Welcome to the forum.
I can't tell you how many times I have seen issues (all kinds)
when you save to pdf. Try Printing to pdf instead. This method seems to be
a lot more stable.
Thanks will try printing to pdf see if this becomes more stable and more accurate
Have also tried the pdf viewer settings but this makes no noticable difference
Thanks again for the quick replies
You mean the whole drawing is not printed to scale? This could simply be print settings in your PDF viewer. If you are using Adobe Reader, for example, it usually defaults to "Fit To Printable Area" in the Page Scaling option. Make sure it is set to "None", or whatever the 100% scale option is in your viewer.