Re: [MedievalSawdust] Re: Grain in joints and finishing questions
Most of the 16th c. six-board chests appear to have been treenailed; some appear to have used iron nails. Treenails have the advantage here as they are flexible, so can accommodate some cross-grain movement without splitting the boards. Using kiln-dried quartersawn material also helps. Thick stuff won't move as much as thinner.
I use Tremont nails in slightly oversize holes. My main problem is cupping as the boards shrink in dry climates; this is exacerbated by my use of 1/2" boards for the sides (to save weight).
I made a couple of clamped-front chests with full 1" thick lids (milled from 5/4 lumber) treenailed to battens about 2" wide, as seen on surviving 13th to 15th c. chests. I was worried about differential movement, but the customer reported the lid stayed flat.
Speaking of clamped-front chests, this is another example of a medieval technique that modern authors would say cannot work. The joints between the legs and the panels are cross-grain, and frequently involve wide boards. Sometimes you can see where this has indeed caused the panels to crack, but quite a lot of them look just fine. It's possible that the peg holes in the tenons were elongated (this is what I usually do), but it's also possible that the combination of flexible pegs and thick lumber accommodates all the cross-grain movement.
By "mechanically" do you mean with nails, dowels, or screws? or by
cutting a strip out of the ends (esentially making one great big
finger joint) I'm guessing both would be best.
- --- In email@example.com, AlbionWood <albionwood@...>
>I'm guessing from the context that "treenailing" is using some kind
> Most of the 16th c. six-board chests appear to have been
> treenailed; some appear to have used iron nails.
of narrow pegs as if they were metal nails -- but could you
> I use Tremont nails in slightly oversize holes. My main problem isElongated how, please?
> cupping as the boards shrink in dry climates; this is exacerbated
> by my use of 1/2" boards for the sides (to save weight).
> It's possible that
> the peg holes in the tenons were elongated (this is what I usually
> do), but it's also possible that the combination of flexible pegs
> and thick lumber accommodates all the cross-grain movement.
Also, the book which started my thinking about this issue, says
that "when assembing a box or drawer [this is one where the grain of
all four sides is the same] turn the boards so tha annuual rings
curve out [...] The board's natural tendency to cup will keep the
corner joints tight at the edges."
Gillian [grateful with the patience of this group for her questions!]
- --- In firstname.lastname@example.org, "msgilliandurham"
>Treenails are basically wooden nails. There really isn't much
> > I'm guessing from the context that "treenailing" is using some kind
> of narrow pegs as if they were metal nails -- but could you
> elaborate, please?
difference between pegs and treenails, except the latter sounds
cooler. It's more the way they are used that's different: Treenailing
implies (to me at least) fixing one board atop another, whereas
pegging is a way to lock mortise and tenon joints together.
Note well, however, that these terms aren't rigidly defined, so other
writers may use them in different ways. (I think in boatbuilding a
treenail means a peg with a head, like an unthreaded bolt, so it can't
be pulled through a board. But what I know about boatbuilding
wouldn't cloud your vision if it was in your eye, so...)
>When pegging a wide, cross-grain mortise-and-tenon joint, you can
> Elongated how, please?
elongate the peg holes in the tenon so that the tenoned board can move
without opening up the joint. For example, a breadboard end might be
fixed with three (or five) pegs. The center one is done the usual way
(i.e. drawbored - the hole in the tenon is offset slightly toward the
shoulder, relative to the holes in the mortise) so all movement is
away from the center. The other holes (also drawbored) can be
elongated slightly across the grain, so that the tabletop can shrink
or swell without cracking.
I don't think this was ordinarily done much in the MA because thick
riven planks don't actually move that much, and because the pegs are
flexible enough to accommodate some movement. But I wouldn't be
surprised to see it on clamped-front chests or tabletops in the late MA.
> Also, the book which started my thinking about this issue, saysThis is true only if the board is losing moisture and shrinking. The
> that "when assembing a box or drawer [this is one where the grain of
> all four sides is the same] turn the boards so tha annuual rings
> curve out [...] The board's natural tendency to cup will keep the
> corner joints tight at the edges."
outside of a log shrinks more than the inside, so it cups opposite the
curvature of the rings. It's also only true for plainsawn (flatsawn)
lumber. Quartersawn lumber has little tendency to cup.
Even if intended (and I'm sure none was), no offense was taken. This is
one of the most civil mailing lists I've even subscribed to.
A little better rested now, watching Le Tour on the TV.
[mailto:email@example.com] On Behalf Of Conal O'hAirt Jim
Sent: Saturday, July 01, 2006 12:41 PM
Subject: RE: [MedievalSawdust] Grain in joints and finishing questions
>I didn't sleep much either last night....
> Charles Joiner
> Rambling, running on 4 hours sleep.
forgive me if I was blunt.
Baron Conal O'hAirt / Jim Hart
Aude Aliquid Dignum
' Dare Something Worthy '
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A short story on grain.
In High School we designed and built our own furniture instead of bird houses. I designed a game table with a checkerboard in the middle. The board had all of it’s grain going in one direction. Then I wrapped it in a frame of walnut with the grain going along the sides of the checkerboard. I filled out the bulk the table top with poplar that ran in two directions and then banded the eight sided table top with walnut that ran in four different directions. The walnut came from someone’s grandfather’s barn attic, many years old. The poplar was kiln dried.
My shop teacher was in on all of this planning and execution. He should have been executed. We built our projects an hour a day for several months so it did not get a finish until late in the game. By then it was too late anyway. Wood, even when removed from the tree grows and shrinks. I had to fight the top to re-glue all the joints when they pushed each other apart. In disgust, the table now has a painted piece of birch plywood.
Projects like the 6 board box have room for the legs to get longer etc. you have just an angle to another.
If the lines crudely denote grain direction. The interior swelling and shrinking directly affects every other joint. Adding things like dovetails, biscuits, dowels and pegs also affect your results.
From: firstname.lastname@example.org [mailto:email@example.com] On Behalf Of msgilliandurham
Sent: Friday, June 30, 2006 9:07 PM
Subject: [MedievalSawdust] Grain in joints and finishing questions
My thanks in advance for any responses I get to the questions below.
(and yes, this group will get *heavy* mention in my class next
I've been reading some books on modern carpentry (filling in the big
honking gaps in my very rough-and-ready knowledge) and one of them
insists that for a box with a lid, the front, back, and sides of the
box all need to have the grain running the same way, (i.e., parallel to
the bottom) or "the joints will fail".
… trimmed for digest users.