Reading through your first post again Gordon I can better understand your queries on both the 0.01mm tolerance and the confusing E5 rule. Good that they have been addressed and noted on this thread.
This will be my first time competing in the IFC and have already started the first stone. I find it much more interesting cutting stones for comps. And has revived an old hobby I’ve had for over 40 years.
Section E Defiant Freeform.
This freeform cut is also one of the optional stones in the annual comp. with some minor index changes to it and a specified material.
The drawings for both competition stones are identical, yet the index settings for the IFC stone is the reverse. The rotation of the index numbers around the crown drawing are in the opposite direction than they normally go, which would create a stone opposite hand to the drawing.
Also some of the indexes are wrong, the crown is an emerald style cut so all indexes should follow the girdle indexes, which they don’t.
For example step 3 girdle index is 13 so step 7, 14, and 21 should be 13. But their not they are 15.
This error is also in the annual comp. stone.
When doing a freeform stone you have to remember that the stone is not symmetrical and, therefore, girdle facets cut when doing the pavilion will not necessarily line up with the crown steps. When you do a symmetrical stone, a girdle cut at 96 index is actually 48 after transfer, but because there was also one at 48 that now becomes 96, you do not recognise the difference. For a non symmetrical stone, a girdle facet cut at say 11, becomes 96-11 i.e 85. I haven't checked all the numbers on the comp stone, but I suspect that is the answer, unless someone has made a mistake.
I got that wrong about the index numbers being incorrect on the crown and girdle. Getting myself confused by looking at both sheets at the same time and not picking up on the differences you mentioned Bruce.
I know the IFC stone will cut regardless of which direction the indexes go, but I had two stones disqualified in last years comp. because they spiralled in the wrong direction.
My fault for not reading all the rules and missing the part about spirals having to rotate in the correct direction. Below is the relevant rule.
SPECIAL CONDITIONS C
“All designs must be cut according to the diagram, i.e., the facet position, basic shape, direction of any spiral effect and meet points must conform to the diagram. However, facet sizes may be altered slightly if necessary, to achieve meet points”
My stones spiralled the wrong way because my index wheel was numbered in a clockwise direction, creating an anticlockwise spiral. I have since changed the numbering on the index wheel.
It normally does not matter which way its numbered. Round, oval, square, rectangle, triangle etc will all come out the same, but freeform cuts will be opposite hand.
I don’t want to be a nit-picker Paul, but by the rules judges could disqualify any stone cut opposite hand to the drawing.
If you click on the number surrounded by the greater and less than symbols, usually <96>, you can change the direction of the index numbers to suit the orientation of the numbers and index orientation relative to the lap on your machine.
I’m going to reverse the indexes Gordon so the stone will cut according to the drawing. I only picked up on this when I started to cut the stone on Wednesday. But happy it’s sorted and I can carry on with it, the corresponding rule for this in the IFC is E2
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