Machining/Resizing Pipe

wiltbank · 2005-11-13T12:48:35+00:00

Greetings, folks...Let me preface this by saying I'm a complete and utter novice when itcomes to this art -- to the point where this question is actuallyasking what tool I need.Using some standard brass 3/4" pipe, I want to resize portions of itdown to 1/2", similar to this shape: this be done with, say, a mini-lathe? I was under the impressionthat a lathe was strictly for shaving down an item, but I've hadsomeone else suggest it can be used to actually change the diamater inthis respect.If it is possible are there any structural disadvantages?Thanks!Rob

Nov 13, 2005 23 Replies

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cs_posting 20 years ago

So you anneal it again. This method can work, if the form is something you can melt out again.

Yes, also some parts are drawn from seamless tubing. Techniques tend to be a combination of hammering, burnishing, spinning, and drawing, often with different makers choosing differently even for the same part. For example the bell section can be formed as a cone (possibly with an insert to complete it) and hammered to expand the flare and spun to shrink the neck, or you can spin a flat disk into the bell and join it to a seperate cone... Tapered tubes can be formed from trapezoidal sheets and drawn to size, or simply drawn down from tubing over a mandrel, using an annealed fender washer as a die.

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cs_posting 20 years ago

The instrument industry does produce some parts by machining down and boring out barstock. Typically they like not to do precise cutting operations more than once, so it would be done with step drilling and a custom reamer, but CNC equipment both within the industry and at job shops is changing that.

One difference when machined from bar stock is that the material is likely then a leaded brass, C360 say, instead of the unleaded brass more common in tube stock C260, though some is a leaded C330. This has possible implications if the part is a mouthpiece and will not be plated.

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