Hand Tools Archive

i'm sure...
Response To:
Re: wood stiffness ()

David Weaver
on an ideally set power jointer, you could get a rub joint. My mechanical engineer friend has gone to enormous pains to set his tools up (to the point of it being unproductive) and I don't ever remember seeing any part of an open joint coming off of his jointer. He was obsessed with the cast fence that delta made (I think it was a DJ-20 because the fence had twisted to a tiny minimal amount so a starrett certified square would find no light at one end and a tiny small amount at the other).

The point with the hand tooling bits here is that rub joint quality joints can literally be gotten during the normal mode of just planing the rough edge off. If they aren't gotten right away, it's a very short period of time before truing achieves them (less time than most hand jointing or match planing methods would take just to go through the steps once).

There's a link you're missing here, too, as you're comparing power tool joints to hand tool joints. Let's say you have one of these concave planes - the length of the curvature may be over 14 inches or something. Your jointer tables are probably 30-40 inches. Whatever error you have will be spread out gradually over a distance. The plane will generate its flatness error on the edges in the distance from the start of the hollow to the mouth. That's something like 1 1/2 thosuandths over 3 inches. Even if the rest of the joint is mostly flat, you have a gap at the end that's steep and short. It's not like pulling together a gradual error on a power tool joint (as in, you can't actually do it by hand and sometimes it's hard to even get it to clamp shut)

What you're thinking for power tools isn't the same. You can reason through all kinds of scenarios, but until you experience the issue with a hand tool and account for all of the things like what I just mentioned above (the whole error occurs just in a couple of inches on the end of a board - I just realized that - it's not the length of the error that's the issue - it's the length of the distance from the toe to the mouth), it won't make sense to you.

Same error, as we've discussed, in the opposite direction (Convex sole), and the plane creates a long gradual hollow at the most. You can just pull it shut, just like a power tool joint.

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