Kiln Dried Turning Blank...

[John Grace]

I've been working on a piece of wood called Granadillo...a very hard but nice Mexican wood. The web site described the wood as being 'kiln dried'. I started working on it last week...rounding it, truing it up, and gluing on a waste block. Left it for a couple of days and began completing the piece today when I noticed a significant crack had developed across the 'mouth' of the bowl though the base still appears whole. Question...when working with a piece described as kiln dried, should I have sealed the piece in between workings or should it be sufficiently stable? Any thoughts would be most appreciated.

This is particularly frustrating in that this blank is possibly one of the prettiest pieces of wood I've ever worked with and now I made need to leave it in a somewhat 'rustic' state.

THANKS...John

[charlie knighton]

chalk it up to experience.......ain't no always.......best to leave it in shavings, but leaving anything for a couple days is a crap shoot

[John Keeton]

Best plan is to always tie a plastic bag around any piece left on the lathe overnight or for any significant period of time. Keep in mind, that if the wood is green/wet, that you should also use a piece of a Walmart shopping bag between the chuck jaws and the tenon/recess and do not enclose the chuck with a wet blank when applying the plastic bag over the turning. The chuck will rust quickly!

[Faust M. Ruggiero]

The very act of kiln drying wood, especially thick dense wood can cause internal stresses in the wood. Cutting away or even cutting through the wood relieves some of those stresses and allows the wood to begin moving. Any movement can cause warping or cracking. When you began to shape and hollow your blank you changed the balance of the stresses and something gave way.
In order for wood to leave Mexico and get through US customs it must either be fumigated or kiln dried to assure the bugs are not imported with the wood. Who can really say how quickly they dried the wood and what stresses developed during the process. The wood may have been considerably drier on the surfaces than in the middle. My point is that you may not have been able to avoid what happened to you. Feel badly about the crack but don't beat yourself up over how you could have avoided it.
faust

[Dale Bonertz]

How thick was this blank? Through my research anything over 3" thick cannot be kiln dried all the way through (some things I have read even suggest that 3" is pushing it). I think there are a lot of unscrupulous dealers out there that make claims that are not really true. Having said that I agree to bag them if you are not really sure about the moisture content. It may also help to get a moisture meter to check some of these blanks, that are not roughed out and said to be dry. Check the surface prior to turning and once you hollow out the center a bit check to see if it is the same as the surface was before you started turning it (it should be close - within a percent or two or three).

[John Grace]

Dale...Thanks for the ideas, the blank was 4" when I began. Learn, learn, learn...

[John Grace]

John...Thank you, several others have suggested the same concept. Good to know as I have an even bigger blank from the same vendor. I guess his "good to go" statement wasn't completely accurate...I'll 'double-turn' the next one for sure.