ive just finished gluing up a large slab for a dining table, the slab is 40″ by about 72″ and about 1 7/8 thick in white oak
i have two more edge glued pieces to add 2 1/2 wide on each edge and two 4″ breadboard ends, to give a final dimension of 45 by 75
i have plenty of length to play with and my question is how to join the breadboard ends to the slab
cutting tenons in the slab is feasable, cutting the ends straight and square is no problem using a circ saw and a router with a straight edge
i have a couple of options, cut the top to length while cutting tenons for the breadboard ends or using loose tenons and mortising the slab either with a slot cutter or a dadoe cutter
the dadoe cutter would cut a mortise about a half inch deep, the slot cutter is the same depth of cut but minimal width, the dadoe cutter is 7/16 but can be changed easily by resetting the depth of cut
the slab is way too heavy to manuver over any of my stationary tools
Replies
Bread board ends are primarily used to help keep the table top from cupping. They should be attached to the entire width of the top. Either the top or the ends can have a tongue cut on the entire width. This fits into a groove. The bread board ends are then fastened with pins. The top will expand and contract so you use a slotted pin hole in the tongue. Just attaching the bread board ends with dowels or short loose tenons will not capture the entire width of the top. You could use a full length loose tenon as long as it's connected to allow the top to move. It may be a moot point with a thick top since the mass will resist cupping but a 3/4" top often will cup over time. The bread board ends can help but they won't necessarily prevent cupping. After all, the bread board itself may warp. A 30" wide top can easily move a 1/2" or more over the seasons so make sure you allow enough movement room.
Personally, I would use a router and cut a tongue on the top by cutting from both faces. I would cut a groove in the bread board ends. I would stop the groove short of the ends so it doesn't show and cut the tongue back so there is room for it to move. Place the bread board ends, drill through for your pins, remove the BB ends and elongate the holes in the tongue. Only glue the pins in the BB ends.
Beat it to fit / Paint it to match
That is how I did these on a chest.
I chose to run my tennon all the way thru.Webby
Steve, there are obviously many ways to skin this cat. One way that works for me:
Once the slab is cut square, use the router with a large rabbeting bit on both sides of the slab to create the continuous tenon. For your top this would be approximately 5/8" thick. On the tablesaw make the matching dado along the edges of the breadboards. Don't try to machine the parts to a perfect fit; use a rabbet plane on the slab portion to get it just right. After the breadboard ends fit the slab tenons like gloves, add 2 loose tenons to each joint, say 1/2" thick, right in the middle of the thickness and towards the edges of the piece. They get glued into the slab but only pinned through the breadboard pieces.
This is much more complicated to describe in words than it really is.
David Ring
http://www.touchwood.co.il/?id=1&lang=e
David,You mentioned many way to skin a cat...I'm curious about the length of tenon that you and hammer would recommend. I'd be pushing for 1'-1 1/2" tenon thinking more is better and for a table that heavy it'll be moved around by those breadboard ends quite a bit. Any thoughts?
The long tenon that runs the whole width of the tabletop doesn't need to be deep at all. If you're making it with a router as I suggested it would be limited to about 1/2" deep. But this is quite enough. The whole purpose of this part of the joint is to keep the breadboard piece flush with the main slab. This joint gets glued only in the center section - about 8" of it is OK to glue. The 2 additional tenons towards the edges of the tabletop are what's keeping the breadboard from coming loose. I'd prefer them to go some 2" deep into either side. Taken together it is quite strong and will never come loose. The critical part is hand planing that long tenon to fit the dado in the breadboards perfectly. If that OK, then everything will be OK.David Ring
http://www.touchwood.co.il/?id=1&lang=e
David,Thanks, that is good to know. I do use a router for the breadboards, however, I use a straight bit, I don't like the weight of a rabbit bit in the hand held position.
The timing of your question is great as I have been pondering the same predicament. I have seen through dowels used to fasten the m/t joints in place which gives an interesting look when done with contrasting woods.
The Norm Abram design that I am stressing over calls for a 2" wide bread board (on a 31" deep table). His plans say, "Tongue on top is 3/4" thick x 1" wide x 29 1/2" deep. Groove in edge is 3/4" wide x 1" deep x 30 1/4" long. Dowel holes in top should be elongated for top expansion."
In the video, Norm uses three 1/2" dowels which are drilled from the bottom and do not go all of the way through the top surface. The center dowel is fixed (the hole is not elongated) while the other two are elongated. Glue is applied just as the dowel is about to be inserted so that it is only "attached" to the bottom of the breadboard and not the tenon in the table top.
My current thinking is to form the tenon with a cs and router (cut the straight line with the cs, then rout out from there using a jig). Similarly, I plan to use a centering router plate to form the mortise, then square it up with chisels.
My angst is whether or not to adjust these dimensions as the table top in my project widens to 42". I like your idea of having 4" breadboards on your 45" x 75" table top! Similarly, I am wondering if the wider breadboard needs a deeper m/t joint. When is enough enough?
Edited 10/28/2008 10:42 am ET by heartwould
Don't be afraid to change the dimensions of the breadboard to suit your taste. A 2" wide breadboard on a tabletop that is almost 2" thick (like the OP's project) looks absurd to me. We do lots of breadboards that are 4" to 6" wide on tables.IMHO the center dowel you mention is unnecessary. You can just glue the center section and accomplish the same thing. If you're doing decorative pins, then put 'em wherever they look good.David Ring
http://www.touchwood.co.il/?id=1&lang=e
Thanks for your advice! Since the dimensions of the piece have been changed to better conform with the size of the room, the thickness of the available material (and my daughter's fancy), I'm not exactly sure how to make the proper adjustments to fit the overall scale. Heaven forbid that it would become known as "Grandpa's Albatross."
