[timbot1982]

I'm new to CNC machining, so please forgive the ignorance of these questions:-) Can you get good detail and undercuts for sculpture in the round (i.e. statues) using a 4-axis milling machine as opposed to a 5-axis? What’s the difference between them in what they can do?

[svenakela]

4-axis are way more common in any case compared to 5-axis. 4-axis is XYZ with a turning axis, 5-axis is much more complex and the moving/turning directions depends on the setup.
use the search function and you will find some examples.

[Harryman]

You're better off either cleaning up the undercuts by hand, or milling your sculpture in parts to be able to mill undercut areas and then assembling.

5 Axis machines and the software needed, are far, far more expensive, complicated and difficult to tram/align then 4 axis machines.

If it has to be milled, has to be milled in one piece, and can't have any unmilled undercuts, try to farm it out. Cheaper and more timely in the long run.

You can also look at Rapid Prototyping.

[Mike Stevenson]

timbot1982,

The size of your parts can be much larger with a 4 axis setup than for 5 axis for the same money. Big 5 axis costs BIG money. I have done a lot of 4 axis rotary engraving and I think it would be the most practical way to go.

[greatcncwebsite]

Came across a new site out there specifically for 5-Axis machining. There is some basic information about 5-Sided versus 5-Axis.

5-sided programming. Do you need a CAM system? | 5-Axis Machining

[twoartistic]

I have a 4 axis machine, but I only have set up the fourth axis for making turnings. I either leave material sprues on my part to locate it when I flip it over, or I use custom clamping jigs to hold the part in the needed orientation.

There are some parts that you can do in one piece, and in one set up that you cannot do on a 4 axis machine, but unless you are doing high volume, or other special consideration it would be hard to justify the 5th axis. IMO

[twoartistic]

I have a work around solution that I discovered while playing with a design. This works for Solidworks to Artcam, and probably other 3 axis cam software as well. I position my part on the front plane of a flat part in Solidworks assembly. I can use the mate tools to position the part in any position I want. Then I save it as an stl file. The 3D file can be imported into Artcam and is in the position I set in Solidworks. To be really slick, I creat the holding jig and table position as part of the part. I did a sample file with a multi position jig. I have a complex part I am going to be prototyping soon. Now I have the machining all set up as multi stations on my table. Not as slick as my buddies 9 axis machine, but I didn't have to pay a bagilion dollars for it either.

One issue with the stl file, is that it applies some faceting to the part. If I am only machining the top surfaces a smoothing operation in Artcam will soften those out without effecting the part geometry too much. I am hand working or shaping my parts after, so this is not an issue for me.