The clamp knob assembly holds the blade in your scroll saw's blade clamp. There's a knob on both the upper and lower blade clamps. The clamp knob assembly has a wingnut cast onto a threaded metal stud. The stud is machined on the end to provide a clamping surface for the blade. Over time, the clamping surface can wear, which will cause the blade to slip out. The threads can also wear out or strip.
Let's get started.
REMOVING THE CLAMP KNOB 1. Disconnect the blade.
a. Release the blade tension using the blade tensioning lever.
b. Loosen the blade clamp (clamp knob) thumbscrew.
c. Disconnect the blade from the blade chuck.
2. Remove the clamp knob.
a. Unscrew and remove the clamp knob from the blade chuck.
INSTALLING THE NEW CLAMP KNOB
3. Install the new clamp knob.
a. Thread the new clamp knob into the blade chuck.
REASSEMBLING THE UNIT
4. Reinstall the blade.
a. Install the blade into the blade chuck.
b. Secure the blade with the blade clamp (clamp knob) thumbscrew.
c. Tension the blade (using the tensioning lever).
5. Repeat these steps (as-needed) to remove / install the lower clamp knob.