Accurate Tape Measure?

[Jonathan]

i always measure from the 100mm mk.

Same.. it's the obvious solution.

Surely for a frame what's more important is to get repeatability since it's unlikely to make much difference if you measure 600mm and get 600.5mm as with the error you describe every piece will be 600.5mm. The frame will still be square etc, just negligibly off the size you wanted.

[JAZZCNC]

Tapes are for wood and rough material sizing, precision engineers rule is the minimum I would recommend and even then I'd double check every time.!