Bit of an expensive option, but it is possible to use Delcam's Artcam to run the router- it will allow you to import virtually anything- dxf, eps, even bitmap images that you can 'sculpt' into a relief, then carve on the router. It includes a 'spooler' that converts to gerber code, and drip-feeds the router if the file is bigger than the contoller's buffer.
I have an older Gerber router that I wanted to do some relief work on, and found someone who brought round his laptop with Artcam on. It worked perfectly. I think the Sabre is more standard than my router (mine uses a proprietary code rather than G codes), so Artcam is probably overkill for you, but at least it shows that 3D is possible on Gerber machines.
I'm still saving however... |