Re:creating toolpath (cutting stones)
Posted by
Don Rogers
on 2003-05-18 18:41:36 UTC
At 09:14 PM 5/18/03 +0000, you wrote:
question, but your sequence of finishing the marble, glass, and
granite. First, the 60 grit you are using will leave severe sub surface
damage to the stone. It will not be evident until the final polish
stage. A rule of thumb is to never use diamond on a hard back coarser than
380 grit or you will have problems Second, you are using way to many
steps. Rough (380) Final cut (1200), Pre-polish (8000), and Polish
(different for each material but all will be equivalent to 50K
diamond). Working stone is nothing like working wood or metal. It is
hard, but has no elasticity and can be very brittle, hence the damage by
the course diamond grits. By the way, you will need to treat all three
mediums differently. For the Marble, I would use silicon carbide at around
100 to 280 grit for the rough, Final Cut, and then directly to polish, tin
oxide with a smidgen of oxalic acid on a hard felt tool. For Glass, use all
four steps, but polish with cerium oxide on either hard felt or on
leather. Granite is harder than either of the other two, and is also very
grainy. It will finish off about the same as glass, but you might have to
experiment with the polish. On both the Marble and the Granite, spend very
little time with the polish as it will cause and orange peal effect do to
the uneven hardness of the stones. I would check with a monument maker for
their formula for polishing Granite.
Don
[Non-text portions of this message have been removed]
>1st rough miller diamond/nickel grit 60, could be any pattern, itI am a lapidary and faceter. I am not going to address your tool path
>just removes the stock
>
>2nd pre-shaper diamond/nickel grit 120, zig-zag passes to remove
>previous scratches
>
>3rd grinder diamond/resinbond grit 100, removes previous scratches in
>a tight spiralshape toolpath
>
>4rd grinder diamond/resinbond grit 200, removes previous scratches in
>a less tight spiralshape toolpath
>
>5th-8th, 500-3000 grit in a random pattern
question, but your sequence of finishing the marble, glass, and
granite. First, the 60 grit you are using will leave severe sub surface
damage to the stone. It will not be evident until the final polish
stage. A rule of thumb is to never use diamond on a hard back coarser than
380 grit or you will have problems Second, you are using way to many
steps. Rough (380) Final cut (1200), Pre-polish (8000), and Polish
(different for each material but all will be equivalent to 50K
diamond). Working stone is nothing like working wood or metal. It is
hard, but has no elasticity and can be very brittle, hence the damage by
the course diamond grits. By the way, you will need to treat all three
mediums differently. For the Marble, I would use silicon carbide at around
100 to 280 grit for the rough, Final Cut, and then directly to polish, tin
oxide with a smidgen of oxalic acid on a hard felt tool. For Glass, use all
four steps, but polish with cerium oxide on either hard felt or on
leather. Granite is harder than either of the other two, and is also very
grainy. It will finish off about the same as glass, but you might have to
experiment with the polish. On both the Marble and the Granite, spend very
little time with the polish as it will cause and orange peal effect do to
the uneven hardness of the stones. I would check with a monument maker for
their formula for polishing Granite.
Don
[Non-text portions of this message have been removed]