Thanks for your reply Andrew
I understood that the concept of "scale" was only relevant to printing, so I am slightly confused.
Anyhow - leaving that aside - I have been working on a 12m long building drawing - hence the 1 meter units which are most appropriate. So is it unreasonable to want to draw let's say the cross section of 30 x 30 x 3mm angle iron in the detail of my drawing?
Using a similar method to my box sample trim fails in this. i.e. draw two .030m joined lines at 90 degrees for the outside of the angle and then draw two parallel lines spaced .003m on the inside of the angle. Then try to trim the inside corner.
I have tested at larger sizes and it does work, but what is the size limit and why?
This does seem to be a bug.
Yes there were multiple entities in my sample - not sure how that happened.