What form is the best for the lowest friction if a rod needs to spin horizontally on a flat surface?

 

something like this

 

|-----------

 

 

------ = the rod

 

| = the flat surface

 

is there some kind of design that can be etched in them to make the rod turn as easy as possible?

Bearings, bearings, bearings....

Rolling rods are frequently used as bearings, few things are as efficient. AFAIK any modification (besides making them ball bearings possibly) would make them less efficient.

Check if any of the Rolamite variants applies to your needs.

Miguel

I cant use bearings....

 

I was thinking maybe if the tip of the rod was diamond and the surface was also made out of diamond. The rod diamond would have to be as sharp as possible?

 

Would it be possible to make a bearing out of diamond? Would it last forever?

I cant use bearings....

 

I was thinking maybe if the tip of the rod was diamond and the surface was also made out of diamond. The rod diamond would have to be as sharp as possible?

 

Would it be possible to make a bearing out of diamond? Would it last forever?

 

That is kind of what graphite lubricants do. It would be possible to construct the rod out of a diamond and IMO should last longer than one constructed from most other materials so long as there is little vibration or shock (diamonds are notoriously brittle). It would not last forever though, think about a diamond needle on a turntable.