Originally Posted by 63rickert

Ruthlessly tossing whatever fails to meet spec is exactly what Quality Control means.

The simple way to build carbon frames accurate is to build them around an aluminum BB insert. Then machine both sides of the insert at same time. Everyone knows this. It is not done because it adds weight. Eighty to one hundred grams of weight. Bragging rights about frame weight are important to marketing. Marketing wins over engineering every time. A slightly more difficult method would be a small aluminum insert on each side of the BB and then machine those at same time. Building a carbon frame accurate enough to directly press in bearings is possible. We know this because it is being done. If that would scale up is not known because no one has tried it.

To your exact query about making aluminum frames accurate enough to prevent creak (which means accurate enough to work) there is no good reason not to. It is simple. It is not an added cost process. Not machining them accurately only happens when an importer tells the sub to build a bike below the cost of building a bike. In small run shops it will be slightly easier to get the job done if threads are used. There may be some significant costs involved when large importers have been reliant on substandard shops building nothing but BSO.