Linking tasks in MS Project

[Sumit]

Hi,
This is a manufacturing scenario where I need to identify start date for
ordering material and other tasks based on the start date of manufacturing.
Let's assume there are 5 tasks:
1. Define Packaging specification - 2 weeks
2. Issue Purchase Order(s) to external manufacturer - 2 day
3. Order, receive & test raw material - 1 month
4. Manufacture - 1 month
5. Test and report on manufacture - 2 weeks

Task 1 should start 3 months before 4,
Task 2 should start 2 month before 4,
Task 3 should start 1 month before 4, and
Task 5 should finish 3 months after 4.

I configured above by making Task 1 as predecessor of 4 (Start to Start) and
a lead time of 3 months and similar with Task 2 and 3. I made task 4
predecessor of Task 5 with Finish to Finish relationship and a lag time to 3
months.

This worked fine until i gave a start date to project. The moment i do this,
MS Project assigns project start date to Task 4 and backward schedules Task
1,2 & 3 and they are scheduled to start even before project start date.

The requirement is to get earliest start date for manufacture based on
project start date. How do I achieve this? Ideally earliest predecessor
should get project start date and rest should get spread based on lead time
but this is not how MS Project schedules.

Am I missing something? Any thoughts?

Regards,
Sumit.

 

[John]

Hi,
This is a manufacturing scenario where I need to identify start date for
ordering material and other tasks based on the start date of manufacturing.
Let's assume there are 5 tasks:
1. Define Packaging specification - 2 weeks
2. Issue Purchase Order(s) to external manufacturer - 2 day
3. Order, receive & test raw material - 1 month
4. Manufacture - 1 month
5. Test and report on manufacture - 2 weeks

Task 1 should start 3 months before 4,
Task 2 should start 2 month before 4,
Task 3 should start 1 month before 4, and
Task 5 should finish 3 months after 4.

I configured above by making Task 1 as predecessor of 4 (Start to Start) and
a lead time of 3 months and similar with Task 2 and 3. I made task 4
predecessor of Task 5 with Finish to Finish relationship and a lag time to 3
months.60d

This worked fine until i gave a start date to project. The moment i do this,
MS Project assigns project start date to Task 4 and backward schedules Task
1,2 & 3 and they are scheduled to start even before project start date.

The requirement is to get earliest start date for manufacture based on
project start date. How do I achieve this? Ideally earliest predecessor
should get project start date and rest should get spread based on lead time
but this is not how MS Project schedules.

Am I missing something? Any thoughts?

Regards,
Sumit.

Sumit,
You are trying to combine both forward scheduling and reverse scheduling
in one plan, but in an informal way. How's that for confusing.

As described in your post, you will not replicate what you actually
have. For example, the way it is described in your post, tasks 1, 2 and
3 have no predecessors. Task 4 has 3 predecessors (i.e. 1SS-60
days,2SS-40 days,3SS-20 days). Task 5 has one predecessor (i.e. 4FF+60
days). [Note that I am using days here in lieu of months based on the
default definition of 20 days per month (Tools/Options/Calendar tab)].

When configured as stated above, task 4 does NOT start on the Project
Start Date. Tasks 1, 2 and 3 do.

Ok, what I think you really have is the following:
task 1 pred: 4SS-60d
task 2 pred: 4SS-40d
task 3 pred: 4SS-20d
task 4 pred: nothing
task 5 pred: 4FF+60d

With this plan, the only task without a driving link (i.e. predecessor)
is task 4 - manufacturing. When you enter a project start date, Project
will schedule all tasks without a predecessor or start constraint on the
project start date and that is exactly what you are seeing.

Your method tries to define manufacturing as the center of the plan and
It really isn't. Manufacturing is just one step in the whole sequence
that starts with packaging spec definition and finishes with testing
completion. Therefore the project start date should define the first
task in the network - the other tasks will follow in the sequence
defined by their duration and links.

