Inserting marble into a table top?

[Froggy]

Hi everyone, I have a friend who has a Cherry wood table top which is about 50mm thick. He wants me to remove a section from the middle of the table and insert a slab of marble (probably about 15mm). What's the best way to do this bearing in mind the length and width of the marble will be around 400mm x 600mm?
And once I've done this what's the best adhesive to use?

TIA Froggy.

 

[Racers]

Hi,

I was planning to do something similar my self but with teak and slate, I didn't in the end as I was worried about the weight.

I was going to use silicone to seal it in and allow for the expansion and contraction.


Pete

 

[Froggy]

Hi Pete,

He may actually use slate, it's a toss up. How were you planning on making the recess? I don't want to cut right through the table and make a rebate for the slate/marble (ot rather my friend doesn't want me to), but routing out an area that big and keeping it nice and tidy willpose a problem! How were you going to do it?

Cheers Froggy.

 

[No skills]

I've thought about doing something similar with the kitchen worktop when the kitchens done. To make the recess I was going to make a series of cuts with a circular saw about an inch apart (left and right and up and down), chop out the waste squares with a chisel and then use the router to clean up the recess created. To keep the router level over the whole area I was going to use a thick (25mm) piece of plywood screwed to the router base, the ply piece would of course have to be quite long to allow me to slide the assembly back and forth over the recess.

 

[Froggy]

Hi No skills,

You probably won't believe this but...I had an almost identical thought process. Only I was thinking of using a router to make the 'chess board pattern', not a circular saw, as the router would take out more waste. But would it work? Has any body tried this approach? I don't want to find out that it doesn't work and ruin my friends nice cherry table top!

 

[yetloh]

It would be noisy and messy but (corners apart) I think it would be quite easy to do the whole recess with a router. I have done something similar myself, admittedly not as deep, with the router on long guide rods supported on rails either side. That way you can do the whole area to a consistent depth without risk of the router base tipping into the cleared area.

Jim

 

[Froggy]

What sort of rails were they Jim?

 

[Paul Chapman]

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

 

[Froggy]

Hi Paul, That would be a good idea if he didn't alreaday have the Cherry wood table top.

 

[Paul Chapman]

Hi Paul, That would be a good idea if he didn't alreaday have the Cherry wood table top.

But if you do it my way, he'll still have a nice Cherry table top when he gets fed up with the marble.... :lol:

Cheers :wink:

Paul

 

[yetloh]

What sort of rails were they Jim?

Just bits of softwood to raise the router an inch or so. I had stops on the guide rods and the ends of the rails so as to limit travel so that it didn't come off the rails if you see what I mean. Nothing very sophisticated, just had everthing securely clamped down to make it secure and ensure a consistent recess.

Jim

 

[Curlew]

I hate to pour water but no matter how you make the recess the wood must move with moisture change, the marble will not, and so there will either be gaps at the edges or a split in the wood, unless you are very lucky. I don't think it's a good idea to do this. you can get away with it in a kitchen worktop because/ if it's a homogenous material, but solid wood moves much more across the grain than it does in length.

 

[Jacob]

Hi everyone, I have a friend who has a Cherry wood table top which is about 50mm thick. He wants me to remove a section from the middle of the table and insert a slab of marble (probably about 15mm). What's the best way to do this bearing in mind the length and width of the marble will be around 400mm x 600mm?
And once I've done this what's the best adhesive to use?

TIA Froggy.

You need to have the marble sitting loose, perhaps on a flexible base such as a bit of 1/2" insulation of some sort or a piece of old karrimat, to isolate it from timber movements or local pressure points. Flexible mastic around the edge, having left a suitable gap. Or nothing.

 

[No skills]

I would of done something similar to what jacob has said, left a small gap round the edge and seal with silicone. Under the piece I would also have used a bed of silicone to a depth of 5-6 mm - let that go off then sit the stone on top and seal the gap round the edges.

JMO

 

[ondablade]

One necessary requirement in creating a situation where silicone or whatever can handle the movement of the wood is to ensure that the bond line is thick enough. (a bit like the width of the grout line while tiling) Make the gap too narrow and the chances are that the silicone will come apart (shear and tear) over time.

It'd also be desirable to use a biocide containing grade of silicone to prevent fungus and the resulting black staining (go for a dark colour?), although maybe food contact could be an issue with that. Also a top quality (quite a lot more expensive) high polymer content grade like PCI which is likely to be longer lasting. (the cured material has better physical properties)

Spacers (beads and the like) tend to be necessary to get control of the thickness of the bond line.

Even if the grout line is wide enough the silicone may develop quite a pronounced upwards bulge as the gap narrows - I've had this effect with joints between tiles and door saddles fore example.

There are ways to minimise this by incorporating a purpose made compressible strip (rubber/foam tube and the like) in the gap so far as I can remember, but you also need to make sure that the top surface of the sealant is finished in a concave U shape to give it some room to move without bulging above the surface.

