Turtle shell three in the OZ comp.

[Faceting Frank]

Yesterday on the Australian facetors Guild forum they announced that they are going to extend the final entry date for stones being entered into the annual comp. It was the 1st of June, but now extended by two weeks.
Have already entered my stones, but asked if it was ok to enter Turtle Shell Three, the concave cut stone I didn’t  get to enter. The answer was yes.
Got my concave cutter in bits at the moment, so hopefully will get it working and get to cut it in time.

[FlashGP]

Great Frank, hurry up and reassemble your machine.

Regards
Gordon.

Ps the original was cut in Tourmalike sand concave cuts and looks great in a ring I made for my daughter.

Peter Stringfellow proof cut the concave version.  I didn't have my concave finished at the time.

Regards
Gordon

[Faceting Frank]

Will have that working over the weekend no problem Gordon. Have as stone on the machine at the moment that will be finished Saturday.
Have the stone dopped and ready to go, but will cut the stone crown first and finish the flat pavilion facets before starting the concaves. Problem I had before was overcutting, didn’t understand the different cutting speeds of flats and concaves.
So this time will finish all the flats and lay the concaves over them. Squeezing them down to the girdle for a perfect meet, I hope.
Looking forward to cutting it.

[FlashGP]

Hi Frank,

Sounds good.  I usually cut the flats, even where I am cutting a concave facet because it is easier to rough in the stone on a standard lap. 

On the Spoked Concave in last year's comp, I cut 32 pavillion facets so I could line the concave facets up with the indexes used for the crown.  Then rolled the pavillion.  The trouble was on the stone I was going to submit I was out of allignment and cut 2 indexes away from where I should have been.  Now have long allignment dops to get closer to alligned before I start fine tuning to the facet.

Should have submitted the stone anyway, but it made a really nice pendant.

[Faceting Frank]

Got it finished and mailed today.
 
Didn’t get to spend anything like the time I normally take on a comp. stone and made an arse of the E facets. But learned a bit more about concave cutting.

Cut the concaves with 3000 diamond and baby oil on 12mm copper, that cut quickly and left a good finish.
Don’t know how you guys find polishing Quartz with Cerium on Lucite, but I find it needs a lot of pressure on the facet. No exception with concaves for me, only problem the dowels spring down quit a bit.
Used 11.5mm diameter plastic, forgot the name but not as hard as Lucite, with brass shafts. The smaller diameter is perfect and leaves a nice crisp edge regardless of excess polish. But the shafts are going to have to be hardened steel.

[FlashGP]

Hi Frank,

I tried Lucite once using a lap my wife bought and reverted to the darkside lap before polishing a facet.

Was lucky enough to score 2 x 12mm darkside mandrels with 1/4 inch shafts made for a polymetric from Aussie Sapphire.  Old stock sellout.

Clarrie Trevena on the Gold Coast makes matched sets of copper and pewter mandrels, 12mm with 1/4 inch brass shafts.  The copper is fitted, but he casts the pewter onto the shaft then turns both down to size.

His pewter is an aluminium alloy bearing metal of medium hardness.

Regards
Flash

[Faceting Frank]

Hi Gordon,
That’s the problem with mandrels no one sells them, have to make my own.
Going to make up some tin alloy coated copper mandrels, to use 3000 and 60k diamond for pre polish and polish.
Though looking at the way the 3000 went through this quartz, 3000 may be my first cut.

[FlashGP]

Hi Frank,

I cut with 3000 on copper or brass then prepolish with 8000 on copper before the darkside with 50k diamond or Linde A.

My mate turned up an old tap spindle to make a brass mandrel.  Added a stainless 6mm shaft salvaged from a printer.