Anyone tried to cut slate?

[shoeshine]

I am looking to cut some v-carves into natural slate for a client. Just ordered a 60deg Vbit from Fred over at Centurion.

I'm not finding a lot of information out there.

Any thoughts on speeds/feeds?

Do you use any kind of cooling?

I've already dusted an Onsrud bit trying some scrap @ 13,000/0.1ips, which were the recommended settings from the wiki pdf for marble (got a nice rosy/orange glow at the tip as the carbide melted)

now admitedly, the centurion bit has a very different geometry, but I hesitate to blow another $35 on a test without a little more knowledge.

Anyway, any input or leads on where to find more info would be greatly appreciated.

Chris

[rb99]

Is slate dust one of the bad ones?

Be careful...

RB

[rcnewcomb]

Slate - (Metamorphic Stone) A fine -grained rock formed from clay, sedimentary rock shale and sometimes quartz.
Hardness scale: 3

What you call slate and what I call slate may not be the same thing. Is there a stone wholesaler in your area that could verify that what you have has a hardness of 3 or less?

Basically you should be able to carve any stone with a hardness of 3 or less.

We've cut slate at 13K @ 1ips with pass depth no greater than 0.125" per pass. A vacuum nozzle was held near the bit to keep it cool and minimize dust.

The only time I have melted carbide was with granite, and with some fired tiles that were about as hard as granite. Granite is a 7 on the Mohs hardness scale.

[shoeshine]

...with a little help and reassurance from Tom Byerlee (Thanks Tom) and my local stone place (they said the slate I had from India should be a Moh's #2 or less) I went ahead and bit the bullet and tried the centurion 60deg Vcarve bit with great success.

I ended up using:
pass depth .025 / 13k rpm / feed .3 / plunge .1

Very minor wear noticeable on the bit only under magnification.

Not sure at this point why I dusted the onsrud bit so fast. I -was- trying to take a much larger chunk with each pass. The stone place also said that as slate is sedimentary, sometimes there are layers of silica and other material trapped in pockets. might have hit one? who knows.

photo attached of two test tiles - one tile just cut and the other with copper leaf applied to the grooves, should weather down to a nice patina outside. (got a little movement on the tile to the left, i.e. the toolmarks, got to work on my hold down jig)


43028.jpg

[rhfurniture]

Chris,
Which software did you use to cut those characters? I have a job involving Chinese characters coming up, and considering buying Vcarve pro for it.

Ralph.

[joe]

Thanks Chris for your posts. Your pieces are outstanding. The natural V carv, without the copper, is my favorite.

I've got to try using stone in my signs. I've been planning on a Christmas Program, for gifts, and this may work in very well.

It looks as thought stone holds a chrisp edge. I may try Dr. Crumley's Snake Oil Mask to see how it works.

Keep up the good work and show us more.

Joe
www.normansignco.com

[rcnewcomb]

Isn't stone carving fun?

[shoeshine]

Ralph, I am using the recent version of partworks that came with my bot (v. 2.015). Which, as I understand, is essentialy Vcarve-pro. I just pulled a gif of the characters off the web and used the "fit vectors to bitmap" function.

Chris