Difference between Skeleton and Master?

[fiebigc]

I've only ever used the master model merge for top down design. It sounds like skeleton models have long since replace the master model merge as the preferred method. Could some give me a little introduction to skeleton design and how it differs from MMM? Thanks.

 

[Asho Pulsar]

Do search in Mcadcentral forum "Master model merge and Top down design or creation of skeleton model" as a keyword.Surelyyou'll get the result.

 

[David Butz]

The two Top-Down-Design techniques are really quite different. For example:


Master Model:


You design a gizmo which is housed in a two-piece split plastic housing. The only sensible way of designing the housing is to do the entire non-split shell, probably as a surface model. In this case, include the surface model as a "master". Then create each of the housing parts, copy in the master, delete "half" the model in each, add features, and solidify.


Skeletons:


You design an articulated machine. In this case you want to capture all the motion possibilties with a simple lightweight collection of entities like datum planes, axes, and curves. This has two important advantages. (1)You can cause the machine to go through its ranges of motion early in the design process, before you have built or added solid components, and much more easily later. (2) When you do assemble "real" components you can simply "hang" them on the skeleton. This is not only easier; it also avoids complex and unwanted parent-child relationships which would make the assembly less amenable to modification.


You design an instrumentation module containing several actuators, sensors, and circuit boards in a rectangular box. If you use a "space claims" skeleton of planes, coordinate systems, etc.in a skeleton model, you can assemble the various components to these datum features, and more flexibly move things around by moving the parent datum features only.


Map Parts:


This technique is not as commonly mentioned, but useful in its own right. You have the main components of a machine assembled, but have not yet created all the manifolds and "plumbing" which is going to connect them. You can create a special part in the assembly that includes only the massless reference geometry necessary (bolt-hole axes, surface copies of exhaust port flanges, etc.) for creation of the secondary connecting parts.Then youuse this particular part as a reference when creating the "plumbing".


The other very powerful tool to explore for Top-Down efficiency is Layouts.


Hope this summary is useful.