It should be easy to implement on a LEAD with a high Z mod. Then add a rotary axis under either the x or y axis. You would have to use the plug from either the x or y axis and change steps per mm in grbl when you use it.
Saw the LEAD Lath, that might be a starting point but I'm wanting to make it much simpler and not need a second machine. Basically I want to make one like what my Laser cutter uses. You simply clamp it to the table and plug it in. The Rotary Axes then takes place of the Y axes and the rotation is proportional to the Y travel. This way it is plug and play and you don't need to change the GRBL back and forth.
That only works if you're doing 2D, maybe some simple, fairly shallow 2.5D work- you design in CAD such that your design's Y height is equal to your workpiece's circumference. If you have a 3" diameter cylindrical workpiece, you create a design of 3*pi in height- about 9.3" high- and it'll map over. If you want to do anything else, you have to start changing machine parameters so that you can use degrees, not millimeters. Much easier on a 2D laser than a 3D router.
I understand, I'm not looking to make a CNC lathe, just something to do simple engravings on a cylinder, much like a laser cutter. So if my stock is 1" diameter and 6" long I can draw it out as a flat piece, add text, maybe a simple design and trace at a minimal depth. It would have it's limits for sure, but that's the trade for simplicity.
If you go the extra step to add a rotary axis why don't you go just a little step farther and add the electronic that can do a 4 axis control?
BlackBox can do Rotary using Vectric Wrapping Rotary Machining and Wrapping - Aspire V9.5 User Guide as shown in the Lead Lathe
In your situation, I would: buy a rotary axis mount it to something that will always keep the head and tail stock aligned have your existing CNC drill mounting holes along the axis you pick to be the rotary axis and in a location to which you can accurately and repeatedly return. In my case I am going to choose the Y because it is longer. I will have the rotary lines up 100 mm from Y0 (Home). Mount said rotary and calibrate it. Easy peasy. The issue you may have is Z axis height which is why I suggested a high Z mod. Or, remove spoil board material below the rotary cutting area. I like my rotary lathe, but when I get done with modifying my regular CNC router, I plan to add a rotary axis to it as mentioned above.
Yep, that's the plan. Z shouldn't be an issue as I am 3" higher than the standard LEAD1010 now. I have a raised Waste board now that I can remove to gain an additional 3" in Z. I plan to use it as a small surfacing router as well. I'm also working on a design for the raised waste board so I can easily level it. As it is now it is about 0.0015" out on the X and even less on the Y. I'm thinking maybe some stiff spring washers might allow me to loosen/tighten the mounting screws to level that out. (Parallel to the X and Y)
