How Do I Design a Pulley With Multiple Layers of Ropes

gerald_kreissig

I am in the process of importing and extending a design of a mobile crane from Solidworks to Onshape.

Instead of simply importing the parts and assemblies from Solidworks to Onshape, I am redesigning the Solidwork parts in Onshape Part-Studios and then create assemblies. The main reason is the flexibility, I can achieve in adjusting and manipulating the newly created parts and therefore I am able to simulate the behaviour of the crane movements.

The next step would be the design of the pulley with multiple layers of ropes around the sheaves.
Here are some views, how the design looks like in SolidWorks: 

Now the question is: how can I design the 3-dimensional layout of the ropes in Onshape?

I can import the design from SolidWorks

but since Onshape only supports part imports and not feature imports, I cannot manipulate and change this imported design.
And I have no clue, how I would create such a design from scratch!

Any advise is appreciated!

Best Regards

        Gerald Kreissig

mlaflecheCAD

@gerald_kreissig it involves a bit of surface trickery to build a robust helical 3D path for the rope, see this example, in the rope folder in the part studio:  https://cad.onshape.com/documents/a8f5529bb2aaec5b3d6e2724/w/904d60a4e7ff9f79b74d0c53/e/9c06ec9ebaa3b0b1018f4b50.  An elongated 3D path is created for the rope to follow.  



Fun side note, Isolate works great for surfaces and curves as shown here

mahir

Alternatively, you can play connect-the-dots. Using standard OS tools this would require multiple sketches/sketchplanes and bridging curves. Also, I believe there are several 3D sketching featurescripts that would do what you want with a little finagling. Here's one.
https://cad.onshape.com/documents/9bddf41e8d9f461ea10840f8/v/131849b5116cc7c1367e35ae/e/79da65d8fe27fc8ee2900deb

john_mcclary

@mlaflecheCAD
That's a neat trick

GWS50

Yes that is a very neat trick...I've got to try and use that, love it