I am considering turning my LEAD 1010 with high Z into an XL C beam machine with a fixed high Z axis. One of the upgrades I plan for is to add a rotary axis. I am aware that GRBL can't manage full 4th axis, so I am planning to stick to wrapped 4th axis/Y clone (XZA rather than XYZA) However, in the future I may want to switch controllers and add a full 4th axis. Would it be possible to mount the 4th axis on the moving spoilboard plate, or would I need to convert back to a standard gantry configuration? The 4th axis I am looking at is from SPAM 3D and weighs 5kg. I would probably need to add some linear rails to help support the weight. 4th Axis dividing head cnc Rotation Axis activity tailstock Thoughts? On another note, is there actually much of an advantage to moving in 4 axis as oppose to 3? I asked over on reddit, but didn't get much of a response. From what I've read it let's you carve more complex objects and could be faster, though would be interested to her more experienced opinions. My eventual goal is to carve globes like this one:
I'd consider adjusting the base frame and cutting into the table to give you room for 5 axes to carve globes like that- you really only want to hold them from one spot and then cut perpendicular to the surface as much as possible. The more axes you have, the less rigid your motion chain is. You want to move as few axes as possible at any given moment in time and you want as few axes on any given chain (workholding chain- table, and toolholding chain- gantry/head) as possible. For example, I wouldn't waste time roughing globes from cylindrical stock in 5 axes, I'd turn them quickly down on a 4th as batchwork, then transfer to a fifth for the precision carving- which is slow, but doesn't take much cutting force. A small dedicated lathe type machine like @Giarc made would be a good idea for this type of work. It's just XZA (like a basic 2-axis lathe), very simple framing, quick and cheap to make and adjustable to the type of work you do. Technically, for a globe, adding a B axis to the spindle on his machine so it can tilt side-to-side along X would give you access to all points on the sphere and wouldn't significantly alter the machine design. Maybe that would be the way to go. Three axes to the tool and one for the workholding wouldn't be ideal, but it would be simple. Then you could totally rough and finish on the same machine. But I don't know if it'd be worth converting a LEAD 1010 to that, I'd probably just scratch-build it.
Thanks for link. That CNC lathe is essentially what I had in mind. I was mostly wondering how two Nema 23s would handle moving a whole assembly. It's not a very useful idea, your other suggestions would work much better, I was mostly just curious. On that video, the user manually rotates the model to carve each face individually. Ideally I would like to have something similar, as it seems a simple way to achieve complex carves that I want (nothing with any tolerance, just art). The LEAD is just the machine I have lying around
With the High Z mod on the LEAD, you could put a 4th axis under it sort of how I did my lathe. I would make a spacer for both ends of the rotary axis so that lining it up parallel with the Y axis edge is easy and consistent. If it were me, I would line it up on the side with the homing switch. Then you could set your homing pull off to whatever distance from that switch you need for the Y axis to travel down the center of your rotary axis. If you use a spacer it will always be the same. That way it would be an easy set-up. 1) mount the rotary using your spacers, 2) home the machine, 3) disconnect the X axis stepper and connect to your rotary stepper, 4) change your x steps/mm (most likely to be 26.667 steps/mm ( technically it is steps/degree for my set-up).
