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Hollow Form Turning - A Trifern Class #2: Wood Selection

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Blog entry by trifern posted 04-28-2011 11:02 PM 6678 reads 12 times favorited 14 comments Add to Favorites Watch
« Part 1: Sign Up Part 2 of Hollow Form Turning - A Trifern Class series Part 3: Class Update »

Wood Selection

Almost every hollow form I turn is from local hardwoods and is turned green.

Why use green wood? Green wood is relatively inexpensive, easy to obtain, and easy to turn. It is nearly impossible to find, or afford, large kiln dried wood suitable for turning large pieces. Construction sites, firewood cutters, arborists, and landscape recycling centers are all excellent sources for wood. The biggest problem I have with green wood is my greed. I bring home more wood than I can use.

When harvesting fresh wood, the first step is to remove the pith. This is the very center of the log and has the most stress. I try to keep the wood in as large of pieces that I can manage and store. The larger pieces allow more flexibility in how the wood can be used in the future. I will coat all the end grain with Anchorseal.

The greatest advantage of harvesting my own wood is I am in control. I can orient the piece based on grain, color, and defects by cutting away the unwanted areas. Since this is inexpensive, I don’t feel guilty about wasting wood. I’ll waste as much wood as necessary to get the desired blank. Do not look at a log and try to figure how many pieces you can get out of it in order to maximize. Look at the log and discover the one or two prime blanks.

One of the biggest traps in wood turning is using expensive and exotic woods. Most of the pieces all look eerily similar to the original block of wood when finished. We become shy when cutting expensive wood, are fearful we will ruin the piece, and don’t want to cut away all the beautiful grain.

The most important aspect of any vessel is its form. The form is the skeletal backbone of all other aspects; grain, color, finish, texture, size, and so on. A piece with perfect form painted black looks better than a piece with killer grain that has poor form. Therefore practice your form on inexpensive, disposable wood until you can cut the perfect form – then apply these skills to the perfect wood with killer grain.

“Green wood always cracks and distorts…”

Uneven moisture loss in wood will cause it to crack and check. Turning hollow form vessels relatively thin and relatively even wall thickness will allow it to dry at an even rate. The piece also needs to be turned from start to finish in a couple of hours or less.

Most woods will dry just fine with even wall thickness somewhere between 3/16” to 5/16”. Vessels with wall thickness between 3/8” to ½” should be placed in a paper bag for a few days to slow the drying process.

As wood dries it will shrink and move. The amount of shrinkage depends on the orientation of the grain. Wood shrinks along the length of the grain approximately 0%, radial to the log shrinks about 4%, and along the growth rings about 8%. This knowledge helps predict how a piece will distort as it dries. David Ellsworth is a master getting great, predictable movement in his pieces. Most of my vessels are turned from end grain. This grain orientation has the least amount of distortion. I do not mind some distortion in my finished pieces. I believe it adds to the organic look and feel.

The next class we will mount some wood on the lathe and begin the shaping.

-- My favorite piece is my last one, my best piece is my next one.



14 comments so far

View MyChipCarving's profile

MyChipCarving

476 posts in 1844 days


#1 posted 04-28-2011 11:46 PM

Do you ever turn a hollow form from dried wood if you have it available?

Time to fire up the chainsaw and get ready.

-- Marty, https://www.MyChipCarving.com, 866-444-6996

View hairy's profile

hairy

2095 posts in 2251 days


#2 posted 04-28-2011 11:53 PM

Very good! Thanks!

-- in the confusion, I mighta grabbed the gold ...

View Karson's profile

Karson

34901 posts in 3120 days


#3 posted 04-29-2011 12:27 AM

Thanks Joe.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware karson_morrison@bigfoot.com †

View trifern's profile

trifern

8132 posts in 2486 days


#4 posted 04-29-2011 12:27 AM

Marty, I will occasionally turn a bowl from dry wood. I rarely, if ever, turn a hollow form from dried wood.

-- My favorite piece is my last one, my best piece is my next one.

View RichardH's profile

RichardH

295 posts in 1721 days


#5 posted 04-29-2011 07:39 AM

Hi Joe,
I may be skipping ahead, but I’m curious if you finish the piece, apply dye, varnish, etc. while it is still green or if you do that some time after everything has dried?

Thanks, Richard

-- "It's supposed to be hard. If it wasn't hard, everyone would do it...It's the hard that makes it great."

View reggiek's profile

reggiek

2240 posts in 1989 days


#6 posted 04-29-2011 05:41 PM

Joe, great class start. I see now why you turn end grain pieces….and thats a good rule of thumb on the drying thicknesses. Do you use a moisture meter at all? I’ve heard both good and bad about using them to determine the right amount of moisture for turning?

I’ve had some green pieces dry faster then I can turn them sometimes and end up dry turning…It makes a lot more dust and is harder on the tools (heat and friction). The only benefit is that you can turn to final form and finish the piece without too much distortion.

-- Woodworking.....My small slice of heaven!

View jockmike2's profile

jockmike2

10635 posts in 2966 days


#7 posted 04-29-2011 08:17 PM

Thanks Joe, you’re a good teacher.

-- (You just have to please the man in the Mirror) Mike from Michigan -

View Grumpy's profile

Grumpy

19586 posts in 2570 days


#8 posted 04-30-2011 03:12 AM

Well done Joe. Looking forward to your next session.

-- Grumpy - "Always look on the bright side of life"- Monty Python

View Roger's profile

Roger

15039 posts in 1523 days


#9 posted 04-30-2011 02:49 PM

I’ve got a fresh limb from a downed tree a few weeks ago. It’s about 8-10” diameter.
Would this be big enough to us after I cut the pith out of it?

-- Roger from KY. Work/Play/Travel Safe. Kentuk55@bellsouth.net

View sedcokid's profile

sedcokid

2683 posts in 2318 days


#10 posted 05-01-2011 03:51 AM

Thanks Joe, I am looking forward to the remainder of the series!

-- Chuck Emery, Michigan,

View GaryK's profile

GaryK

10262 posts in 2707 days


#11 posted 05-12-2011 11:49 AM

Great! Keep’em commin’

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View Ken90712's profile

Ken90712

15144 posts in 1908 days


#12 posted 05-13-2011 11:44 AM

Very interesting post, great info thx.

-- Ken, "Everyday above ground is a good day!"

View Transition's profile

Transition

339 posts in 1263 days


#13 posted 07-23-2011 06:19 AM

I like your philosophy as much as your work. I have made a commitment to use only reclaimed, primarily local wood. Expense is always a consideration, but more that that, I have not really seen any exotic wood that is more beautiful than what I have found locally. And one of my goals is to reintroduce people to the beauty that they largely ignore every day.

-- Andrew, Orange County, CA - www.TransitionTurning.com

View RolloMartins's profile

RolloMartins

6 posts in 1042 days


#14 posted 01-16-2012 03:42 AM

Thanks for taking some of the mystery out of this for me.

-- "Bully of the world!--Don Q.

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