Moisture Content of Maple for Workbench

I have Christopher Schwartz' book on workbenches and have been in the planning stages of building a bench for some time. I was originally going to use doug fir for the simple reason of economics, but recently acquired some maple from a friend.

The maple has been flatsawn and stickered for almost two years. It spent its first summer in a shady spot outside before being moved into a barn. The slabs vary from about 3-5" in thickness. The slabs were 12' in length, but before transporting them home I cut them into 5' and 7' lengths for storage purposes (I plan to build a 6.5' bench). I checked the freshly cut endgrain a day later, and it measured 15% on a cheap moisture meter. The rest of the wood in my shop reads 6%, though not on freshly exposed endgrain.

While 15% is not dry, it's also not green. On his blog, Chris encourages building benchtops with slabs having moisture content as high as 60%, but goes on to suggest using kiln dried lumber for the undercarriage.

15% is not 60%, however, which leaves me unsure of how to proceed. I would prefer to avoid buying extra lumber for this project, as I now have a surplus of this maple. However, if it's likely going to cause problems, I may err on the side of caution and shell out for some kiln dried lumber for the legs and stretchers.

Thanks,
Josh

@ 15%, it has done about half of the shrinkage that it will end up with at 6%.

The trick is to make sure the top is wetter than the undercarriage when you build it. That way the top shrinks down onto the legs and tightens the joints. If you do it the other way around, the legs will get looser over time as they dry. The same principal applies when you are making stools or chairs.

John,

You don't mention what state you are in. Dry climate? But more important you did not mention the phase of the moon when the tree was cut down:). For that reference you need to refer to the Osage Orange thread. I would measure the moisture content on a freshly cut end not a day later or you can look up the oven dry method to get the true MC. You will need an accurate scale for that.

James

Josh, is your shop climate controlled? If not then your bench will probably stabilize around 10% MC, give or take.

Sticker the slabs in your shop and put a couple of box fans about 10' away. It will help accelerate the acclimation process.

If the other wood in your shop is 6% I expect you live in a fairly dry state.

I have done a couple maple slab tables and a friend of mine used to have a business making slab tables. He told me he had the most issues with maple slabs moving after he finished them. Even when he had them well dried. My first maple slab was 11ish% when I finished it. 3 years later it has a slight crown down the center of it. Maybe 1/4"-3/8". It was dead level when I finished it.
My bet is that your piece of maple will move a lot between15% and whatever it finishes at in your shop. My guess is your bench top wont be super flat....I guess that it depends on how much that matters to you.

For sure, a 5” thick slab will not be fully air dry and stable in two years, and I doubt the 3” would. In my shop 9-10% is at equilibrium, but not in our home.

I remember some years ago, some were buying maple kitchen counter tops to make workbenches. I made my bench many years ago using 2X12 fir.
It has been a stable good bench. I live on the Texas gulf coast. The under carriage is fir.

I built my bench from some air dryed oak, which was about 2" thick. It had been sawn a couple of years, so I went ahead and built it, using Schwartz book, French style bench with the mortise and tenon joints. Have a few cracks in the legs, but otherwise it is very sound.The top was glued in 2 sections, then surfaced, and glued together using threaded rods and every clamp I owned at the time, and after drying had a small bit of a crown. I used my hand held belt sander to flatten the top, and it works great for me.

Design with expansion and contraction in mind. (you do that anyway on everything, right)

If you lay out the grain carefully that will reduce your problems.

Plan to reflatten the top in a year or two.