Forums Beginner Questions 5 sided star facets

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  • 5 sided star facets

    Posted by dantmcgowanmac-com on December 21, 2018 at 7:35 pm

    Hi,
    I am new to faceting and am using an Ultratec V5 machine with the standard 45 degree Table Adapter. I am having an issue with the star facets on my standard round brilliant. On one side they are the nice triangular shape shown in the design. If I go across the table facet to the other side they gradually change to a 5 sided shape with short sides (see diagram). For setting up the adapter, I just followed the manual where you adjust the adapter using a flat lap and the set screws. I am wondering what is causing the change in shape of the star facets and how to keep this from happening next time?

    dantmcgowanmac-com replied 5 years, 6 months ago 4 Members · 4 Replies
  • 4 Replies
  • Frankwood

    Member
    December 21, 2018 at 9:33 pm

    Hi,
    The table is not at 90deg, when you cut it to meet the star facets its not cut deep enough on the 5 sided facet side.
    I’ve never used an Ultratec, so I don’t know what stop system they have. But you can check the 45deg adapter is set correctly by putting some paper on the lap and ink on the adapter. With the stop set for 45deg lower the adapter till it touches the paper, the ink should wipe off evenly. If not then adjust the stop/cheater till it does.
    Depending on how accurate you want the star facets to meet the table you may find you will need to fiddle with the stop and cheater anyway as you get to the pre-polish stage.

    Hope this helps.

    Frank

  • York27

    Member
    December 22, 2018 at 3:27 am

    If your having the issue I think your having, one way I go about it is setting the table adapter to 44.75 (I play with this a little), however when grinding on 1200, I start at 45 to see if they are even all the way around, usually the bottom part is cutting more than the top, so I will keep cutting down at 44.95 or 44.90 or basically until they are all even around.

    Don’t “touch” the stars at this stage, just get really close. Once you go to polish, if you ended on 44.90 (sometimes lower, play this part by sight), then start off around 44.92, check to see if it is polishing evenly across the whole table, adjust as required. Do this until all scratches are gone and you have touched the stars.

    If your having issues left/right you can adjust the cheater a tad to bring them even.

  • rsagems

    Member
    December 22, 2018 at 6:28 am

    Similar to what York27 said, use your cheater to move right-left, use your angle setting to move up (lower angle) and down (higher angle). These angle settings are usually less than a few tenths of a degree. This could have something to do with your transfer perhaps not being perfectly aligned. But if you learn to cheat it doesn’t really matter.

  • dantmcgowanmac-com

    Member
    December 28, 2018 at 5:36 pm

    @RSAGems, @York27, @Frankwood,
    Thanks for the great advice! My next one line up fairly well with just a cheater adjustment needed. Triangles all around for the stars and a great overall cut! Good knowledge to take moving forward when I get to the Table.

    Kind Regards,
    Dan

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