UV workflow practices for complex hard-surface models

I have some rather basic questions in regards to a good uv-mapping workflow and I hope some of the experts here can shed a light for me.
I am currently working on a radial engine that consists of a number of parts. E.g. prime distributor, magnetos, governor, fuel pump, oil pump, carburetor, etc. etc.
Have a look at the wip:

I’d like to texture the model using just one material, so every part needs to be contained on the same uv sheet. Furthermore, there are a couple of elements that are being used multiple times. For instance there are a whole lot of screws and bolts. I want those objects to share the same coordinates on the uv map to save space. Working on this, I am struggling coming up with a good workflow. My approach was to first get all the geometry done and afterwards uv map everything. But doing that, I found myself creating the same seams and uv unwrap the same screw 100 times - which is nuts. To get away from that, I now started to delete all screws but one, uv map that particular screw and then copy it to all the other 100 positions. Obviously that is also not a good approach.

So after all of this, here are my questions:

  1. What’s a normal workflow for a model like this? Model everything first and then UV map, or is it better to model+uv map element by element?

  2. What’s the best practice for those geometries that are being used over and over again? How can one best prevent re-mapping similar parts?

  3. What’s the best practice to unwrap and place multiple objects on one uv map, hopefully with a consistent resolution?

Thanks for reading, and I am looking forward to learn from the pros!

I’m no expert on UV workflows, but for things like screws - couldn’t you just use a procedural material? Some objects wouldn’t need to be UV’d - those which have the same sort of material all over, like screws, bolts, nuts, etc. could just have a procedural material saving you some headache. I know you said you wanted one UV for the whole thing, but is that necessary? You still have to apply nodes to individual pieces anyway, so it seems like a lot of extra work to UV everything. Blender 2.82 introduced UDIMs, so you could have one UV for multiple objects, so I think that’s what you are looking for.

Thanks for the quick reply. The asset is for flight simulator x/prepar3d and the outdated 3d engine of both platforms puts some limitations on the model. For instance one thing I found out years and years ago is that the platform performs way better using fewer, but larger textures instead of lots of smaller ones. Procedural material is out of the question as well, since the engine doesn’t support it. The same is true for a lot of modern functions, like UDIMs. It’s not supported by my platform, hence not useful to me at this moment.

If i was to model something that has lots of the same parts then model one part uv unwrap it texture it then multiply it.

Yeah, that’s what I am doing at the moment. It just doesn’t seem right, because it interrupts the modeling process so much. I wonder if there’s a better way where I can leave the uv mapping as a last step but without repeating the same steps over and over again.

You could probably have used copy object date for the screws if they are the same size, they should then have the same texture, Seams and size of the first screw.

Sorry for the late reply. The forum didn’t allow me to answer, because I reached my 20-post-per-day limit.

Thanks for the tip. I tried that, but it didn’t work in my case. Maybe rotating the screws around messed things up, I don’t know.

Another possible solution I found was to Alt+D to create instances of an object, rather than duplicates. But that doesn’t work in edit mode, so I’d end up with dozens of screw objects. Maybe a small price to pay, but I’m wondering if there’s a better way that works within the geometry of one object as well.