Carving on stones

[drodda]

Has anyone tried to carve in a landscape stone like you see in peoples Flower beds. I don't exactly know what type of stone these are but I think they come in many different types adn tehy are around 6" to 12" round or oval. I have searched the forum but have come up dry. Maybe I don't know the exact phase to get the results that I am looking for?

I have two questions.

1. what type of bits can you use in a PC router to carve in a hard surface like stone?

2. Has anyone rigged up a liquid cooling tub or area to allow the liquid to get recaptured and used again? How would you keep the liquid from gettin all over the Router? Seems water and electricity would not be a good combination? I was thinking of a clear deflection sheild mounted below the router moving with the Z axis that allows the bit to access the stone?

Yes this is just another one of the thousands of ideas that I have had during the many years of looking at the shopbot before I actually took the plunge. Please give me your expert opinion on this and tell me why this is such a bad idea so I can move on to the next bad idea.

[jhicks]

Dave, Sorry I can't answer directly but have many of the same questions. Wanted to try Soapstone but mostly I was frightened off by the hardness, water cooling recommendations, dust in the spindle, and probable excessive bit wear. I do know some folks have done it, some have done limestone apparently with great success. So when you figure it out, I would love to learn how its done.

[drodda]

I am talking a common boulder or rock found when digging in construction sites. the lanscape companies sell these. They also drill a hole in the center and shoot water up through these. If and when I find an answer I will be happy to share my findings. I am not risking as must with a PC router as a spindle if the thing gets ruined. this is the reason that I did not purchase the spindle in the first place. I figured after a year or so of trying to kill the bot I could move up to the spindle.

[earld]

http://www.signindustry.com/computers/articles/1999-CuttingStoneWithWater.php3
This is the most I've found to date on cnc stone operations.
Most mechanical rock work is an abrasive operation, using diamond coated tooling for cutting. I don't know if the ShopBot will feed slow enough for stone cutting. Especially for a high quartz concentration like magmatic and granitic stones. Even sandstone contains a high degree of quartz.
I would consider cutting sandblast masking for face engraving, depending on what the design entails.
my 2¢

[dirk]

I took a glass engraving class a couple of years ago. The engraving process used sandblasting. It was sponsered by Photobrasive
http://photobrasive.com/
I saw a lot of carvings in stone using the same process. One guy was blasting pics on tombstones and there were a lot of examples of engravings on the round stones you mentioned.
Pretty impressive.

[Mayo]

Early on I actually did try engraving landscape paver stone using my bot with a masonry drill bit.
Everything started out looking OK but very soon I noticed the carbide starting to glow red. I then used a spray bottle of water and squirted it on as the bit was cutting. The whole thing seemed rather scary and even though I did have safety goggles on, I still imagined what it would be like having a glowing chunk of carbide lodged into my face or arm, etc.

I never tried it a second time because the novelty and saleability of what I was doing just didn't justify the time it took. If I had a real market for that kind of product, I'd experiment with speeds & feeds more than I did.
And then there was the resulting mud to clean up. Spraying the water kept the dust down and the bit somewhat cooler but also created mud which flew about.

The stone was not poured concrete like most of the landscape pavers - it was something similar to limestone but I forget what it was called. I also engraved into slate floor tile, which went much better, although the slate has a tendency to flake off layers on small inside areas of letters like O & D & P & A & B & R

[tom_fiddler]

I have made a few Concrete molds out of cheap pink foam.
Just a thought
Tom

[jhicks]

Not sure if i'm correct or not but I had some problems with a decorative custom carbide bit breaking on some hardwood turnings and called the manufacturer. He told me that by lubricating the bit (with some spray on tool lubrication)while it was hot, it deteriorated/weakened the carbide and caused it to break the tip. Never knew if this was true but when I stopped lubricating it, it held up. Can anyone verify this condition? Just putting it out there for consideration.

[drodda]

I appreciate all the information. I have messed with a dremel tool and hand carved a name in a rock. this is where this idea come from. It took me quite a bit of time but it actually turned out alright. With that in mind I was wanting to kick it up a notch and have the shopbot do all the long hours of carving while I was off doing something else in the shop.

I had no real marketing plan for this just wanted to know if it could be done?

[don_roy]

HI JERRY,
As for your bit breaking you were probably causing what is called thermal shock.
The bit getting real hot and then spraying it with a cold cooling agent. this produces small microscopic cracks in the carbide and will cause premature failure. If you really need to keep the bit cool ,start cooling it before you start to cut otherwise let it get hot, it will not hurt it.
Hope this helps
Don

[scottcox]

Tom,

How did you treat the foam before pouring? Sand and seal? Any release agents involved?

