Wooden plane flex
thomd
>I rigged up my largest jointer, a 30 inch long beech jointer with a body height of 3+ inches, and a width of 3.375 inches. I couldn't quickly rig the dial indicator near the mouth it was a little forward of that point which means the flex value would be understated, and the flex value from such a long plane would also be overstated relative to it's length relative to a standard jointer. I'm not trying to be really precise here...
I got about 5 thou flex out this p[lane. It took quite a bit of force, so that is probably comparable to the 22 inch jointer, since the same felx over a longer sole is a stiffer result but it was not right in the center. This plane does not have a forward knob, so tweaking it is not really part of the normal pattern of use, one is moreso holding it flat.
I also flexed a half roughed out jack plane blank where I could get right in the middle. it is about 18" long not trimmed and I could flex 5 thou into it with the dial over center.
I then tried the Japanese plane that I was expecting to be a banana. It flexed like a brick. This is a jointer and it was suspended over the two blocks also, so there isn't anything sneaky happening from the sole pattern. After a few pumps it flexed to about 7 thou. I don't know why it was so rigid at first, maybe the blade jamed in there had some pre-stress built in. No real idea.
What is most remarkable is that while the tests are not all that accurate there was an attempt to make similar measurements, and most of the plane were very similar in stiffness, which makes a lot of sense.