Look at each task and determine if it has a real dependency with the
other tasks. If it does than a link is appropriate and the simplest type
of link (i.e. finish-to-start) generally works best. For example, the
material can't be ordered until the PO is issued. Manufacturing can't
occur until the parts arrive and testing can't start until the
manufactured item is completed. Furthermore, testing shouldn't finish 3
months after the product is completed, rather it will (no "should" about
it) finish when the testing is done. If that is 3 months later, fine but
according to your estimated duration for test and reporting, that whole
sequence will finish 2 weeks after the product is built.

The bottom line is, don't try to force the issue. Lay out the plan in a
logical sequence. Project will calculate all the dates and then you can
see if the end goal is met. If not, rework the plan until it is.

Hope this helps.
John
Project MVP

 

[Sumit]

Hi John,
Thanks for prompt response.
I guess by "(i.e. 1SS-60 days,2SS-40 days,3SS-20 days)" you meant lag
instead of lead else I get the same result. Even with this, the problem is
that the earliest task is not scheduled first and second task appears little
after that, instead they all appear in same line.

The timelines that I am trying to enforce are more from a Directive
standpoint. According to the co guidelines it is mandatory to ensure these
tasks have stated lead/ lag times.

Going by your suggestion, instead of enforcing it through dependency I would
create a macro to validate the plan on each save. I guess this would be a
better way to ensure conformity and reduce the complexity in the plan.

Does this sound OK to you?

Regards,
Sumit.

Hi,
This is a manufacturing scenario where I need to identify start date for
ordering material and other tasks based on the start date of manufacturing.
Let's assume there are 5 tasks:
1. Define Packaging specification - 2 weeks
2. Issue Purchase Order(s) to external manufacturer - 2 day
3. Order, receive & test raw material - 1 month
4. Manufacture - 1 month
5. Test and report on manufacture - 2 weeks

Task 1 should start 3 months before 4,
Task 2 should start 2 month before 4,
Task 3 should start 1 month before 4, and
Task 5 should finish 3 months after 4.

I configured above by making Task 1 as predecessor of 4 (Start to Start) and
a lead time of 3 months and similar with Task 2 and 3. I made task 4
predecessor of Task 5 with Finish to Finish relationship and a lag time to 3
months.60d

This worked fine until i gave a start date to project. The moment i do this,
MS Project assigns project start date to Task 4 and backward schedules Task
1,2 & 3 and they are scheduled to start even before project start date.

The requirement is to get earliest start date for manufacture based on
project start date. How do I achieve this? Ideally earliest predecessor
should get project start date and rest should get spread based on lead time
but this is not how MS Project schedules.

Am I missing something? Any thoughts?

Regards,
Sumit.

Sumit,
You are trying to combine both forward scheduling and reverse scheduling
in one plan, but in an informal way. How's that for confusing.

As described in your post, you will not replicate what you actually
have. For example, the way it is described in your post, tasks 1, 2 and
3 have no predecessors. Task 4 has 3 predecessors (i.e. 1SS-60
days,2SS-40 days,3SS-20 days). Task 5 has one predecessor (i.e. 4FF+60
days). [Note that I am using days here in lieu of months based on the
default definition of 20 days per month (Tools/Options/Calendar tab)].

When configured as stated above, task 4 does NOT start on the Project
Start Date. Tasks 1, 2 and 3 do.

Ok, what I think you really have is the following:
task 1 pred: 4SS-60d
task 2 pred: 4SS-40d
task 3 pred: 4SS-20d
task 4 pred: nothing
task 5 pred: 4FF+60d

With this plan, the only task without a driving link (i.e. predecessor)
is task 4 - manufacturing. When you enter a project start date, Project
will schedule all tasks without a predecessor or start constraint on the
project start date and that is exactly what you are seeing.

Your method tries to define manufacturing as the center of the plan and
It really isn't. Manufacturing is just one step in the whole sequence
that starts with packaging spec definition and finishes with testing
completion. Therefore the project start date should define the first
task in the network - the other tasks will follow in the sequence
defined by their duration and links.

