Burr Question

OK this is going to make me sound like I don’t know what I am talking about, because I probably don’t. The wood hole saws that have a bit in the middle and then a round saw to be able to cut out a circle from wood, are those made in a smaller scale for jewelry making? I am struggling to bring a design to fruition and would love to be able to cut a shallow ring in metal to hold a piece of tube in place. I am just afraid when I try to solder 5 small tubes in a straight line that things will go haywire real fast without a good way to anchor the tubes. Any suggestions for me? Thanks

I have seen them as lapidary diamond tools to carve a hole in rock. Be sure to use under water.

What is the diameter you’re trying to achieve?

Have you considered a disc cutter?

If you only want the holes to act as a soldering jig there are many easier ways to hold parts in place while soldering. Since you are soldering tubes, I assume along their lengths, the simplest would be to hold them in place on a charcoal block with small u-shaped staples of binding wire driven into the charcoal.
Without a diagram or a clearer explanation of the project this is my best guess.

If I understand the question, which I may not, it sounds like you are attempting to stand the tubes on their end, and hoping to cut round channels they would sit in?

If this is true, why not drill 5 holes that the 5 tubes would fit into,tightly, and then solder them? This would avoid the possibility of the tubes swimming away.

As mentioned above, without an image or sketch to go from, I have no idea if I am even picturing this project, Or issue correctly are all.

What I typically do is find the center of your hole. Center punch it, drill a small hole with a drill bit. Then use bigger and bigger ball burrs till you get what you want. Keep them oiled and go slow. Same idea as a hole saw.