Shrinkage and UNIFORM WALL THICKNESS?
charlie b
which will reduce / minimize distortion of turned pieces due to
wood changing dimensions as its Mositure Content changes.
If you turn "green" - and you don't want the piece to self destruct
as it dries - uniformly thin walls is often touted as THE Tried
and True method for minimizing or eliminated this nasty habit
wood seems to have - especially fruitwoods.
Now there are tables and tables of wood shrinkage data
for all sorts of woods - Radial % Shrinkage, Tangential %
Shrinkage and T/R Ratios that you can use to calculate
HOW MUCH a given dimension will change - as its Moisture
Content changes - anywhere between "green" and "oven
dry". How to USE that data in a meaningful way - well
that's what I'm working on.
Here's the first draft for your review and comment.
If you find holes in the info you think should be filled
or
If you see something that looks WRONG
or
If you have questions
PLEASE
e-mail me (my e-mail address in this post is real)
http://web.hypersurf.com/~charlie2/Turning/BowlShrinkage/BowlShrinkageTOC.html
I'm working on End Grain turned pieces and shrinkage
and will post the url here when the first draft is done.
Greg G.
>...
>Here's the first draft for your review and comment.
>If you find holes in the info you think should be filled
>or
>If you see something that looks WRONG
>or
>If you have questions
>PLEASE
>e-mail me (my e-mail address in this post is real)
>
>http://web.hypersurf.com/~charlie2/Turning/BowlShrinkage/BowlShrinkageTOC.html
>
>I'm working on End Grain turned pieces and shrinkage
>and will post the url here when the first draft is done.
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.
Gerald Ross
The bowl in the logette picture looks upside down. Or is it to be a
natural edge bowl?
--
Gerald Ross
Cochran, GA
Preserve Bacteria.. Its the only
culture some people have.
Bill Noble
them green to no thicker than 1/8 inch - maybe 1/4 inch at the foot, they
will warp and dry fine - then just refinsh the foot
"Greg G." <gr...@nospam.com> wrote in message
news:8bolf51t6oe27hvd7...@4ax.com...
nailsh...@aol.com
> 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
charlie b
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.
Kevin Miller
> 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?
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
--
Kevin Miller
Juneau, Alaska
http://www.alaska.net/~atftb
In a recent poll, seven out of ten hard drives preferred Linux.
Greg G.
>"Greg G." <gr...@nospam.com> wrote:
>>
>> 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?
>
>most fruitwoods are prone to splitting into toothpicks - but if you turn
>them green to no thicker than 1/8 inch - maybe 1/4 inch at the foot, they
>will warp and dry fine - then just refinsh the foot
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.
Bill Noble
"Greg G." <gr...@nospam.com> wrote in message
news:92mpf59tt6q78sldg...@4ax.com...
> Bill Noble said:
>
>>
>>most fruitwoods are prone to splitting into toothpicks - but if you turn
>>them green to no thicker than 1/8 inch - maybe 1/4 inch at the foot, they
>>will warp and dry fine - then just refinsh the foot
>
> 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
DOC D
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
Greg G.
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.