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TOP-DOWN HUGE ASSEMBLY MODELING - COULD I USE LAYOUT SKETCH MOSTLY?

Question asked by Rohana Wickrama Archchi on Jul 11, 2020
Latest reply on Jul 13, 2020 by Matt Peneguy

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I am comfortable with creating Tp-Down assemblies (big or small) using a master sketch. But, down the road, I found the parts created from the master sketch carry all the sketches in the master sketch. That led me to manually hide (and make visible) out from a bunch of (so many) sketched, planes, etc. It is doable (kind of easy).

However, I believe building up on the layout in the assembly (which is a top-level master assembly (TLMA), but not necessarily the final assembly: I mean, the final erection assembly can to be created with the help of this TLMA) is better where all the components now have only the few (some times just a one compared to so many using a master sketch) required sketches of features.

It looks like good and also not good. As I am new in Solidworks, I would like to get some feed back from the good users of Solidworks. I want to make sure that anybody down the road could be able edit the model. Please reply.

I attached my model up to now.

Using CREATE LAYOUT

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Layout Design.zip1.3 MB

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Matt Peneguy Jul 11, 2020 4:06 PM

I don't have SW 2020 at home. But, I don't know anyone who uses that Layout functionality. If you are to use it I would only use it for small assemblies.

For Top Down modeling the only robust method that I've found that works for large assemblies is the Skeleton Sketch Method. The basic idea is that you insert a SSP (Skeleton Sketch Part) at the top of the feature tree for every assembly. Parts and subassemblies within the assembly are driven from the SSP. All of the subassemblies within the assembly have their own unique SSPs in them that are driven by the top level SSP. Inside those subassemblies and parts or subsubassemblies are driven by the subassembly SSP...And this can go as many levels down as required, but one huge rule is that the references are always pushed down and only 1 level to avoid circular references. So NEVER have a relation from a subassembly SSP to the assembly SSP. That's the gist of it. You can find all kinds of information about the SSP method by searching this forum for "SSP". If you are specifically concerned with large assemblies read through Skeleton Sketch Part Method for Large Assemblies.

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Rohana Wickrama Archchi @ Matt Peneguy on Jul 11, 2020 5:05 PM

Thanks Peneguy. I agree with you: the layout functionality is kind of not used despite it pops up at creation of a new assembly. I have already done a model using a master sketch (MS) which is similar or the same to SSP. It is fine.

I am a little bit concerned about each and every part created out from the MS carries forward all the planes and sketches - FIGURE-5. But, the final assembly is fine. It opens fast enough.

Most of my friend use bottom-up. I rather like the Top-Down for big assemblies: I think, SSP is the generic methodology.

The link you provided is great: I will go through.

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John Stoltzfus @ Rohana Wickrama Archchi on Jul 13, 2020 8:38 AM

Rohana Wickrama Archchi - What you show is different than what we do with the SSP. The part files should have very little information in them, needing only the primary planes and the sketches required for the Extrude or Surface features for that part only. It appears that you are using a part into a part method and that isn't how the SSP should work.

Look at the SSP as being a process to organize what happens in the Main and all Sub-Assemblies. For me the SSP process is mostly used to create a parametric model for ease of change and error diagnostics. The SSP can also be a big help in organizing the feature tree, by adding related sketches and planes into folder. If you need to add a sketch to the SSP, do yourself a big favor, roll back the feature tree and place your info in the right place, don't just keep adding it to the bottom.

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Rohana Wickrama Archchi @ John Stoltzfus on Jul 13, 2020 3:28 PM

Thanks John for the reply.

Your comments was very helpful.

Also thanks to Matt Peneguy.

To understand SSP, I worked on the model as per the pdf document (Skeleton Sketch Part Method.pdf) found in the link: https://forum.solidworks.com/thread/204898#comments

It is very good.

I will keep using SSP as well.

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Matt Peneguy @ Rohana Wickrama Archchi on Jul 13, 2020 3:36 PM

Rohana Wickrama Archchi wrote:

Thanks John for the reply.
Your comments was very helpful.
Also thanks to Matt Peneguy.
To understand SSP, I worked on the model as per the pdf document (Skeleton Sketch Part Method.pdf) found in the link: https://forum.solidworks.com/thread/204898#comments
It is very good.
I will keep using SSP as well.

Glad that pdf helped.

Two things that I've changed since I created that pdf are that I try to use planes instead of sketches if possible and I have started to prefix the part/asm name with a number to indicate what "level" the part is at. Sometimes parts lose their external references when I use sketch entities. Planes seem to be more stable.

