Expected Finishes & Finish to Finish relationships

Sebastian

If the only predecessor for A2 is A1 by a FF-relation, then I would expect this behaviour.

Expected finish is a constraint which has an impact onto an activity’s duration. Then P6 will miss a FS relation and put the start date as early as possible - i.e. onto the data date.

Dieter

Clear, concise answer thank you.

So in basic terms when scheduling without expected finishes then durations are constraints, when scheduling with expected finishes then durations are not considered as constraints.

Sebastian

As far as I learnt the algorithm, duration becomes a variable if you’ll apply Expected Finish.
I didn’t check the influence of "Link Budget and At Completion for not Started Activities" under the tab "Calculation" in view Projects.

Regards
Dieter

Just checked, apparently no influence.

Thank you again for your investigations.

You’re welcome.
I was curious as well.
Dieter

Sebastian

I am afraid that you are still confused on an important point; a Finish-to-finish (FF) relationship is not an “Expected Finish”. These are two different things.

Expected Finish is more of an internal function that forces the activity’s remaining duration change so as to cause the early finish of that uncompleted activity to occur on a set date. You cannot set an Expected Finish to occur based upon another activity’s finish date.

I believe that you are probably thinking of using FF relationships, which only constrain the successor activity to finish no earlier than the predecessor activity finishes. Obviously two matching FF relationships between two activities (assuming 0 lags) would force the two to finish at the same time.

It is important to be sure to use the correct terminology when discussing technical matters so as to prevent confusion and possibly erogenous advice. Good luck!

Thank you.

You are right to clarify, I am aware of the difference & I believe that Dieter understood me correctly.

My last paragraph which began:

"However, if an expected finish is now put on activity 2 that ’forces’ it to finish at the end of activity 1..."

Should have been written/read as:

"However, if I enter an expected finish date on activity 2 that is the date that would align it with the finish date of activity 1... "

The background is that the programme is scheduled without expected finishes, a global change is run that populates the expected finish field with the "finish" date that is currently shown, the data date is progressed and the program is scheduled using expected finishes, a global change is run that removes the expected finishes and then throughout the rest of the day the plan is scheduled without expected finishes. The reason for doing this is as a form of auto update. This process is the clients current requirement - there are obviously issues with this method, of which this particular case is one example.

Sebastian

I understood you that way and assumed you know the meaning of Exp Finish.

The procedure you described in my opinion is very dangerous and may (will) lead to some unexpected results.

1. Global change to set exp Finish --> Orig.Dur set to variable --> schedule --> may set new original duration
2. Global Change to remove Exp Finish --> new Orig.Dur is fixed.

Another remark (out of topic) to the way you link activities: In my opinion each activity has at least one predecessor and one successor and in general should be linked by Finish-to-Start. The activity linked only by Finish-to-Finish: when can it start? which other activity had to be completed before? FF should be reserved to Level of Effort and to real exceptions only. IMHO

Regards
Dieter