Don't you just need a G-Code generator? Visual Mill is one. Dolphin is another. I hear good things about both. Each is under $2K. Each generates G-Code from CAD. I think Dolphin is 2.5D. Visual mill does conversions from 3D solid drawings. Turbo CAD has a package too. But I've not heard a lot about it. If you go to the Sherline site there are some free tools in this department.
Also check out the DIY_CNC and / or CAD_CAM_EDM_DRO gorups at Yahoo groups.
There are also several people retrofitting the drive controller using the PC based program Mach 3 with stepper and / or servo drives from Rutex and / or Gecko.
But that's all time intensive. If you have the cash, maybe buying it makes sense.
Hope that helps.
-jd |