Replacing a part with an assembly

kveeser · ‎Mar 13, 2009

Dear ProE users,

Here is my situation.....

When a singlepart is used in a top level assembly and a weld stud or weld nut is added to the part a newsub-assembly is required. A new assembly is created with the part and weld stud or weld nut. Then the new assembly has to be replaced with the single part at the top level which is actually the same part but with an added component. This may be in many places and takes a while to replace all the constraints to eachassembly it is used. We are considering taking all of our single parts and adding them to an assembly even though there may not be an additional component added to it at that time. This would allow us to add or subtract parts without having to swap out a part for an assembly or the other way around because they would always be at the assembly level.

Does this make sense?

Is there another way to approach this?

any suggestions on this subject would be appriciated.

Thanks,

Kevin

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fred_roy · ‎Mar 13, 2009

Hi Kevin,

That's exactly how we do it. Even if there are no studs or nuts on a
part, we still create an assembly for it. It works fine for us.

Have you ever tried the Replace Unrelated Component command
(Edit/Replace)?

It may be a way to speed things up when you need to replace your part
with assemblies.

Good luck,

Fred

gkbeer · ‎Mar 13, 2009

Kevin - Yes, and No.

Yes - For the reasons given it makes sense.

No - It's a bit like worrying about being hit by every car in America, while
walking across the street.

I call these kind of assemblies, Alligators. Most of them sit around doing
nothing but eat.

These alligators load your session unnecessarily. It costs more in terms of
compute resources. Models will take up more virtual memory. They will take
more time to load, as they consume additional cpu cycles. You will spend
more time query selecting deeper into the assembly. Your model tree will be
that much longer. Same goes for the layer tree.

*In the end it's futile*, because you will start with one part in an
assembly, discover that several more are needed, then end up in the same
boat when one of those parts needs to be replaced by a subassembly.

*It never ends, **and you are the one who has to spend extra time dealing
with it. **Long term it's just too expensive.*

All anyone can do is the best they can, based on the knowledge available.
Then deal with the problems as they arise.

Glenn

kimndave9 · ‎Mar 13, 2009

I've hoped for a long time for a convert-in-place command from part to
assembly or, better, no distinction at all.

It might be tricky to handle prior parts, but it should be possible to
add the capability to new parts.

Key-locked inserts are the main factor for me, but the 'We can't machine
it, make it a weldment" is another participant.

Another approach would be to create an interchange assembly. It should
help a little.

Dave S.

Glenn Beer wrote:
> Kevin - Yes, and No.
>
> Yes - For the reasons given it makes sense.
>
> No - It's a bit like worrying about being hit by every car in America,
> while walking across the street.
>
> I call these kind of assemblies, Alligators. Most of them sit around
> doing nothing but eat.
>
> These alligators load your session unnecessarily. It costs more in
> terms of compute resources. Models will take up more virtual memory.
> They will take more time to load, as they consume additional cpu
> cycles. You will spend more time query selecting deeper into the
> assembly. Your model tree will be that much longer. Same goes for the
> layer tree.
>
> *In the end it's futile*, because you will start with one part in an
> assembly, discover that several more are needed, then end up in the
> same boat when one of those parts needs to be replaced by a subassembly.
>
> *It never ends, **and you are the one who has to spend extra time
> dealing with it. **Long term it's just too expensive.*
>
> All anyone can do is the best they can, based on the knowledge
> available. Then deal with the problems as they arise.
>
> Glenn
>
> On Fri, Mar 13, 2009 at 11:55 AM, Kevin Veeser <kveeser@hatcocorp.com <br="/>> <>">mailto:kveeser@hatcocorp.com>> wrote:
>
> Dear ProE users,
>
> Here is my situation.....
>
> When a single part is used in a top level assembly and a weld
> stud or weld nut is added to the part a new sub-assembly is
> required. A new assembly is created with the part and weld stud or
> weld nut. Then the new assembly has to be replaced with the single
> part at the top level which is actually the same part but with an
> added component. This may be in many places and takes a while to
> replace all the constraints to each assembly it is used. We are
> considering taking all of our single parts and adding them to an
> assembly even though there may not be an additional component
> added to it at that time. This would allow us to add or subtract
> parts without having to swap out a part for an assembly or the
> other way around because they would always be at the assembly level.
>
> Does this make sense?
>
> Is there another way to approach this?
>
> any suggestions on this subject would be appriciated.
>
> Thanks,
>
> Kevin
>
>
>

