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Im looking for help/ suggestions with a business I'm looking to expand. I currently hand carve stone sculptures. These are small ( size of toaster). Im looking to automate the sculpting and be capable of a Lifesize human sculpture.
Ive looked at robots for a long time but it seems the software isn't as readily available as it is for a cnc. Also cnc may be more accurate and faster. Is my thinking correct with this? Any ideas or thoughts on how to approach this would be great. Thanks
A robot arm does not have the rigidity (by 100x) for cutting in stone etc.
A human sized sculpture in stone will be heavy.
A human sized 4-axis mill (horizontal) is quite easy to make.
But the vertical rotary axis (c axis) gets huge moment-arm loads from being milled about 1.8 m high at the top vs base plate height.
A secondary support at top is very much indicated.
This support (arm) can be removable, and the last bit of the sculpture at top cut off as a last op.
1.
For making life-sized object about 50 cm max width, about 0.02 mm in angular resolution at 250 mm radius, and having high rigidity to avoid chatter, means a very rigid rotary base of about 30.000 counts - 60.000 counts / rev mechanical resolution.
The wider the base is at support points, the better it will work.
I would aim for about 1 m diameter, 30-40 mm thick cast iron disc, on a base of 1.2x1.2 cast iron.
It is possible to ghetto build and sand the outer edge of the rotary to about 0.02 mm in flatness, and use it to flatten the carrying ring area of the base.
Make the base plate as flat as possible with flap wheels and 125 mm angle grinders and a *machinists* ground straightedge.
About 0.04 mm is fairly easy and fast (noisy, messy, unpleasant).
Same for rotary part.
Relieve one of the 2 about 0.04 mm except about 50 mm at edge.
Using powered lubrication like a diesel fuel auto pump, and spindle oil, the rotary part will float with near zero friction.
You may want to check this out;
https://www.youtube.com/watch?v=Q1VDHF9yM1o
There are more than a few places around the world that are carving stone with a robot. Rigidity as it applies to accuracy is a concern, but if you are carving sculpture it may be a lesser concern. Surface quality would (in my mind) be more important. As far as software is concerned, I have used RhinoCam to generate standard Gcode files for wood sculptures that were translated thru IRBCAM for use on an ABB 6400 robot carving station. My joinery was tight enough that a piece of stationary couldn't be slipped between parts. You may want to take a closer look at these systems.