Post by mirthmgr on Nov 21, 2017 4:34:25 GMT
Having successfully done some test cuts in labradorite, some research taught me that marble is much, much softer. So, I went to my local Home Depot and picked up some natural marble tiles. I got two 8-packs of 3"x6" tiles for just under $8 each, one the brightest white they've got, one more of a cream. I've just done a couple of tests so far, but it's mostly workable. It's a little brittle, so it likes to get surface chips; I'm going to have to fine tune my speeds and depths to figure out what works best. I did find the cream color to be more brittle than the white. With both of them, the dust is super fine. No surprise since its composition is similar to limestone, but it looks and feels pretty much like lime; took me back to lining the field in little league. The dust also stays put and doesn't seem to want to go anywhere. If it were flammable, I'd worry, but as it was it just made clean-up really simple.
First cut was the cream. You can see where the eye on the right side of the mask chipped:
The second cut was in the white. It didn't chip as much as the cream, but there were still some small chips right at the edges. The marble took a .5mm chamfer beautifully, though, so that eliminated the bulk of the chip marks. I didn't mess with any low grit to remove the tool marks on the side, but I did hit it with 2000-12000 grit wet sponges and it seemed to take a polish very well. Taking the time and starting with something lower should make it pretty easy to remove all tool marks (as long as you can get into the nooks and crannies).
Once I've got enough pieces ready to justify mixing up some resin, I'm going to try filling in the area surrounding the moon with charcoal black. Each piece is about 40mm in diameter, so I'm going to add some eye screws and turn them into pendants (crafting jewelry pieces was my primary reason for getting a CNC in the first place). Since the material is so cheap (a buck per tile), it should be a fun medium to experiment with. Even if it doesn't machine perfectly, I figure I can design some pieces that will take advantage of the aged look that the small chips give.
Geekiness alert: I learned a little more about the Mohs scale of mineral hardness while I was researching this. Turns out that labradorite is not technically a mineral, so its position on the scale is fudged a bit (it can vary depending on composition), but it usually lands around a 6-6.5. Marble, being primarily calcite, is only a 3. Each integer on the scale is twice as hard as the previous, so labradorite is about 8 times harder than marble. I had to take it incredibly slow with the labradorite, but it machined beautifully with no chipping. Marble machines much more easily, but the chipping is pretty prevalent. I'm going to see if I can find some attractive mineral slabs that fall somewhere in between on the Mohs scale to see if there's a happy medium.
First cut was the cream. You can see where the eye on the right side of the mask chipped:
The second cut was in the white. It didn't chip as much as the cream, but there were still some small chips right at the edges. The marble took a .5mm chamfer beautifully, though, so that eliminated the bulk of the chip marks. I didn't mess with any low grit to remove the tool marks on the side, but I did hit it with 2000-12000 grit wet sponges and it seemed to take a polish very well. Taking the time and starting with something lower should make it pretty easy to remove all tool marks (as long as you can get into the nooks and crannies).
Once I've got enough pieces ready to justify mixing up some resin, I'm going to try filling in the area surrounding the moon with charcoal black. Each piece is about 40mm in diameter, so I'm going to add some eye screws and turn them into pendants (crafting jewelry pieces was my primary reason for getting a CNC in the first place). Since the material is so cheap (a buck per tile), it should be a fun medium to experiment with. Even if it doesn't machine perfectly, I figure I can design some pieces that will take advantage of the aged look that the small chips give.
Geekiness alert: I learned a little more about the Mohs scale of mineral hardness while I was researching this. Turns out that labradorite is not technically a mineral, so its position on the scale is fudged a bit (it can vary depending on composition), but it usually lands around a 6-6.5. Marble, being primarily calcite, is only a 3. Each integer on the scale is twice as hard as the previous, so labradorite is about 8 times harder than marble. I had to take it incredibly slow with the labradorite, but it machined beautifully with no chipping. Marble machines much more easily, but the chipping is pretty prevalent. I'm going to see if I can find some attractive mineral slabs that fall somewhere in between on the Mohs scale to see if there's a happy medium.
