AnsweredAssumed Answered

Zero Dimension Flips Direction.  Is it possible to predict the behaviour?

Question asked by Rob Edwards on Feb 27, 2017
Latest reply on Aug 4, 2020 by Dara Kong

Morning All


I have asked a similar question before, but to no avail.  As an incentive I have enough spare points to avoid moderation so would be delighted to show my appreciation


Our core business is Doors.  I have opening sizes from site surveys, in some cases they are to the finished floor level (FFL) and in other cases to the subfloor, this necessitates the provision of an offset based on the predicted thickness of the finished floor material.


Ideally I would like a simple layout sketch something like this...

The problem is that the sketch is not stable after the FFL dimension has been set to zero

the dimension flips direction if it is increased

When I first did this sketch it worked consistently, but lacking confidence in it's reliability and wanting to make this forum post, I broke it.

The trouble is I have no idea of any rules that govern this situation and it would be too costly if a mistake were to happen.


Please could someone either explain the behaviour, or suggest a 'bombproof' workflow for this situation.


For example here I have created a new plane coincident to the Top Plane with Flip Normal. 

It seems to be holding steady and working correctly, but I have had them flip direction at random times in the past.

What do you think? If it goes wrong it might be difficult to spot a small but crucial error.


Thanks for reading