end grain drying allowance

[Kevin Jenness]

I plan to make some end grain vessels of straight grained white ash around 8-9" diameter. Is there a good rule of thumb for initial wall thickness to allow for truing up after drying?

 

[hockenbery]

A quick look at a wood shrinkage table will give you a close estimate
End grain turnings will dry closer to round than side grain turnings
I have never twice turn end grain hollow-forms or vases. Some goblets I turn from dried wood.







There are lots of variables so leave a little extra.
If you turn a 10” diameter piece with a 1” thick wall
The dried diameter will be about 9.5 x 9.25
The wall thickness will be .95 to .925

Returning endgrain can be hard on the wood and any tool bounce can split a thin wall.
In returning I would do the inside first then the outside to reduce the chance of splitting the wall.

These are slides I use in a greenwood turning demo

http://aaw.hockenbery.net/WORKING%20WITH%20green%20wood-HOcompressed.pdf

 

[Kevin Jenness]

Thanks for doing the arithmetic for me. I realized as I was in the shop after typing my post that the answer was at hand in the shrinkage tables. Normally I would not return hollow forms but I want to try putting a lid on some of these. I think I will turn some to about 5/16"finished thickness and a couple with a wall thickness of 5/8"-3/4" for returning. I have a 17"-21" diameter butt log 7' long so I can do some experimentation. If I can get past the pith checks present in the log ends I may try a full diameter piece.

Thanks also for the handouts. Speed definitely helps when turning green wood. I sometimes get surface checking on burls while hollowing even with misting the surface. The good thing is that they usually close back up most of the way and are obscured by the burl figure

 

[Richard Coers]

I have yet to ever second turn a hollow vessel. Even with my cremation urns, I just return the opening so the threaded inserts slide in.

 

[Doug Freeman]

Normally I would not return hollow forms but I want to try putting a lid on some of these.

Depending on the project, when I want a lid on a HF, I have returned the whole and only returned the opening. Depends how round you want the finished piece. End grain doesnt warp much and will be more round when dry.

Usually light cuts can be made to round up the lid end (leaving some extra matl in that area. Depends on the wall t and overall size sometimes a steady rest is required due to vibration.

 

[John Jordan]

I make lots of lidded vessels, small to quite large. I NEVER turn the vessels twice, but rough turn and re-turn the lid. End grain orientation doesn't move much and ash is quite stable-a great wood for green turning. Lots of pictures of these on my Instagram @johnjordanwoodturning.

John

 

[Steve Worcester]

I make lots of lidded vessels, small to quite large. I NEVER turn the vessels twice, but rough turn and re-turn the lid. End grain orientation doesn't move much and ash is quite stable-a great wood for green turning. Lots of pictures of these on my Instagram @johnjordanwoodturning.

John

I can't argue with that