The levels work like this:

0.SSP

1.Asm SSP

1.Asm

1.Part

Then inside of 1.Asm:

1.Asm SSP

2.Asm SSP

2.Asm

2.Part

Then inside 2.Asm

2.Asm SSP

3.Asm SSP

3.Asm

3.Part

And so on.

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5 Replies

Matt Peneguy Jul 11, 2020 4:06 PM
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Correct Answer
I don't have SW 2020 at home. But, I don't know anyone who uses that Layout functionality. If you are to use it I would only use it for small assemblies.
For Top Down modeling the only robust method that I've found that works for large assemblies is the Skeleton Sketch Method. The basic idea is that you insert a SSP (Skeleton Sketch Part) at the top of the feature tree for every assembly. Parts and subassemblies within the assembly are driven from the SSP. All of the subassemblies within the assembly have their own unique SSPs in them that are driven by the top level SSP. Inside those subassemblies and parts or subsubassemblies are driven by the subassembly SSP...And this can go as many levels down as required, but one huge rule is that the references are always pushed down and only 1 level to avoid circular references. So NEVER have a relation from a subassembly SSP to the assembly SSP. That's the gist of it. You can find all kinds of information about the SSP method by searching this forum for "SSP". If you are specifically concerned with large assemblies read through Skeleton Sketch Part Method for Large Assemblies.
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- Rohana Wickrama Archchi @ Matt Peneguy on Jul 11, 2020 5:05 PM
  Mark Correct
  Correct Answer
  Thanks Peneguy. I agree with you: the layout functionality is kind of not used despite it pops up at creation of a new assembly. I have already done a model using a master sketch (MS) which is similar or the same to SSP. It is fine.
  I am a little bit concerned about each and every part created out from the MS carries forward all the planes and sketches - FIGURE-5. But, the final assembly is fine. It opens fast enough.
  Most of my friend use bottom-up. I rather like the Top-Down for big assemblies: I think, SSP is the generic methodology.
  The link you provided is great: I will go through.
  Like • Show 1 Like1
  Actions
  - John Stoltzfus @ Rohana Wickrama Archchi on Jul 13, 2020 8:38 AM
    Mark Correct
    Correct Answer
    Rohana Wickrama Archchi - What you show is different than what we do with the SSP. The part files should have very little information in them, needing only the primary planes and the sketches required for the Extrude or Surface features for that part only. It appears that you are using a part into a part method and that isn't how the SSP should work.
    
    Look at the SSP as being a process to organize what happens in the Main and all Sub-Assemblies. For me the SSP process is mostly used to create a parametric model for ease of change and error diagnostics. The SSP can also be a big help in organizing the feature tree, by adding related sketches and planes into folder. If you need to add a sketch to the SSP, do yourself a big favor, roll back the feature tree and place your info in the right place, don't just keep adding it to the bottom.
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    - Rohana Wickrama Archchi @ John Stoltzfus on Jul 13, 2020 3:28 PM
      Mark Correct
      Correct Answer
      Thanks John for the reply.
      Your comments was very helpful.
      Also thanks to Matt Peneguy.
      To understand SSP, I worked on the model as per the pdf document (Skeleton Sketch Part Method.pdf) found in the link: https://forum.solidworks.com/thread/204898#comments
      It is very good.
      I will keep using SSP as well.
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      - Matt Peneguy @ Rohana Wickrama Archchi on Jul 13, 2020 3:36 PM
        Mark Correct
        Correct Answer
        Rohana Wickrama Archchi wrote:
        
        Thanks John for the reply.
        Your comments was very helpful.
        Also thanks to Matt Peneguy.
        To understand SSP, I worked on the model as per the pdf document (Skeleton Sketch Part Method.pdf) found in the link: https://forum.solidworks.com/thread/204898#comments
        It is very good.
        I will keep using SSP as well.
        Glad that pdf helped.
        Two things that I've changed since I created that pdf are that I try to use planes instead of sketches if possible and I have started to prefix the part/asm name with a number to indicate what "level" the part is at. Sometimes parts lose their external references when I use sketch entities. Planes seem to be more stable.
        The levels work like this:
        0.SSP
        1.Asm SSP
        1.Asm
        1.Part
        
        Then inside of 1.Asm:
        1.Asm SSP
        2.Asm SSP
        2.Asm
        2.Part
        
        Then inside 2.Asm
        2.Asm SSP
        3.Asm SSP
        3.Asm
        3.Part
        
        And so on.
        Like • Show 2 Likes2
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TOP-DOWN HUGE ASSEMBLY MODELING - COULD I USE LAYOUT SKETCH MOSTLY?

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