Cutting Obsidian Chipping Problem

[Dan]

so i was asked to make a cross i had thought to make it out of obsidian but when i tried to cut it on my saw it just chipped all along the edges of the cut. can someone give me some tips on working with it? i had planed on making the cross and then framing it in wood to contrast the black stone and red paduke wood.

[David G]

Dan, obsidian is very prone to chipping. A band new saw blade that is thin and runs 100% true is your best bet. It will also tend to chip on the rough grinding wheels as well. I use a band saw with a new blade and start on the fine grinding wheels, takes longer but reduces chipping. The other trick when grinding the outline shape is to put a tiny bevel on all the edges, this will grind/sand off as you progress but helps to stop chipping. Also make sure there is plenty of water to lubricate everything.

 

David

[yloh]

Dan.

Have you tried backing your piece before sawing it. Glue a piece of wood or something on the back of your obsidian.

I think it will hrlp.

Yloh

[Dan]

thanks guys those are good tips i only have one type of blade i dont do much stone work to buy several blades but ill try backing the stone and i had though since its a type of glass to score the surface so that it will break along the score rather then into the keeper section.

[Joe Aimetti]

Obsidian is basically glass, so any technique used for cutting glass should work on it. It is also Knapped to make arrowheads and small sharp pieces of it are used in the medical field; primarily plastic surgery because like glass, the chipped edge is sharper than the finest metal blade produced ( down to the molecular level ). It can cut between the cell walls so scars are minimal.