Finishing a Marble circle for a cake stand.

[Paul Gilbert]

I have a marble slab with a rather rich history in our family. It started out as a Dresser top which was owned by my great - great grandfather and subsequently destroyed in a fire, migrated to an end table built by my father for me and then was destroyed by Katrina in New Orleans. For the end table this top ended up as a 2.5' hexagon. It has resided in my shop since then.

Now my daughter wants a cake stand for Christmas made with this marble. I have a tile saw which will work to get close to a circle, but can I then glue it up to a face plate and turn it round? Will carbide tools work? I don't have any, other than the Hunter cutter on my Jamison hollowing rig. If they will work, what do I need - the round ez-tool one or what? Would the T shaped diamond tool used to true up matrix grinding tools work?

What do I use as polishing media for the edge and to brighten up the surface?

 

[Glenn Lefley]

If it’s real marble, your not turning it on a lathe. First to hold it you would need diamond drills to drill holes for screws got a faceplate. Then you would need diamonds tip tools with a water jet coolant . Held in a cross slide, like a metal lathe I would think!
But I could be wrong. Nothing is impossible,

 

[stu senator]

1 - Make a fixture like a circle cutter for a band saw and adapt it to your tile saw.
2 - Make a fixture like a router circle cutter and mount a (I think) 4" grinder, what wheel to use I don't know but I watched a counter installer cut a sink opening with one freehand. Do not know what he used to polish as too much dust.
3 -Take it to a stone yard and have them do it.

Stu

 

[Richard Coers]

Take it somewhere that has a water jet machine. You'll have very little hand work to that surface finish.

 

[Timothy Allen]

If it’s real marble, your not turning it on a lathe. First to hold it you would need diamond drills to drill holes for screws got a faceplate. Then you would need diamonds tip tools with a water jet coolant . Held in a cross slide, like a metal lathe I would think!
But I could be wrong. Nothing is impossible,

Well, this depends on what, exactly, "real marble" is... To geologists, the term "marble" refers to metamorphosed (recrystallized) limestones. An ideal pure limestone is made up of the mineral calcite, and when metamorphosed, the resulting marble would also just be calcite. Calcite is around the same hardness as copper metal or acrylic plastic, so presumably it could be turned with tool steel or carbide cutters. That said, most limestones, and thus most marbles, are not pure. Furthermore, non-geologists call a lot of stone "marble" that is not marble at all. If you want to know whether your "marble" is real marble, drop some acid on it (i.e., dilute HCl) -- it will fizz.

But yeah, a metal lathe type of setup with water coolant would probably be more appropriate than the typical wood lathe. But you probably don't need diamond tooling for pure marble.

 

[Timothy Allen]

Actually, just thinking about this a bit more, once you get it as close to round as you can with your tile saw, you probably could glue it to a faceplate and finish it on your wood lathe using abrasives -- wet sanding... The abrasives regiment for polishing stones is really not all that different from any other kind of sanding and polishing, except that with stone I think one tends to go to much finer grits because stone can typical take a very fine polish.

 

[john lucas]

I don't think the carbide will work. Certainly not the Hunter it will chip the edge of the tool. I would buy a diamond wheel for an angle grinder and rig that up to the lathe. If you see how I use my router on a router table on the lathe it would pretty easy to rig up a carriage to hold the angle grinder and slide it in for light cuts.

 

[Mark Jundanian]

Paul, my advice is to take it to a counter top shop other stone working business. Tell them the provenance and I bet they'll be inclined to help. And outsourcing the stone work is not going to diminish the value of the finished piece, which still needs a turned wood pedestal.

 

[Glenn Lefley]

I

Actually, just thinking about this a bit more, once you get it as close to round as you can with your tile saw, you probably could glue it to a faceplate and finish it on your wood lathe using abrasives -- wet sanding... The abrasives regiment for polishing stones is really not all that different from any other kind of sanding and polishing, except that with stone I think one tends to go to much finer grits I’d because stone can typical take a very fine polish.

Id be really scared to glue a round stone to a faceplate then turn the lathe on. That sounds like a trip to the morgue to me.

 

[John Torchick]

Take it to a shop that does countertops. They cut for size and cut for sinks. They should be able to say what they can do and what it would cost. Like to see the finished project.

 

[Greg Norman]

Your best bet would be to buy something like these if you can find them to fit on your tile saw. Most have a 1/2” arbor to fit a flat lap machine but some companies offer custom boring to fit any arbor. I would cut it as close to a circle as possible with the saw blade then switch to these to grind a smooth circle and then polish.
You’ll need a backing plate like this
https://www.ebay.com/itm/282438030136

and some flat lap disc of different grits, like these.
https://www.ebay.com/itm/114123768729

If this is more than you want to spend for a one time use you could turn a flat plywood disc bored to fit the arbor on your tile saw and glue on a silicone carbide sanding disc to do the same thing. I’ve not worked much with marble so I’m not sure of the proper grit sequence. I’m sure you could talk with a lapidary supply and get that info.
I would contact
https://kingsleynorth.com/
and ask for advice on proper grit sequence.
I would only use the tile saw for this project. Stone can be turned on a wood lathe but it requires a massive investment in proper tooling and it’s a very steep learning curve. Most importantly it is VERY dangerous in the early stages of that learning curve.

 

[Rob Fridenberg]

This isn't the task to save a few nickels on. Let a pro do it - especially since the material has sentimental value. Plus - they can put a nice shaped edge on it like they do for the countertops.

 

[Glenn Lefley]

This isn't the task to save a few nickels on. Let a pro do it - especially since the material has sentimental value. Plus - they can put a nice shaped edge on it like they do for the countertops.

I so agree. If you tell them back story, it won’t cost near what you think it might. It will take them literally no time to cut on water jet table.

 

[Dean Center]

When you get this project done, one last step, given the history of this stone, is for your daughter to increase the coverage on her homeowner's insurance.

 

[Glenn Lefley]

When you get this project done, one last step, given the history of this stone, is for your daughter to increase the coverage on her homeowner's insurance.

Or should he increase his insurance while he is working on this?