Greenwood Drying dynamics for spindles/branchwood etc

[Random Orbital Bob]

Is it right to assert that spindle blanks are more forgiving than bowl blanks in the splitting department? In general, I find that branch wood turned green tends to a) keep its shape better and b) split a little less than bowl blanks.

I'm conscious this is really generalising here because I've had plenty of branchwood that's split right down the core (holly, laurel, eucalyptus ie the usual suspects). Equally, I've had plenty of oak, chestnut and birch that has been better behaved.

As I understand it the majority of shrinkage (and therefore splitting stress) occurs perpendicular to the direction of the grain. Is this correct? In a log form would this be the cause of radial cracking? If that is true then a bowl blank at say 9" by 2" will have a huge surface area of grain exposed across which it will want to shrink will it not? Whereas a 3"x3" spindle blank has less cross grain shrinkage potential.

So is that why, spindle blanks that I've harvested about 6 months ago and are on the drying journey (sealed ends, air drying), but by no means dry ,seem to survive cracking once turned better than bowls with a similar drying history?

I appreciate rough turning bowls is the answer to faster drying. This is a more generic question about spindle drying.

Along the same lines, branchwood literally picked up off the ground and perhaps with spalting well underway, would necessarily be more dry than greenwood would it not? (Assuming it had been down for a few years and also assuming equal thickness)

What I'm saying is is it possible to harvest dead branchwood and cut out a good few years of the drying time?

 

[Tazmaniandevil]

I did a wee experiment with some freshly felled silver birch 2 years ago. I cut 3 same sized lengths from a section of trunk, sealed one with paint, left one unsealed, and rough turned one before sealing the ends and placing in a paper bag with the shavings. It might be coincidence, but the sealed one with the bark still on was still fairly wet but only has a single crack at one end extending about 1" into the 18" length. The unsealed one was cracked s badly as to be useless. The one in the paper bag was intact and pretty much dry. There must have been some moisture left in it, because it went a bit oval after trueing up and leaving in the shed for a month or so.

 

[Random Orbital Bob]

That's interesting. You would expect the one in the bag would have been in the most humid environment and therefore, whilst hopefully not cracked, would be the wettest.

The non sealed one is expected ie it dried too unevenly. The sealed plus bark, easiest storage solution but slightly more risky then bagged. I just don't understand why the bagged one would be more dry than the non bagged one given the relative humidity inside the bag?

The management of cracking, both good. What I would like to know is if branch wood discovered off the tree, literally lying on the forest floor, if uncracked, would it be close to dry enough to turn or at least in perhaps 3 months as opposed to 3 years.

 

[AndyT]

I have had some success making tool handles from odd fresh branches from the garden, under 2" diameter. Stuff I did not need straight away went in a carton full of shavings for a year or more and seemed to dry nicely without cracking.

If I wanted to make something straight away I used the microwave oven which was good for little bits like these.

Starting with a piece big enough for one handle - about six inches long - I roughly turned it to get the bark off and get it round. I then put it in the microwave, on 'defrost' for two minutes, waited for five minutes / until properly cool and repeated a few times. (Put some paper towels underneath to soak up the sap from the first few heatings.) Generally 4 - 6 heatings was plenty. You could feel the difference as the piece got lighter, harder and slightly oval.

 

[JimB]

I've used the microwave same as Andy except I put the wood inside a paper bag to save arguments with the wife. I usually zap on high for about 20 seconds then remove. Repeat until it seems dry. It's best to finish off with a piece of olive which smells as if you're cooking.

 

[Jacob]

Branches fallen off are already rotten and past it except for firewood - that's why they fell off, unless they are living wood brought down by external forces (adjacent falling trees etc).
I've found that green ash up to about 4" dia will dry slowly (several years) without splitting if kept undercover but unheated e.g in a shed.

PS and kept in long lengths - any splits then just in the ends.

 

[Spindle]

Hi

Literally millions of green spindles have been turned without further splitting - it was the bodger's method to turn wood green and stack it outside to season until the batch was ready for collection. Spindles cut from anywhere but the centre of the stock will tend to move to an oval section as they dry - this may or may not be noticeable.
I think riving the stock also goes some way to eliminating internal stresses in the resulting blanks.

I pick up any interesting looking wood - if it proves to be of no use for fabrication it can always go on the multifuel

Regards Mick

 

[Random Orbital Bob]

Hi

Literally millions of green spindles have been turned without further splitting - it was the bodger's method to turn wood green and stack it outside to season until the batch was ready for collection. Spindles cut from anywhere but the centre of the stock will tend to move to an oval section as they dry - this may or may not be noticeable.
I think riving the stock also goes some way to eliminating internal stresses in the resulting blanks.

I pick up any interesting looking wood - if it proves to be of no use for fabrication it can always go on the multifuel

Regards Mick

Good input thanks Mick. By riving, do you mean splitting down the pith with an axe?

 

[Spindle]

By riving, do you mean splitting down the pith with an axe?

Hi

To a point, yes. It's better to look up riving wood on the web to get the full story - essentially the wood is split with wedges or an axe, the splits can follow the path of inherent weakness or existing fissures can be used as an indication of where to split - both result in less areas susceptible to splitting ending up in the blank.

Regards Mick

 

[Random Orbital Bob]

Gotcha. I have seen that procedure at craft shows etc. I'll do some research as it sounds useful to minimise splitting. Essentially it sounds like you're deliberately releasing tension in the wood by following an existing stress fracture

 

[JimB]

I've found hawthorn branches dry without (much) cracking.

 

[CHJ]

....- it was the bodger's method to turn wood green and stack it outside to season until the batch was ready for collection. .

Conversly it's normal to bore any sockets in green turning just before assembly whilst still green, this way as the hole collapses to an oval it grips harder on the inserted spindle. Orientating the grain direction in the two pieces (90deg) maximises natural grip.

 

[Random Orbital Bob]

been looking a riving...its a delightful form of splitting green wood. Might just have to get a froe at some point.

 

[JimB]

been looking a riving...its a delightful form of splitting green wood. Might just have to get a froe at some point.

Been meaning to make one for years but always ended up with using the axe. Some blokes use part of a car spring mounting a handle in the eye.

 

[woodfarmer]

I am told the best thing to use is a leaf spring from a Mercedes truck. Being old I use an electric Fro.