Oak splitting

[Howey65]

Hi, I make small beakers out of oak and have recently started to get a problem with splitting.

Initially I “drilled” the centre out with a series of festnor bits gradually getting bigger. To speed things up and as I’ve got more confident, I’ve started to hollow out with my bowl gouge and finishing with a box scraper. However, I’ve found that the oak im using is tending to split more readily.

I would appreciate advice or comments. I’m confused because when using the festnor bits there seemed to be more heat generated which I would have thought would stress the wood more than the bowl gouge.

Any advice appreciated.

The wood spindles are 100mm square by about 110mm long. The centre is hollowed to about 75mm diameter and 80mm deep. Once I’ve hollowed out I would then turn the outside, but I’m getting splits before I even touch the outside.

 

[Stigmorgan]

What's the moisture content of the wood /humidity of where you're working? If the wood is wet it will dry quickly once you have turned it which would cause the splitting, likewise if you ha e a high humidity and the wood is very dry it can also split. I made the mistake of putting a finished very very dry piece above my fishtank, when the crack opened up it made such a noise I thought the aquarium had burst.

 

[Phil Pascoe]

Does the 100mm square include the heartwood?

 

[Howey65]

What's the moisture content of the wood /humidity of where you're working? If the wood is wet it will dry quickly once you have turned it which would cause the splitting, likewise if you ha e a high humidity and the wood is very dry it can also split. I made the mistake of putting a finished very very dry piece above my fishtank, when the crack opened up it made such a noise I thought the aquarium had burst.

The wood is fairly dry and acclimatized to my workshop. It’s the difference between using a series of forstner bits or bowl gouge that seems to make a difference? I’ve put it down to different stress on the wood, maybe the heat and moisture created by the forstner bits helps stop the cracking - although counter intuitive.

 

[Orraloon]

Are you hollowing out the end grain? That usually is more prone to splitting than done the other way.
Regards
John

 

[paulm]

The wood is fairly dry and acclimatized to my workshop. It’s the difference between using a series of forstner bits or bowl gouge that seems to make a difference? I’ve put it down to different stress on the wood, maybe the heat and moisture created by the forstner bits helps stop the cracking - although counter intuitive.

Not sure how the forstner bits can create moisture ?

If the bowl gouge is being levered against the rim of the cup while turning it could cause cracking, otherwise it seems more likely that recent pieces of the oak have faults in them and it's just coincidental with the change in method ?

 

[Phil Pascoe]

I'll try again - Does the 100mm square include the heartwood?

 

[Howey65]

Hi, I’ll give it another go. The oak doesn’t contain heartwood. I may just have a bad batch with flaws that I couldn’t see.

 

[Duncan A]

Turn the outside first - and put the question in the turning section