Popular Woodworking 2008-10 № 171, страница 53

because it will press down the grain of the wood as the cutter slices it. If the mouth is tight, then the cutter will be unable to get under the grain and lever it up ahead of your cut. tearing out the grain. This sounds reasonable, but there's more to it.

The sometimes-forgotten problem with a fine aperture is that it makes your tool more likely toclog. especially if you have thcchip-brcaker set close. So a tight mouth is usually a time-consuming set-up. unless you have a smoothing plane dedicated to fine cuts.

1 start closing up the mouth of a tool only when my othereffous fail: I've sharpened the iron. IVe set it to take a fine cut. and I'm using the tool that hasa high (62°)angk of attack. If all those efforts fail. then 111 weigh my choices: Tighten up the mouth and face some clogging issucs.or get out the card scraper or sandpaper and call it a day.

No 6: Chipbreakers

If you follow the conventional wisdom for setting yourchipbrcakcr. you might hate your handplane.

What's the conventional wisdom? According to Charles Hollzapffcl's seminal 19th-century work on the cuttingact ion of tools, you should set your smoothing planc'schipbreakcr .02* from the cuttingedge of your iron (other respected sources say to set it even closer) and to haw an extremely tight mouth.

This. Holt zapffel says, prevents tear-out.

This, says your neighborhood editor, makes your plane choke.

So here's the problem: If high planing angles reduce tear-out, and skewing a plane reduces your angle of attack, then how can skewing the plane reduce tear-out?

Chipbreakerscando more harm than good in a handplane. Whenever I'm having troubk with a plane (especially if the plane is choking or refuses to cut), the first place I look is the chipbreaker. Whenever I fettle a new or vintage handplane and the thing worn behave, the first thing HI do is swap out its chipbreaker with another plane that hasa workingchipbrcakcr. In almost all cases, this solves my problem.

So what isthc purpose of the chipbreaker? My cynical view is that it became widely used so toolmakcrs could use a cheap, thin steel cutter and reinforce it with an inexpensive iron or soft-steel plate. This is supported by the odd names given tochipbreakcrs. Some cariy sources call them capirons. double irons, break irons or top irons. In other words, not

Break-dow n at the chipbreaker. I be chipbreaker is supposed to reduce tear-out. butk'ti is set too closely, k win clog your plane. When you hase a problem with your tool, investigate the chipbreaker first.

everyone agrees that they were designed to break chips.

Early planes had thick irons and didn't have chipbreakers, even during the age of mahogany, whkh is hard to plane well.

In my view, the chipbreakers primary purpose in a modern plane is to mate with the tool's blade-adjustment mechanism and to aid in chip ejection. Oh. and it exists to frustrate you.

So in what position should you place jour chipbreaker? I set mine back about Vu" in a smoothing plane - sometimes even a little further back if the mouth istight. All I'm really trying to do is to prevent clogging

Which begs the question: Why did I list a chipbreaker as one of the ways to reduce tear-out? Well. I did mention one use for the chipbreaker in a modern Bailcy-stylc plane - it mates with the tool's depth-adjustment mechanism. This mechanism allows you to easily set your tool to take the finest cut possible. whkh really will reduce tear-out.

No. 7: Skewing

I keep a list in my head of what I call "The Woodworking Mysteries" - things I pretend to understand but arc outside my grasp.

One mystery is howa tree can pump water to the furthest reaches of its branches. There arc many clues as to how it works, but a complete picture eludes me. Another mystery is about how yellow glue actually works. Again. I've never read a satisfying explanation.

A third mystery relates to handplanes and basic geometry. One common strategy for reducing tear-out in a board is to skew the plane as you make the cut. This strategy was beaten into my head by all my teachers both dead and living It's repeated on the Internet by pcopk I deeply respect and trust. And I do it myself in my work.

But if you do the math, you see how this strategy docsnt make much sense.

l.ct sstart with a fact: The higher thcangk of attack when you plane a board, the less likely you arc tocxpcricncc tear-out. Another fact: Skcwringa plane in use reducesyourangk of attack. Mike Dunbar, the founder of The Windsor Institute, explains this in the ckar-est way possible. When a shavingcncountcrs a plane iron, the angle of attack is like a hill that the shaving has to walk up. If you walk straight up that 45* hill, that's a lot of work. When you skew the tool, it's like the shaving is walkingupthe hill at a lower angle. Or put another way. it's a bit like buiklinga road up

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