The TOWA bobbin tension gauge puts a numerical value to the amount of tension placed on a bobbin. This is very helpful as it allows you to quantify the amount of tension placed on a bobbin thread, so you have a benchmark to base bobbin tension. To measure the tension of your bobbin, place your bobbin inside the bobbin case with the thread unwinding the correct way, then insert into the TOWA gauge. Pull your bobbin thread and guide it underneath the bottom wheel, over the top of the top wheel and then inside the catch. As you pull the thread to the side, you will see the top wheel move down while the numbers increase. The higher the number, the tighter the tension. To loosen the tension, turn the screw in small increments counter-clockwise. Think, lefty-loosy righty-tighty. We recommend making small adjustments when tightening or loosening the tension screw. Think of the screw as a face of a clock, when adjusting, adjust in 15 minute increments.
Don't be lured by the temptations of the digital version of the TOWA gauge. It may give you an reading (which may or may not be the same as your manual version), but it does not do what we find to be the most valuable feature of a TOWA gauge, which is the bouncing of the needle when there is something wrong with the bobbin (like lint or a damaged/defective bobbin or bobbin case). On the manual one you can clearly see this, but the digital gauge “averages” the readings and just give you a number, thus not giving you this vital information.