4/5 axis

[jcnewbie]

How would you put in simple words the difference between 4/5 axis machining to 3 axis machining ?

[bobhaha]

4th axis can control other things such as a lathe for 3d working on a table leg for example, or for swapping out tools or what ever. 5th axis can be used for even more complex things like controlling pitch of a rotated object or controlling the pitch of the z axis (control the rotatory tool)

[Superman]

Think of a cube

3-axis will only allow you to machine features viewed from the TOP face
holes can only be drilled along Z axis
4-axis on a vertical will allow you to machine TOP, FRONT, BACK and BOTTOM. A horizontal can do FRONT, LEFT, RIGHT, BACK ( TOP cannot be done on a horizontal )
and depending on the 4th axis configuration - everything in between these views ( depending on your set-up ie 3-jaw chuck, vice, tombstone and so on )
5-axis allows you to tilt that 4th axis for access to 2 more faces to machine

There is usually one face that cannot be presented to the tool, this face can be inside a vice, on a fixture, stuck to a table ( it depends on the part, but it has to be held somehow )

There is tooling available that can be used to to get to non-presented faces on the 3 & 4 axes using an "aggregate head" ( right angle head is a simpler form of the tool), aggregate heads can be angle adjusted-but not by CNC code, it is set-up prior to the job starting )

[jcnewbie]

Thanks for the info.

I have a question.. How about projecting letters onto a curved surface. Does one need a 4/5 axis machine ( or an attachment of an aggregate on a 3 axis) or a 3 axis machine to program the part.

[ObrienDave]

That would depend on the angle from the spindle axis, how deep the letters are, the geometry of the letters in relation to the surface, and the curvature of the surface.
99.9% of my programming was all 3 axis.
Having never done any really radical departures from the spindle, I would think that about 60 degrees from the spindle could be considered a maximum.
I have personally done engraving like that up to about 15 degrees.
If the edges of the letters need to be perpendicular to the surface, then yes, you need 5 axis.
If not, 3 axis minimum, or 4 axis if you need to do multipal faces in one setup.

[ObrienDave]

Just for fun, I made a toolpath using projecting a pocket toolpath onto a half sphere.
This is a 3 axis toolpath done in V9.
Zip file includes .STL file for verify.