Steaming case hardened maple?

[David Utterback]

I have about 30 bd ft of tiger maple that seems to be case hardened. After face jointing and planing, it quickly cups. I would like to use it to make small boxes for gifts so have been cutting in pieces about 30" long. The rough sawn material is a good inch thick.

Could a trip through a steam box relieve the internal tension so that it will machine properly? If so, how long should it take to dry and stabilize prior to working? Sounds like a bit of work but might be worthwhile.

[ernest dubois]

I guess you mean the wood has not yet seasoned or attained its moisture equilibrium yet. Steaming isn't the solution to your woes, getting the wood in condition to be worked is what's needed. Best is to let it stand out of doors, for your 1 inch stuff a year is sufficient from the time of fiber saturation to equilibrium, and then a few months inside, then machine it, giving some allowance for getting at the working dimensions. When you don't know the date of fiber saturation - it's a fancy way of saying when that maple tree was cut - just leave if for roughly a year from now, you'll be fine that way.

[Mel Fulks]

If it's going to be used just for small boxes of thin wood can you just resaw it now?

[John TenEyck]

Case hardening is related to improper drying. Are you sure that's the problem or could it be that the wood just is not at EMC with your shop? How long ago did you bring the wood into your shop? What's the MC of the wood compared to wood that's been in your shop for many months? If they are the same then you have a good argument that your problem could be due to case hardening. If they aren't then you just need to let the maple acclimate to your shop until it's at EMC.

If it is case hardened, I'm not sure it can be relieved. Maybe one of the real drying experts will come along to answer that.

John

[David Utterback]

Thanks for the responses. This wood has been sitting inside my basement for well over 2 years. On the first set of boxes, the cupping was worse, I believe, on thinner boards after resawing. It creates gaps at the corners of box joints. Miter joints are impossible.

[Mel Fulks]

I won't say that improper drying is not the problem. Only that I've never seen any that didn't have some case hardening.
Sellers often say they take special precautions, I interpret that as " our maple is no worse than what you bought from somebody else". When I've had to make thick bar rails from two 8/4 pieces of maple I routed out about a 1/16 from both pieces leaving no more than 1 inch of glued perimeter. None done like that have had any opening.

[ernest dubois]

Thanks for the responses. This wood has been sitting inside my basement for well over 2 years. On the first set of boxes, the cupping was worse, I believe, on thinner boards after resawing. It creates gaps at the corners of box joints. Miter joints are impossible.

The problem is surly not then that it hasn't had the chance to reach equilibrium unless there are some very strange circumstances in that basement relating to moisture and ventilation and all the other particulars. I wonder which way the cupping occurs in relation to the growth rings.
But case hardening happens when the drying schedules and moisture evaporations get crossed up for one of those technical reasons or the other one and the cells of the wood collapsed, big gaps opening up internally, oh it's all very ugly, sometimes called honeycombing and it's often easily detected on inspection of the surface indicated by sunken in areas and gross unevenness. It is one of the risks involved in getting artificially dried out wood.

[Lee Schierer]

Do you remove equal amounts of material from each face during jointing and planing?

Have you checked the moisture levels with a meter?

Has the lumber been stacked for 2 years with stickers between each layer?

[ernest dubois]

At some point here Krenov goes into the forces at work in your wood.