Video in the below thread explains making upgrades to the Harbor Fright aluminum clamps:
An easy upgrade for Harbor Freight bar clamps
Paul Sellers also has a blog entry on how-to-do-it:
https://paulsellers.com/2017/01/screwfix-sash-clamps/
Some here may find this information useful.
An easy upgrade for Harbor Freight bar clamps
Paul Sellers also has a blog entry on how-to-do-it:
https://paulsellers.com/2017/01/screwfix-sash-clamps/
Some here may find this information useful.