Lots of mini-lathes being converted to CNC here, but I haven't seen a real good answer to the toolchanging problem. People do mount the cutoff tool on the rear, which I guess gives you 2 tools, and there have been some complicated looking rotary changers built, but it seems like gang tooling is the easy way out and I would expect to see more of it.
I first saw gang tooling associated with a product called the "Accu-Slide" that let you convert a Hardinge to CNC just by clamping the thing to the ways:
The idea on a gang lathe is to use a long slide, and let the machine's X and Z motions select the tool. To select a tool, the slide moves right to clear the workpiece (no tailstock used on a gang lathe!), the tool is selected by moving the slide in or out, and then the slide moves back left to bring that tool to bear.
Very simple! The key is going to be having long enough slide travel to carry enough tools. I learned a lot reading about gang lathes from manufacturer's web sites like Omniturn. For example, they use an 18" long slide with 10" of travel.
Along the way, I have also mused about converting Asian machines to use linear slides. A gang tool conversion is a perfect opportunity, because you probably need to fabricate a new longer slide anyway.
It turns out the Omniturn-sized slide would work well on my Lathemaster 9x30 lathe, so I did some sketches in Rhino to see how it might work:
The circles show swing over cross slide and swing over apron top. If I install a 1" thick aluminum gang slide with clearance for some 12mm linear rails, I lose about 1/4" of swing over the gang slide. Given how they're used, I can live with that. I would think some pre-ground tooling plate of 6061 (or preferably 7075/Fortal) would be ideal.
The drawing shows mounting the 12mm linear rails to the bottom of the gang slide, and then bolting the blocks to the apron. I would bolt them either side of the male dovetail, leaving that dovetail intact so I can go back to "stock" if desired. The ballscrew drives from the side, much like Ron111's Lathemaster conversion you see on another thread.
Toolposts are attached using the single T-slot that runs along the front of the plate. One could buy commercial QCTP's like Phase II, but that's way overkill. I would make them up in the AXA size, and just use a set screw to load the tool holder against the wedge. Alternatively, you can design the holders to go right to the T-slot, but you'd have to shim to get height adjusted.
This does not seem that hard to fabricate, yet would add tremendously to the power of you CNC lathe conversion by solving the toolchanger problem. Not sure why we haven't seen someone do it yet.
I will look into it further when I finish my basic Lathemaster conversion, but there's lots of folks on these boards who would probably turn out a finished result a lot faster than me.
Let us know how it goes if you decide to give it a try!
Cheers,
BW
PS I will be keeping my design notebook and eventually build log on my web site here:
http://www.thewarfields.com/cnccookb...GangSlide.html