2) The piston is mounted onto the piston rod with a thread. I don't like using a thread for alignment in such a critical area. To my way of thinking the thread should be for fastening, and the alignment should come from the fit of a tapered or parallel section of the rod in the piston. Works on the 12" to the ft scale ok John, why not in 5", just a little care needed to cut the thread. Also, never fir brass or phosphor bronze nuts!!!! I did and one fine day, there was a bit of a bang!!!!!!!!! ....Sounded and expensive bang!!!!!!!...... Fortunately, the Pea os built big enough so when the piston locknut comes off, it breaks it up and just stops the loco going anywhere. Dave. Having said that, the Sweet Pea is a fine workhorse and great way for people to express their own individuality. Many diff designs, mines and 0-4-2 side tank, no cab but spectacle plate as per padarn quarry engines. Dave. 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.