Hi there

I am sorry if I have posted this is the wrong place but I am looking for some advise and not really sure where else to go? Please advise?

I wonder if you can help me? I have recently started a new project, which is a bespoke design. There are many prototypes to be designed and manufactured. These prototypes will tested against eachother and further design will be required until they are satisfied they have the right design to build the final product.

I have obtained a task list/drawing output list from the design team for the first prototype. I also have a build schedule from the manufacturers.
I have asked the design team for their work estimate against each task but I have been told they cannot give me this. Their reasoning is that being designers, they will keep refining and refining the design as they want to acheive optimum results. I was told they expected me give them the drop dead need date for each drawing, and they would deliver to these dates.
My argument is this: without knowing work estimates, and resource assignments to each task, how can I demonstrate to my boss (the PM) that the design team have enough resource to deliver the required drawings within the timeframe required?

Surely if I do what has been suggested by the design team then as a project we are accepting that we work on the "we'll get it done" philosophy and this cannot be sustained?

Can someone please give me some advise, as I really do not know what to do? Ultimately my boss has bought me in to create a project plan which shows realistic delivery dates. Whichever way I look at this, there still remains a finite resource with dealines to meet. Without work estimates how can I ensure resource is level loaded, and without doing this then how can a reasonable design duration be estimated effectively?

I look forward to hearing from you, and please, if I have got this wrong then do explain.

Thanks