Who else is using mostly/only "bottom up" modeling methods?

[Lapuo]

I am using bottom up , same procedure with mates in assembly.
For weldments i like to use multibody.
Sometimes i use multibody and save bodies external (this method always worked for me without any issues)

[jcapriotti]

Sometimes with all the chatter about the various top-down modeling methods and very little about plain old bottom-up modeling I wonder who else does no or very little top-down modeling.

Trying to be specific I’ll add a little list off the top of my head; I don’t know that every one of the lines below are really top-down vs bottom-up type things, but they tend to get drawn in sometimes.

• Piece parts in part files, weldments and assemblies in assembly files.
• Multibody modeling only used for ref geometry or tool bodies; one part number per file.
• No Master Models
• No Skeleton Sketch Parts
• No parts referencing other parts through a parent assembly.
  edit: - Primary mating method is part geometry to part geometry (on rare occasion ref geometry if face ids likely to be change such as imported customer/vendor model); Mating origin to origin or coordinate systems is not used.

Who else models in this way in day-to-day practice?

Thank you.

We operate exactly like this. Top-Down would only be used for really early conceptual designs, typically before part numbers are assigned.

[HerrTick]

“Bottom-up” doesn’t get a lot of discussion because there really isn’t much to discuss.

You build, you assemble, maybe assemble some more. No context. No continuity. Easy-cheezy.

[bnemec]

“Bottom-up” doesn’t get a lot of discussion because there really isn’t much to discuss.

You build, you assemble, maybe assemble some more. No context. No continuity. Easy-cheezy.

Agreed, mostly. I could have asked in a bunch of different ways, but each thing I tried became too wordy, so I tried to just keep the question short and open ended.

There’s a bit more to it that what you stated though. I was reading into the extras that people offered about why they stick with bottom up when they do so. Where simple bottom up becomes not so easy is when the entire data set is best described as the “Standard Parts Library.” Maybe 2% of our hardware part numbers are OTS, the rest are special and have been or may be revised. I’m trying to get a feel for how other places with similar situations use the software.

[nordstjernen740]

Our production assemblies are exclusively bottom up and I can’t imagine it any other way for us. We highly encourage part reuse so that bottom up is pretty much a necessity.
Top down can be used as a design tool, but we can’t allow it into the production assemblies due to globally allowing and encouraging part reuse regardless of context.
We make lots of “similar”, but custom machines, so there is a lot of value to be gained by sharing parts and not locking them down to a single context.
Also, we like to reduce bottle necks by encouraging “partial” releases. Managing full top down assembly trees in the context of frequent partial releases without full approval and review is a recipe for mistakes.
You can get some top down “like” tools by building reference geometry parts and assemblies. We have a universal “planes drawing” for machine lines, These are used as mating surfaces in assemblies and a tool for references and/or making temporary “in context” references to when designing. The temporary references are to be removed and fully defined with as much design intent as is practical in a single part context prior to production release.

[bnemec]

Our production assemblies are exclusively bottom up and I can’t imagine it any other way for us. We highly encourage part reuse so that bottom up is pretty much a necessity.
Top down can be used as a design tool, but we can’t allow it into the production assemblies due to globally allowing and encouraging part reuse regardless of context.
We make lots of “similar”, but custom machines, so there is a lot of value to be gained by sharing parts and not locking them down to a single context.
Also, we like to reduce bottle necks by encouraging “partial” releases. Managing full top down assembly trees in the context of frequent partial releases without full approval and review is a recipe for mistakes.
You can get some top down “like” tools by building reference geometry parts and assemblies. We have a universal “planes drawing” for machine lines, These are used as mating surfaces in assemblies and a tool for references and/or making temporary “in context” references to when designing. The temporary references are to be removed and fully defined with as much design intent as is practical in a single part context prior to production release.

nordstjernen740 are you using PDM Pro? If so how do you handle partial releases and versions?

[nordstjernen740]

We utilize pdm pro and manage. The “calculated” engineering bom in Manage is the master from which releases are cut.
Solidworks portions of the Manage bom are always “live” to the latest version of the solidworks assembly (with optional visibility to “as-built” or previous versions)

We postprocess excel exports from the bom in Manage to “help” engineers select their full or partial releases which ultimately get sent to sap and prod ctrl.
Some of this relies on the engineer to manage their release strategy with notes and common sense, but we have built tools like “release from bom compare” to help them out and for the most part engineers are able to do so.
We are also working on closing the loop fully by storing release context data in the bom database in some way, but we aren’t quite there yet, but have a couple of feasible roadmaps to do so. Release data is project context specific data for each release line item in a bom so it is difficult to store in a standard “live” bom (portions of which may be may be shared in other projects) without the use of so-called “items” or context specific bom fields. Manage has “ref specific fields”, but they have some limitations that we are working on to get us there.

Our system is highly dependent on enforcing a “backfit rule”. If the part doesn’t backfit it gets a new number and/or you cut releases for the machines in the field to make the new version work. no exceptions. Any revisions requires that the engineers gives information in the part card on what to do with unissued inventory to bring it to the current rev.
Because of this, the “where used tree” is important for our engineers.

A similar system could definitely be implemented with just pdm or anything that gives you live access to the computed solidworks bom, but Manage just has some better bom management and visibility tools especially when it comes to non-solidworks data.