Breadboard ends advice

[Russ59]

I have made a pine blanket box but still have the top to make.
I will be joining boards together with glue and biscuits and adding breadboard ends but what I want to know is, when I have the ends on, the main top boards wont be supported on anything (lengthways) if someone sits on it, so would glue and biscuits be strong enough, but if I make the top boards the full length of the box then add the bread board ends it will be far too long.
I hope you get the gist of what I'm aiming for.

Russ

 

[Mar_mite]

Once the boards are glued up it will be as strong one piece. It will be fine.

 

[custard]

Russ, if the breadboard ends are attached to the top just with biscuits they won't be strong enough to support a sitting person. The glue joint is end grain to long grain, which is very low in strength, plus it's not a proper breadboard end in that it can't accept the shrinkage across the top, so a weak joint will be weakened further over time.

 

[Mar_mite]

I think the op knows this. I think he is asking how strong the glue joint is along the long grain. Front to back as it were across the top of his blanket box.

 

[Jacob]

I have made a pine blanket box but still have the top to make.
I will be joining boards together with glue and biscuits and adding breadboard ends but what I want to know is, when I have the ends on, the main top boards wont be supported on anything (lengthways) if someone sits on it, so would glue and biscuits be strong enough, but if I make the top boards the full length of the box then add the bread board ends it will be far too long.
I hope you get the gist of what I'm aiming for.

Russ

Got it!
I wouldn't bother with the bread board ends. Horses for courses - you don't need them. You could just put on a bit of lipping if you want to cover the board ends. Or you could lip it all round with a bit of moulding - contrasting hardwood?
Personally I wouldn't bother with the biscuits either - they help to align boards but make a weaker joint

 

[custard]

I think the op knows this. I think he is asking how strong the glue joint is along the long grain. Front to back as it were across the top of his blanket box.

Let me be clearer, I don't mean the top will fail under the weight of a sitting person, I mean the glue joint between the breadboard ends and the main top will fail. In a year or two there'll be a gap between the breadboard ends and the main top that you'll be able to look down and see the biscuits. If the biscuits weren't there the breadboard ends would drop off. Not nice either way.

Either make the top with the correct joints for breadboard ends (which could look very attractive), or don't bother with breadboard ends.

 

[Mar_mite]

Wood won't shrink along it's length, why would there be a gap? Also, don't glue breadboard ends on across the end grain, allow for expansion/contraction.

 

[deema]

I think you may wish to consider one of three options, two of which have been mentioned.

The first, which is Jacobs suggestion is to do away with the bread board and just glue up wood lengths to make the top out of. This is a very traditional way of making a blanket box, which was a utilitarian object. The top running over the edges of the sides will have a good strength. If you use a good glue, the glue joint should be stronger than the wood itself. No need for biscuits.

2. If you use as you suggest breadboards, these should be Mortice and tennoner together and draw pegged on. No glue should be used in the joint with the breadboard. The breadboard will not only help to reduce cupping and incidence of the top going out of flat, but will also add significantly to the strength of the top as a consequence of the Morticer and tennon construction.

3. The third option is to a build a frame and have a single or two loose panels to make up the top. It will look very elegant, be very strong, be less prone to twist and warping and use less material.

 

[Russ59]

Thanks for the constructive advice, its my first woodwork project since leaving school in 1975, I've impressed myself with the build so far.
The reason I asked this question is that I thought adding breadboard ends would stop the whole top cupping as against just having end grain showing, or could I be assured this wouldn't happen. Also how thick does the top need to be?

Jacob you say biscuits aren't needed when joining my boards, why not?

 

[Jacob]

..
Jacob you say biscuits aren't needed when joining my boards, why not?

They do help to align the boards but with a bit of fiddling you can align them anyway - "butted" - it used to be called a "rubbed" joint but with slow modern glues it's a combi of rubbing and clamping joint. But the biscuits themselves introduce weakness, as compared to a straight butted joint.

 

[Mar_mite]

..
Jacob you say biscuits aren't needed when joining my boards, why not?

