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Lou Jacobs

Lou Jacobs

Joined
Jul 18, 2018
Messages
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Location
Baltimore, MD
Website
loujacobswoodturning.com
I occasionally have folks in my shop who are interested in the effect of drying on the rough-turned bowl, and who struggle to understand (as I struggle to explain) different grain features of different parts of the tree. I’ve been looking through my modest woodworking and turning library for good illustrations of the various options for where a bowl blank could be located in the log, and effects of same on shrinkage, as well as inherent figure in different parts of the tree, crotches, reaction wood, etc. I’ve got Hoadley as well as Raffan’s books, but the best I’m finding is in O’Donnell’s Turning Green Wood. It’s OK but not quite as clear for the layman as I’d like to have at hand to just be able to pull out for display. If I were a better sketcher, I’d do it myself. I wonder if anyone has a great, clear reference they’d recommend? Maybe you’ve created such a resource yourself?
 
Todd Hoyers notes are the best. Todd graciously gave me permission to use an earlier version in classes. He just asked that I give him credit.
This is a one page that shows warp IMG_0166.png

These are a couple diagrams of bowl shrinkage cross sections on a bowl centered on the center of the log.
Cross section are parallel to the end grain and perpendicular to the endgrain.IMG_0167.pngIMG_0168.png
 
I really enjoy turning wet wood to finished pieces. I really enjoy the natural distortion the drying creates. A point that I really haven't seen mentioned is that different layers will shrink at different rates. (heartwood less than sapwood, and both (usually) less than bark)

I've done some thin(ish) wet bowls with some sapwood on just one edge and it creates a little pucker in the rim. Same with hollow vessels, a little sapwood will tighten and flatten out. Sometimes it will stretch to where it looks like it gets waves that you see and feel.
 
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