tighten (something) on (something else)
1. To fasten something tightly onto something else. The last step of the assembly is to tighten these four feet on the legs of the table. He forgot to tighten the new antenna on the top of the car, so I couldn't listen to the radio on the drive home.
2. To tighten some part of something else. Make sure you tighten the valve on the tank to stop it from leaking. We'll need to tighten every single nut and screw on this rig, or it could fall apart in the middle of the race.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
tighten something on(to) something
to make something more tightly attached to something. Will you please tighten this nut onto the bolt? I tightened the lid on the pickle jar.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.