Shrinkage and UNIFORM WALL THICKNESS?

Hey Charlie,

Thanks for the link and the work you've put forth - gratis. Being a relative novice I'm always up for any info I can get.

I've been debating over whether to bother attempting to turn a peppermint peach tree that was recently cut. My last efforts at turning pear were disappointing at best, but experience of sorts. The pear was a bland figureless wood which molded and split easily. Although I dismissed it right off the bat, that nagging voice got me to wondering: How does peach fare and is it worth the trouble?

Greg G.

The bowl in the logette picture looks upside down. Or is it to be a natural edge bowl?

I believe he did that to show the difference in grain orientation, not to show a difference in the shape or style of bowl. Note the rim shape and appearance does not change, only the shape placement on the wood.

Everyone that knows Charlie's work knows he is an exacting fellow!

Robert

Another example of the "what's obvious to the author - may not be obvious to the reader".

I've revised the first page (the Table of Content) to show two possible orientations of a bowl in a Half Logette - and why the one with the "bottom" on the Pith Side of the Half Logette was used for subsequent pages.

Going for the BIGGEST bowl possible from a Half Logette is often the obvious choice for someone new to turning bowls. In the excitement of trying something new and wanting to jump in and get started, it's easy to not realize that most, if not all of the pretty sapwood is going to be turned away. The temptation of BIG can thus overshadow NICE.

Since we often turn green wood - it's so readily available - wasting time on some woods which are proned to cracking and splitting, and the disappointment that goes with those experiences - might be avoidable.

So what I'm searching for is quantifiable predictors / indicators of which woods to avoid and which to go after. I realize that wood, as it dries has a ton of variables that affect the outcome. With all the shrinkage data available for most woods, I've been searching for indicators in that data and this approach holds some promise. Figuring out how to put the results in an understandable and useful way is what I'm working on - this stuff being the latest attempt - an earlier look at the Tangential to Radial Shrinkage Ratio being useless, though intuitively an avenue to look into.

I'm a weird left brain/ right brain person who wants Quantifiables - and visual images to be able to see and understand a concept. The quantifiables are easy - thanks to spreadsheets. Illustrating the results in an meaninful way is the hard part.

Anyway - regardless of which way the intended bowl is oriented in the Half Logette, the idea of predicting the basics of how the bowl's shape will change - and by how much - is what I'm after. The questions I'm asking for feedback on are

- Does this approach make sense to you?

- Do the tables and illustrations convey what one can expect as the turned piece dries?

- Can this information help your selection of woods to turn - or avoid?

Feedback will be much appreciated.

To me, it is a good article from a theoretical standpoint. What is most useful to many turners I suspect is less the why than how to mitigate the effect. It's good to know why wood behaves the way it does, but it's important to be able to use that knowledge to solve the problem that behavior presents.

One thing that Soren Berger turned me on to years ago was to stick a board tangentially across the opening of the bowl. As it dries, it tries to shrink but the board holds it in place. After it dries it maintains that shape. Sort of like steaming wood - after you bend it and it dries it doesn't go back to straight.

Because the wood isn't 'allowed' to move as much, it also helps reduce cracking. Note that I do coat the bowl with end grain sealer and store in a paper sack for several months. It doesn't dry any faster, but it's much closer to round when I get around to turning it.

The drawback of having a stick on the bowl blank is they don't stack as well. Oh well, can't have everything I guess...

...Kevin

Thanks, Bill. Good advise for any green wood - but not having anything "peachy" to view, is the wood really deserving of the effort? If it is devoid of character it's hardly worth the trouble. The pear sure was a disappointment. I'll try Googling up a pix...

Greg G.

I personally like peach/apricot/plum wood - it has nice colors and grain. Pear and other plain woods invite improvement via Ritz dye - see my post a month or two ago on a technique I like

Fruit wood is difficult to keep in tact, but IMO they have some beautiful color and characteristics to them. Peach is worth the effort, as is plum and apple. They also smell great while turning. In my experience, your are going to lose some of the bowls, but that is to be expected with most green turnings. In the words of one of my favorite philosophers, "Life (substitute wood) is like a box of chocolates, you never know what you're going to get."

Happy turning.

Doc D

Thanks for the input, Doc and everyone. Suppose I'll have to give it a shot. There are probably 10-20 small blanks hiding in there. At least I can give the girl who planted the tree many years ago something out of it - she was rather heartbroken when it reverted to producing drippy, worthless fruits, many of the major limbs split, and it became rather misshapen. (It was planted as an ornamental.)

Greg G.