Moderators: Random Orbital Bob, nev, CHJ, Noel, Charley

 Reply
User avatar
By Sheffield Tony
#1268351
Jacob wrote:Or just do 3 feet in the trad way. Innately self levelling, simpler. There's nothing about a big table which demands more feet. Just more stuff getting under the feet of those sitting around it.


Just to mildly disagree, if you went for 3 feet, that equation above would need the cos(36) replaced by cos(60). Where 5 feet at 550 mm long would be fairly stable, you'd need 3 at 900mm long for the same stability - i.e, right to the edge of the top. Or educate people not lean their butt on the edge of the dining table !
User avatar
By MikeG.
#1268357
Sheffield Tony wrote:
Jacob wrote:Or just do 3 feet in the trad way. Innately self levelling, simpler. There's nothing about a big table which demands more feet. Just more stuff getting under the feet of those sitting around it.


Just to mildly disagree, if you went for 3 feet, that equation above would need the cos(36) replaced by cos(60). Where 5 feet at 550 mm long would be fairly stable, you'd need 3 at 900mm long for the same stability - i.e, right to the edge of the top. Or educate people not lean their butt on the edge of the dining table !


Four feet, then, would need to be of the order of 720 long, and would work perfectly with the 8 chairs proposed for this table (which don't work at all with the currently proposed arrangement). I think we can assume the floor will be flat enough to eliminate the need for Jacob's (perfectly valid) point about 3 being un-rockable. Four feet also leads to an obvious octagonal central piece, which would be so much easier than the 5 sided thing to make.
User avatar
By Jacob
#1268388
Sheffield Tony wrote:
Jacob wrote:Or just do 3 feet in the trad way. Innately self levelling, simpler. There's nothing about a big table which demands more feet. Just more stuff getting under the feet of those sitting around it.


Just to mildly disagree, if you went for 3 feet, that equation above would need the cos(36) replaced by cos(60). Where 5 feet at 550 mm long would be fairly stable, you'd need 3 at 900mm long for the same stability - i.e, right to the edge of the top. Or educate people not lean their butt on the edge of the dining table !
In that case there are a huge number of unstable tables in the world! I wonder how often they fall over?
I suppose the fault in the maths is in assuming that someone would put their whole weight on the very edge of a table to start with. This would be difficult to do in practice, whilst your feet were still on the ground. Even if they wanted to climb up stand on the edge they would be cautious about it and not be caught out, unless very drunk. :shock:
User avatar
By MikeG.
#1268413
I think the worst case is when everyone is seated and one or two on the same side of the table lean on it at the same time. The chairs would ordinarily protect the table from anyone who felt like perching their bum on it. I've certainly had pub tables tip slightly with people leaning on them. The other classic is when people on opposite sides of the table lean on it at the same time, cancelling each other out.............and then one of them sits back before the other. Whoopsy......
User avatar
By Jacob
#1268415
Here's the best photo I could find of the round table I rescued some years ago. It was a skip find, just the top, no pedestal. Top of two mahogany boards about 20mm thick diameter 12OO.
The framework is cleverer than it looks.
The two bearers aligned with the grain could be screwed tight as there would be no movement along them. The two cross pieces reach right across, across the grain, but without touching the rim apron. They'd need to accommodate movement and be screwed through slots, or better still held with buttons.
The 4 joints would be M&Ts but dry fit and with horizontal space in the mortice for movement.
These bearers and the apron itself were about 30 x 44mm.
The rim was made up of two layers of sawn softwood 8 pieces following the curve coursed like brickwork just glued and nailed (to each other, the hoop itself screwed to the top). The original was veneered but my bodge replacement was just painted black. There must have been enough flexibility in the circular rim to allow movement.
So the whole thing is lightweight but well braced enough to stay flat and allow movement.
The original pedestal would have been fitted to a square block 44 deep, sitting between the bearers (where there is a light patch). This had hinges and a catch - at least you could see where they had been.
If I was doing a circular table I'd definitely follow the same design, perhaps just scaled up or down according to size. Perhaps make the thickness the full 25mm on your 1.8m diameter.
It had held together well for 100 years or so.
I made up a non trad pedestal with 3 legs - quite close in - you could tell at a glance that it wouldn't be a good idea to sit on the edge!
PS the whole thing quite easy to do, except for veneering the apron. The top had a thumbnail moulding formed on the edge.
PPS Buttons just need to be loose fit too. They aren't structural they are just there to keep the top located in place, particularly if you were to lift it by the edges. If the top lifts a mm or so when you lift it that's OK as long as it goes back in place - better than being too tight and transmitting stresses.

IMG_1152.jpg
By Bremner
#1268493
Thanks very much for all your replies guys, very interesting reading and I’ll be sure to take your advice on board once the project starts. I’ve got the job booked in for the back end of this year, I’ll be sure to report back and let you know how I’m getting on and any design changes I make!