I've done some digging and figured out how to create new catalogs and filter out only the objects I need from the existing catalog. I was able to whittle down the VAV box catalog from roughly 220,000 in ACAD MEP 2014 to the 12 or so that I use. I noticed that manufacturers of HVAC equipment have Revit files for their products, so I decided to turn my attention that way.
Since I use AutoCAD MEP, I had our CAD manager convert the .rfa files to .dwg, but at this point I'm a little lost. For a dual duct VAV box, for instance, I can't create a new MvPart from the entire model, just one block in the model. More frustrating is the situation with the Titus single duct VAV boxes with reheat coils, as there is only a single file. Do those need to be edited first in Revit and then exported as separate files for each size box?
I know this is a long question with no quick and easy answer. If anyone has a tutorial or how-to that they know of for creating MvPart catalogs in MEP from manufacturer's .rfa files, that would be a huge help.
In order to get the correct geometry from a parametric family in revit you will need to load the family into the current revit project and then place one of each size into your revit model. Once you have created one of each size you can export the model as a dwg. Just make sure you export it as a 3D solid and not as a polyface mesh. Once converted to a mvpart you will get much better results from a 3D solid than from a polyface mesh. Meshes as mvparts are unable to be flattened using the standard Export to Autocad commands and require additional work that 3D solid mvparts do not.
I figured something like that would be required. In the meantime, though, I have another issue.
I started the process of creating dual duct VAV box MvParts from the Titus .rfa files that were converted to .dwg. Unlike the single duct boxes, I already have individual drawings for each size box, so I don't need to worry about parameters.
My first time I left the files as-is, which meant that the 3D block was actually a number of other 3D blocks lumped together, so I couldn't get the views to work correctly. I selected the individual blocks (main box, two inlets, outlet, and control modules) and used WBLOCK to save those as a single object. When I opened the new file, it was all one block, just like I wanted.
I started back through the MvPart creation process following the help files and got to connector placement. Even though I have selected my new block as the model to pull views from, I'm not getting the correct objects when I go to place duct connectors. Rather than the entire model appearing, all I get are the two control modules. I'm starting to feel like I'm in a little over my head with those whole MvPart creation thing. I've attached a couple screen shots of before and after I click to place the connectors on my model. Let me know what else I can provide to help you help me.
I believe what you are seeing is a result of the 0,0,0 bug. You should open up each block and make sure that the origin of the block is at 0,0,0. I would not recomend using nested blocks in your design as this can also cause the situation you are seeing.
I'm trying to avoid having to make all these 3D object from scratch myself. If I explode the blocks and then WBLOCK a new one from the exploded pieces will that help?
Sorry if these questions seem a little rudimentary. I have about a year of experience with AutoCAD, but only a few months in MEP and this is my first time working on the backend to make new parts and catalogs.