High Torque Knob for M8 Screw - Two Versions

This knob uses an M8 coupler nut so that higher torque can be used. There are two versions - one which provided for metal-on-metal contact of the coupler nut, and one which “cushions” the end of the coupler nut (see photos and cross sections). The knob is designed specially for an M8 coupler nut 24mm in length.

In addition to the two knob versions, a “TestSocket” piece is included - this can be quickly printed to test the fit of the coupler nut, so that the print can be scaled up or down as needed. It is advised to print this piece first, because coupler nuts have relatively high tolerance limits. I sized the knob for a couple nut purchased from Midwest Fastener - coupler nuts from other sources may require adjustment in the size of the knob.

The coupler nut is a tight fit in the knob socket - I tapped the coupler nut gently into place with a small hammer.

Print Instructions

I printed in PETG :

• 0.3mm layer height
• perimeters = 3
• infill = 20% grid
• print with the knob handles down

CAD

The OnShape 3D CAD files for this are here :

https://cad.onshape.com/documents/a813134cfff18542190c7b13/w/817d19b9f6238cb24db13337/e/84b587288b33d1064c4ed2b9?renderMode=0&uiState=64af4ccf00ac484cd9dcf748