The suggestion to try Doug Hewson for correct sized 12ba hex screws hex has done the trick. As I type this a pack of said screws is winging its way across the Pennines. Doug's 12 ba hex are 2mm (0.079ins) across flats compared to the correct size of 0.090ins and compared to 0.098/0.099ins that most suppliers are peddling. I'm sorry I can't remember whose idea it was to try Doug Hewson but many thanks. Barrie Purslow MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.