Tips on securing tabletop breadboard

[Jim Murphy]

Darn... it turned out much better than expected. SO.... I know I need to glue and pin the center board, but any tips or tricks on pinning the outer edges? REMEMBER, we're dealing with discount walnut here. (Wow...I had a B eye Tee Sea Haitch of a time getting enough of Charlie's walnut to work for me... can you say warp? can you spell twist? would you believe a 6/4 board produces junk?_
Oh well.... help me attach this breadboard. 36" width on the tabletop.

 

[FredP]

what i like to do with breadboard ends is drill a few 1/4" holes through the bottom of the BB end and through the tenon. I only partially go into the top part of the BB end. I dont like the dowels to show on the top. then remove the end and elongate the holes in the tenon for expansion. then i put the BB on and use dowels. i only put glue on the last 1/8" or so of the dowels so they are glued to the end and not the tenon. clear as mud eh?:gar-Bi

 

[woodlaker2]

I built my first oak dining room table this past summer for a friend and used breadboard ends approx. 32" long. Once the BB jonery was cut, I cut out sections of the tenon leaving 3 approx. 7" long sections before glue up. The gaps in the tenon were meant to ease the stresses due to wood movement over time. I then drawbored the holes for the pins (1 pin in each 7" tenon section), and glued only the very midpoint of the center 7" tenon and inserted a pin. For the two outside pins I relied on the drawbored pins to hold the breadboard edge. After 6 months with usual seasonal changes in humidity the joints remain tight.

As others here have mentioned before, be sure of your moisture content before glue up; account for seasonal wood movement .....i.e., use your best guess if comfortable with that or consult reference materials/internet for the wood species used then use your best assessment in doing your drawbored holes (they will tighten up a bit when the weather warms and the humidity goes up if not in a controlled environment).

Good luck!

 

[Gofor]

Jim, I did like Fred stated:

These are views of the bottom side:

First I drilled three holes through the bottom of the end, tenon and about 3/16" into the top side with a forstner bit :

Then I elongated the holes in the outer tenons:

The top view when put together. I used 3/8" diameter oak dowels.


Working fine after 2 years. The top was originally flush when built, as it was humid. Since then it has shrunk up to 1/4" overall width (Letting the breadboard extend about 1/8" on each side) during the dry winter months. Expands back some during the summer, but still stays tight up on the joint.

Hope this helps

Go

 

[Bill Clemmons]

Jim, I built a table this past summer w/ breadboard ends. It's very similar to what GO posted. A single hole through the middle tenon, then elongate the end holes to allow for wood movement.

View image in gallery​

View image in gallery​

This pic shows how I clamped the breadboard end in place while the glue was drying. I didn't want to connect a bunch of pipe clamps to span the 8' length. The width is 36".

View image in gallery​

HTH

Bill

 

[Jim Murphy]

Okay, guys, great advice, but I have several "how to" and "why" questions.

First, what is the purpose of cutting out parts of the tenon? Can't I just leave the tenon full length? Is there a movement issue here?

Second, I'm thinking of using a plunge router with 3/8" spiral upcut. Is that a problem versus drilling with a Forstner?

Third. How critical is ensuring the elongation of the outer two pins is exactly parallel to the end? I'm thinking I need to use a guide bar set parallel for the elongate action. Is this overkill?

Fourth. Do I really need to glue the tips of the outer pins? I'm going to need to clamp the breadboard to the table to close up the gap, and it seems that installing the pins under tension would adequately hold them in place.

Fifth.... Ain't NCWW such a great place. Sorry I've been away, it's great to be back.

 

[Bill Clemmons]

Okay, guys, great advice, but I have several "how to" and "why" questions.

First, what is the purpose of cutting out parts of the tenon? Can't I just leave the tenon full length? Is there a movement issue here? Yes, there is a reason, although I can't remember the exact details w/o going back to the books. I think it has to do w/ weakening the breadboard end if you take out that much wood. For the two outside mortises, you want to leave them a little wider than the tenons to allow for wood movement. You can make the center one a fairly snug fit.

Second, I'm thinking of using a plunge router with 3/8" spiral upcut. Is that a problem versus drilling with a Forstner? I used a 1/4" spiral upcut bit in my router table to make the mortises. It worked fine. Just have to make it in several passes, going a little deeper each time. My mortise depth was 2". The breadboard end was 3" wide.

Third. How critical is ensuring the elongation of the outer two pins is exactly parallel to the end? I'm thinking I need to use a guide bar set parallel for the elongate action. Is this overkill? This is fairly critical! If the elongation angled into or away from the table, when the top expanded and contracted, it would either move the end away from or into the table. You want it to remain exactly parallel to the table for a nice tight fit.

Fourth. Do I really need to glue the tips of the outer pins? I'm going to need to clamp the breadboard to the table to close up the gap, and it seems that installing the pins under tension would adequately hold them in place. I always glue mine. W/ the top and end moving against each other, and the pin moving in a different direction, you can't rely on tension to keep everything tight. When you install the pins, do it from the underside. Push the pin through until it just exits the other (top) side. Then put a drop of glue on the shaft of the pin and drive it in another 1/8 -1/4". This keeps the glue from sealing the tenon to the mortise, which is a definite no-no on the two outer tenons. When the glue dries, use a flush-cut saw to trim it off. This puts any glue smear on the underside of the table, not the top.

Fifth.... Ain't NCWW such a great place. AMEN!!! Sorry I've been away, it's great to be back.

If you have access to old issues of Fine Woodworking, there is a good article by Christian Becksvoort on breadboard ends in issue 183, p. 36.

HTH

Bill

 

[Gofor]

Jim, to add to what Bill said:

IIRC (which is getting harder every day!) the reason for not cutting a full depth mortise in the entire bread board is to prevent it having a tendency to bow in the center when the main table shrinks back under lower humidity, while still giving it good strength to support someone leaning on it. The stiffer breadboard end also tends to prevent the main top from bowing (which is why you still leave the shallow mortise). You could probably get the same result using biscuits for the shallow parts and dominoes or floating tenons for the deep parts if you have that tooling.

As for getting the elongated cuts perfect, it helps keep the breadboard tight against the entire width. However, I did not "draw pin" mine. The elongated holes in the picture were trued up with a chisel, but there was no side loading. I did prime them with a bit of wax in the holes, though, before assembly, to keep any glue squeeze-out from sticking the pin to the hole in the tenon. I also spread glue on the center tenon to full depth.

A spiral cut router will do just fine IMHO, and probably better than I did with a chisel. However, whatever I did, I got lucky and it is working fine. Do not elongate the holes in the breadboard end, tho.

If your wood is dry, the shop is dry, and the table will be in climate control, this all may be a moot point. We open the windows in spring and fall, so the humidity in our house changes a bit with the seasons. I build with the idea that there will come a time when the furniture will not be in a controlled climate.

As for gluing the end pins, I put a little glue on a pencil erasure end and daubed it in the very bottom (top was upside down) . Just enough to stick it. A dab of CA on the end of the dowel will probably work as well. More is not better in a sliding joint.

Go

PS. Still getting good use out of the dado set I got from you. Thanks again and welcome back to the menagerie!!