Hi Bill - In my experience there is not an upper limit, but there is typically *something* in the SKP file that is unnecessarily complex from a geometric perspective... a landscape topo, plants / trees, a desk chair, light fixtures, etc... so I'd recommend the following steps:
- Make sure you have the latest FormIt Add-in - v1.9.4 - LINK
- In FormIt, open the SKP file, use layers to turn off the visibility of unnecessary objects for Revit
- The Revit import is WYSIWYG - so 'hiding' geometry in FormIt will keep Revit from processing it on import
- Save the AXM file and import this using the FormIt add-in for Revit - hopefully this resolves the issues...
- If you still have long import times, then try importing in 'chunks' to identify the problematic geometry
- In FormIt isolate one layer at a time - use the 'export visible' option in the export dialog - then save that exported axm - and import to Revit - save
- Repeat the above steps to build up your Revit model in chunks and identify the issue...
Hope this helps! If you continue to have trouble let us know and we can attempt to help with the problematic file
Tobias