I get a lot of questions about tear out. (I know, you're jealous of my life.) Specifically I get questions about ways to alter a plane or features of a new plane that will prevent tear out. I have already talked about my views on bells and whistles on tools on this blog but I think it needs repeating.
Tear out is not a mystical event whose roots lie in the deep past only understood by some monk high up in a cave on the side of the Matterhorn (and I do mean the one at Disneyland). Tear out is an indication of 1 of 3 things:
- You went the wrong way in relation to the wood grain
- Your blade needs sharpening
- You're taking too deep of a cut
Yes, maybe I'm over simplifying here but I think that is a good thing. While things like mass and blade angle and whether the plane was built on a Tuesday evening after a meteor shower can help make tear out less of an issue, the above 3 things are ALWAYS in play.
Let's look at an example:
I'm jointing the edge of some very curly Cherry panels for a blanket chest I'm making in The Hand Tool School. The grain direction is indeterminate from looking at the face grain so I take a pass in the direction I think is right.
I always say the best way to read the grain direction is to take a plane pass. If it tears and jumps around, go the other way.
The plane shudders a bit and jumps down the length of the board leaving torn grain behind it. Guess what? I went the wrong way. So I change direction and go the other way and the plane goes kinda smoothly along the edge leaving a mostly smooth surface with small patches of torn grain in the darker curly parts. Welcome to figured wood. There is a prevailing grain direction but even then you get these little switchbacks that exposed end grain and change the direction of the fibers constantly. It is these little hiccups that give up the lovely figure and chatoyance we prize so much.
Well I've got the direction of the plane pass right now, what's next?
Sharpening the blade should be a given. It makes work easier and cleaner and whenever tear out shows up that should be the first thing you do. A razor sharp blade eliminates tear out easily in all but the most ornery of woods. Grab any rusty hunk of plane and put a razor sharp blade in it and you will be surprised how well it deals with that torn grain.
But's here's the rub. I just sharpened this blade. I know its sharp. The still slowly oozing cut on my left pinky is a testament to that when I carelessly nicked it while putting the blade back into the plane.
Finally I grab my mallet and tap the body of the plane, reducing the depth of cut. Reset the wedge and take a pass. The pitch changes dramatically going up a few steps on the Mixolydian scale (I only plane to medieval musical scales) and the action of the plane smooths out. You can see the difference in my shavings coming out of the plane. The new ones have more of a gossamer quality to them and are much longer as the plane cuts through the end grain sections instead of stuttering and creating shorter shavings.
A few more passes of the plane and here is what I have now. Remember you have to plane to the bottom of the potholes created by the original tear out before you can gauge if it is working.
Problem solved. No need for fancy bevel angles or swapping frogs for a higher pitch. Sharpen, change directions, and lighten the cut.
There will always be a board that will put up more of a fight than this one. Exotic, jungle wood for instance is much harder to deal with. But at its heart I think you will find some variation of these three elements will solve your problem.
This "Hand Tool School" series is provided courtesy of Shannon Rogers, a/k/a The Renaissance Woodworker. Rogers is founder of The Hand Tool School, which provides members with an online apprenticeship that teaches them how to use hand tools and to build furniture with traditional methods.
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I've found these same principles apply to power planers and jointers as well (albeit they're certainly more difficult to control.
I was destroying some nice pieces of curly maple I had, until I dropped brand new blades into my powered planer and jointer, and stepped down to taking off 1/32-1/64" at a time. Suddenly, flawless cutting. Even on tight grain bends!