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Brian Kent
02-11-2016, 5:30 PM
A local university cut down a very old oak. A friend offered me some of the wood. The problem is it is cut in slabs 3-4" thick. Is there anything I can turn with a cross section of a trunk?

Doug Ladendorf
02-11-2016, 6:15 PM
How about a platter?

Brian Kent
02-11-2016, 6:28 PM
I wonder if that would be structurally sound. I guess I make cutting boards thinner than 3", so if it is not full of cracks it could work.

Steve Peterson
02-11-2016, 7:47 PM
If they are 3" thick cookies, then they will probably be full of cracks within a day. They might survive if they were split down the pith or if one large crack opens up (and you end up with a pacman shaped piece).

If they are slabs, then they will dry just like any other wood. Seal the ends and wait. You can make platters or small bowls.

Steve

Mel Fulks
02-11-2016, 8:04 PM
Not that it matters, but why did they cut them like that ? Brand new fine chain saw? Some of us who have had to pay to get large trees taken down ,and specified it was to be left for fire wood use ,have had to explain that 5 foot long logs would not fit.

Brice Rogers
02-11-2016, 8:56 PM
My response is a bit "tongue-in-cheek", but if it is a bunch of 3-4 inch thick "cookies", perhaps make a whole bunch of small things like candlesticks, pens, pepper grinders? Also, I've heard of people using slabs like that for garden walking pads.

Oak turns pretty nice (I just finished turning a bunch of live oak that I got from a tree that uprooted in the Hidden Meadows community in Escondido, Ca. - - BTW, they still have the main trunk laying on its side - - I stared at that nice chunk of wood but decided that I didn't have the strength to get it into my truck).

Mark Greenbaum
02-11-2016, 9:08 PM
What type of oak is it? I turned some Bur Oak (white species) from a dying tree that they core dated to over 365 years old. I turn one bowl about a month after it fell (12" diameter), and it was perfectly round with 3/4" walls, within a month the rim had gone really wonky, and the bowl is oval, with a 1/4" wide x 3" long crack in one side. My wife loves it because she was at the library where the tree was when it fell down. I've turned a couple small items that stayed there shape. Keep the pith out of the turnings - is the lesson I've learned. Can only lead to bad results.
Make pens and candlesticks is a great idea for shallow pieces. Or small cocktail plates (6" diameter). Post pictures, please.

John Keeton
02-11-2016, 9:10 PM
I am sure I would feel differently if I lived in an area where wood was scarce, but I have long since gotten past the feeling I have to turn every piece of wood that becomes available. Turning cross sectional oak would be problematic and potentially dangerous unless it was a standing dead tree that was fairly dry. And, unless one likes counting growth rings, it wouldn't have much going for it in the "beauty" category.

Brian Kent
02-11-2016, 9:13 PM
Mel, all I know is that this was a gigantic old oak on the University of Redlands lawn. I'm sure the only consideration was getting it into pieces they could life.

My friend nabbed one piece that is 11" long and 22" wide, which in this case means it is probably a branch. I'll watch for the cracking.

Wow, Hidden Meadows. 5-10 minutes away. If I was strong enough to put it in my truck I would put it in my truck if I had a truck.

Brian Kent
02-11-2016, 9:17 PM
John, there is plenty of wood around here if I just develop relationships with the cutters. My friends have been on the lookout for me since a recent strong windstorm.

"Yes, I would love some wood!
No, I can't really use branches. They crack too much.
No, pine has too much sap.
No, palm trees are like trying to cut spinning bundles of straw.
Eucalyptus - it twists and cracks apart, but sure. It is beautiful.
But thank you for checking for me."

John Keeton
02-11-2016, 9:31 PM
Brian, I am sure I take for granted the abundance of walnut, cherry and maple around here.

Brice Rogers
02-11-2016, 10:31 PM
Last week I read on another SMC forum the topic of T/R ratio (tangential to radial shrinkage) and did some on-line searches. I found that that shrinkage quotient is a potential indicator of whether or not something is going to crack. A low ratio is good and a high ratio is not (unless you are intentionally looking for warpage). http://montgomerycountywoodturners.org/Documents/Tip29-MoistureContentandWoodShrinkage.pdf

The oak that I got from the golf course was live oak (T/R of 1.42). That is on the lower end of the scale. I could distinguish it some other oaks from the leaves and the pointed acorns.

Bur oak has a T/R ratio of 1.97. But if the wood came from a branch, it will have different/higher internal stresses than if it is from a straight trunk section.

Southern Red Oak has a T/R ratio of 2.40.

Laurel Oak (which also grows around here but has round stubby acorns) has a T/R ratio of 2.47. That is quite prone to cracking.

What do you folks do when you get fresh green wood to minimize the chance that it will become cracked firewood?

Mark Greenbaum
02-12-2016, 8:14 AM
I know what you're supposed to do with green wood: turn twice - first to a 10% wall thickness, and weigh, and record date and weight on the piece. The store in paper bag with shavings, and reweigh every couple of weeks until the weight drop stops (denotes it's dry). Then re-turn to final shape and wall thickness. OR - turn while green to a final shape and wall thickness, and finish, then hope it does not warp beyond your desired intentions?

BTW: The pieces of bur oak that did not warp were all from the large branch sections, but had been stored on a pallet outside for several years. I guess because I had no pith in the pieces, they were more stable.

Bruce Lewane
02-12-2016, 9:18 AM
At the bottom of a laminated bowl, the circular grain of cross sectioned wood adds quite a bit of interest and beauty.
Have to say I envy folks with so much free wood.
Around here, where sawmills are every where, guys are charging so much that buying blanks on line and having them shipped is cheaper than buying locally.