machining stone etc.

>Well, I put the marble tile on my machine and ran a carbide

1/2 round engraving bit through it a few times. Seems to cut
pretty easy from the little I have seen so far. I have no idea
as to what type of marble this is, or if it is even marble at
all. It is a floor tile, not ceramic, but some kind of stone.

I got a couple of very small chips in a couple of spots,
but you can hardly see them. I need to get a different size
tool, Monday, so I will let you know the results then.

Patrick, since you have done this before, how are the machined
areas polished when you're finished cutting?

Bill>

If your cam software is capable of using a "constant-scallop" setting on the
finish cut, then you should set the scallop level to a very small value and
let the machine do as much of the work as it can.

If this is lettering, then I would not polish the inside. I would clean up
the cut with an abrasive stone, or even sandpaper and leave it at that.

If this is a graphic, or has larger areas that you want to polish, then you
would start with a coarse sandpaper (If the area is large enough, feel free
to use a palm sander) and progress towards an extremely fine sandpaper,
making sure that you have a: completely finished with each grit before you
move to the next [this means that all the scratches in this area are the
size of the abrasive particles from that grit]; and b: you have cleaned
away with water ALL the residual abrasive from the previous grit. This is
tedious and time-consuming work, but even more so if you have progressed to
your third grit and can suddenly see a scratch that should have come out
with your first grit. It is only going to get more obvious and the only way
to remove it is to start back at the first grit.

This is NOT the most modern way to do this, there are lots of tools and
diamond pads and bits that can save lots of time but cost lots of $$.

Now, I would like to point out one more thing - you could sandblast this and
pretty much be done with it. I know quite a few folks who have cnc vinyl
cutters just cut the logo, or whatever, out of vinyl and use that as their
stencil. There is no need to polish or clean up [except for the adhesive
that holds the stencil on] unless you have a very intricate design. Most
memorial places will do the sandblasting for a song.

I'm sorry your friend has decided to remain anonymous, they obviously know a
lot about machining stone. I would have appreciated the contact.

Patrick