Breadboard table top questions

[Kevin Rich]

First, this forum is awesome. I have learned a ton by just being a silent reader. I made my first comment earlier so i figured I should go ahead and make my first post. I have been trying to teach myself neanderthal ways through youtube, mistakes (i mean creative problem solving opportunities), and forums like this. I am working on a laundry room table for a friend and need advice on a few points. Full disclosure, I used a router sled to do the bulk of the flattening but am doing everything else by hand. Thanks much in advance!

Rough description
33" by 77" total. Cheap dimensional 2x8 wood from big box store. Final thickness is about 6/4. Bread board ends that have 1 inch groove plus 1.5 inch tenons into the 7.5 inch bread boards. I have cut the mortises out and it is a good tight fit. I just need to clean the shoulder a little more. I plan to support the table top only on the sides and back leaving the area below the table open.
Attachment 396605Attachment 396608

Question 1:
Can a breadboard support the weight of the table? 1 inch groove across the width and 4 tenons that are 1.5 inch long and 3 inches wide.

Question 2:
Do I need some sort of stretcher or support to keep it from sagging at 1.5 inches thick? i'm hoping the support along the whole back side helps. It will lay free over top of 2x2 boards bolted around the room into the studs.

Question 3:
Instead of gluing the middle tenon, can i glue the very front of the table top and let the back end change twice as much as each half would have? This seems reasonable but if i have pegs I would need to make more space for movement of course.

Question 4:
Would making doing a drawbore peg in the breadboard help the ends support the weight?

[brian zawatsky]

Hi Kevin! Glad to see your post, jump on in - the water's fine.

my 2 cents: I feel that a 7.5" wide breadboard is too much for a 1.5" long tenon to handle. I would worry that the amount of leverage able to be applied with such a long lever (6", comparatively speaking) would eventually break the breadboard-to-table joint, either by splitting the breadboard along the cheeks of the mortise (this would be my bet) or by breaking the tenons. For the sake of comparison, my dining table was made with 4.5" wide breadboard ends & 2" long continuous tenons.

I think you'd be plenty safe to support the top along 3 sides (left, right, and back) with nothing underneath as long as you beefed up your breadboard joints by either making the ends narrower or lengthening the tenon & deepening the mortise (both of which would shorten the present length of the top).

As long as you give the table top some room to move in the back, you should be fine to fasten the front tenon tight and let the others slip. I would absolutely drawbore the breadboard joints; I don't think it will add anything in terms of shear strength, but it will definitely help pull the joint tight while still allowing it to move if left unglued. Again, my dining table is 46" wide, ends are drawbored & pinned tight with 6 pegs and even with all that tension in the joint the table top is still able to move freely.

From your description i am picturing a top that is captured between 3 walls. May I ask why you are bothering with breadboard ends when you won't be able to see the endgrain anyway? Or am I mistaken?

[Kevin Rich]

Thanks for the help! I was hoping with the one inch groove added it would be like 2.5 inch tenons. I think I can add another inch to the tenons and still fit.

The top is captured between three walls. I want to make the breadboard for two reasons. I have heard it might help the table top not twist (or at least as much) and I wanted to learn how to make it. I believe there is no way to learn like practicing. I have about a dozen chisels I bought for a dollar each and I figured a groove and mortise would be great ways to get better at them. I think I’m on my fourth version of, “whoa, so that is sharp”. I’ve quickly realized which chisels I sharpened better.