things to consider: 1) having enough thickness in BB wall to cut threads that will hold a BB. 2) proper size BB shell to hold thread-in type BB. 3) finding someone that has the equipment and know-how to cut an inch or or of threads in both sides of the BB shell.

i won't be surprised if there are those that will get into why this is being attempted. good luck though.

however, there are some press-in adapters that fit a certain diameter of BB shell that may be of help. for instance, BB30 to BSA. maybe PF30 to BSA.

like this: