2.5-Axis vs 3-Axis

[JamesBond]

Ok, here is a basic question.

What does 2.5-Axis, 3-Axis, 4-Axis and 5-Axis mean?

(I'm trying to figure out how to get a 1/2 axis )
-JamesBond

[balsaman]

2.5 axis is is basically a 3 axis machine that the z axis basically is either up, or down, nothing in between. Like a plotter. 3 axis is basically x and y and z, which is two horizontal axis perpendicular to each other and a vertical axis. 4 axis or more is where you may have a rotary table, indexer etc added to the conventional 3 axis machine axis'.

I think anyways...

Eric

[HuFlungDung]

Hi James,

You are in luck! I just so happen to have a 1/2 axis unit you can add to your mill so you can be the first to have 3.5 axis

[JamesBond]

Hu,
I hope you'll sell me your half axis for 1/2 price
(I have a board stretcher I'll trade)

Does the same thing apply when software talks about 2.5-Axis and 3-Axis programming?

Thanks
-JamesBond

[HuFlungDung]

Yes, generally speaking 2.5 and 3 would be similarly referred to. I think the original limitation may have been on mills that only have an XY servo system and manually operated quill.

A few older controllers may not be able to perform a linear XYZ move either, but they can do XY or YZ or XZ, so this would be 2.5 axis. Since YZ and XZ are not very useful since you are restricted to one plane, the Z axis would be called for by itself, then any XY would be called. This permits you to still make a certain class of 3d part, but only ones with Z level movements allowed.

[CAMmando]

In Milling:

2 Axis, Usually X and Y only.

2.5 Axis 2 Axis With Multipl Z Level Features. Any single feature (pocket island whatever) is at a constant Z level, but there may be multiple features at various z levels. The description of a Mill with a manual quill is good, but the 2 1/2 axis terminology is moreoften used to describe the programming capability. So for example a basic milling software may support 2.5 axis programming.

3 Axis Usually X,Y and Z includes simultanious 3 axis motion. Could be complex surfaces or planar cuts that are rotated out of axis.

4 axis usually incorporates the addition of a rotary table or indexer (B or A axis).

5 axis incorporates both A and B axis. Machine construction varies from simple rotary on rotary to fully articulating heads. In milling the 4th and 5the axis movement is usually defined by A and B axis rotation.

IN 4 Axis Wire EDM:

Uses X,Y and U,V.

X and Y are the lower wire guide axis and U and V are the upper guide axis. Programming the pairs independantly allows for interesting geometric possibilities. Very popular in extrusion die work where a die wants to be round on the entry side and transition evenly into a very conplex shape at the other end.

If you can get a good deal on a half axis, go for it. If you can find 2 of em' you will have a whole axis for a bargain. I will throw in a bag of A.I.R., 2 buckets of propwash and some muffler bearings with mine if you want it.

[Paul_S]

The other posts pretty much covered the subject.

2 ½ axis is typically X & Y interpolation, Z positioning; Y & Z interpolaton, X positioning; and last and not least, Z & X interpolation and Y axis positioning.

And G17, G18, and G19 to switch between the 2 ½ axis modes.

G17 X & Y interpolation.

G18 Z & X interpolaton. (X & Z if the X axis sign of the moves are in reversed to the cartesian coordinate system rotation. As looking down on a lathe or looking toward Y+ from Y- front of a mill. The reverse G2 is CCW and G3 is CW so to the operator G2 looks CW and G3 looks CCW.)

G19 Y & Z interpolation.

3 axis is X, Y and Z interpolaton.

The 4th axis, A axis typically rotates around the X axis.
A 5th axis, B axis typically rotates around the Y axis.
A 6th axis, C axis typically rotates around the Z axis.

Depending on the control, the machine builder, and/or third party add ons. the 4 axis could be any combination rotations and axis words.

Some controls have the option of switching the G18 from ZX to XZ to accomodate the operator. G18 ZX is programmer preferred. G18 XZ is operator (non-programmer) preferred. The latter format is typically used in conversational programming where the operator must specifiy CW or CCW in an XZ move.