Sit at the preacher curl machine with your upper arms resting on the pad and grasp the handle with an underhand grip. Slightly rotate your torso and shoulder forward toward the working arm to create a comfortable angle. Keeping your elbow fixed on the pad, curl the weight up toward your shoulder by flexing your elbow and squeezing the biceps. Slowly lower the weight back down under control and repeat.
Log your lever preacher curl (turned torso) sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.