Thread: Is there a maximum size for an end grain box?

Originally Posted by Gensol

A read a forum post which suggested there is a problem turning larger end grain boxes. Is this true and why?
If there is a practical size limit and what would that be?
I assume it would depend on the type of wood. Is more dense, straight-grained wood more suitable?
I would appreciate hearing your experience.

Depends a lot on the timber you are using but the main issue once you get over about 80mm diameter is the natural movement of the timber. Density is not important but stability is. If you look into the 3 types of shrinkage, you will understand why the radial and tangential movement becomes a problem (too much to explain here without boring the bums off everyone else!. Apart from a good chance of cracks developing, your lid is more likely to stick tight, or only fit in one exact position after a while. Lineal shrinkage doesn't have any effect on this type of project.

To add to what Vern has already mentioned, wood movement whilst you are turning can also become a significant issue as removing wood also releases natural tensions in the wood. A blank can go oval as you turn it.

An "end grain blank" is a pretty generic term as the blank could be,

• the whole cross section of a trunk or branch, generally termed "pith in," or
• "boxed heart" not the whole cross section but still has pith in, or
• any position across the cross section of the trunk / branch.

The position of the "end grain blank" within the trunk / branch of the tree i.e. upper (tension) or under (compression) side of a branch, trunk but near a branch (crotch wood), dictates the potential natural tensions in the blank, and how much it may move.

Then there is the issue of "how dry is it?" Green wood moves a lot in the initial stages of drying, seasoned wood will still move but not as radically.

The short of it is - all wood moves! Some more than others. Part of learning how to turn includes understanding and managing the inevitable movement. Restricting blank sizes is one way to manage movement.

Thanks for taking the time to reply guys.
I will experiment with some Crows Ash I had milled from a dead tree 30 years ago and some large table legs that are probably 80 years old. Hoping for minimal movement but I don't need a suction fit lid either.
i imagine it would still be better than turning from a side-grain blank.

Lidded boxes can be turned end grain or side grain, but the orientation of the grain within the blank will dictate potential movement in both types of blank. Even experienced turners still get caught out.

See if you can get hold of Keith Rowley's books "Woodturning Projects" and "Woodturning - A Foundation Course" as both are full of great information and will explain some of this.

Another excellent resource comes from our friends across the ditch - SAWG - The South Auckland Woodturners Guild. I know a lot of these members personally and they are among the best turners you will ever find, lots of talent, experience, skill & knowledge but best of all they are very proactive, share knowledge and promote all aspects of wood turning.

Projects | South Auckland Woodturners Guild Inc. (sawg.org.nz)
Tips & Jigs | South Auckland Woodturners Guild Inc. (sawg.org.nz)

The Guilds book on Woodturning titled “The Beginners guide to Woodturning” copies are available for NZ $20.00. It is the best value for $20 you can get in woodturning.

Enjoy!