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How do we create accurate sketches from API or imports or?

kiwileekiwilee Member Posts: 8
Hi Guys,

Sorry if this question is really obvious. I am just getting started with OnShape.
I usually work with SolidEdge ST7 in 100% Synchronous mode (I see no need for Parametric for any of my work... unless the software forces me to).

I'm trying to bring accurate Airfoil profiles into a sketch so I can then loft them along a rail or 3d sketch.
I can add a svg to my project but can't for the life of me get it into the sketch.
Obviously a very basic requirement.
So how do I do it.

Any complex 2D drawing will usually be generated outside of the software then brought in.
For Gears I can do this linked within Solidedge and the gears and relationships are live 3D parts.

So how do you guys bring in a 2D file for use in a sketch?



Best Answers

  • philip_thomasphilip_thomas Member, Moderator, Onshape Employees, Developers Posts: 1,381
    Answer ✓
    Whenever airfoils come up - I feel compelled to write something :)
    Here at Onshape, there are two people with advanced degrees in Aeronautical Engineering - I am one of them.
    All the questions listed in this thread come up form time to time and whilst I am not making policy statements here, I can give some insight into why we have done what we have and probably more pertinently, why we haven't.

    STL import comes up from time to time. We do not currently support STL for the following reasons;
    1) Onshape is designed primarily to meet the needs of the mechanical design community and for the most part (in terms of geometry creation at least), we are very close. STL import does not form part of this basic workflow. There are many good content aggregation sites that offer standard parts in any number of b-rep formats and sidestep needing to work with the messyness that is STL.
    2) If we imported STL, the next 'n' requests would be for tools to fix bad files and then manipulate them (stretch, twist, blend). This is about as productive as trying to rake leaves on a windy day. There are specialty tools that cater to those with these specific needs and I am happy to point people to them.

    That is not to say that we are not listening to the wants of our users. Once we understand specific needs and workflows, we can certainly look at functionality that might help specific-needs groups.

    Importing images - an awesome tool (just not for turbine blades or airfoil sections). This is another common request and has a certain amount of utility. I cannot commit to a timeframe, but it is very likely that Onshape will support this at some point. This capability has some very cool use cases; as a background for renderings or reviews to give your design some context or as the basis of a design starting with a concept sketch. Aerodynamic sections however, are far too precise to rely on 'tracing by eye'. Better workflows involve reading in the output of an analytical source (program, excel table etc) as either x,y,z data or a 2d curve (dxf,dwg) - both of which we will be supporting, and then extruding or lofting. Another route would be through the api enabling existing spline points to be modified. This opens up the possibility of a direct link between an Onshape document and a data source to say, evaluate the performance of two different aerodynamic planforms without having to manually modify the CAD model. 

    As you can see, we are thinking about these (and all) issues. Please keep your comments and suggestions coming so that we can understand exactly what you're trying to do and prioritize time and development resources. :)
    Philip Thomas - Onshape

Answers

  • kiwileekiwilee Member Posts: 8
    edited April 2015
    Thanks guys, trust me to try do something first off that hasn't been implemented yet.
    James_McPherson11762, I'll try your work around. Thanks for the tip.
  • kiwileekiwilee Member Posts: 8
    So you can use .stl files either. This seems odd. 
  • philip_thomasphilip_thomas Member, Moderator, Onshape Employees, Developers Posts: 1,381
    Answer ✓
    Whenever airfoils come up - I feel compelled to write something :)
    Here at Onshape, there are two people with advanced degrees in Aeronautical Engineering - I am one of them.
    All the questions listed in this thread come up form time to time and whilst I am not making policy statements here, I can give some insight into why we have done what we have and probably more pertinently, why we haven't.

    STL import comes up from time to time. We do not currently support STL for the following reasons;
    1) Onshape is designed primarily to meet the needs of the mechanical design community and for the most part (in terms of geometry creation at least), we are very close. STL import does not form part of this basic workflow. There are many good content aggregation sites that offer standard parts in any number of b-rep formats and sidestep needing to work with the messyness that is STL.
    2) If we imported STL, the next 'n' requests would be for tools to fix bad files and then manipulate them (stretch, twist, blend). This is about as productive as trying to rake leaves on a windy day. There are specialty tools that cater to those with these specific needs and I am happy to point people to them.

    That is not to say that we are not listening to the wants of our users. Once we understand specific needs and workflows, we can certainly look at functionality that might help specific-needs groups.

    Importing images - an awesome tool (just not for turbine blades or airfoil sections). This is another common request and has a certain amount of utility. I cannot commit to a timeframe, but it is very likely that Onshape will support this at some point. This capability has some very cool use cases; as a background for renderings or reviews to give your design some context or as the basis of a design starting with a concept sketch. Aerodynamic sections however, are far too precise to rely on 'tracing by eye'. Better workflows involve reading in the output of an analytical source (program, excel table etc) as either x,y,z data or a 2d curve (dxf,dwg) - both of which we will be supporting, and then extruding or lofting. Another route would be through the api enabling existing spline points to be modified. This opens up the possibility of a direct link between an Onshape document and a data source to say, evaluate the performance of two different aerodynamic planforms without having to manually modify the CAD model. 

    As you can see, we are thinking about these (and all) issues. Please keep your comments and suggestions coming so that we can understand exactly what you're trying to do and prioritize time and development resources. :)
    Philip Thomas - Onshape
  • michael3424michael3424 Member Posts: 623 ✭✭✭
    If we imported STL, the next 'n' requests would be for tools to fix bad files and then manipulate them (stretch, twist, blend). This is about as productive as trying to rake leaves on a windy day.
    <snort!>
  • gzgz Member Posts: 13
    edited May 2016
    Aerodynamic sections however, are far too precise to rely on 'tracing by eye'. Better workflows involve reading in the output of an analytical source
    Sure, that's a better way than tracing by eye.

    You know what's worse than tracing by eye?

    Not being able to trace anything at all.

    So unless 2d importing has been implemented and I haven't noticed it, that's where we currently are:  with no options whatsoever.

    Seriously considering printing a bitmap image  out and then using a projector to project Onshape onto that physical print.

    All for want of a 2d import.
  • traveler_hauptmantraveler_hauptman Member, OS Professional, Mentor, Developers Posts: 419 PRO
    gz said:
    So unless 2d importing has been implemented and I haven't noticed it, that's where we currently are:  with no options whatsoever.
    You have 2 options now that Featurescript is out. You can put your 2d pattern in a DXF format and import that inside a sketch, or you can put it in CSV format and write some featurescript to import that as a feature (an edge or face). 
  • philip_thomasphilip_thomas Member, Moderator, Onshape Employees, Developers Posts: 1,381
    edited May 2016
    @traveler_hauptman - thank you. I have been biting my tongue on these forums for months knowing that FeatureScript was coming.
    There are actually two aeronautical engineers on staff at Onshape - myself and @bobt.
    Bob has a cool FeatureScript example that reads standard NACA sections from a CSV file. This can easily be adapted to whatever needs you might have (he will likely post a public link here).
    Have fun!!!!! :)


    Philip Thomas - Onshape
  • bobtbobt Onshape Employees Posts: 7
    Hi,
    Here's a simple blended air foil example using tabulated airfoils. It's fairly simple to import a new table and link it into the feature. If you need any assistance, just ask.

    https://cad.onshape.com/documents/972dc31f395640d97dd6edca/w/8125816b48d1d07ebf0af701/e/b0dd208496a64d28d34778f4

    I hope you find it useful,
    Bob
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