Sisyphus

[stormer]

Hi ian,

I hope you havent started yet, because I would strongly reccommend to go with design option 2.
- The reason is, that the arrangement of the x-rails of option 1 is allmost pointless. The idea to have more than one rail is all about having a broad base (by putting them apart as much as possible) to compensate larger moments (to make the design stiffer).
In design option 2 you have a far better stiffness using the same components, hence you will get closer to your design goal of a 0.01mm precision (wich is tough to achieve)
- Option 2 will also have less debris falling on these rails.

More ideas:
- Another improvement to option 2 in that same direction would be by placing the x-spindle also on the outside, having less debris on it and the nuts beeing in the middle of the 4 wagons (seen y-wise optimum for transferring forces) . The spindle and its nuts can even be put on the outside of the cheek, making it more accessible to adjust (you are going for a 2 nut spring loaded design, I take it), to grease and to clean.
- Increase the cheek plates thickness to 4/3 of what they are now. Same goes for the plates of all the z-parts.
- Consider side-plates for the moving z-plate to increase the second moment of inertia in x-direction (y-direction is never a problem there)
- Also prepare the design to hold a "real" milling spindle later. Starting cheap with a handhold router is absolutely ok, but you will later want to get a spindle built for that CNC-purpose anyway, e.g. in the 2.5KW region.
- If you then will go for a watercooled version, you will also have a quieter machine when milling plastics.