4th Axis DIY Mill?

I've periodically looked into this, because 5 axis is my ultimate goal- whether with OB parts or a scratch build, or maybe both for different materials (an OB one for tooling foam for molding and casting model parts or urethane dies or whatever, and a concrete/mineral-epoxy & rail/ballscrew one for "real" work). Even as recently as early 2016 this was a tall order, but apparently we live in exciting times.

Currently the state of things seems to be that Fusion 360 is the CAM solution, which is nice because it's well community supported and mostly works well, but it's really the only 5-axis simultaneous-machining (ie. all 5 axes moving at once, rather than XYZ with rotary indexing, which they added last year) solution south of $10k. The free version seems to include the Ultimate 5-axis stuff (as long as you're making less than $100kpa yada yada) because I was playing with the demo files recently with my jaw on the floor.

Controller system is most likely going to be LinuxCNC, it's capable of controlling up to 9 simultaneous axes with inverse and forward kinematics- meaning you can make an industrial-style six-axis robot arm with it, too. Downside is you need a PC with a parallel port, a stepper driver board that you can plug into it, etc. rather than just an Arduino or RasPi. You can get MachineKit images for RasPi/BBB, and it has an XYZA image already made, it seems, but everything I'm seeing points toward it being more hassle than it's worth vs just buying a more extensible x86 PC.

If you don't actually need true 4+ axes and can get away with rotary indexing, then building a simple rotary table (stepper, belt, angle plate, face plate) and manually writing in the 4th axis G-Code between machine movements is entirely doable. There are several ways to skin this particular cat, and there's nothing preventing you from starting incredibly simple with a system just designed to 3D-rout multiple sides, and work up towards a full industrial-type system.

Whether you need a post-processor for moving the Fusion G-Code to LinuxCNC, I'm not sure, but it doesn't seem like it as long as everything's in a standard position/tool orientation format, which it all seems like it should be.

You'll have to independently look into all of this and figure out your own best move. Once you graduate from linear Cartesian builds, you're a little out there on your own from what people are primarily set up to provide as turn-key solutions at hobbyist pricing. Makes you wonder, though, if 5-axis 3D printing could be a thing. With proper bed adhesion and thermal control, I don't really see why not?!

 

actually there are 5 axis 3d printers coming to market (or so a couple of companies say) though I'm not quire sure of the benefit as of this point. but it does have a small milling option!

 

The extra two axes would primarily be for indexing- eg. maintaining cylinders' concentricty to the print head for proper line orientation- though true 5 axis printing with non-flat layers could be a fascinating proposition.

 

makes sense, the programming will be hell I think

 

There was a link in a thread in this forum for a business named Automation Technologies that happens to be 20 minutes from my home that has and trunion/rotary assembly that is designed to be integrated into a 3-axis mill.

While working for and at the big jet engine companies I used Siemens NX CADCAM software to model and then program to machine these parts. The secrets to being able to program for 5-axis machining is to have the right software and then being smart enough to know how to model and then create the kinds of toolpaths you would need in addition to understanding the setups you would need. For the most part the great thing about 5 axis machines is that even if you aren't doing simultaneous motion machining you can can pretty much machine the part complete using only two setups.
Machining prismatic parts in this manner is referred to as 3 plus 2 machining because you can pretty much do 3 axis machining and tilt and rotate positioning to access all of the features on the part.

I am looking forward to getting into Fusion 360 to see what it is capable of doing for me.