I have read several articles about using tongue & groove bread board ends, and have recently had the chance to include this design into a large cherry kitchen table design. The table is quite large (~72 x 42″), and will include 6 bread board ends (2 for the table itself and 2 for each of the 2 extensions). As shown in several of the artlcles, I used a file to elongate the outer holes in the tongue after drilling the holes for the dowel pins. As I was filing away I started to think about this joint and if there was a better way to make it. I saw 2 potential problems which caught my initial attention; (1) this joint leaves unsealed end (& surface) grain and (2) the filing process seemed a bit less controllable than I would like. My biggest worry is the exposed end grain as it will “breath” moisture in and out as the seasons come and go, and we have all seen how this can crack the ends which would be disasterous for this joint. Perhaps I am over-engineering this but the following design and process changes are pretty simple to impliment and I do not think they have down-sides.
Let me know what you think.
Design:
(1) I applied wax to all end-grain on the tongue. [seal]
(2) I added a bit of wax to the end grain of the elongated holes in the tongue. [Seal and lower friction against the dowel pin.] Friction was something I worried about more with the files holes).
(3) I added a bit of glue to “inner” part of the hole so that the dowel is secured at both ends, without getting glue near the face grain of the tongue.
(4) I thought about adding wax or graphite (from a pencil lead) to the face grain of the tongue to seal and/or lower friction but decided in the end not to do this. I was woried about the wax getting “gunked-up” over time, and with the end grain “sealed” perhaps sealing the face grain was less important.
Process:
(1) To make the dowel jointing process more accurate and more efficient I used a router for both milling the tongue as well as for drilling and elongating the holes. As is shown in several artlicles, I used 2 router guides, one on each side of the table to mill the tounge. My router guides were pretty thick cherry (~1.25″ thick), so they are pretty stiff. I added some holes and slots to the router guides so that after the tongue was milled I could easily secure the router for each of the 5 holes. After fitting the breadboard end and attaching it to the table, I replaced the 1″ router bit with a 3/8″ spiral bit and drilled the 5 holes with the plunge fear=ture of my router, then after removing the breadboard end the elongated the outer holes in the tongue with the router.
Replies
Steve,
I love breadboard table top construction. It's a very "honest" way of achieving the mechanical requirement of holding the glued up panel from "warping" too much. It's construction is ovious and the joinery is quite visible.
I think you are much too worried about potential problems. Yes, there's endgrain to deal with. It will do what it will. Don't be too concerned about it. The table top will move with the seasons. It's width will change by as much as 1/2" (depending on your local humidity range). The length of the end cap will not change at all, meaning there will be only one time of year that the length of the end cap and the width of the glued panel are the same. At all other times, one will be greater/less than the other. That's a characteristic of the joint and part of its charm. The wood will give up and absorb moisture without problem through end grain, through the walls of long grain, and through other tissue.
Build it. Finish it with shellac, lacquer, varnish, whatever. Enjoy it.
Wax it if you like the look, but don't count on any of these finishes to stop moisture transfer.
Rich
thx for your input. Perhaps I was worrying too much about the unsealed end grain. I too very much enjoyed making the bread board ends. There was someting very rewarding about achieving a tight "cross-grain" joint essentially with just pins (and a wee-bit of glue).
You should look at Green and Green furniture and see their wonderful treatment for breadboard ends. Also Gary Knox Bennet has a very whimsical approach to the breadboard end. His book "Made in Oakland" is very intersting if you enjoy studio furniture.
http://www.cambiumbooks.com
Steve, if you want to reduce moisture movement through the ends (a good idea, I think), you need to use something other than wax, which is very moisture-permeable. I suggest dewaxed shellac, because it is easy and fast and offers excellent moisture resistance.
Don't worry about friction on the joint, there isn't _that_ much movement going on!
I too use the router to drill & elongate the holes. Also I try to slightly drawbore the holes, so it holds the joint really tightly even if the breadboard end shrinks.
"Everything should be made as simple as possible, but no simpler." A. Einstein
http://www.albionworks.net
I am not sure what you mean by drawbore. I take it you mean in the perpendicular direction to the "standard" direction but only towards the table end so the joint stays tight.Thx,
SteveO
Drawbore means to offset the holes for the pegs slightly - the hole in the tenon is slightly closer to the shoulder of the joint than the holes in the mortised piece. When you drive the peg in, it has to bend a little and compress, which draws the joint together very tightly. A very old trick."Everything should be made as simple as possible, but no simpler." A. Einstein
http://www.albionworks.net
Neat trick onthe drawbore !
Thx.
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