what's the right way to machine the middle of a rod?

[Ken from ontario]

I'm working on a piece of Aluminum rod 1.9" in Diameter,3.5" long I want to machine the middle part 1" wide, to a diameter of 1.25", 1.187" away from either ends ,the workpiece will have a "dumbbell" shape.
I have been using my triangle carbide insert ,it does the job but I'm taking .003" on each pass, it'll take forever to get to the desired diameter.

Should I cut two beveled reliefs on either ends first and then machine in between?what cutting tool is more appropriate.
I'd appreciate your help.

 

[mikey]

Ken, I would use my parting tool and define the end cuts. I would make two cuts per side to widen it, then go in with a 1/4" HSS tool with a somewhat pointed end and then round the nose of the cutter. The cutter will cut both ways, toward the chuck or toward the tailstock. If you use a 15 degree relief angle on the sides and leave the top flat, it will easily take a 0.030" deep cut in aluminum.

 

[Ken from ontario]

Mike, thanks for your quick reply, I'm on my way back to the shop to do it, will let you know .

 

[wawoodman]

Why not cut the end sections, and fit straight rod between them?

 

[mikey]

Mike, thanks for your quick reply, I'm on my way back to the shop to do it, will let you know .

Forgot to tell you that it is called a round nose tool and is very handy. I use it mostly in brass but have cut steel and aluminum with it. Leaves a nice finish, too.

 

[Wreck™Wreck]

You are creating a groove so use a grooving tool or at that depth a parting tool, if there is a radius at the bottom rough with the parting tool then finish with a round profile tool of the correct radius. If a NC lathe program the angles and radii using both sides of the parting tool.

If doing so on a manual machine turn one face at a time using the compound when finishing.
Use a tool like so https://www.iscar.com/eCatalog/Family.aspx?fnum=417&mapp=IS&app=27&GFSTYP=M

 

[Ken from ontario]

Forgot to tell you that it is called a round nose tool and is very handy. I use it mostly in brass but have cut steel and aluminum with it. Leaves a nice finish, too.

It worked perfectly Mike, thanks. I happened to have exactly the tool you described, it was part of the set of of 6 I got from LMS as my training set, it looks like a grooving tool with a round nose and a 22° relief angle on the sides, I didn't dare taking off .030" on each pass , the most I removed was .015" ..

Why not cut the end sections, and fit straight rod between them?

The part I'm working on is going to be a drawbar wrench/ hammer with a hex wrench on one end and a flat on the other end , your way works but I'd prefer it to be one piece just like a hammer .

If doing so on a manual machine turn one face at a time using the compound when finishing.
Use a tool like so https://www.iscar.com/eCatalog/Family.aspx?fnum=417&mapp=IS&app=27&GFSTYP=M

That bit is on my shopping list , I have their nogaflex indicator holder and it is a decent tool.

 

[mikey]

Glad that worked out, Ken.