Milling off rotary table. Quality???

[zaebis]

Ok here is a hypotetical setup. Mill with a rotary table square to the table.
I lower the endmill into the stock while rotating rotary table (a-la lathe) with the endmill in the centerline of the stock material. What quality finish (concentricity) should I expect? I need very concentric finish (perfectly round like on lathe) but I also need to go inside the stock from the side (not just from the face) so rotary table cant face up. I need it ro face 90 to the mill table.

And would the finish be any better if I cut with the side of the endmill vs its tip plunging straight down?

[Cmailco]

First of all, always explain your setup in terms of axes; ie, rotary axis parallel to machine's 'X' axis or rotating about the 'X' axis. It's a lot less ambiguous and easier to envision.

Secondly, why not just state what you're trying to achieve in terms of 'finish', 'concentricity', etc.? What kind of tolerances and specifications are you working with?

Can you post a model, print, anything that might give us a better idea of what you're working with.

Regards,
Chuck

[zaebis]

Originally Posted by Cmailco First of all, always explain your setup in terms of axes; ie, rotary axis parallel to machine's 'X' axis or rotating about the 'X' axis. It's a lot less ambiguous and easier to envision. Secondly, why not just state what you're trying to achieve in terms of 'finish', 'concentricity', etc.? What kind of tolerances and specifications are you working with? Can you post a model, print, anything that might give us a better idea of what you're working with. Regards, Chuck

Ah ok. Rotary table with its rotation axis parallel to X of the mill (e.g. rotating about X of the mill)

I generally understand that the end result will be perfectly round since stock rotates about the cutting tool but I am concerned about the wall finish. I am not sure on tolerances but I need 2" round snout that I will cut to fit into 2.002" round bore (that was done with boring head) and rotate in it freely without stucking.

The part profile is something like this....


_____ ____
___| |___| |___
|
|
---------------------------------- X axis

[RICHARD ZASTROW]

Typically end mills are made with a negative angle on the axial face. This is done so the peripheral edge (at the diameter) sweeps the surface of a linear cut. This slight angle will leave a raised surface at the center of the cut.

To avoid this raised surface, the end mill should be ground flat. That is perpendicular to the end mills rotating axis. That means one flute can reach the center of the end mill or there will be no clearance for the grinding wheel to grind any other teeth.

We had to do this when milling rotary dies. This operation was similar to what you describe for your problem.

Hope that helps without confusing you. LOL

Dick Z

[Cmailco]

Rich brings up a good point, in regard to standard tooling.

Most of the tooling dedicated to turn/milling operations employ a wiper flat for that very reason. Then a specific offset (from X centerline) is used to turn/mill. The cusp height is determined by the amount of offset and let's just say, this all gets a bit complicated without decent diagrams.

If you shoot me an email, I'll be more than happy to send you some of the information I've used over the years.

Regards,
Chuck