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Hello!

I seem to recall someone sharing a way to drill a hole into brass without creating a burr inside. I'll be adding some water keys to my King and this would be very helpful, if such a trick exists.

Otherwise, I'll gladly take any helpful hints you can offer. Thanks!

this is my non-professional solution, lets see if any pros agree with me

drill a tiny pilot hole
Drill the hole the size you actually want
take a very fine round file and smooth the edge of the hole

Was thinking about this recently also. Want to add a water key to my eb tuba after the valve block. Water collects there and the only way to get it out is to spin the horn. Was thinking about trying to make a tool like a pick with a small bend by the tip to go inside the hole and clear the burr.....

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Grumpikins wrote: ↑Sat Dec 16, 2023 7:09 pm Was thinking about this recently also. Want to add a water key to my eb tuba after the valve block. Water collects there and the only way to get it out is to spin the horn. Was thinking about trying to make a tool like a pick with a small bend by the tip to go inside the hole and clear the burr.....

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I thought about using a dental pick (my brother in law is a dentist, so he gives me whatever I need!) for that as well. Thanks!

I think the Inquirer is referring to avoiding leaving a burr on the interior edge of the hole.

If you're talking about venting a rotor, I have a shortcut that some may think is horrible, but if you were talking about anything else, I got nuthin'.

bloke wrote: ↑Sat Dec 16, 2023 7:17 pm I think the Inquirer is referring to avoiding leaving a burr on the interior edge of the hole.

Yep.

which is why I suggested a needle file

https://www.amazon.com/Hardened-Strengt ... =8-10&th=1

Back when I was an aircraft mechanic I had a reversible deburr tool for deburing the back side of holes in sheet metal where you couldn't remove the panel. The cutting edge flips up and let's your insert it into the hole to clean up the back side. Might not have enough clearance though for a water key due to the bend in the tubing

You can minimize burrs in thin brass by dubbing the drill or by using a zero rake drill.



Once, for a really supper thin, one-off, tube for an experiment I had the university machine shop fill the tube with a low melting point metal alloy, like Woods metal, then drill. No distortion of the tube and no burr. Then you can remove the metal by putting the tube in hot water. Old timers used to use pitch or tar for controlled bending of thin wall tube in much the same way.

Real deburring tools are curved, so you can reach the Inside Edge of a hole, I have a way of getting rid of a burr without a deburring tool but whatever, it's not a needle file.

When "venting" rotors (OK...I almost always remove the rotors, but...) this works:
(I do this when venting my OWN rotors on my OWN tubas.)

- Drill very slowly (less pressure) when nearly punching through (ie. don't "punch" through).
- Do it with DRY rotors. (I use lamp oil with no additive to lubricate all of my instruments' valves, so it does evaporate.)
- Once drilled through, put a tiny drop of oil on the hole, and oil the burr (thicker oil, like SAE 30).
- Turn the rotor slowly (reverse direction, or barely forward, then reverse) over the burr, to flatten to burr out.
- The oil will allow a slow drill bit to pick up the shavings (from the flattened-down burr) and pull them out. This can be repeated.

(At least, when I do this, my rotors turn freely, and I'm done.)

Again, I would do a customer instrument in a different way...
Also, I would use a hardwood dent hammer handle (inside the casing - on a customer instrument) to flatten down the buff and re-drill once or twice. I've never used a de-burring tool on rotor casing vent holes.

With my own instruments, I've never (later) observed any "witness" (rub/scratch) marks on rotor bodies from having done it my "cheat" way.

BUT !!!
The final drilling of a hole MUST be slow/gentle - as to (mostly) AVOID even MAKING much of any sort of burr.

to clarify:
When doing my own instruments, I don't bother to remove the rotors.

yeah...and I also have easy access (right in the shop) to high-velocity hot water - to flush any possibly-left-behind bits of brass out the main slide outside slide tube.