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By jsleight
#1310806
Hi,

I'm planning to build a simple dining table using hairpin legs, and was hoping to get some advise on whether or not the design will work.

My main question is whether or not you think this will be sturdy enough and not sag/bounce in the middle too much? Do you think I need support across the width of the table, or will the thickness of the top be adequate? And is the 50mm support thick enough or should it be thicker (in height).

This is the design:

1800x850mm top made from 24mm birch plywood, with a 50x48mm center support bar/stretcher, made from the same 24mm birch ply (two pieces side by side). All glued together. Four three rod hairpin legs.

Pictures:

Screen Shot 2019-10-04 at 16.05.25.png

Screen Shot 2019-10-04 at 16.04.55.png


Thanks!
By gog64
#1311901
I think that will sag pretty quickly. Is there a reason for not making an apron? If so, I’ve seen thin tops like that reinforced with right angle steel section routed & glued in. I think that sounds horrible (sorry to be blunt), but each to their own. I like birch ply for a lot of things and 2 x 1 inch laminated together (to make a 2 inch thick top) with a Formica surface works great as a kitchen / dining table. My kids favourite “restaurant” beat you to that one though!
By Fitzroy
#1312200
I’ve just finished a small desk 1050mm x 550mm with a 21mm thick top from recycled mahogany (repurposed Victorian wardrobe). Lengthways it’s fine but widthways it’s very flexible and I’ll be adding some ribs front to back to stiffen it up.

The use of hairpin legs seems to exacerbate the issue as they have little grip on the floor and tend to splay easily.

Fitz.
By jsleight
#1312375
Thanks everyone, I've revised the design to include additional support over the width of the table as well, which will hopefully support it better. I have a couple of variations, one with lap joints and a simpler one with butt joints.

Screen Shot 2019-10-10 at 18.08.39.png

Screen Shot 2019-10-10 at 17.58.37.png


What do you think?
By gog64
#1312676
First of all, take my advice with a big pinch of salt, I've only ever made bigger tables like this with some variation of aprons and braces. So I could very well be talking rubbish here, but I think that will work much better. You've designed a reinforcing structure to resist bowing from vertical force. It's a laminated board so other natural movement should be pretty low. I don't much like hairpin legs myself, but the canting (splayed angle) puts them in constant tension, so they will naturally resist racking from lateral knocks and pushes. The fact that each leg has almost zero contact area with the floor will also avoid racking by skidding the table when knocked!

I'd just crack on with it, don't overthink the reinforcement. If it was me, I'd just use some more of the ply on edge and domino each corner to align them nicely (dowels or biscuits would do) in a square. Those joints won't "do" anything, they would just keep the "box" aligned & neat when fixing to the top. It's all ply, no need to worry about movement, just attach to the top any way that's secure. I will be tarred and feathered here, but if it were me I'd just pocket hole and glue it on. I wouldn't make a table like that personally, but on the other hand, it's only a couple of hours work tops and you should end up with a serviceable table.
By jsleight
#1312706
OK great, thanks again! I‘ll give it a go with the extra supports. This is the first large piece I’ve made so it’s all a bit of an experiment.

One other question, is there any rule or standard minimum size for the height of stretchers/aprons?