Help with flush stone setting

[CopperTreeArt]

Hello! I've spent weeks trying to flush set a 3 mm stone. I took a class and my teacher said to use a 3 mm stone setting burr to do so. My stone always seems to pop out once I push on it from behind.

When you flush set, what size burr would you use for a 3 mm stone? I've also tried a 2.7 mm burr but found it is too small and when I try to make the hole a little larger, I make it uneven. I'm thinking of buying this burr ...which is a 2.9 mm. http://www.riogrande.com/Product/Rio-High-Speed-Steel-Stone-Setting-Bur-29mm/345711?Pos=4

Also, do you drill with your flex shaft in hand or using a drill press? I've tried both but am curious which works better. Any help is greatly appreciated!!! Thanks!

[khmetalwork]

3mm stone = 3mm bur.

Often the bottom of the stones aren't cut correctly, if it's a belly bottom it won't sit down regardless of the hole diameter. Try using a bud or ball bur to open the hole below where the girdle will sit.

Soham harrison on youtube has a nice flush setting tutorial.

[khmetalwork]

Open a little at a time, obviously stills need to be smaller in diameter than the girdle.

Also, always measure your stones and your burs, not always what they are supposed to be.

Always use my flexshaft.

[CopperTreeArt]

Thank you!

[GKJdesigns]

If the seat for the stone is almost large enough, but still just a tiny bit too tight for the stone to go in, at that stage the flexshaft is often too imprecise and risks making the seat too large. You can use the bur in a pin vise to manually make micro enlargements until it just fits. If you have a snug fit, the stone should not easily push out from behind after being set.

[CopperTreeArt]

Thanks so much!