File associations

I have a client who is complaining that after having installed a new setup on Windows 10 and installed both V5 and V6 they cannot make any file associations work automatically (double click) with V5 - specifically STEP, DWG, DXF and STL. I tried a few experiments here on my Win 8 machine and I can’t either with .stp - and it doesn’t even show up in my Windows file associations.

Paradoxically, my .dwg association on this machine is already with V5 (if I double click) - who knows why? But not the .dxf, that opens with V6. In file associations, I have this…

Which corresponds to the reality, However, trying to change either one in the Windows file association panel doesn’t work. Nor via right on a desktop icon and Properties or via Open with…

I know the file association stuff with Rhino has been messed up since a long time, this was already a problem when V5 replaced V4. I was trying to find the registry hack to force the file association so I could give the procedure to the client, but it wasn’t obvious to me where it was.

@brian - do you have an idea what to do to make this work?


I need to log off for awhile now, may not be back on tonight - any way I can get an answer on this today so I can tell the client what to do tomorrow?

TIA, --Mitch

Hi Mitch,

This is because Rhino 5 didn’t advertise itself as being capable of opening all the file types that it could open. To fix this:

  1. Unzip (581 Bytes)
  2. Double-click the .reg file to add the registry keys to Rhino
  3. Now, when you right-click .step, .stl, and all the other types Rhino supports, an option to open with Rhino 5 x64 exists.

Does this help?

Yep, seems to work here at least - I will send it over to the client tomorrow. Thanks!

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While we are at that:

When DWG is associated with Rhino6, the small icon in Windows Explorer is the same as for 3DM.
In Rhino5 the icon for DWG was (slightly) different.

How to achieve the same (different icon) in Rhino6?


Hi Charles - perhaps @brian has another trick up his sleeve for this one.
A quick Google tells me that it is not possible to change this through the Windows UI and multiple sites refer to a utility by Nirsoft…

Thanks Wim.

The problem is, when I associate *.DWG with Rhino6.exe, the file type of the DWG changes to “Rhino-3D Model”.

Regardless which means I use further to set the icon, it is for both DWG and 3DM then.

You can see that easily using this tool:

I made an icon to play with: (8.3 KB)

Any idea how to get around this?


Hi Charles -

No, I don’t - but solely based on the name of that app…

… it sounds like you are using the wrong tool to do what you want. You are not changing the default program for a file type, you are changing the icon of a file type.

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Many thanks @wim.
Using the correct tool it exactly works as expected.

Hi Charles,

It appears that we could make this even better by not only registering “capabilities” with Windows, but also registering a zillion different file types with Windows.

Right now, the installer registers “Rhino6.Document” as “Rhino 3D Model”. Because we’re registering Rhino as being capable of opening “.dwg” as “Rhino6.Document” they all get the same icon.

We could add icons to Rhino for each file type, and also register each file type as “Rhino7.Document.DWG” with the description “DWG (Rhino 7)” or something. Would that be clearer?

Hello Brian

Sounds very good!
While I think a single other icon for all the diffferent types could be sufficient.
Something like a left or down arrow overlay or so.

The change in the file types handling is very welcome.
Thanks for it.

OK, here’s the issue to track…