Need some joint advice

[JSJ]

I am not that experienced in joinery nor the strengths of each type of joint, but I do know that end grain to end grain glue ups are weak. So I am making this table for my daughter in law from 2 1/2" thick x 15" wide poplar. The photos show miter joints on the two ends of the top, but I am not sure if that is going to be a strong joint. If I went that route, I would put 4 or 5 dominos in the joints prior to glue up. I would appreciate the favor of all of your ideas, as well as ideas/thoughts on changing the design a bit to make this thing a bit stronger. Here is a picture of the table:

Thanks in advance!!

Jeff

 

[Mike Davis]

Your way is probably the best.

Just be sure to put the dominoes away from the outside edge.

 

[Martin Roper]

The photos show miter joints on the two ends of the top, but I am not sure if that is going to be a strong joint. If I went that route, I would put 4 or 5 dominos in the joints prior to glue up.

That's exactly what I would do. I think that will be plenty strong.

For your glue up, cut a couple spacer boards to length that would fit temporarily between the bottoms of the legs. That will form a rectangle and keep everything square in the clamps.

 

[dancam]

+ on the domino splines.

 

[JSJ]

Thanks guys for the sage advice!!!

 

[mdbuntyn]

There's a support bar, or two, underneath as well

 

[beloitdavisja]

A non-domino alternative if you don't mind some endgrain showing on the top: either dovetail or box joints would be strong as well. For dovetails, I'd make the vertical pieces the pins, and the horizontal the tails. If you want to hide the endgrain, you do either halfblind (where the tails show on the vertical sides), or hidden (full-blind) dovetails.

But the domino would be quick and easy I don't have one so I always like alternatives.

 

[McRabbet]

I agree with others that Domino's are the best solution here, but be certain to allow for wood movement across the table slab but cutting wider mortises for dominos away from the center one (just use the width adjustment on the tool). If the wood is the same for the uprights and the top, you shouldn't have any different expansion between them.

 

[redknife]

If you choose the Domino reinforced miter joint, make some test pieces. That way you can make sure your settings don’t lead to a backside blowout.

 

[marinosr]

Agree that dominoes are a good option but I still don't know if it will be built to last. Stretchers are a proven and well-used technology for a reason. Racking forces on the table will cause those joints to fail over time without a stretcher.

 

[Rwe2156]

Agree that dominoes are a good option but I still don't know if it will be built to last. Stretchers are a proven and well-used technology for a reason. Racking forces on the table will cause those joints to fail over time without a stretcher.

IMO a miter joint will look best, but is going to be the weakest. But river tables are built that way I guess. Splines will not add that much strength, tenons or dowels would be better but if there is any forces on the "legs" all the rotational torque is magnified and focused right on the joint. A tongue and groove butt joint with long through dowels is probably going to be the strongest. Lots depends on where its going and what its' being used for. If its just sitting there you can get away with a horrible design.

Good questions to ask regarding tables does is pass the vacuum cleaning smash test?

 

[Martin Roper]

This cantilever table was made with just bridle joints.

 

[JSJ]

Thanks all for passing on your wisdom! I also agree that a stretcher down low on the design would be best, but not sure the "customer" is going for that look I am going to present that option to her. One other thing that just occurred to me is that I don't have a saw capable of cutting a 15" wide x 2 1/2" thick board on a 45* angle. So I ripped the rough 17" wide board into equal halves, so I can handle that mass on my machines. I'll glue them back up when all are surfaced...she'll never look that close. My table saw (Sawstop PCS) is maxed out at 2.5" on a 45 so I probably could do that. I was also considering a butt joint with dominoes and some sort of brace/bracket (like a mini-corbel of sorts). She can live with some end grain visible. I agree with DrBob, as designed by the Chinese, it may not pass the vacuum cleaner smash test.

 

[Rwe2156]

There's a limit to that cantilever stuff. And what does that guy weigh, 130#?