Look at each task and determine if it has a real dependency with the
other tasks. If it does than a link is appropriate and the simplest type
of link (i.e. finish-to-start) generally works best. For example, the
material can't be ordered until the PO is issued. Manufacturing can't
occur until the parts arrive and testing can't start until the
manufactured item is completed. Furthermore, testing shouldn't finish 3
months after the product is completed, rather it will (no "should" about
it) finish when the testing is done. If that is 3 months later, fine but
according to your estimated duration for test and reporting, that whole
sequence will finish 2 weeks after the product is built.

The bottom line is, don't try to force the issue. Lay out the plan in a
logical sequence. Project will calculate all the dates and then you can
see if the end goal is met. If not, rework the plan until it is.

Hope this helps.
John
Project MVP

 

[John]

Hi John,
Thanks for prompt response.
I guess by "(i.e. 1SS-60 days,2SS-40 days,3SS-20 days)" you meant lag
instead of lead else I get the same result. Even with this, the problem is
that the earliest task is not scheduled first and second task appears little
after that, instead they all appear in same line.

The timelines that I am trying to enforce are more from a Directive
standpoint. According to the co guidelines it is mandatory to ensure these
tasks have stated lead/ lag times.

Going by your suggestion, instead of enforcing it through dependency I would
create a macro to validate the plan on each save. I guess this would be a
better way to ensure conformity and reduce the complexity in the plan.

Does this sound OK to you?

Regards,
Sumit.

Sumit,
First of all "lead" time is expressed as a minus value (i.e. it occurs
before or leads the subject task), and "lag" time is express as a plus
value. So for example, 1SS-60d describes a lead of 60 days.

If all tasks have the same start date after you have applied links with
lead or lag, I suspect your Tools/Options/Calculation tab is set for
manual, or dates have been manually entered thus setting a constraint
which will not allow the task to move.

With Project, (or any other scheduling application), you never "force" a
timeline. Forcing a timeline is a process used by individuals who do not
understand the basic principles of schedule management. Unfortunately
this is often the case with management, customers, or those new to
scheduling.

I don't know what your "co guidelines" are but if they advocate
mandatory lead/lag times then those "guidelines" are all wet and need to
be trashed. They have no bearing on good scheduling practices. In the
manufacturing scenario you presented the only place I could see the
potential for a lead/lag is vendor lead time. For example, the PO is
placed and the vendor has a lead time of 40d to do this thing before he
can ship the parts. If you do not wish to physically represent this lead
time with an actual task, (which by the way I recommend), then you can
show the receipt of material as a lag from the date of PO place.

I you're still not in step with this approach then consider this. In
your example the test and report task has an estimated duration of 2
weeks yet the guidelines say it "should finish 3 months after [the item
is built]". Here's a basic question. If the item is built would it not
go directly to test (assuming the test equipment is available) and then
wouldn't the report be written immediately after the test, give or take
a day or two? So why does a 2 week task "wait" so it can "meet" a
mandated 3 month delay? It makes no sense and in the business world,
time is money. The idea is to accomplish something in the most efficient
way and mandated schedules are not efficient.

John
Project MVP

Hi,
This is a manufacturing scenario where I need to identify start date for
ordering material and other tasks based on the start date of
manufacturing.
Let's assume there are 5 tasks:
1. Define Packaging specification - 2 weeks
2. Issue Purchase Order(s) to external manufacturer - 2 day
3. Order, receive & test raw material - 1 month
4. Manufacture - 1 month
5. Test and report on manufacture - 2 weeks

Task 1 should start 3 months before 4,
Task 2 should start 2 month before 4,
Task 3 should start 1 month before 4, and
Task 5 should finish 3 months after 4.

I configured above by making Task 1 as predecessor of 4 (Start to Start)
and
a lead time of 3 months and similar with Task 2 and 3. I made task 4
predecessor of Task 5 with Finish to Finish relationship and a lag time
to 3
months.60d

This worked fine until i gave a start date to project. The moment i do
this,
MS Project assigns project start date to Task 4 and backward schedules
Task
1,2 & 3 and they are scheduled to start even before project start date.

The requirement is to get earliest start date for manufacture based on
project start date. How do I achieve this? Ideally earliest predecessor
should get project start date and rest should get spread based on lead
time
but this is not how MS Project schedules.

Am I missing something? Any thoughts?

