I had a new user ask me why master model features could not be created and live happily in an assembly. Ashamedly, I could not come up with a compelling reason. I actually tried a couple of simple things and I don't see why it wouldn't work - at least in theory... For a simple assembly with a few parts, couldn't this work? Might this be a quick and dirty top down design method? Any thoughts on this - reasons to run away from the idea?
(why does this question make me feel like a complete newbie?)
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At first thought I think you could have the Master Model as part of your assembly, but I wouldn't recommend it.
One of the benefits to this method (Master Model) is the parts are ONLY referencing the master model (its parent) and not needing to pull into memory anything else. If the Master was in theassembly then the entire assembly needs to be pulled into session when working on the part. You won't see that, but could slow things down.
Another draw back is if you have parts in the assembly that need to move as with Mechanism then you wouldn't be able to move parts since they are dependent on static assembly features.
Having the Master in the assembly would also open up the oportunity to create many circular references which can be a real headache to resolve.
In general the Master Model should be the upper control of critical geometry and the assembly should be JUST the grouping of all the parts together and thus where Mechansim is used. There are exceptions, but creating geometry features in an assembly is not a good practice either.
These are just the first few things that come to mind. Even for a simple assembly I would use a master model if there are critical things to control between parts. If its simple enough I just wouldn't even use a master model.
Don't know if any of that is compelling enough to run away, but a few things to consider.
Sincerely, Mark a. Peterson Sr Design Engineer Igloo Products Corp -
Hi Nate, Nice to "see" you on the exploder. Virtual is as good as it gets from this side of the world.
As I understand it the Master Model technique was the early Top Down Design method with ProE. Also as I understand it PTC developed Skeleton parts to take over the Master Model function.
Mark's comments cover things pretty well though I would say that if you folk are running the higher level license then to use a Skeleton instead of the Master Model part. The real difference is that Skeleton parts are designed for the job as they always assemble at the top of the tree, even before the Assy datums and the skeleton does not show up on your BoM. If you only have the basic licence I don't think you get that functionality so the Master Model method will let you do almost the same things but you have to manage its tree location yourself and it will show in a BoM.
Whichever way you go I would only use non solid features in the driving part. In our Skeletons we use the various datum features and surfaces and collect these in Publish Geoms for use in other parts via Copy Geoms. I agree with Mark that you need to be extra careful with mechanism type assemblies. I personally think that either the Master Model method or Skeleton part Top Down Design gives very robust and easy to understand assemblies and are easier to use that the Layout method.
Happy to comment further if you want to get back to me directly.
Regards, Brent Drysdale Senior Mechanical Designer Tait Radio Communications New Zealand DDI +64 3 358 1093 www.taitradio.com
On 8 April 2011 08:20, Nathan Rollins <-> wrote:
> Greetings, > > > > I had a new user ask me why master model features could not be created and > live happily in an assembly. Ashamedly, I could not come up with a > compelling reason. I actually tried a couple of simple things and I don’t > see why it wouldn’t work – at least in theory… For a simple assembly with a > few parts, couldn’t this work? Might this be a quick and dirty top down > design method? Any thoughts on this – reasons to run away from the idea? > > > > (why does this question make me feel like a complete newbie?) > > > > Thanks… > > > > -Nate