Inserting marble into a table top?

[Sportique]

Hi Froggy,

If you choose to do the job using a router on skis then take a look at this post https://www.ukworkshop.co.uk/forums/flattening-my-workbench-t48511.html for a good example of sturdy large-scale skis.

BUT, if it were me I would follow Paul's method:

Hi Froggy,

I don't think your friend's proposal is a very good idea. If I were doing it, I'd make a new top from MDF, add a Cherry surround to that creating a hollow in the middle, and then glue the marble to the MDF. I think that would make a far sounder job.

Cheers :wink:

Paul

and, as he says, your friend would still have his solid cherry top

That's my penny worth

Dave

 

[Froggy]

Hi Guys,

Sorry that I haven't being replying but I've been away. Thanks for replies, they've brought up some interesting points. There is, however, a lot more to this story, but at first I thought I'd just keep it simple and let you know what I thought was important to get the answers required. I was wrong so here's the whole story. Origonally we were going to make a 'frame' with the Cherry planks rebate the centre for the insert (material still undecided, but probably marble or slate) and then (this is where it gets interesting!) reinforce the underneath of the table as it's not going to have any legs, it's going to be suspended from a very large beam!! How it's going to be suspended is the subject of much debate as my friend thinks that if he suspends it at particular angles using chains it wont swing! I disagree and think that only ridgid supports will stop it swinging.
That was the plan, and already there's a lot to discuss. The plan however, faultered at the first hurdle becaused the stock was too wide to go through my planner and the local ebeniste (cabinet maker) who was tasked with planning it, decided to also glue all the pieces together and put scarves (this is a french term, not sure what they're called in English) on the end. I have no idea why he did this and when asked by my rather irate friend neither did he! So now we have a table top rather than a frame. If we cut it up again to restart we will be short of wood and my friend refuses to buy more and restart. So we have to make the recess for the insert. I didn't want to cut the centre out and rebate for the insert because I think it will weaken the table too much when it is suspended from the beam.
I know it's a very eccentric project; my friend is quite eccentric and now the project has become more complicated, because the French ebeniste did more than was required or asked of him and to be honest made a bad job of the planning.

 

[ondablade]

On hanging a table on chains Froggy - I'd say you are right about the swinging. I think short of very widely spacing the suspension points at roof level (which would mean it would still swing, but take more force and mean the chains could end up at 45deg or more and take up a lot of room space - and still unless they were pushed right out to horizontal they wouldn't completely prevent swing) it's going to swing pretty easily.

The other issue is that unless the table and the two chains form a parallelogram (where the chains are parallel - which would leave it free to swing) the table will tip (move out of the horizontal) as it swings.

Even replacing the chains with rigid rods and presuming the top mounts are well spaced wouldn't prevent it swinging unless the corner joints were rigid - and then the rods would flex unless they were very stiff.

It'd be easy enough to settle by making a model in card - this would give a rough sense of how much harder it got to make it swing with increased top hanger spacing (the resistance arises with increased spacing because of the tipping effect - in that case you have to lift the table and chain vertically on one side while it drops on the other to get sideways movement), and would demonstrate the tipping in action. It'd be easy enough to lay out a scale drawing too...

You could reduce any swinging to something fairly minimal though by dropping an unobtrusive chain vertically from the centre of the table underneath to the floor, and making sure that it was well tensioned. (by placing the suspension chains in tension) It'd all have to stay well tensioned long term though.

Maybe you could pull the roof down, or find there was enough movement in the floor above to have to keep on adjusting the chains!

In that case the two suspension chains at each end could even be secured from the same (strong) hanger at roof level. i.e. so that the two chains and the table top made a symmetrical triangle with the point upwards. The table top would also need to be rigid enough to transmit the forces (battens?) without developing a dip in the middle.

 

[Lons]

Hey Froggy

Easier to get a new friend :lol: :lol: :lol:

Bob