multiple start-finish dependancies

[minimadmark78]

Due to the nature of my project it is clearer to shedule everything form the
end date, however I have a problem when when using multiple start finish
dependancies.
example:
76 - Sample Ordering takes 10 days and needs to be done in advance of
77 - Board Fixtures which starts 09-aug and
78 - Tooling changes which starts 04-aug

I have used 77SF, 78SF which is giving me a start date of 09-Aug - what I
actually need is 04-Aug as samples need to be available for the earlier date
not the later for both to be achieved !

Can anyone tell me who I need to go about this?

 

[davegb]

Due to the nature of my project it is clearer to shedule everything form the
end date, however I have a problem when when using multiple start finish
dependancies.
example:
76 - Sample Ordering takes 10 days and needs to be done in advance of
77 - Board Fixtures which starts 09-aug and
78 - Tooling changes which starts 04-aug

I have used 77SF, 78SF which is giving me a start date of 09-Aug - what I
actually need is 04-Aug as samples need to be available for the earlier date
not the later for both to be achieved !

Can anyone tell me who I need to go about this?

You've run into a major problem with scheduling from Finish in Project.
It assumes that if you schedule from the finish date, instead of a
start date, that you want all tasks to start ALAP. Like in JIT delivery
in manufacturing. It sounds as if this is not the case in your
situation, as it isn't the case in most projects. You want, for most
tasks, just the opposite. Tasks to start as soon as possible, the
default condition when you schedule your project from the start date.
It also sounds as though you are worrying a lot about exact dates on
which the tasks must start and finish, and trying to use linking to
force pre-conceived dates for things to occur. And running into the
usual problems with this approach.
It's hard to explain online, but with CPM scheduling, it really makes
no difference whether you schedule from the start, or schedule from the
finish. The basic schedule will be the same, based on your task list,
estimated durations, and dependencies. So if you create the schedule,
and the duration is 200 days, does it really matter if you schedule it
to start tommorrow, and it shows it finishing 10 days later than the
deadline, or, you schedule it to finish by the deadline, which tells
you you should have started 10 days before tommorrow? Same predicament.
You have to shorten the schedule (attack the CP) by 10 days. Of course,
it you have 10 days extra, either way will show you that too. 10 days
extra is easier to deal with.
I suggest you reschedule your project scheduling from the start date,
then adjust as neccessary to get the finish date you desire. I think
you'll find it a little less problematic.
Hope this helps in your world.

 

[minimadmark78]

Thanks Dave, having read your post and now many other people reference
scheduling problems, it does appear the only true way to get a grip of
Project is to schedule from the start date. In my case I have been trying to
make someone elses plan more logical - Big mistake. back to the drawing
board.

 

[Steve House [Project MVP]]

I like to think of it this way. We have a fixed date by which we MUST be
finished. But it's by no means engraved in granite that it WILL finish by
that date - the only thing certain is that we in the deep stuff if it
doesn't. My problem as PM is how to arrange the work so we actually can
finish on time. The problem with scheduling backwards is that it assumes an
on-time finish and calculates the date each task will start IF nothing goes
wrong. But we don't work from finish backward - time only goes in one
direction and we're actually going to do the work from start-to-finish. We
won't know if it'll go according to plan until we get there and actually do
it and the only thing you can really count on is nothing ever goes exactly
according to plan. So the best scheduling backwards can give me is the
absolute latest date that we theoretically could start the plan in a perfect
world. Now I need to pick a date comfortably AHEAD of that date and
actually build the work schedule from start date forward, manipulating the
variables that I as a manager can control - how many people to put on a
task, for example - so that the calculated end date is on or hopefully well
before the required end date.

 

[adamtanboonkwang]

Due to the nature of my project it is clearer to shedule everything form the
end date, however I have a problem when when using multiple start finish
dependancies.
example:
76 - Sample Ordering takes 10 days and needs to be done in advance of
77 - Board Fixtures which starts 09-aug and
78 - Tooling changes which starts 04-aug

I have used 77SF, 78SF which is giving me a start date of 09-Aug - what I
actually need is 04-Aug as samples need to be available for the earlier date
not the later for both to be achieved !

Can anyone tell me who I need to go about this?