Exporting all parts in assembly as SLDPRT?

tony_459

I need to export the parts of an assembly, and while I prefer STEP, STL, or Parasolid, the files are very large in these formats. I'm working to defeature my parts but I don't know that I can shrink these files enough without sacrificing valuable geometry features.

I noticed that in Part Studios you can export SLDPRT files and that these can be far smaller than other formats. A 4.1 MB STEP file became a 1.2 MB SLDPRT file.

Trouble is... there is no option to export all the parts in SLDPRT files from an assembly tab. I could go to all my part studios and select the parts I want to export and export them as SLDPRT... but I would have to comb through my part studios to find just the right parts, and I would have to do so in many documents because the assembly is so large that I decided early on to split the model into documents which I placed in a folder. I think I have about ten documents.

So I'm wondering---is there an easy way to export the parts of an assembly in SLDPRT files (one file per part, in a ZIP archive is fine)? If not, any chance we might see this in the future? Small files are essential if I want to simulate large assemblies without excessive defeaturing, and SLDPRT seems to be the better format on this front.

Thanks! 

tony_459

Follow-up question is anyone knows: what makes SLDPRT such an efficient format that it can store geometries at 25% of a STEP file? When you load the SLDPRT file in some app for 3D visualization, will there be extra computations necessary to display the part? In other words, is there a cost to the small SLDPRT file size? 

NeilCooke

A SLDPRT file from Onshape is just an old version of Parasolid in a SolidWorks wrapper so exporting as Parasolid will be the same. 

MBartlett21

@NeilCooke
Is there any way we can export an Onshape assembly as a SLDPRT (like how SolidWorks can save an assembly as a part)

Additionally, can we export Onshape assemblies as a SLDASM in a zip folder?

NeilCooke

@MBartlett21 no, the only way would be to do some in-context workaround (copy all bodies). However, if I remember correctly, when SolidWorks encounters an assembly import, it gives you the option to input as a part?

A Parasolid assembly file is just as good as a SLDASM file so there would be no benefit I believe. 

tony_459

Thanks, Neil, but I see a huge difference between SLDPRT and X_T. Maybe you meant that the binary Parasolid format (X_B, which doesn't seem to be an option for export) should be the same size as SLDPRT?

An example: a 9.5 MB STEP file becomes a 7.2 MB X_T file but a 2.8 MB SLDPRT file. The file is of a tire with a tread and to defeature enough for export as STEP or X_T is to reduce it to a sad version of its original self.

Another example: A 20.6 MB STEP file becomes a 12 MB _T file but a 6 MB SLDPRT file. The file is of a car grill with a honeycomb pattern and to defeature it enough for export without SLDPRT is to lose the thing that makes it distinctive. I'd get a functional but visually unappealing part.

I see similar drops in other parts. 

Sadly, I need my files to be small, and neither STEP nor X_B are good enough for my geometries. SLDPRT is the only format that seems to work and it would be fantastic if we could more easily export the parts of an assembly in this format!

NeilCooke

@tony_soares459 why is file size an issue? Can you zip the x_t file? I’ll take a look tomorrow to see if I can find a better solution for you. 

tony_459

Hi Neil!

I need to simulate my assemblies in a multibody environment (external to Onshape) and I'd like to share those models  

The assemblies are slow to load (in my multibody environment) if the part geometries are very large... so I need them small. I run into issues if the part geometries add up to more than 10 MB total. I can maybe live with 20 MB.

My latest model (of a Bobcat 3650 UTV) started at 135 MB (STEP), which gave me pause! Aggressive defeaturing slashed the size to 75 MB (STEP) and I *think* I can bring this down to the 20ish mark---though the model will be less visually appealing. SLDPRT would allow me to keep more key features like tread and honeycomb patterns---though it's possible that even with SLDPRT I might have to defeature all that I can to get in the 20 MB size mark.

Also, to share the models I need the total file package to be modest if not small in size. Compressing is an excellent option, but I worry about the real estate taken by the file archive once it's decompressed. Having lived on a Macbook Pro with 125 GB which strangely never seemed to have more than 5 GB worth of free space, I know how discouraging it can be to realize you've run out of space and have to decide which of your large files to delete and which to keep. 

So that's that! Thanks again for all your input!

tony_459

But having to be frugal with file size can be a good thing. I'm learning which features bloat files the most, and that's great info to have. Fillets I already knew I should use scarcely, but take the honeycomb pattern in my grille---a 20-by-10 grid of hexagons adds up to 2.7 MB (STEP) but a 20-by-10 grid of circles is only 0.4 MB! So now I know how to approximate that honeycomb without having to hide altogether

Now I need only find a similar hack for the tire tread. I replaced a tight pattern with lateral grooves with a small number of lugs which look... not good... If I'm lucky, then 4-5 longitudinal grooves will be enough for a decent tread look (because a few cylinders on the tire periphery beats the 120 polygons in my original tread pattern and the 20 polygons in my uglier version).

philip_thomas

@tony_soares459 - I want to help you, but I am scratching my head in perplexion.
Addressing your issues in no particular order.

• If your Part Studios are taking a long time to open, we usually find that the common mistake is modelling too many parts in a single Part Studio. The fastest number of parts is one - a Part Studio should only be used to model one part unless a second is geometrically related. There are many reasons for this (all covered in training).
• 'Sharing' your data as you describe should be independent of 'file size' - sharing a Document sends nothing other than an email to the recipient.
• If you need to export data, Onshape supports multiple formats and I have tested Parasolid vs SLDPRT. I note that SLDPRT is approx 35% smaller. I find this 'interesting' rather than 'significant'. This difference should not impact your workflow unless it is a limitation imposed by your analysis tool.
• There is no benefit inside Onshape to defeaturing geometry - all that happens is that the facetized resolution goes up.
• Saving an entire assembly as parasolid/sldprt - I would probably go with an in-context Part Studio just as Neil said.
• As I read your post, I keep getting hung up on your 'file size' problem. This is one of the problems we set out to fix when developing Onshape - in fact, our solution was simple, there are no files. Many of our analysis partners are 'connected cloud' solutions that analyze the Onshape geometry natively - meaning no data is exported and therefore 'file size' is irrelevant. Have you tried Simscale or Simsolid? (appstore)

We really want to help you, but we do not control exported file size as the format is governed by the format specification and the complexity of geometry going into it. If you are experiencing anomalous results, please share a Document with support so that we can look at what you're doing. There is no reason for you to store any Onshape data on your laptop (thats a significant security advantage to our customers) and so available HDD space becomes irrelevant as Onshape takes exactly 0MB of disk space.
I am curious, what standalone analysis tool can only take 20MB files as that is an absolutely tiny dataset?

Happy to help

chrisjh777

This is an interesting discussion.  I am sure that exporting Solidworks format used to be available, because I used to use Onshape as a filter to get around the stupid "Future Version" issue with Solidworks files.  

Whenever someone sent me a Solidworks file generated in a SW version more recently than 2015, I would download the file to Onshape and re-export in SW format so my copy of SW 2015 could open it.

At some time, Onshape's ability to export  SW format has been withdrawn.

NeilCooke

@chrisjh777 it's still there, but for parts only