i don't think it's a problem with newton but you could ask at the newton forum if there is something special to know about small objects in the centimeter range.

you could also try to use the double precision dll instead of the single precision dll. it is included in the newton sdk.

can you post an example for experimenting?

btw. newton clamps updates to the 60..600hz range. if you update with less than 60hz then newton will do sub steps.