How stable is green sweet chesthut

[gaci]

Hi all can someone tell me how stable is green sweet chestnut, im able to get a good 400x100 piece to turn a large centre bowl for a table, but can only get green ?.
Grant

 

[Random Orbital Bob]

It will be absolutely hideous within days of you finishing it. After a month in a centrally heated house it will be oval in shape and the rim will be as wobbly as if it were waney edge

Your only way forward is to get the chestnut and rough turn it to somewhere around 1/2" wall thickness or at least quite a bit thicker than you want it to end up. Then let it dry for 6 months in a cool, airy space. You'll need to seal the end grain ie at either end and a common recommendation is also to wrap it in newspaper to slow down the water loss to avoid cracking.

When you come to rechuck it after it's stopped losing water, it will be oval but hopefully not cracked and then you go careful until it's retrued and then finish it. That should then be stable enough to use. Even using this method, it doesn't guarantee a no cracked dry blank and normal procedure for woodturners is to rough turn a batch of blanks on the assumption that one or two will survive the drying process. it's a natural product and a bit hit or miss I'm afraid.

You can of course purchase kiln dried bowl blanks in numerous different species from a variety of turning blanks suppliers which would allow you to proceed straight away.

 

[CHJ]

I doubt that Rob's 1/2" wall thickness would be enough for rough turning on something approaching 400mm dia.

I personally would be inclined to make it double 30mm + if very wet/green.

I would expect 2.5% shrinkage at 20% moisture and 5-6% at 10% moisture tangentially on something like Chestnut.

Of course the thicker you have to leave it to recover a 'round' object the more risk of splitting.

 

[paulm]

Sweet chestnut does love to split on you when you turn your back on it for a minute ! Smells great though when turning, a bit spicy maybe, and mellows to a nice buff/ochre colour.

 

[CHJ]

If you can get hold of a good piece of dried timber especially if it has burrs, it can be exceptionally attractive.

I've found if I want to use it for spindle work then cleaving it green as you would for chestnut fencing is the best option, that way the tensions and movement takes place whilst drying and I just live with the lost diameter in the twists and turns of the stock.

 

[paulm]

It also has loads of tannin in it, so clean off your lathe and tools regularly or you'll get rust patches develop quite quickly, damhikt

 

[Dalboy]

I always leave mine rough turned to about 1" or above depending on how thick I want the end wall thickness. I then seal the outside only and leave as stated before in a dry covered area with good air circulation fora good 6 months and test either with a moisture meter or by weighing it until I get an even weight over a period of time. I also make a small dimple in the chucking pint to aid re-cutting that to round after drying, the original chucking point will need to be made larger than normal to allow this other wise when you re-cut the tenon it could end up to small for your jaw set.

 

[gaci]

Thank you guys for all your information.

 

[SVB]

I doubt that Rob's 1/2" wall thickness would be enough for rough turning on something approaching 400mm dia.

I personally would be inclined to make it double 30mm + if very wet/green.

I would expect 2.5% shrinkage at 20% moisture and 5-6% at 10% moisture tangentially on something like Chestnut.

Of course the thicker you have to leave it to recover a 'round' object the more risk of splitting.

Agreed. 10% of diameter is the rule,of thumb i use, so 400mm is close to 40mm wall to guarantee a decent thickness and round shape when returning.

S