Can not download the CAD model on Onshape

[oxtonggue233]

The documents are view only. Could you please open the download pemission? That will a great help.

[tjacobs]

Same request @SteveNguyen , we can't actually copy the onshape doc to print and make small mods to a copy because it's set as not copyable, could you update it?

other people have just imported the stls, but we would like the construction item history...

[SteveNguyen]

Hi, I activated the "export" option on the onshape document. Does it solve your problem?

[nyxrobotics]

Hello,
When I open Onshape or Step files, I don't see any rods or ball joints, but your images appear to have ball joints.
Is there a way to open a complete assembly that includes ball joints and all fingers?

[tjacobs]

so export just exports the final STL - i'm looking to be able to copy the workspace so i can see the history and edit that in my copy, is there a clone workspace option you can enable?

[oxtonggue233]

Hi, I activated the "export" option on the onshape document. Does it solve your problem?

Thank you！Now I can download the CAD model and make some modification. Thank for your sharing.

[SteveNguyen]

so export just exports the final STL - i'm looking to be able to copy the workspace so i can see the history and edit that in my copy, is there a clone workspace option you can enable?

Hi, yes it will be done soon. I am waiting for @Jeremy-Laville who is currently on vacations :)

[Jeremy-Laville]

Hello, When I open Onshape or Step files, I don't see any rods or ball joints, but your images appear to have ball joints. Is there a way to open a complete assembly that includes ball joints and all fingers?

Hi,
with the onshape link, you should be able to open "Finger" assembly or "Right hand" assembly documents. You should normally see all the components inside !

Step files are only plastic parts.

[Betatester777]

Hello,
I’m experiencing the same issue — I can export the STL file, but I’m unable to make any modifications to the project.

Additionally, Isaac Sim crashes whenever I try to import the assembly from this specific project. Other, non-protected projects import without any issues.

Could you please assist?

[Jeremy-Laville]

The Onshape document is now Public. Any Onshape user (with login) should be able to copy it !

[Betatester777]

Hi @Jeremy-Laville,
Thank you for your quick help — I can now clone and edit the project.
Amazing!!!

[Jarvis-Geun]

Hi! Thank you for this amazing project :)

I have a question regarding the Onshape model:

I found the URDF tab inside the Onshape interface, but I’m not sure whether it is actually possible to export the model directly to URDF from Onshape.
My goal is to import the hand model into Isaac Sim (version 5.0.0) and test pose detection.

So far:

• I successfully imported the Onshape assembly into Isaac Sim using File → Import from Onshape
• However, all the links and joints are disconnected, so the hand appears as a collection of individual parts rather than a functional articulated model.

Do I need to manually create the URDF myself? Or is there a recommended way to export a proper URDF (or other robot description format) directly from Onshape for this hand model?

Any guidance would be greatly appreciated.
Thanks again for sharing this project!

[Jarvis-Geun]

Hi @Betatester777,
From your explanation, it seems that the model was successfully imported into Isaac Sim.

I’m wondering if the structure of the model remained intact, or if any of the joints/links were broken during the import process.
It seems that the joints and links are not connected after importing the model into Isaac Sim.

Do you have any recommendations or best practices to ensure the model imports correctly?

[Betatester777]

Hi @Jarvis-Geun ,
Not solved yet.

I’ve tried all three major import paths, and each one hits a different limitation:

1. Direct import from Onshape → Isaac Sim

This produces multiple issues:

• lost joints
• wrong joint orientations
• incorrect joint limits
• broken kinematic structure

So a clean import is basically impossible with this route.

---

2. onshape-to-robot (Onshape → URDF → Isaac Sim)

This gives much more control, but there are hard limitations:

• URDF does not support spherical (ball) joints, so I’m currently trying to replace each sphere joint with three revolute joints (XYZ chain).
• Isaac Sim does not allow closed-loop chains inside an articulation → any loop of joints is automatically broken, deleted, or converted to fixed.
• According to NVIDIA’s PhysX docs, a closed loop can be formed only by removing one joint from the articulation and reconnecting the loop using PhysX D6 joints:
  https://nvidia-omniverse.github.io/PhysX/physx/5.4.2/docs/Articulations.html#closing-loops
• onshape-to-robot also requires strict naming conventions for links and joints:
  https://onshape-to-robot.readthedocs.io/en/latest/design.html#naming-links
  Non-URDF joint types are simply ignored.
• The first link must be fixed/grounded or URDF export breaks:
  https://onshape-to-robot.readthedocs.io/en/latest/design.html#fixed-robot

So URDF export technically works, but only for tree structures, not closed loops.

---

3. onshape-robotics-toolkit (ORTK)

I tested this toolkit as well, but ran into severe dependency/version issues and didn’t manage to complete an export.

---

Summary

Yes, the model does load in Isaac Sim — but:

• the kinematic loops break,
• spherical joints are not supported in URDF,
• and the structure does not remain intact after import.

I'm currently evaluating the best approach to preserve the closed-loop mechanism, likely using a hybrid workflow (URDF articulation for the tree, plus PhysX D6 joint to re-close the loop afterward).

Any best practices for preserving closed-loop kinematics and spherical joints during import would be appreciated.

[Betatester777]

Hi @Jarvis-Geun ,
By the way, I’m currently making progress on importing a single finger module, but it’s not finished yet:

I’m removing all fixed joints by merging the corresponding parts (Boolean union).
Planned merged link:
2 servos + bushings + finger-frame1 + finger-frame2
→ combined into a single rigid body.

The two ball heads are also being merged into one solid part so URDF doesn’t treat them as separate links.

I’m replacing the original ball joint with a stack of three revolute joints (XYZ chain) to approximate a spherical joint, since URDF doesn’t support actual ball joints.

This is helping me keep the kinematics as a tree (no closed loops), so onshape-to-robot can export it properly without dropping joints.
Still a work in progress — I haven’t fully validated the import in Isaac yet.

WIP: https://cad.onshape.com/documents/f9223ab9c4e361fafa916e20/w/0dcc4ecc42abf1164b7f0891/e/9d2669f08603e70be1f5a133
https://cad.onshape.com/documents/f9223ab9c4e361fafa916e20/w/0dcc4ecc42abf1164b7f0891/e/fdfc39c14b5ba75e291a69a4
https://cad.onshape.com/documents/f9223ab9c4e361fafa916e20/w/0dcc4ecc42abf1164b7f0891/e/cf290bd08c971da72ad77065

[Jarvis-Geun]

Hi @Betatester777 ,

Thanks for your quick response!

Based on your explanation and shared links, I am also planning to modify the URDF so that I can successfully import the hand into Isaac Sim.

I really appreciate the detailed information — it’s extremely helpful.

I’ll continue experimenting on my side, and I’ll make sure to share any progress or findings as soon as I have them.
Thanks again for sharing your work!