What is a "77B-Cup Bur" used for? =>22 photos

 In my previous essays, I wrote about how and why claws should be made round. This essay seems repetitive, as there are many aspects of this 'series on mini-claw settings' that I didn't want to miss any of them.

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 This "77B" cup-bur is all that you really need to 'round' your claws (of any size). Inside of this bur are teeth just like a file that you use. They won't scrape the metal as it is rotating (but NEVER use it at a high speed).

 In this photo, ALL OF THE CENTER STONE CLAWS WILL NOW BE UNIFORM IN SHAPE.

 At a high speed, the bur teeth slide along and doesn't get a chance to do its 'metal shaping'. At the higher speed, it will just ruin the metal and damage the delicate claws.

Why are the burs finely shaped on the rim, this is so the teeth will get more contact to the 'claw tip'.

 Don't be alarmed that there could be two different sizes of "77B" burs in finishing these tips. The center stone usually has a larger size claw that is solely used for security.

 The cup-bur needs to be held at an angle 'away from the stone'. 

 You just don't want the rotating bur edge to cut into the (soft) faceted stone.

 Here is a great example of the different sizes of claws for this pendant. Always keep a wide supply of 77B burs near you at all times for this finishing process. 

  As many of these cup-burs in this photo have 'smooth & rounded edges', this is not good. These burs which I had in my collection were only acting as a display of what can happen to these smaller sized burs. They are now on their way to be discarded. 

  If some of the claw tips are not well formed, I suggest in filing them to a correct shape, then the 'rounding' action can easily commence.

  Always hold your #77B cup bur at an angle 'away' a vertical position. If you are setting delicate and soft stones, the rotating bur teeth could destroy the stone in seconds.

Always select a larger bur for all of the large claws on the center stone.

  Another idea, or option is to 'pre-cup' your claws. If many of your selected stones are absolutely too soft, such as an Opal, Emerald or even Amethyst. 'Being safe', is better than damaging the stones.

  The angle of the bur is also essential as the rotating bur won't damage the soft and delicate stone. It is advisable to tilt the bur away from a vertical position.

 Uniform sized claw tips are very essential, and this cup-bur will this create a nicer appearance.

 

  This is the method that I use to reshape the 77B bur on an oilstone. The teeth of the bur are now more exposed and closer to the edge of the rotating bur. When you see the teeth being exposed, then you've accomplished your task.

 The cost of these 77B burs is not cheap as they are among the most expensive in any setters' inventory, but what they can do in stone setting is just remarkable. 

KEEP THEM WELL LUBRICATED WHEN IN USE. 

 This is the 'best shaped' bur that will do the rounding of your claws. There is no need to use any sized file. Your claw tips will now remain uniform, as this is very important. 

  If you are setting a large expensive Emerald, I would use my Cup-Bur on the flaw tips FIRST!!!

 

 On this pendant there could be three sizes of burs that will be put to use.

 Here is another view of the Emerald and White stone ring.

Don't place your bur on your bench-peg like this. It needs to be placed solid on your ring clamp.

 Here is a wonderful photo of the 'bur teeth' of the 77B being exposed.

 Some of the packets of 77B burs come in 6 sizes, this will give you greater knowledge to know what burs to use in the future.