The table in this thread is very similar to the overall dimensions of my daughter's table (45" x 75" vs. 42" x 80"). I'm looking forward to seeing how this one turns out! It would be great to be able to use White Oak (quatersawn would be really beautiful), but the cost is a bit much here.
Edited 10/28/2008 4:22 pm ET by heartwould
thx for the advice guys i was cutting a dadoe in the slab and tongue into the breadboard end, but either way would work of course
the whole table weighs about 250 lbs, al quatersawn white oak
i'll post more pics as the project continues, if there's interest
and her's where it started
350 bdft, quartersawn white oak, about 1100 pounds, yes in that little van!!
Several ways to do this. When I do these, I shoot for a 1-1/4" tennon. If you don't care if the tennon shows, just run a dado (OK, groove) down the length of the BB end stock. If you want a stopped mortise, you can either do it by hand (a true PIA) or you can do it on a TS with a dado blade, raising the blade into the workpiece (sounds scarrier than it is if you take appropriate precautions with feather boards, etc.) and just cleaning up the ends by hand (that's the way I usually do it). Or, since it's end grain and pretty easy to hide the patch, you can run the groove through and glue in matching filler pieces to close up the ends. Another option is the Greene & Greene look -- a contrasting piece designed to disguise the wood movement -- hard to describe, so look it up if interested.
I make the tennon either by hand with a rabbet plane if I'm so inclined (tho' you can cut the shoulders with a guided circular saw if you want), or use a router with a guide fence and a pattern bit, removing stock from both the top and bottom of the slab. You pin and glue the joint tightly at one location, and elongate the pin holes in the tennon, and use no glue, at the other locations. If the table is going to be against the wall, I'll generally pin the front so movement is to the rear. If not, I'll generally pin the middle so movement is minimized at both edges.
As another poster noted, you want the fit to be pretty tight -- I usually shoot for a fit that requires some mallet work to assemble the joint. Otherwise, it may tend to get a bit floppy later in life. Drilling the pin holes requires that you assemble the joint, drill the holes, and then disassemble the joint to elongate all but one hole in the tennon. Since the joint is made tight, you may want to consider leaving the BB stock long until final assembly to give you something to pound on when assembling/disassembling, and then trim it to length after final fitting.
Mike Hennessy
Pittsburgh, PA
Edited 10/28/2008 12:57 pm ET by MikeHennessy
I got taught that bread board ends are done as shown in the attached drawing.
Another option, but not really practicle in your width is a sliding dovetail.
i did consider a sliding dovetail, but the top is too large for my skill level
your suggestion of the spline and tenons is the way to go, cutting the faces and shoulders should be straightforward with a router and straight edge
suggestions as to dimensions? the breadboard end is about 4 inches and the top slab is still about 7 inches too long and about 1 7/8 thick, the breadboard ends are 2 3/8 thick with some minor planing still required
a picture of the pedastal is attached for those who are interested
Edited 10/29/2008 6:41 am ET by steve
The table is pretty massive.
I'd probably make the spline and tennons 3/4-inch thick or so, and the tennons about 3-inches long. Square pins coming all the way through the top would probably look good, at least to me.
If you wanted to try sliding dovetails, you could do them with a slight taper, and cut the ends over length, trimming them to final length once the ends are slid onto the top and pinned into place. To work right the taper has to all be on the bottom so the top stays flush.
Steve, you are well on your way to a very beautiful piece!
I have a jig to cut the tenons with a router, essentially a larger oversize base which wraps around and references off the end of the slab. FWW had an article on this type of jig many years ago.
I would plug the tenon with long grain wood, like poplar or your base wood, so the long grain faces out, toward the end grain.
I'd mortise a bread board to fit over the tenon.
You can attach the breadboard with plugs running through the top, or if you have such a plug in place, from the end with a screw. The breadboard holes for the plug would be slotted at the ends to accomodate for wood movement. Cap the ends with a decorative through tenon looking plug made of ebony or other decorative wood. Glue only in the center. Regards, Scooter"I may be drunk, but you're crazy, and I'll be sober tomorrow." WC Fields, "Its a Gift" 1934
Great suggestions! I'll see if I can find the FWW article on that router jig.
Thanks, Scooter!
Imagine a "C" the top of the C is the router base in plywood or mdf. It then extends past the tenon location and using other stacked blocks of mdf, goes down about a half inch, with the bottom stack of mdf coming back toward the bit about an inch to match up with the proposed end of the tenon.
That final stack is only a quarter inch mdf. That stack keeps the tenon shoulder at a pre-determined length, say a half inch or so. But you could also clamp a straight edge to do the same thing.
I built mine using quarter inch mdf in about 2 hours. Regards, Scooter"I may be drunk, but you're crazy, and I'll be sober tomorrow." WC Fields, "Its a Gift" 1934
Scooter, will you please send photos and/or the plans that you used? I'm becoming more and more visual as time passes.
I don't know how to post a photo. I am stupid. Please email me at [email protected]. I will look for the FFW article tonight. I am sure I have a reference to it, if not the actual article. Regards, Scooter"I may be drunk, but you're crazy, and I'll be sober tomorrow." WC Fields, "Its a Gift" 1934
It's on the way!
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