Regards,
Sumit.

Sumit,
You are trying to combine both forward scheduling and reverse scheduling
in one plan, but in an informal way. How's that for confusing.

As described in your post, you will not replicate what you actually
have. For example, the way it is described in your post, tasks 1, 2 and
3 have no predecessors. Task 4 has 3 predecessors (i.e. 1SS-60
days,2SS-40 days,3SS-20 days). Task 5 has one predecessor (i.e. 4FF+60
days). [Note that I am using days here in lieu of months based on the
default definition of 20 days per month (Tools/Options/Calendar tab)].

When configured as stated above, task 4 does NOT start on the Project
Start Date. Tasks 1, 2 and 3 do.

Ok, what I think you really have is the following:
task 1 pred: 4SS-60d
task 2 pred: 4SS-40d
task 3 pred: 4SS-20d
task 4 pred: nothing
task 5 pred: 4FF+60d

With this plan, the only task without a driving link (i.e. predecessor)
is task 4 - manufacturing. When you enter a project start date, Project
will schedule all tasks without a predecessor or start constraint on the
project start date and that is exactly what you are seeing.

Your method tries to define manufacturing as the center of the plan and
It really isn't. Manufacturing is just one step in the whole sequence
that starts with packaging spec definition and finishes with testing
completion. Therefore the project start date should define the first
task in the network - the other tasks will follow in the sequence
defined by their duration and links.

Look at each task and determine if it has a real dependency with the
other tasks. If it does than a link is appropriate and the simplest type
of link (i.e. finish-to-start) generally works best. For example, the
material can't be ordered until the PO is issued. Manufacturing can't
occur until the parts arrive and testing can't start until the
manufactured item is completed. Furthermore, testing shouldn't finish 3
months after the product is completed, rather it will (no "should" about
it) finish when the testing is done. If that is 3 months later, fine but
according to your estimated duration for test and reporting, that whole
sequence will finish 2 weeks after the product is built.

The bottom line is, don't try to force the issue. Lay out the plan in a
logical sequence. Project will calculate all the dates and then you can
see if the end goal is met. If not, rework the plan until it is.

Hope this helps.
John
Project MVP

 

[Sumit]

I totally agree with your view John.
I guess these guidelines were setup more as a rule of thumb to ensure people
don't miss these tasks in an environment where managers don't use a tool to
schedule and manage projects.

I built a strong case and shared your views with the management. We've a
meet around this let's see how it goes.

Regards,
Sumit.

Hi John,
Thanks for prompt response.
I guess by "(i.e. 1SS-60 days,2SS-40 days,3SS-20 days)" you meant lag
instead of lead else I get the same result. Even with this, the problem is
that the earliest task is not scheduled first and second task appears little
after that, instead they all appear in same line.

The timelines that I am trying to enforce are more from a Directive
standpoint. According to the co guidelines it is mandatory to ensure these
tasks have stated lead/ lag times.

Going by your suggestion, instead of enforcing it through dependency I would
create a macro to validate the plan on each save. I guess this would be a
better way to ensure conformity and reduce the complexity in the plan.

Does this sound OK to you?

Regards,
Sumit.

Sumit,
First of all "lead" time is expressed as a minus value (i.e. it occurs
before or leads the subject task), and "lag" time is express as a plus
value. So for example, 1SS-60d describes a lead of 60 days.

If all tasks have the same start date after you have applied links with
lead or lag, I suspect your Tools/Options/Calculation tab is set for
manual, or dates have been manually entered thus setting a constraint
which will not allow the task to move.

With Project, (or any other scheduling application), you never "force" a
timeline. Forcing a timeline is a process used by individuals who do not
understand the basic principles of schedule management. Unfortunately
this is often the case with management, customers, or those new to
scheduling.

I don't know what your "co guidelines" are but if they advocate
mandatory lead/lag times then those "guidelines" are all wet and need to
be trashed. They have no bearing on good scheduling practices. In the
manufacturing scenario you presented the only place I could see the
potential for a lead/lag is vendor lead time. For example, the PO is
placed and the vendor has a lead time of 40d to do this thing before he
can ship the parts. If you do not wish to physically represent this lead
time with an actual task, (which by the way I recommend), then you can
show the receipt of material as a lag from the date of PO place.

