Holy Cats! This will be a rambling blog! But it is what's happening here!
We had a wonderful visit from a very dear couple, at least to us. Both of us guys served as 'Best Man' for each other, and our wives were 'Maid's of Honor'. We were all school chums but he graduated in Geology and me in Forestry - so we went different ways. It is still always good, after 50 years, to get together again, even if just for a short time! We had a couple of days this time, so went to see the Ronald Reagan Presidential Library, on St Patrick's day. Very nice day!!
In the Shop - during the past week I had fun by sawing the shoulders and over-sized tenons. The process will be continued this week to cut down the tenons to fit their individual mortises. Meanwhile, my wood is both losing and gaining back moisture. However, the overall trend is still proceeding downward.
RH here is low in the heat of the day, but gets pretty high during the cool nights. Daily temps ranging from 20 deg. to 70. My little out-building shop is not immune to rapid cooling and warming, although insulated. Once the interior mass of the shop warms up - enough heat will be retained during nights to keep the RH somewhat lower. My RH meter - not too accurate - reads near 70% in the mornings and near 25% in afternoons. If I could just get the RH to hang in around an average of 35% to 40% I think the moisture content will get stabilized at the desired level. The wood has now been in the shop three weeks.
Anyway, I this afternoon, got started into chiseling and sanding the short tenons to fit the mortises, milled a while back. Unfortunately the largest moisture content differences now exist between the legs of the table and the thru tenons.
The legs are hanging in around 7%, but the apron's (tenon pieces) are still at 9%+ . I feel that the tenons need to get down a bit before fitting. Maybe they will by the time all of the short tenons (those boards are presently down to 7%) are finished.
These tables will be going to Phoenix and we want the thru tenons to stay tight. The calculated maximum shrinkage from 7% MC to 6% on these 4 1/2" wide thru tenons is .01782" or about 1/64". To me this is do-able shrinkage. More shrinkage might be a problem. This calculated shrinkage movement is over-estimated, as this is using straight tangential values. The real amounts will be less than this, but to be safe will go with the maximum movement figures.
I really wouldn't be fooling around all this calculating if it weren't for having such wide thru tenons. Now I know why 3 inches wide is the rule of thumb maximum. Especially, when the only choice is to use more or less flat grain, which isn't a good thing in the first place. Who? me worry?;)
Octogenarian's have an earned right to be a curmudgeon.
Chuck in Lancaster, CA