This book http://www.amazon.com/Setting-Tile-Home ... 1561580805 (Setting Tile by Michael Byrne - it's a really good tiling manual that mixes the technical detail with the practice of tiling) if my memory hasn't gone off details some of these methods in the context of installing expansion joints.

I've seen others talk of using one of the highly PVA polymer modified flexible tile cements to lay tiles on tables and the like.

Whether or not I was using a silicone or a tile cement I'd definitely want to go carefully, and put it in detail (via a drawing) to the technical support department at the factory (not some doofer at a retailer's shop) of a good maker of both materials like PCI BASF before committing....

 

[Lons]

Hi guys

Forgive my ignorance but i don't see any real problem :?

I made a coffe table at least 8 years ago and it's been in my centrally heated living room ever since with absolutely no issues whatsoever. Pics below were taken 10 minutes ago!

Admittedly, mine is made of well seasoned oak (top and sides from offcuts of t&g flooring (top is 2 thicknesses glued together) and the inset is a piece of blue pearl granite around 760 x 660 x 30mm thk - weighs a tonne :roll:

Also mine is a full depth recess and granite is supported on bearers and blocks - spacers to hold to correct depth and sitting on a bed od std silicone. Gap between granite and oak is minimal and as said, vurtually no movement, shrinkage or splitting

Maybe I've just been lucky but i intend to make a table when I've fitted my kitchen using oak and a 1500 x 900 x 25mm thk offcut from my kitchen worktops (Mistral composite - like Corian).

cheers

Bob

 

[ondablade]

Nice table Bob. There's a smart move built into the design, in that the strips of oak framing the piece of stone are all placed so the grain is running lengthwise, and are fairly narrow - and the table is pretty small. All of which should give minimal movement.

Yours seems much the safer way to do a new top, but Froggy has been asked to cut out a 400x600 depression in what is presumably a solid/one piece table top to enable the dropping in of a piece of stone - which means relatively rather more movement in the cross grain direction. Maybe even a possibility of splitting the remaining cross grain strips if they end up fairly narrow and the stone (or the table construction) somehow restricts movement.

The question in that case I suspect becomes whether or not it can be done reliably at all.

There's nothing wrong with guesstimating how much the wood may move, and then what width of silicone is needed to accommodate this, but get it wrong and there's various sorts of problems that can emerge. e.g. a deep bead of silicone relative to the width of the gap may cause problems - because quite a small change in the width of the joint will result in a sizeable change in volume, and the material has to go somewhere. Which can lead to bulging. Tearing too if it's required to flow too much, which is why flexible packer strips and high quality silicones are sometimes used.

It all depends on the situation. If it's your own house then I guess you just rework the joint if anything goes wrong, but if it's for somebody else or you were a manufacturer it'd pay to design the joint by figuring how much the wood might move, and then deciding the gap with reference to data sheet information on the silicone. Your average Joe tiler won't necessarily know much about this - he may not even bother with expansion joints, but either way he'll be long gone before problems emerge and he gets fingered.

Mould is a real risk in standard silicones in domestic situations in my experience, but again your narrow gap minimises the visibility should the issue arise...

 

[Racers]

Hi, Froggy


I was going to make a hole right the way through and rebate the edges to suport the slate.
In an existing top you could use a guide rail and router to cut a hole and then a rebate cutter to cut a shoulder.

Pete

 

[Steve Maskery]

Nice table, Bob, but as Ian says, it's not the same scenario. You have almost no cross-grain issues there because of the frame structure. A solid top is a different matter.

If I were to rout out such a large expanse, I'd do it this way:
1 Measure from the edge of the table to the far side of the slab. Lets say this is 800mm.
2 Make a thick rigid sled 1.7mm long (2x800 plus a bit) and a bit wider than the base of your router.
3 Mount the router in the middle of the sled and screw 50mm-wide battens to the ends of the sled as stops.
4 Clamp a couple of stops to the table, one at each end, so that the sled can move to and fro by the length of the cut out.

You can now slide the sled back and forth, side to side, to excavate the recess.

There was a beautiful table at Cheltenham last year. Solid oak top with a similar recess, in which was a piece of wild figured something-or-other, covered by a sheet of glass. But that top was cut right through and the inserts rested on rebate strips. I'd do it that way, but the customer is always right.
S

 

[Lons]

....... :-# ](*,) (hammer) #-o ...........

Stupid person - my only excuse is that I'm not at my best posting in the wee hours :?

Of course you're right Ian and Steve, hadn't thought about the grain orientation, it's bound to move.

BTW Steve, I don't agree that "the customer is always right". If they insist on a particular method and it goes wrong, guess who gets the blame. As I'm sure you do also, I sell my skills and experience way ahead of the product and if i don't like what they want I won't do it. I value my reputation more than the work. (Usually find the customers will listen though0

Bob