 

[Wiley's Woodworks]

You've got all the right info scattered throughout the responses, so I'm going to pull out how I do these joints and add one more suggestion. A properly done miter joint is strong enough for a side table where all the force is going to be straight down. It will give the piece the cleanest look, and as long as you cut your miters cleanly so the joints are perfectly aligned with no gaps, it will show off a little of your craftsmanship. IMO butts, laps, or even dovetails will expose end grain which will turn a different color when finished.

Now, the best advice IMO from all the responses:

• You and Mike are right; dominos inside a miter are the best joint and probably the easiest.
• Mike is also right about putting the dominos as close to the inside surfaces as you can. Use the largest domino you can. 5 will be plenty.
• Martin's idea is genius!! The spreader board (it has to be fitted precisely to form a perfectly square box) lets you clamp up like you're building an ordinary box. I'm going to use this technique in the future. After moderate clamp pressure square up the "box" as you would any box.
• Chris (redknife) is right on!! Test your domino fit and clearances on test pieces before you touch the real boards.

Now, my hack: when you're ready to glue it up, do a preliminary coat of your chosen wood glue diluted with water to a 25-50% solution. Carefully paint the miter cuts--the end grains--with the solution, making sure you keep it out of the mortises. Let it dry until soft but not hard. Then glue up as normal and clamp as normal. The diluted mixture penetrates deeper into the end grain, and the full strength glue bonds to itself with 100% strength, resulting in a much stronger joint. I've tested this unscientifically, and it takes a lot more muscle to break apart the 2 stage glue up. I do this on all my picture frames.

Your boards are thick enough that you will have plenty of glue surface--over 3 inches-- to create a strong joint reinforced by the dominos. The top is so thick, and the length is so short, that IMHO stretchers are unnecessary.

 

[Martin Roper]

There's a limit to that cantilever stuff. And what does that guy weigh, 130#?

I think the lesson from that cantilever table is that a 90° joint can be made massively strong with a relatively simple joint. In that example one 90° joint is supporting well over 100# despite the fact that all the force is exerted on a lever arm.

In the OP's proposed table the two "legs" share the load making it inherently stronger than the cantilever desk. Any weight placed on that table is exerted straight down both legs, not on the joint. For any force applied from above, there is no opportunity for a lever as in the cantilever. The only possible lever that could be exerted on this table is from the side. I can't imagine a scenario where enough force could be applied from the side to break the joint.

 

[Martin Roper]

Now, my hack: when you're ready to glue it up, do a preliminary coat of your chosen wood glue diluted with water to a 25-50% solution. Carefully paint the miter cuts--the end grains--with the solution, making sure you keep it out of the mortises. Let it dry until soft but not hard. Then glue up as normal and clamp as normal. The diluted mixture penetrates deeper into the end grain, and the full strength glue bonds to itself with 100% strength, resulting in a much stronger joint. I've tested this unscientifically, and it takes a lot more muscle to break apart the 2 stage glue up. I do this on all my picture frames.

Your boards are thick enough that you will have plenty of glue surface--over 3 inches-- to create a strong joint reinforced by the dominos. The top is so thick, and the length is so short, that IMHO stretchers are unnecessary.

I just recently heard of this.

I've never done that to glue up boards, but I have done it to the edges of MDF to prevent it from wicking up all the paint or finish, but with mixed results.

 

[Wiley's Woodworks]

I just recently heard of this.

I've never done that to glue up boards, but I have done it to the edges of MDF to prevent it from wicking up all the paint or finish, but with mixed results.

I know what you mean about "mixed results" with MDF or any type of pressboard. None of them get along with water under any circumstances. I panic when a drop of sweat hits MDF. I might put normal strength Titebond on MDF, press it in with a steel putty knife, wipe it off with a dry cloth, let it sit for 15 minutes, then glue up normally. I have no idea if this would strengthen the joint. My SWAG is the joint strength would increase moderately, not significantly.