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brian
03-19-2006, 11:46 AM
I have a customer who asked for a address sign done out of blue stone(which I believe is a form of sandstone)
Can I use a carbid bit or would I need a diamond bit(if so who makes them)
Any suggestions of bit type and cutting speeds would be appreciated.
Brian

billp
03-19-2006, 09:56 PM
Eastern Marble in New Jersey sells diamond bits. I'm on the road this week so I don't have my rolodex with me, but I think you can google them. they might be in Scotch Plains, NJ

joe
03-20-2006, 06:48 AM
Brian,

I'm very interested in how you get along with this project. I've haven't any experience in this area but am sure it will come up. So keep us posted.

tony_mac
03-20-2006, 11:47 AM
Hi Brian,

We have a customer here in the UK engraving Sand Stone and he made the following comments.

Use Standard Carbide cutters

Cut at multiple Z passes of around 0.04"
Spindle speed around 15,000 rpm
Feedrates around 40 inches per minute
No coolant – just good dust extraction

A couple of his designs being engraved into stone.


6150


6151

Hope this helps,

Tony

wcsg
03-20-2006, 06:37 PM
I need to try this.

brian
03-20-2006, 08:25 PM
I"ll be curious to see what it does to a carbid bit.Years ago I worked on a site where they cut sandstone with a diamond blade and wet saw.I remember someone commenting on how the diamond blades didn't last to long.
Thanks Brian

joe
03-20-2006, 08:50 PM
Brian,

Bill P. reports to have carved marble with a carbide bit with little bit wear.

donchapman
03-20-2006, 08:51 PM
Great info, Tony.
Please ask your customer what specific sandstones he has been successful routing and if he knows or can estimate how hard they are on the Mohs' scale of rock/mineral hardness which is a 1-10 scale with talc as 1 and diamond as 10. Sandstone is generally grains of quartz (7) cemented by silica, lime, clay, or iron oxide and can vary greatly in hardness and courseness. I'm even wondering if the sandstone he is routing has so much lime content that it is more akin to limestone than most sandstones. I've never tried routing sandstone but it seems like the quartz in it would dull even carbide bits very quickly.
Inhaled silica from sandstone is very dangerous because it can cause the chronic lung disease of silicosis for which there is no cure, only prevention. Please advise your customer to use good ventilation and a respirator. Even if it is not necessary as a lubricant, some water mist or spray might be useful to keep the sandstone out of the air.

Aside: Pure limestone is often soft enough to cut with woodworking tools and is calcium carbonate which generally dissolves harmlessly in the lungs. But many limestones have impurities that are harmful if inhaled.
Thanks

jhicks
03-22-2006, 10:16 AM
I have been asked to pilot some carving in Soap stone and this is the 1st time I've seen an input which is greatly appreciated. Is soapstone the same as bluestone?
Any input is appreciated as I have heard so many negatives, I'm not sure I want to even try it. This post gives me hope so thanks for any speed, feed, bit, depth max cut etc.

tony_mac
03-23-2006, 07:21 AM
I asked our 'stone carver' about cutting soap stone and bluestone and he simply said.

"There's no exact science to this because every stone will have different cutting properties. I simply experiment by starting very slowly with small stepovers and z level passes".

A key point is to ensure the machine setup is as rigid as possible. With minimum tool length out of the collet and minimize deflection on the Z axis by lifting the job off the table closer to the gantry.

Hope this helps,

Tony

donchapman
03-23-2006, 07:41 AM
Soapstone is composed of talc, the softest mineral on the hardness scale of talc (1) to diamond (10), but it, like limestone, can vary somewhat in hardness depending on its particular variety, exposure to the elements, etc.
Soapstone can usually be scratched with a fingernail, so it should rout easily, although I've not done so and do not know proper feed rates, etc. I'd start shallow and slow and work up.
"Bluestone" is an inexact description of whatever the locals or seller call their blueish stone, sort of like "ironwood" describes the hardest local wood and varies all over the world. Locally I've seen both a sandstone and a slate for sale as bluestone. The slate is much softer than the sandstone. Brian said in his message that the bluestone he is referring to is thought to be a sandstone.