ptc-356958 · ‎Mar 14, 2009

We handle all of our sheetmetal parts as assemblies for a different reason, though. I'm not as concerned in the assembly as I am with the final drawing, of the part. Changing a drawing to take out the part and insert an assembly means redoing the drawing.It's a bigger PITA for us to do that. Also, fundementally, we handle all of our sheetmetal "assemblies" as parts. In other words, regardless of how they go into the Sheet Metal Department, they're coming out as a single part, all welded together. So the few parts we do have that may be single pieces, you could make the argument, as Glenn Does, that an assembly isn't necessary. We have gotten bitten too many times in the past however requiring the addition of a weld nut or stud and the detail drawing is scrap (for the most part). We don't really see the loading as Glenn points out, although he does make a valid point.

gkbeer · ‎Mar 14, 2009

I don't believe I was saying "Never create an assembly with only one part."

Only that it should not be "Always." for the reasons given. (I'm often
called on to work on jobs with massive product structures. I'm pretty
sensitive to modeling practices that slow down a computer.)

When my experience tells me that a given component has a high risk of
turning into an assembly, I'll do that, but I won't turn that into a
"general" work rule.

I'm sure there are job sites, where the nature of the work, makes the
likelihood of a component needing to become an assembly, quite high.

So getting back to the original question...

Is it a good idea to always wrap part models inside of assembly models, to
guard against the need to add a part?

Maybe my answer should have been, "It depends the kind of work you do."

Glenn

wfalco · ‎Mar 14, 2009

I do not understand why a buffer assembly, which is light in weight, under a
PDM umbrella is a problem. It is like leaving a blank between items on a
manual BOM back in the board days. The benefits far surpass the inclination
not to.

gkbeer · ‎Mar 16, 2009

On Sat, Mar 14, 2009 at 8:46 PM, cs2kplus <-> wrote:

> I do not understand why a buffer assembly, which is light in weight,
> under a PDM umbrella is a problem. It is like leaving a blank between items
> on a manual BOM back in the board days. The benefits far surpass the
> inclination not to.
>

"Light in weight" -- That is the heart of the difference of opinion.
Neither side of the difference is wrong or right. Both have their merits.

For me, in the project I've been working the last couple years, Checking out
the top level assembly yields in excess of 2500 unique items. The total part
count is far larger. I'm not about to nearly double that count by requiring
every part be wrapped in an assembly.

Think about it, a couple thousand extra assemblies in the product structure.
If each has 3 default datums, that is an additional 6000 datums that must be
retrieved, regenerated, loaded into the graphics card...

Try it, take a part, create 3 default datums, then pattern one of them 6000
times. Save it, erase it, retrieve it, modify the spacing, regenerate it
again, spin it. Try to select all of them and put them on a layer. Then ask
if I have cause to be worried about that kind of overhead.

For the work I do, it's a problem. Even requiring something simple, like a
default coordinate system in every model, can add noticeable time when
dealing with the top assembly. The person detailing individual part models
will never see it as a problem. The guy that has to deal with the full
assembly, he gets hammered.

The most scary words I ever hear are "Let's add that to the start part."

I'll repeat though, thats the work I have to deal with, Others and those
they work with, may never deal with assemblies so large that it makes a
difference. Lucky them.

So again, the answer should really be, "It depends the kind of work you
do."

Glenn

PS, Ask me sometime why I don't like family table driven fasteners.

FrankMenendez · ‎Mar 16, 2009

We come across this often. However, in a top-down design world using external copy geoms and csys', restructuring is much less of an issue. We have more of an issue with correcting the associations to the WTParts since the new "describing" CAD doc is an assembly. With CAD Doc templates, we can even start off the assembly at the correct revision.