Avoid compressing soft wood fiber

[Wakahisa Shinta]

I recently made two sets of saw horses from 2x4 boards that I saved from the crates for some power tools. I don't quite know the exact species of wood, but it is soft. The saw horses utilize mortise and wedged tenon joinery that can be taken apart for compact storage. Certain parts needed stopped dadoes, which I cut with freshly sharpened chisels. Here is where I ran into problem. The chisel compresses the wood fibers prior to cutting them, making the shoulders of the dadoes not as smooth as I would like.

I experimented a bit and used a razor blade to score a line prior to chopping with a chisel. This works out a bit better, but not great. I then resorted to repeated scoring with the razor blade to depth (3/8"). This works still better.

They are saw horses, so the aesthetic isn't all that critical. However, I would like to know if anyone has a solution to this problem. Is it dull chisel that is the problem? Please keep in mind, I am a novice at hand tools and sharpening.

[Brian Holcombe]

If you are chopping the line, then you might simply be leaving too much material to chop. What you could do it chop shy of the line and then pare to the line.

[Ryan Mooney]

If you are chopping the line, then you might simply be leaving too much material to chop. What you could do it chop shy of the line and then pare to the line.

This ^^

Sometimes I end up having to pare back in 3-4 or more passes to get a decent cut depending on the type of wood and how studious I've been at sharpening the chisel.

[Nicholas Lawrence]

If you are chopping the line, then you might simply be leaving too much material to chop. What you could do it chop shy of the line and then pare to the line.

+1

The chisel is a wedge, and driving it into a board will cause the beveled side to push the flat side in the opposite direction.

Or you could just need to sharpen your chisel. Try paring some material, and see if it cuts easily and leaves a smooth surface. If not, your edge may need some attention.

[Stanley Covington]

Without seeing the work or the chisel, the most likely culprits are:

1. Dull chisel. No such thing as a chisel that is too sharp.

2. Bevel is too great. Make the bevel angle smaller. You might try going as low as 20 degrees. How long your chisel edge will last however, will depend on the nature of the wod being cut and your technique. Some chisel edges will chip, while others will roll if the angle becomes too small. And while a low-angle bevel might work well for soft woods like palownia, it will likely fail very quickly on harder woods like Ipe or Keruing.

3. Technique: Start in the center of the cut, well away from the layout lines, and make smaller, shallower cuts to create a V-shaped trough. After the necessary depth is reached, then cut straight down from the layout lines. This trough will relieve forces created by your chisel on the layout line, and make the cut cleaner with less tearout, so long as your chisel is sharp and the bevel not too high.

1, 2, and 3 above are the same thing Brian, Ryan and Nicholas were writing.

4. Use a marking gage with a sharp blade to score the wood deeper. Maybe you are already doing this.

Woods that have relatively weak summer wood combined with relatively had winter wood, like Douglas Fir, Southern Yellow Pine, or Radiata Pine, can often be hard to cut cleanly. They also tend to be hard on chisel edges. The point being that soft woods can be harder to work cleanly than harder woods. There is a Japanese term 適材適所 read "tekizai tekisho" which is used to mean "The right man for the job," but which came from working wood (perhaps boat building), and literally means "the right material in right place." Often it is wisest to choose the wood species to be used to match your tools, techniques, time, and budget even of that means sacrificing some performance in the finished product or other goals. Perhaps your choice of this very soft wood was based on cost, or weight. But perhaps it would be better to select a different material next time.

2 drachma.