Scott

[jhicks]

Don, I believe that's what I was told about the cause but never heard the 2nd part about starting out with a cooling agent and cutting with it. Thanks. I think I'll stay with other materials and leave the hard stuff to others while monitoring for photos.

[don]

Until I'm able to leave my day job( really 2nd shift) I'm cnc toolgrinder and make\regrind carbide mills,drills and various other cutters. If you can imagine it, we can make it. We flood the tool with an oil coolant while regrinding\manufacture. And the above information is correct about using any kind of coolant after the tool gets hot, it will make microscopic cracks and become brittle and break down or break apart, sometimes immediately.

I've engraved my business card and the customers logo into granite and marble. I was using 3flute 60degree v-bit with a shear angle that I made. I haven't used any form of liquid to cool the tool while machining. (to avoid the mess) Instead I use a cold air gun simular to this one. http://www.vortec.com/cold_air_guns.php
On the acrylic of my dust skirt I've drilled and tapped a hole for a fitting with a short flexable nozzle that point towards the cutting tip. I have a small valve to regulate the air flow, so the dust collector can pick the dust up.

I haven't tried any large projects, the largest was the business cards and the logo of the potential customer.(scaled up to 6"w x 3.5"h)
I used the same feed and speeds for both Granite and Marble. If I remember correctly feed was .3 inches/second and spindle speed seemed to be the best around 10500-12000.

Will be experimenting again as soon as I'm able to find time to grind a different cutter that I'm attempting to design.

Don

[jhicks]

Don, that looks like a cool solution. If you develop a custom bit geometry that seems to deliver, I think you might find a market for some. Let me know how your trials go. I would be interested in more agressive cutting but one step at a time I guess.

[drodda]

Don,
What are you doig waisting all this time typing? Get designing that cutter. we are all waiting for your results so we can flood you with requests for the cutteers.

On a more serious note. We appreciate your input on cutters. Seems like you have probably forgotten more than I already know about them.

I have been looking into the cooltool air cooling for some time now. Just have not jumped and bought one yet.


Dave

[dwight]

Don,
I too need your bits as I have been asked to route etchings and letterig in polished granite and have NO idea where to get the bits or what feed rates or spindle speeds to us as I use a simple trime router for my wooden signage

[rcnewcomb]

Be prepared for sticker shock on diamond bit prices for granite work:
external link to Diamond Bits (http://www.defusco.com/index.php?cPath=25_33&gclid=CLrBg5DIk4kCFTzqJAodFj lnAw)

[donchapman]

I've hand carved and sandblasted stone for several years. The scorpion is shallow hand v-carved into slate floor tile which is so soft it can be carved with woodworking chisels. The dogs are hand carved into Texas limestone, also soft enough to carve with woodworking tools. The fancy tombstone is Vermont marble and the decorative carving was done by Joseph Kincannon of Archaic Stone Carvers in Austin, TX. I then spent about 80 hrs. hand v-carve lettering the inscription with carbided tipped stone carving lettering chisels I ordered from England. The black negative mask I used for layout. The Psalm I sandblasted into sandstone after cutting a mask with my vinyl cutter from Hartco sandblast masking mtl.

I've experimented briefly with trying to shallow dry v-carve limestone tile with a woodworking carbide v-bit on my ShopBot and the bit heated up very quickly so I stopped. However there is a thread somewhere on this site of some folks who have used VCarve Pro to do some dry CNC routing successfully.

I suggest anyone attempting CNC routing of stone try the soft stones like limestone and slate and go very shallow and see the problems and results before attempting harder stones. Granite is very hard. Marble varies but is much softer than granite but harder than limestone and slate. Sandstone varies in hardness but is always extremely hard on tools and dangerous to breathe the dust.

For most people, sandblasting may be the easiest option. You can mask the stone and have someone else blast it. However sandblasting does not provided the wonderful shadow/light contrasts of v-carving



2262


2263


2264


2265

[myxpykalix]

There is a soapstone dealer in town here and once i bought some for a person to carve some stuff with it that turned out nice. However it was handcarved and with small dremel type tools not on a bot. Point being if a small tool and hand tools can do it a bot can do it (maybe). But this was smaller rocks not boulders.

[donchapman]

Jack's right. Soapstone should rout easily on a ShopBot, although I've not tried routing it myself. I have handcarved some and it's so soft and easy that I forget it's a stone.

[rcnewcomb]

Here is a soapstone example (sorry the contrast is so poor).

The piece was about 12"x24". We carved it with a PC router. The feedrate was 1 ips @13K. The bit was a CMT 3/4" V90.

2266

[donchapman]

Looks good to me!

[normand]

get asbestos free soapstone.
2267 This stuff can be run unnatended it will never catch on fire.