Creating a Parts Studio from 8020 Extrusion components

edward_petrillo

I've modeled dozens of structures incorporating 8020 T-slot extrusion using SolidWorks.  The extrusion profiles are readily available for download.  My standard workflow involves 1) creating a unique part of of each required length, or creating multiple configurations of a single part with different extruded lengths; 2) building up a fully defined assembly using mates and array patterns as appropriate.  The model is optimized by either editing parts in context within the assembly or toggling back and forth between parts and assembly. 
The example shown here, uploaded from SW, is typical; https://cad.onshape.com/documents/39ea805230aa4d98ab704507/w/53343bb054004fef981aad71/e/0754ef2f708a4dfab5afb945

I've mastered the techniques of multi-part modeling in Onshape Parts Studios, but I have been unable to develop an effective workflow for building a structure like the example from scratch in a Parts Studio.  I've tried two approaches:  1) pasting the extrusion profiles into sketches, extruding parts, and building up the model by patterning and trasforming; 2) populating a workspace with individual components and incorporating them as derived parts into a Parts Studio.  Several hours of determined effort have yielded generally unsatisfactory results, including watching the "working" icon spin endlessly while copying and pasting sketches, and finding that documents containing only a few components have ballooned to hundreds of megabytes in size as repeated attempts to place parts correctly accumulate (a real problem while on the free plan). The studios I've created and discarded contain parts that can't be manipulated parametrically or misalignment errors that are difficult to spot and fix. 

The individual frustrations I've encountered are too numerous to list, but they all seem to flow from incorporating something from outside the parts studio rather than creating it within by sketching.  Placing sketches or derived parts precisely where you need them is severely limited.  Can anyone suggest a workable approach using the current Onshape toolset?  Are there new capabilities on the horizon that would help?

_Ðave_

With the current tools I would simply create the different extrusion lengths from the sketch and then insert the needed parts into an assembly to mate into position. I wouldn't position the parts in the part studio. See link for basic sample.

edward_petrillo

Right now I'm building extrusion frames in SW and importing them as static objects into Onshape, where I can use multi-part modeling to create the rest of the model.  The process bogs down when the frame needs to be edited.  I've been sold on the advantages of multi-part modeling in parts studios, so it's a real drag when it falls short.

Building an assembly from extrusion parts in Onshape is less convenient than going back to SolidWorks, where I can edit parts in context and use configurations.  See the advice in this thread:  https://forum.onshape.com/discussion/1797/constrain-and-edge-in-a-plane-in-assembly#latest

Mates in Onshape are really optimised for controlling relative motion. The process is unnecessarily laborious if you are trying to capture static relations: these are generally better dealt with in a part studio wherever possible.  I agree!

The extrusion shapes do not present mate connectors that will properly align the parts in all situations, so mate connectors have to be added with lots of input that is less convenient than using the SW mating tools. 

andrew_troup

edward_petrillo said:

... Placing sketches or derived parts precisely where you need them is severely limited.  .....  
Are there new capabilities on the horizon that would help?

We are led to believe this is so.

You can help by voting on these improvement requests

https://onshape.zendesk.com/hc/en-us/community/posts/205369568-Group-constraint-for-sketches

https://onshape.zendesk.com/hc/en-us/community/posts/205328777-Add-Precision-Copy-Move-Rotate-to-Sketches

Voting is cryptic: click on the unlabelled up-arrow at the left and check that the counter increases.
To check if you have already voted at some future date, vote again and see if the counter increases or decreases, if it decreased, click it again....

Following an IR does not seem to forward messages when the topic gets discussed, but you can use it as alternative way of flagging for yourself that you already voted.


Also,  you might also care to raise an IR for positioning of derived sketches.

It has been discussed repeatedly on the forum, and Onshape have indicated they hear our concerns, but it seems an IR has not yet been submitted

(or if it was, it got deleted when "Derived sketch" was implemented - it pays to submit every suggestion separately, rather than bundling related suggestions which may not be implemented simultaneously).

philip_thomas

FWIW - I have been experimenting with 80/20 workflows. I am not saying that mine is perfect and certainly we will be having a number of meetings to define functionality that will help. If anyone feels that they have a document that shows a good workflow, please feel free to post it here.

https://cad.onshape.com/documents/c580e27423694410bef202da/w/91d3e298c1b342b2b8b73303/e/c47150fe6a50496fa93aa026