The primary function of any screw used on a coffin was to secure structural elements together. Smaller versions of these thumbscrews designs were used to attach coffin plates. Thumbscrews were used to attach the coffin lid to the body of the coffin. Thumbscrews were also designed for permitting leverage during tightening of the coffin, a process which was done by hand.
Thumbscrews are similar in construction to ‘caplifters’, consisting of a plated metal head soldered to a long iron screw. Thumbscrews differ from coffin screws, which are simpler in design. Click here to learn more about coffin screws.