Limestone?

Post by **GarySeibs** » Thu Apr 10, 2008 1:38 pm

Hi all! I'm a high school shop teacher and my students are always coming up with new applications for our Techno 4 x 8 router that we've had for 2 years.

We get great results in wood, MDF, and acrylic but we have beautiful native limestone here in the middle of Kansas that I would love to try to carve.

Has anyone done this? What kind of speeds / feeds work? Our router has the servo motor and we get very good results with feed speeds up to 180 ipm on mdf but I'm uncertain on stone. 20-30 ipm? Slower?

I'm a newbie to the forum (first post) and maybe I've missed some tooling tips as well but I have had great results with Vortex tooling.

Post by **TReischl** » Thu Apr 10, 2008 3:01 pm

There are some posts on the forums concerning cutting stone. Yes it can be done.

Some things you need to be aware of:

Dust, WOW! You will need to protect yourself and the machine. Cutting with a coolant will definitely help, but your machine needs to be set up for it.

Cutters, it will eat them of course.

With a router cutting stone, it is more like abrading rather than true cutting, the stone chips before it cuts, so you need to work with feedrates.

Good luck, and make sure to post some of your projects!

Post by **RoutnAbout** » Thu Apr 10, 2008 4:40 pm

Hello Gary, Welcome to the forum.

There is a wealth of information and knowledge on this board, So don't hesitate to ask your questions.

GarySeibs wrote:Has anyone done this? What kind of speeds / feeds work? Our router has the servo motor and we get very good results with feed speeds up to 180 ipm on mdf but I'm uncertain on stone. 20-30 ipm? Slower?

Yes you can. I used Vcare Pro to machine a business card into Granite a couple years ago. I used an old Bosch Vbit for this job as I didn't want to abuse my good tooling. I have a few of these around for projects like this.
Approx Feed: 10 - 20 ipm
Low RPMs: 9000 - 10000
Depth Per Pass: .100
Like TReischl mentioned above, The stone will eat your cutters. The tool erodes the stone away instead of actually cutting. They will dull fast and possible even chip or break. But it can be done. The main thing is to keep that tool "cool".

After thinking about what tool to use, I decided to use a carbide tool with a flat face tool with very little rake and low primary and secondary relief. My thought behind this is, the more rake and more relief, the cutting edge becomes sharper, but thinner and weaker. Less material at cutting edge causes the tool to break down faster. I hope that makes sense. Below is an end view of some geometry.

I didn't use any coolant or mister, because I didn't want oils soaking into the stone, or the slop of the dust and oil all over the machine or table. I used compressed air pointed at the point of impact. I mounted the nozzle so that it blew the dust towards my pickup mouth of the dust collection. Make sure you keep the air on the point because it won't take long and the tool will be toast. (make sure no flammables are close because it could cause a spark)

You also might want to find your local tool grinders in the area. They always acquire tooling out of specs and possble will work for your needs. Let the know what your trying to do and they'll help you out.. Take them a small sign or plaques with their logo on it.
Hope this hopes, and again welcome to the forum.

Post by **GarySeibs** » Thu Apr 10, 2008 8:27 pm

Thanks for the help. I've cut / carved some native limestone with basic wood chisels with ease due to the softness of the stone. I don't think I'm interrested in cutting any stone harder than limestone but we'll see...

I don't think I'll try to do any liquid cooling but we do have a very effective dust collection set up so it shouldn't be a problem there...just have to give it a try!

Regards,

Gary

Post by **RoutnAbout** » Thu Apr 10, 2008 8:46 pm

Good Luck Gary, and be sure you watch for sparks and clean out your dust collection prior in case there is a spark

Post by **Tony Mac** » Thu Apr 10, 2008 8:49 pm

Hi Gary,

You might find these threads interesting,

http://vectric.com/forum/viewtopic.php?p=259#259

http://vectric.com/forum/viewtopic.php?p=360#360

http://vectric.com/forum/viewtopic.php?p=15816#15816

Good luck.

Tony

Post by **GarySeibs** » Thu Apr 10, 2008 9:15 pm

Thanks for the finds, Tony. Great information that gives me a little more confidence that I won't destroy things...I'll leave that for my students!

Post by **Tony Mac** » Mon Jun 02, 2008 10:27 am

More very useful information about cutting marble on the ShopBot Forum,

http://www.talkshopbot.com/forum/show.c ... #POST68285

Tony