They do help to align the boards but with a bit of fiddling you can align them anyway - "butted" - it used to be called a "rubbed" joint but with slow modern glues it's a combi of rubbing and clamping joint. But the biscuits themselves introduce weakness, as compared to a straight butted joint.

For this application, and considering the op hasn't done a glue up since 1975 biscuits will be advantageous. I think what you are saying is that a biscuit breaks up a long run of glue and is therefore a weak point? It's an interesting idea, I have always used biscuits and have never had a joint fail.

 

[RogerP]

Biscuits don't add any strength to long grain glued joint - but they are useful for easy alignment. However I've always managed okay without them. If the boards want to cup there's not much, if anything, you can do to stop them. The best answer is to use quarter-sawn radial cut wood.

 

[ayuce]

Biscuits don't add any strength to long grain glued joint - but they are useful for easy alignment. However I've always managed okay without them. If the boards want to cup there's not much, if anything, you can do to stop them. The best answer is to use quarter-sawn radial cut wood.

Roger you mean even breadboard ends with M/T won't help aginst cupping ?

 

[Mr T]

The reason I asked this question is that I thought adding breadboard ends would stop the whole top cupping as against just having end grain showing, or could I be assured this wouldn't happen. Also how thick does the top need to be?

It depends on what you are making it in, I don't think you've mentioned that so far, if it's redwood there is a good chance of cupping, if it's kiln dried hardwood less. Alternating the orientation of the annual rings will help to reduce it. One option instead of BB ends would be batons slot screwed across the the grain on the underneath of the top. Not so elegant but they would not be evident when the lid is closed.

Chris

 

[RogerP]

Roger you mean even breadboard ends with M/T won't help aginst cupping ?

Help is one thing stopping is quite another. Really well made and correctly fitted end boards can disguise small amounts of movement but using quarter sawn timber is by far the best insurance.

 

[ColeyS1]

Surely biscuits/ tongues increase the surface area, therfore having more glue to hold the same thickness timber ?

 

[custard]

Surely biscuits/ tongues increase the surface area, therfore having more glue to hold the same thickness timber ?

Some people claim tongues, or at least loose tenons like Dominos, can actually increase the chances of edge joint failure. Their thinking goes along the lines that as the board shrinks across the grain the loose tenon, which has opposing grain direction, will attempt to push the joint apart. It's interesting that biscuits have their grain running at 45 degrees, presumably in recognition of this.

Personally I've never encountered this problem but there you go.

I often use biscuits or tongues or Dominos when edge jointing, but purely to help alignment when I'm gluing up on my own. The workshop where I trained however frowned on using anything, they argued that if the workpiece is subsequently shaped a biscuit risks becoming exposed by the shaping which would ruin the workpiece. Fair point, their designs called for a lot of subsequent shaping and they had plenty of craftsmen available to lend a hand during a glue up.

 

[Jacob]

I first noticed it after trimming short lengths from the ends of a sycamore table top. The boards had some joints with plywood slips and some plain butted joints. They snapped easily at the plywood slips but the butted joints were stronger than the wood - the wood would break sooner than the joint. That's strong enough so there was obviously no need for any addition to the joint. In fact slips, dominoes etc end up being the weak spot. Probably because it's harder to get 100% glue in the joint whereas with butted joints I always flood both sides with glue - too much is better than too little.

 

[Sawyer]

I wouldn't use biscuits to fix breadboard ends; in time the joint is almost guaranteed to fail, because it's relying on end grain to long grain gluing. Mortice and tenon is needed as you have to rely on mechanical strength rather than glue to allow movement.

 

[Russ59]

Well I finally glued my boards up (with biscuits :wink: ) and going to leave it end grain.
I had to do a bit of sanding both sides because with not having a planer/thicknesser some of the boards where standing proud of the next one to it but I'm happy with the outcome. Just needs trimming to size and routing edges now.
I'm also unsure on what to finish it with. Would just wax suffice?

Here's a pic.



And what its going on.