It could be a 5.5mm x 1mm pitch screw. The easiest way out, may be to tap it to the next imperial or BA thread and use a matching grubscrew? Cheers! Hubert ----- Original Message ----- From: "Harry Wade" <hww@xxxxxxxx> To: <modeleng@xxxxxxxxxxxxx> Sent: Wednesday, November 21, 2007 3:41 AM Subject: [modeleng] Mystery thread >I am presently converting a 14" Rockwell wood bandsaw for metal cutting and >I need to match the thread of a grubscrew (missing) for a David Brown >reduction gearbox, which I assume was made in the UK. The screw diameter >measures .216" and the pitch is between a 24 and 28tpi but it is neither a >24 nor 28. The .216" is dead-on for a US #12 machine screw but it isn't >that. Anyone have an idea what this thread might be? > Regards, > Harry > > 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. 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.