In this video, we show how they adjust the trimmer when a machine is consistently missing trims. This is a sensitive, trial-and-error adjustment: if the blade is set too tight, it can shear off and need replacement, while if it is set too loose, the machine will not trim. They note that this adjustment is only recommended when trims are being missed regularly, not for an occasional missed trim on heavier threads such as metallic.
To begin, they remove the needle plate to expose the trimmer. The moving knife extends outward, while the black piece beside it is the fixed knife. They loosen the two Phillips head screws slightly, then place a 1.5 mm Allen wrench into the Allen screw between them. Tightening this screw changes the pivot point, causing the fixed blade to rock up and down. They emphasize that this should be a very small adjustment, with only a slight movement of the Allen screw before the Phillips screws are tightened again.
They then test the adjustment using a piece of thread folded into a loop. After pulling back the moving knife, they place the loop over the point of the knife and gently slide it forward until it trims. A proper adjustment produces a clean cut. They explain that the trim should happen just as the flat edge of the moving knife reaches the end of the fixed blade, leaving only the point sticking out. When the thread trims cleanly at that exact position, the trimmer is properly adjusted.
After adjusting the trimmer, clean out loose thread and lint with items from embroidery cleaning supplies.