setting-screw

from The Century Dictionary.

• noun A screw by which cams or timing devices may be so adjusted as to do their work as desired.
• noun A set-screw; a screw by which pulleys or collars are fastened or adjusted on a shaft. The screw passes radially through hub or collar, and bottoms or beds upon the shaft, holding the hub or collar from slipping round or lengthwise. Sometimes the set-screw enters a counterbore made for it in the circumference of the shaft.