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Turning Brass on 7x16?

 

I made a 5in brass cannon from 1.25" C360 brass on a big Southbend lathe at my local Markerspace and plan to try it again on my LMS 7x16. What tooling and speeds are recommended?
 

C360 turns nice with flat on top HSS on the 7x in my experience. Really sharp with a tiny nose radius worked great for me. I turned almost 50 feet of 3/8" into little 1/2" long orifices and never found anything that cut as well as flat HSS. It did not like carbide or any top rake on the steel in my experience. I spun it around 8 to 900 rpm and fed .002" per rev and got a really nice surface finish.?

Ryan
On Sep 21, 2024 at 8:46?AM -0400, CBJessee-N4SRN via groups.io <cbjesseenh@...>, wrote:

I made a 5in brass cannon from 1.25" C360 brass on a big Southbend lathe at my local Markerspace and plan to try it again on my LMS 7x16. What tooling and speeds are recommended?
 

I turn brass all of the time on my mini lathe.
Use high-speed steel tool bits.
High-speed steel can be sharpened better than carbide tools.
This is a mini lathe, so cutting speed is not too critical.
Regards,
John Mattis (retired mechanical engineer)

On Sat, Sep 21, 2024 at 5:46?AM CBJessee-N4SRN via <cbjesseeNH=[email protected]> wrote:
I made a 5in brass cannon from 1.25" C360 brass on a big Southbend lathe at my local Markerspace and plan to try it again on my LMS 7x16. What tooling and speeds are recommended?
 

The main things are no top rake & stoning a tiny flat (instead of a sharp edge) on drill bits.? Those sharpening differences keep the tool from pulling itself into the work.
?
Roy
 

It might not be clear to everybody what "stoning a tiny flat" really means.? This is called "dubbing" a drill and here is a pretty good photo I found online.

It isn't really a less sharp edge (you still want a very sharp edge), but one with zero rake angle.? This prevents the drill from corkscrewing in with soft metals or plastics.? It is a VERY handy little trick.? As another bonus, it is safer when drilling soft materials because it is far less likely the drill will "grab" into the material as a sudden surprise.

Inline image

Charles E. "Chuck" Kinzer
On Saturday, September 21, 2024 at 04:21:52 PM PDT, Roy via groups.io <roylowenthal@...> wrote:


The main things are no top rake & stoning a tiny flat (instead of a sharp edge) on drill bits.? Those sharpening differences keep the tool from pulling itself into the work.
?
Roy
 

I've turned brass fitting many times on the LMS 5100.? ?Never went to specific bit geometries - just used the indexable carbides from low-priced sets or other chinese turning tools.
--
Lone Tree, Colorado? ?USA
 

Good find! The picture is better than my text ;-)
?
Roy

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