Build an FDM toolhead for a cnc machine, which:
- Allows interchanging a cncFDM toolhead with a traditional spindle on the same (3 or more axis ) cnc machine without mechanical rework ( reconfiguration of software is ok ).
- Uses standard 1/8" diameter ABS welding rod as input material.
- Keeps construction cost inexpensive
- Has good reliability. The heater shouldn't need rebuilding/replacing every 20 hours of runtime, for example. I'm willing to sacrifice more difficult construction to achive this goal.
- Leverages Gcode and other common cnc tools to save work. No need to re-write motion algorithms, acceleration profiles,etc etc, they are already available.
- Has accuracy deviating by no more than 0.010" on x and y axes, and 0.020" on z axis. This will require melt flow compensation and other techniques used by commercial vendors.
Assumptions and goals that contrast RepRap ( and are one of the main reasons I started this blog ):
- Line level power is ok, since cnc machines already have it available.
- ABS plastic is the main material, other materials that are more environmentally friendly can be accomodated but are not the focus
- Use existing tools that are commonly available, even if they are not GPL/free. For example, I do not care which solid modelling package is used to create the STL, as long as it works.
- It is ok to have parts that require a lathe or a mill to make. Of course, avoiding work is good, but "assemble with hand tools" is not all that important.
One other point I'll mention is that this is a problem that has been solved by many commerical vendors, most notably Stratsys. Their patent literature describes in some detail the many challenges ( and solutions, woo hoo! ) one might encounter along this journey.
Since I'm not intending to sell or in any way profit from this project, ( at best others may follow this path and construct one themself ), I do not have any problem learning from and employing the patented techniques that commercial vendors use.
Of course, the RepRap project is the best source of inspirational ideas :)