I you're still not in step with this approach then consider this. In
your example the test and report task has an estimated duration of 2
weeks yet the guidelines say it "should finish 3 months after [the item
is built]". Here's a basic question. If the item is built would it not
go directly to test (assuming the test equipment is available) and then
wouldn't the report be written immediately after the test, give or take
a day or two? So why does a 2 week task "wait" so it can "meet" a
mandated 3 month delay? It makes no sense and in the business world,
time is money. The idea is to accomplish something in the most efficient
way and mandated schedules are not efficient.

John
Project MVP

Hi,
This is a manufacturing scenario where I need to identify start date for
ordering material and other tasks based on the start date of
manufacturing.
Let's assume there are 5 tasks:
1. Define Packaging specification - 2 weeks
2. Issue Purchase Order(s) to external manufacturer - 2 day
3. Order, receive & test raw material - 1 month
4. Manufacture - 1 month
5. Test and report on manufacture - 2 weeks

Task 1 should start 3 months before 4,
Task 2 should start 2 month before 4,
Task 3 should start 1 month before 4, and
Task 5 should finish 3 months after 4.

I configured above by making Task 1 as predecessor of 4 (Start to Start)
and
a lead time of 3 months and similar with Task 2 and 3. I made task 4
predecessor of Task 5 with Finish to Finish relationship and a lag time
to 3
months.60d

This worked fine until i gave a start date to project. The moment i do
this,
MS Project assigns project start date to Task 4 and backward schedules
Task
1,2 & 3 and they are scheduled to start even before project start date.

The requirement is to get earliest start date for manufacture based on
project start date. How do I achieve this? Ideally earliest predecessor
should get project start date and rest should get spread based on lead
time
but this is not how MS Project schedules.

Am I missing something? Any thoughts?

Regards,
Sumit.

Sumit,
You are trying to combine both forward scheduling and reverse scheduling
in one plan, but in an informal way. How's that for confusing.

As described in your post, you will not replicate what you actually
have. For example, the way it is described in your post, tasks 1, 2 and
3 have no predecessors. Task 4 has 3 predecessors (i.e. 1SS-60
days,2SS-40 days,3SS-20 days). Task 5 has one predecessor (i.e. 4FF+60
days). [Note that I am using days here in lieu of months based on the
default definition of 20 days per month (Tools/Options/Calendar tab)].

When configured as stated above, task 4 does NOT start on the Project
Start Date. Tasks 1, 2 and 3 do.

Ok, what I think you really have is the following:
task 1 pred: 4SS-60d
task 2 pred: 4SS-40d
task 3 pred: 4SS-20d
task 4 pred: nothing
task 5 pred: 4FF+60d

With this plan, the only task without a driving link (i.e. predecessor)
is task 4 - manufacturing. When you enter a project start date, Project
will schedule all tasks without a predecessor or start constraint on the
project start date and that is exactly what you are seeing.

Your method tries to define manufacturing as the center of the plan and
It really isn't. Manufacturing is just one step in the whole sequence
that starts with packaging spec definition and finishes with testing
completion. Therefore the project start date should define the first
task in the network - the other tasks will follow in the sequence
defined by their duration and links.

Look at each task and determine if it has a real dependency with the
other tasks. If it does than a link is appropriate and the simplest type
of link (i.e. finish-to-start) generally works best. For example, the
material can't be ordered until the PO is issued. Manufacturing can't
occur until the parts arrive and testing can't start until the
manufactured item is completed. Furthermore, testing shouldn't finish 3
months after the product is completed, rather it will (no "should" about
it) finish when the testing is done. If that is 3 months later, fine but
according to your estimated duration for test and reporting, that whole
sequence will finish 2 weeks after the product is built.

The bottom line is, don't try to force the issue. Lay out the plan in a
logical sequence. Project will calculate all the dates and then you can
see if the end goal is met. If not, rework the plan until it is.

Hope this helps.
John
Project MVP