Assembly from 3D Parts

[jlucasemail]

What is the best practice for assembling a 3D diagram from components using AutoCad 2016?

I'm drawing a model steam engine with maybe a 50 or so parts and would like to print/view individual parts (for machining) and also the completed model to check fit and appearance.

Should I create a separate drawing for each individual part, save each as a block and then assemble the blocks into a composite drawing?  I tried this on a simple sample and find that changes in the component drawings (even if cosmetic and not changing the "fit") are not reflected in the complete drawing!

Might it be better to to create each component in a separate layer of one drawing?  Seems this would allow changes to show in the final but I will have quite a few layers!

I'll probably need to have some sub-assemblies (frame, cylinder etc.) to make this manageable.

I have not done anything this complex before and would appreciate advice on the best approach.

Thanks

[Patchy · Accepted solution]

50 parts, use 50 drawings

Use XREF and keep the size of the drawing down.

[jlucasemail]

Thanks, exactly what I needed.

[LyleHardin]

I agree with the Xref solution. It may get a bit hairy if part sizes change, but beyond using Inventor there's not much you can do about it.

Also, you can place each Xref on it's own layer so when you freeze those layers, the entire Xref disappears. This is handy for viewing your assembly in viewports where you can freeze viewport layers and even change viewport layer colors (assuming the entities in the Xref are on layer 0) without affecting the whole drawing.

If you haven't already, I highly recommend looking into the Layout Tools (look at your ribbon when you're in a layout tab) and using the Base view, then projected views, etc. I'm not sure how they'll work with Xrefs, but its a great way to show 2D views and sections of your completed model as well as shaded or hidden line 3D views. 

[Anonymous]

Color me weird but when I design a machine with a number of components I create each part on its own layer. Mostly because when creating each part there is a specific spatial relationship to all the other components.

Edit, I should add that these are 3D solid objects. From the assembly model I can save out each part (or sub-assemblies) as needed to genrate machining drawings or for model part re-use.

[jlucasemail]

I've tried both methods.  Took a while as I had to learn about layouts, paper space etc!

Using layers is easier to make certain each new piece fits properly.  Trouble is each part requires a layer for the diagram, a layer for dimensions and a layout so it can be printed with border, scaling etc.  Seems to me this will be quite unmanageable with 50 or so parts.

Using xref allows each part to be in it's own file with layout, dimension layer, scaling etc.  Same template can be used for each part, just customising print scale and diagram label.

To overcome the problem with fit I'm going ahead with the xref approach but for each new part drawing an outline in a temporary layer in the assembly diagram.  Then exporting the outline to its own file to be completed. and imported back with xref.

Am I missing anything here?  Thanks.

[LyleHardin]

For your 'outline' (if I understand correctly) use the command FLATSHOT to create a 2D view of your 3D part.
For dimensions, be aware of ANNOTATIVE dimensions and you won't have to use different layers for dimensions on different scales. (Again, if that's what you mean).
I still highly recommend using the Layout features for base views and projected views for your dimensioning and final 3D drawings.

[dgorsman]

You can separate your 2D drawings and 3D models.  This is also beneficial since it allows for detailing several parts per drawing (I use the terms "model" and drawing as different concepts here).  Keep the 3D in 3D, and drawings as drawings.  It also allows you to create one to several base drawing files that can be copied to create consistency.

Create a new DWG file with title block, dimensioning, etc. in the layout and XREF the required parts into model space.  Create viewports with required/desired scales in the layout.  Dimension and annotate as you need in the layout.  This way you don't have annotations and dimensions clogging up models (requiring freezing layers) and don't need unique layers for every single part.

[jlucasemail]

ANNOTIVE dimensions.  New to me.  Tried and looks great.  Thanks.

"...and XREF the required parts into model space.."  Don't understand.  I can create a 2D diagram with several parts.  I can put a viewport around each. However, I can only xref the diagram, not one of the parts on the diagram.  Also, I get the complete diagram including dimensions.  I'm missing something here!

Phew, this is a struggle.  I have lots of experience with software and even a certificate in engineering drawing - back when we used pencils and a proper drafting board. So, thanks for the help.