Post #287714 by Tamapoutini on Fri, Feb 23, 2007 1:25 PM

On 2007-02-23 11:42, flynny wrote:
Hi Guys - Toggles
A lady I work with saw some of my work and wanted me to produce something in Ameythyst with a matching toggle and plaited cord. Is this stuff harder than Jade on the old scale, because it took me ages to put 2 holes through the toggle using diamond burrs. Question is how do you see something so small when drilling with water ( will post a pic to this thread, I know it's a little bit non tiki)

Also what speed do you cut jade at, I have a 6 inch diamond trim saw with variable speed but the settings are min/max, not much help I know, whilst cutting a small slab I noticed the point of contact on the stone momentarily glowing, Am I pushing the stone through to quickly?, the saw was set about half speed, I guess around 2700 rpm or should I increase the speed. There was plenty of coolant.
Regards
Flynny

Aha. Some very good questions. I see you are eager young Jadi; follow me...

Re:Amethyst - Yes, those crystalline/quartzy-type rocks are pretty hard (physically & on tools!) Not so commonly understood is the difference between Hardness & Toughness. Hardness is measured on the Mohs-scale (jade approx 5.5 - 6.5, amethyst is more like 7) and is really just a guage of what-will-scratch-what; not really a sign of how good a stone might be for carving. The reason nephrite is such a good carving material is due to its extreme Toughness caused by the microscopic grain/fibres which run through it, similar to wood (only tougher!) Despite their hardness, many crytalline stones (amethyst, citrine, quartz, agate, etc) can have pretty crappy structures holding them together & can easily/often fall apart.

Q:How do you see whilst working under water? A: Not very well...

Re:saw-speed - I dont really know. Id guess my own trimsaw (non-variable, boo hoo) would do somewhere in between your slowest & fastest speeds..?? (5000-6000rpm doesnt sound excessive; give it a go...) As long as there is enough water/lubricant there really shouldnt be a problem. *If the tip of the blade and/or the contact point of the stone is glowing then there ISN'T enough water getting into the right place & you are dicing with burning out the diamonds on your tools and/or having an accident. RULE #1 is make sure there is enough water!!! (it does happen from time to time & isnt instant death to your diamonds but I want to impress it now as something to avoid at all costs)

Ill leave it there for now as I know there are more specific questions coming...

May the Torque be with You. T3-PO :)