Wood movement is something I had always heard people mention but not something I had really spent a lot of time thinking about (besides knowing house doors would be tight or loose depending on the season) prior starting to learn about woodworking.
The fortunate thing about living in Adelaide is that we don’t experience the seasonal variations that many other places do. As you can see from the table below (thank you Wikipedia) the humidity basically varies from the mid 30’s up to the low 60’s, while the average high temps ranges from ~15C up to ~30C.
I don’t have the exact spec’s for Tasmanian Oak… however assuming its somewhat similar to White Oak.. the wood movement I would expect for a 350 mm quartersawn board… going from 15C @ 60% to 30C @ 36% is around -3 mm… which actually isn’t too much at all.
In the Tasmanian Oak bed I’m making for Isaac I was ultra conservative and allowed for up to 8-9 mm movement in the footboard’s main panel as I had taken an estimate from reading some forums online.
The outdoor table I made years ago out of some old Oregon rafters would have benefited from some knowledge of wood movement… when I first cut the boards and used an old hand plane to thickness the boards and edge joint them I was so happy with how flat and square the table was (as far as rustic furniture goes..) however I now watch it warp and change over the seasons even here in Adelaide. Breadboard ends may well have been a good way to keep it all flat, however the change in the width of the boards would mean at some stages the breadboard would overhang the main tabletop and other times might be level with the edge of the table…
While its fascinating to watch the rustic tabletop change over the seasons… I really don’t want movement in furniture like Isaac’s bed to be ruined because I didn’t think about wood movement… so hopefully my over conservative approach means the bed should last the test of time – if Isaac doesn’t destroy it 🙂
A great tool for anyone who wants to estimate wood movement is The Woodshop Widget: Â http://woodshopwidget.com/
The Woodshop Widget is available as an app on iPhone’s and Android devices, however you can also access it at the website link I’ve list above. The widget was conceived, designed and developed by Kenneth Woodruff and is an aid that Marc Spagnuolo (The Woodwhisperer) has recommended during some of his video including this overview video on YouTube from back in 2010: https://youtu.be/3cEGSHchBPc
The Woodshop Widget also has many other features like calculating board volumes, comparison between two species of wood, a squareness calculator and also a shellac mixing aid.
A very neat little widget that I’m sure I’ll be using a lot more in the future!