought a Millers Falls No 7 Jointer Plane a few weeks ago that had a pitted blade in it. While most people would look at a blade like this and immediately think that it belongs in the trash, I decided to see if I could get it to work well enough to slice thin shavings off a piece of cherry. Diamond dressers, one of the more expensive options, perform best where some type of accurate feed and contact adjustment are available. I had de SSS before I had the Tormek and the reason I prefer to use it here is because it is less messy. If you have one, now is a good time to use it. Most block and bench plane blades are ground to 25° but some smart folks argue that there need only be clearance under the heel of the bevel.

It is now pretty easy to do the final part with the hand stones and the veritas plane holder thngamajig. I don’t get into harder steels and thick irons because I found the irons present unnecessary problems. Just that we can get caught up in the exactness or intolerance of other angles and forget that it doesn’t have to be something so rigid. The plane iron in our example is 75 mm wide, 95 mm long to the beginning of the bevel, and a bevel angle of 25 degrees. Many woodworkers use a series of sheets of sandpaper or honing film as their abrasive medium.

Sharpening wood chisels and plane blades is almost a forgotten art with all of the honing wheels and modern grinders but there are still those of us who believe that a good chisel should be treated with the utmost respect and sharpened, by hand, to the point where it will cut a cigarette paper with no tearing. There is definitely a message there and for me the answer finally came once again from Paul Sellers. It is a little slow so you need some patience, but I didn’t want to buy special tools just to true up the blades like you.

Possibly more significant, you have sharpened the blade of your standard block plane in a manner that will give you a lower cutting angle than someone who sharpens a low-angle block plane in a standard fashion (12° bed angle plus 25° bevel, a total of 37°). Please note: the Ruler Trick” is only suitable for use with plane irons and not chisels, as the back of a chisel needs to remain totally flat and used as a reference surface to guide the tool. Cut a strip of sandpaper equal to the length of the chisel you’re going to hone.

Fine stones and sandpaper have high grit numbers which correspond to small abrasive size. However I’ve never truly mastered sharpening knife blades, so for me a Tormek type machine is useful. The table below shows the three most common bench and block plane types and the proper angles at which to sharpen the irons. To calculate the extension for a particular bevel angle, you need to know the exact jig dimensions and the thickness of the blade. The best thing that ever happened to me was watching Paul’s method for sharpening freehand. A joiner plane is a very long plane used only to straighten and join two board edges for gluing.

After picking up a soft Arkansas stone at a local sporting goods store, I was finally able to get my chisels and plane irons kind of sharp. The skew angle graduations cover the range of 10° to 45° in 5° increments, and there are additional marks (18°, 22°, 28°) to cover the angles of popular skew plane blades. Ultimately, all of my students end up freehand sharpening because of the speed and efficiency and indeed variability of creating say an instant change to a 30-degree bevel to make it 40-degrees for chopping mortises in certain types of wood or something like that instead of a hand paring angle.

Since I wrote the above I have actually sharpened a lot of stuff, including bringing old edges back from the dead, and am even more convinced that it is the way to go, for a woodworker that is. If you are a surgeon or just a sharpening fetishist you could go further! There’s a certain feeling of satisfaction of getting a nice reflection on the backs of planes (and chisels of course).

I also have a Tormek (which I use to regrind the primary bevel when the secondary bevel gets too large as I was originally taught by DC). The larger and more sophisticated of the Veritas guides, the MkII is a roller-style guide with a clamping bar that accepts blades up to 2-7⁄8″ wide. I’m a newb, too, but there’s nothing cooler than a well tuned plane pulling gossamer ribbons off of spruce.

The port makes it practically foolproof to sharpen straight chisels and plane irons at the proper bevel angle evenly and repeatably. When I first started working on them, I did all the sharpening and re-establishing the angle by hand first with sand paper and then an oil stone. They have come out with a side securing attachment for chisels, but most plane blades won’t fit.

They’re extremely efficient, they’re less expensive than any other stones, and they cover a far wider range of grits than any other sharpening system. I hope it is evident that one need not be too fussy about grinding angles providing that they are less than the intended honing angle, but it seems to me that there is little point in careful consideration of honing angles unless they can be reproduced pretty exactly.

If you don’t need to use the sharpening guide for other irons, you can leave the settings as they are and then touching up the edge of the iron, in the course of a larger job, for instance, you can re-insert the iron and achieving the same fine edge is very quick and easy. My honing guide has measurements written on it that blades should protrude in order to achieve the desired angle. I have spent the last several days sharpening some of my plane blades and the results are superb. The main reason for a plane from the good old days was to get a true square edge (except for the smoothing plane).

When properly forged like this, O1 will feel smooth and buttery on the sharpening stone and produce a minute wire edge that falls away cleanly leaving a beautifully crisp, surgically sharp edge. This is done by lubricating an extra coarse diamond bench stone ( Diamond Whetstone , Duo-Sharp® & Dia-Sharp® models available) with water and placing the back of the plane iron blade down on the sharpener. 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.

Instead of a single eye bolt as the pivot point, I made a slot that the tool holder fits in. It lets the tool holder move freely, but holds it on a flat, level plane. I have also found that many cutting fluids are often too viscous to be used effectively for hand tool sharpening so we come back to the thinner fluids that are good for floating/cleaning. If the back of the chisel has pitting or heavy rust, start with 80 grit sandpaper until you remove all the pits. Basically, the answer is that the appropriate grinding and honing angles for any kind of plane depend on the quality of the steel.sharpening plane irons

This simple method uses four different grits of wet/dry sandpaper and buffing compound on a leather strip. Although the chisel can be held in the fingers for both grinding operations once you get to grinding the bevel itself a jig can be a big help. With this motorized sharpening system, it only takes a couple minutes to re-establish an angle on a plane blade. For carpenters sharpening is a massive subject but use whatever method works for you.sharpening plane irons

In the world of water-cooled sharpening systems, there is no more respected name than Tormek There are several reasons for this longstanding position of honor. Two plastic rollers at the back end of the 809 guide are made to roll on either a sharpening plate (glass, granite, etc.) and keep the blade at a constant angle during sharpening or honing. The result of all this is that I am now seriously considering investing in diamond plates and using PS’s method which seems to return you to the main object of the exercise very quickly…. This is much more secure and prevents angling due to slippage during sharpening.