Noise Reduction - Sorbothane Printer Feet

Shoutout to evillvi77 and Real 3D Prints for the great designs which made this possible. My finished product used two of Evil's remixed feet and two of my own in the rear.

This design enhances the load distribution through the QTY-6 sorbothane domes on printers such as the Prusa MK series which are very back end heavy. 

The logic in the original design is spot on. The 1" 50 duro sorbothane feet work best when supporting 2-4lbs each. For the MK4 printer which weighs about 15lbs, 6 of the sorbothane feet give us a total support weight ranging from 12 to 24lbs. So far, perfect!

Once I installed the 6 evenly spaced single feet, I saw something that I had not considered... In the image above you can see the rear sorbothane hemisphere's squish significantly more than the front. This is because the center of mass is located towards the rear, creating this trapezoidal distributed load. 

These Prusa MK series printers are very back end heavy and distribute most of the weight through the rear feet. A single, evenly distributed foot approach with 6 hemispheres ends up overloading the rear feet (>4lbs ea) and underloading the front feet (<2lbs ea) as the mass teeter totters about the center feet. In essence, sorbothane effectivity is not being maximized with all these contact point locations.

To counter the back end loading and to force more weight through the front feet, I remodeled the STL file to get a baseline and created the double sorbothane foot mount. This design eliminates the middle feet as these supporting points are moved to the same “in-line” support location in the rear.

Despite how hard this was to capture in a 2D image, the pictures illustrate the better load distribution through more uniform sorbothane squish.

Please check out the linked models for additional details and parts you may need for this upgrade!