Thread: How strong does the apron have to be?

Don't worry about the base twisting without the top, that's normal and the top will hold it once it's fixed down.

The cupping boards are going to give you trouble; the edges are no longer square to the face and it's not going to join up flat without dressing it all again

Does the 580mm width include the legs? If not, the biggest issue I think you have is that the base is much too narrow for the top; I'd be going for overall 8-900 wide for an 1100 top. If the 580 includes the legs, it is going to be unstable and, IMO, look quite silly.

I'm also worried about your proposed leg to apron joint.
Based on what I understand is your design, the leg to apron joint will be very fragile and subject to catastrophic failure should someone kick a leg or attempt to drag the table.

I'm also not sure what you mean by the corners of the apron are joined with "bridle joints" -- do you mean finger joints or half lap joints?

Hi.
Thanks for the thoughtful replies Ian and Elan Jacobs. Firstly, that was a typo the apron size is 2580 x 980, so the planned overhang of the table to apron is 60mm. I'm glad you are not worried about the base twisting with the top. The top boards are monsters 275mm wide and I intend getting a local joinery shop to
a) check that the boards are square, probably remachine them and biscuit join. b) If its not considered too difficult or expensive; I may get all the boards ripped into something like 135mm wide

I'm also worried about the legs. Epoxy will make the leg to apron joint strong, but they could still break the leg at the neck when moving it. This could be a caveat emptor deal, with yellow safety warnings on the legs ). The table top boards themselves weigh at least 50-60kg. The thing is wide enough to have some sort of support coming from the centre of the apron to each leg, but its supposed to seat 10-12 people.
If you know of any designs that get around this weak turned leg issue, I'd be very interested.

And a bridle joints is I think a sort of mongrel mortice and tenon joint, for corners.

Ah, 980 makes much more sense. Absolutely rip them in half and shuffle them around to combat movement.

Epoxy will make the leg to apron joint strong

Not necessarily. While epoxy might be strong, it is brittle and doesn't like shock loads; I would suggest a good PVA or PU as a better alternative, they have a bit of give and will not crack as easily. The only situation I would recommend epoxy is if your joins are loose and you need something to fill the gaps.

Cheers Elan thanks for the info. Lo My 'joints' need all the epoxy they can get.

Originally Posted by chopper

I'm also worried about the legs. Epoxy will make the leg to apron joint strong, but they could still break the leg at the neck when moving it. This could be a caveat emptor deal, with yellow safety warnings on the legs ).
[snap]
its supposed to seat 10-12 people.
If you know of any designs that get around this weak turned leg issue, I'd be very interested.

And a bridle joints is I think a sort of mongrel mortice and tenon joint, for corners.

Can you post a photo of your "mongrel mortice and tenon joint" ?
and a sketch of what you propose for the leg to apron connection.

There is almost certainly a type of joint that get's around the "weak turned leg issue" but first I need to see what you have.

Lastly, have you thought about how the table will get from your shed to the customer? 2.7 x 1.1 x whatever the height is can be nearly impossible to get into an apartment.

Hi Ian
Below url depicts bridle joint as I've done it.

Https://en.m.wikipedia.org/wiki/Bridle_joint

I can't seem to reduce jpegs to a duitable forum size and my sketchin sucks.
I just glued all 4 legs to the apron, they have vertical channels that match the apron and just dop over the complette joint,


Anyway all the corner/leg joints are now swimming in titebond 3 and will be left undisturbed for 3 days.

The owner lives in a house close by and I propose taking the ttop as one seperate cargo, and the apron legs frame as load 2. Assemble on site.

Thanks for you interest and hopefully it'll be reasonably sturdy. Maybe they can bolt the legs to the floor )

The top will be fine, but I am not comfortable with the aprons being 8cm high. It is not enough even for a smaller table.

Originally Posted by Wongo

The top will be fine, but I am not comfortable with the aprons being 8cm high. It is not enough even for a smaller table.

Yeah I didn't like the height either, but it was already done so I figured it was a bit late to say. I would have gone to 120 high, 80mm is coffee table size

If there is timber available, I would seriously consider adding a 30mm strip to the bottom edge of the apron pieces. It could be set proud at the outer edge to form a mould.

Where does the taper start on the legs?

If they've been left square up top, they don't start tapering 'til after the apron, then you may be able to simply affix extra crosspieces between the long rails, rebated to the appropriate inside face of the legs, to effectively "double" the leg joint and increase racking resistance and load support across the short end of the table.

An apron inside the apron, as it were.

Of course, this depends on how you've fixed the diagonal corner braces and whether they can be removed/shifted.

Originally Posted by chopper

Hi Ian
Below url depicts bridle joint as I've done it.

Https://en.m.wikipedia.org/wiki/Bridle_joint

now you have me really worried.
Does your use of the term "bridle joint" mean that the apron is 80 mm wide and 30 mm high?
Or are you using "bridle" to mean a finger joint?

I just glued all 4 legs to the apron, they have vertical channels that match the apron and just drop over the complete joint,

Anyway all the corner/leg joints are now swimming in titebond 3 and will be left undisturbed for 3 days.

Attached is a scan from Illustrated Cabinetmaking showing how table aprons and legs are normally attached to each other.

Thanks for all your consideration. And you are absolutely correct. The apron is 30mm wide and 80mm tall/vertical. Despite 45 degree bracing in every corner and on the middle cross bits....the whole thing flapped/twisted like twig in a gale..ie when I glued the heavy legs onto each corner. But...illumination struck, I ran up a couple of Oregan boards 40 x 80mm that fit exactly between the cross braces at each end. Than I clamped it really hard, to the existing blackwood 30 x 80mm apron...and hey presto it was a 70mm wide apron piece and the rigidity of the end improved by ? 20%. I am going to completely go over the whole apron and laminate a second 30 x 80 blackwood board onto the current flimsy structure. Then I think it'll have a chance of a decent life.

I also spent a lot of time shaping 80mm tapered plugs to squeeze in between the top of the table leg and the 45 degree corner brace in the apron corners. Once the apron is beefed up I think I can move forward.

I must admit to being less concerned with how much the apron frame wobbles from side to side -- as once attached to the top this movement will be irrelevant -- but more worried about the apron to leg joint. It is the depth of this joint that determines how strong the connection is, and thus how sturdy the whole table is. The width of the apron members is not that important.
In the picture I posted you can see how a deep apron is morticed into a square section of the table legs creating a rigid and strong joint.