Possible to bore 10mm (OD) stock to a depth of 1 inch with a hole diameter of 8mm?

[KillJoy149]

I am assuming you have access to a Lathe???

If so, use a Boring Bar. You would work out 4MM from Center.

If you don't have a Lathe...... I don not know of a "safe" way to mantain tolerances.

KillJoy

[Cobra]

Thanks a lot for the quick reply. Yes, I do have access to a lathe (not mine), which is why I don't know much about it. So if I understand correctly I can bore an 8 mm hole, but how deep can I make this hole?

[KillJoy149]

That depends on the accuracy of the lathe, the length of the boring bar, and the skill of the machinist.

In theory, you could hame a tube from a rod if you wanted to.

KillJoy

[pogo]

Yeah, sure. A 1mm wall should not pose much of a problem.

If you needed a much thinner wall, one trick I've heard is to take the cut all at once with a slow feed. Such as, drill the 10 mm tube with a 7 mm drill, and bore with a slow feed to 9.5mm.

That way, the thin material is left behind without any distortions caused by subsequent boring.

You can make this as deep as your boring tool is long. For an 8mm hole I would not try for much more than 2-3" or so. A carbide tool has greater stiffness than HSS or a 5 dollar cheap chinese boring bar.

I would be more inclined to buy a metric drill bit and maybe a reamer, extra long if necessary, and chuck the material in the lathe with the drill bit in the tailstock. I've pilot drilled with a 1/4" drill bit into aluminum and titanium to a depth of 10" or so very well centered.

The trick is to turn the material and fix the drill bit. The drill will tend to wander torwards the center.