Ratcheting Clamp Lever - M4

“Ratcheting” is perhaps not exactly the correct term for this, but the design does allow for the clamp handle to be moved without moving the clamping screw. This is a simpler version of commercially available clamping levers. The cheapest clamping lever I found online was $7; this one costs about 10¢ to print, plus you need to provide a screw and one or two nuts.

This version was designed as a proof of concept using an M4 x 30mm socket head cap screw, but the basic design can be adapted to fit other screw sizes and lengths.

The cross section view shows how this works : Lift the lever to clear the nuts and reposition the lever, push it down to engage the nuts and tighten or loosen. The lever can be used in two different ways:

• To use in a blind hole, insert the screw into the lever, thread a single nut onto the screw and, then screw the screw tightly into the blind hole. The lever can then be used to tighten or loosen the nut.
• To use in a through hole, insert the screw into the lever and screw two nuts onto the screw. Position the two nuts so that they are just clear of the lever, and then tighten them together so that they are jammed in position with the nut faces parallel to each other (if desired, use thread locker fluid to make sure they stay locked in position). The screw can now be screwed into the through hole until the nuts are just making contact; the lever can now be used to tighten or loosen the screw in the through hole.

Print Instructions

Print in PLA using the 3mf of gcode files provided. I used PLA for design and testing, but PETG may be a better choice for actual use. In general :

• 20% rectilinear infill
• perimeters = 3

Note that the lever should be printed with the handle down and flat to the print bed (see photos).

CAD

The OnShape 3D CAD files for this are here :

https://cad.onshape.com/documents/07031ed471585ebd487ef649/w/c89745ba3cf641769ae6f359/e/9c11364cfeeda293642cde1e