Prusa Anti Vibration Noise Sorbothane Feet

Printer feet should:

• Not wobble, be firmly connected to the frame, and support the printer
• Isolate and eliminate vibrations to improve print quality
• Dampen noise caused by those vibrations to improve quality of life In addition, if you are using an LACK enclosure, not see it move.

Although OK, the stock feet do none of these well.

The only material that is truly designed to do the latter two is Sorbothane. Read about its properties here: https://www.sorbothane.com/material-properties.aspx This is a scientifically proven anti-vibration anti-noise material, that is similar in feel to a gummy bear, and used to soften vibrations in electronic and industrial equipment, such as a 3D printer.

You need six feet to make these work the best.

For each foot you need

• 1 Sorboholder printed
• 2 Framebrackets printed. Use :
  • The part in this listing, where you insert into the end of the frame. Also listed here - https://www.printables.com/model/83873-t-nut-for-3030-frame-prusa-mk4
  • The official metal m3 nut Prusa part (best option) at https://www.prusa3d.com/product/psu-holder-m3ne/ 
  • Not ideal, but a drop in nut can be used too. Any 3030 M3 drop in nut like these results where you don't need to remove the end of the frame but have a slightly less solid connection  - https://www.printables.com/search/all?q=3030%20m3%20drop
• 1 Sorbothane 1 inch 50 duro dome (see links below)
• 2 M3 12mm screws
• 2 M3 hex nuts
• (optional but highly recommended)1 Woodprotectpad printed (2 sizes included) or any  drink coaster will also do.

Explanation of how Sorborthane works

When the Sorbothane dome is compressed it works best. Too large or stiff a dome and it isn't doing its job. If it is too small or too compressed it can't handle the vibrations. You want to pick a set of specific domes so that the weight supported falls in the middle of the load rating for the Sorbothane, so the domes have optimal compression.

The combination of dome size (1,1.25,1.5 inch) and duro rating (20,30,50,70) tell you how many you need for a particular vibration load (weight). For the printer we can use either four or six. It weighs about 17 pounds with a spool.

After matching 17 pounds to the various combinations of size and compression, using six of this type is the best combination to support 17 pounds:

• 1 inch 50 duro, supports 2-4 pounds each, so six of them support 12-24 pounds
• 17 pound printer weight falls squarely in the middle of this 12-24 range (this is ideal)

All the other combinations of duro ratings, sizes, and quantities gave load ranges that were mostly above or below 17 pounds:

• 1 inch 70 duro support 4-8 pounds so four support 16-32 pounds
• 1.25 inch 50 duro support 5-10 pounds so four support 20-40 pounds
• 1.25 inch 30 duro support 2-4 pounds so six support 12-24 (same as 1 inch but would require larger feet and longer print time)
• 1.5 inch 30 duro supports 4-7 pounds and four support 16-28 pounds Therefore we need to print six feet using 1 inch 50 duro domes!

To understand further read:

• Product description for 1 inch 30/50/70 durometer Sorbothan Isolate IT Bumpers:
  https://www.isolateit.com/hemispheres/sorbothane-hemispheres-bumpers/sorbothane-1-hemisphere-0510115-0510116.html
• Product description for all durothane bumpers: https://www.isolateit.com/hemispheres/sorbothane-hemispheres-bumpers.html Here they are on Amazon. I got mine for $10 for 4 with free shipping/Prime - make sure to get 50 duro ones! (these come in packs of 4 so buy two packs)

Links to Amazon sorbothane

• https://www.amazon.com/gp/product/B0042U6ZDU
• https://www.amazon.com/gp/offer-listing/B0042U6ZDU

You will need six feet exactly so if these are in packs of four you will end up with some extra ones.

Print instructions

• Print everything at 100% infill because you need the printer vibrations to carry through them completely to the Sorbothane domes. 
• PETG is preferred due to the constant weight on the part. 
• Use .2 layer heights. 

The woodprotect pads serve three functions. There are two sizes of these. Pick which one you like. You might print them if any of these apply:

• Sorbothane can stain some surfaces like wood and you have a wood surface.
• Sorbothan is sticky and you don't want them to stick to your table but the pads instead.
• You want to slide the printer around on your table/desk easily.

Assembly Instructions

The goal is here is not to have to re-calibrate the axis. The frames should always be resting on the original Prusa feet while we slide in the new feet. Note that only in the final step do we remove the old feet and attach the new adhesive Sorbothane domes.

• Print out six 'sorboholder' feet, and twelve ‘framebracket2’ (the pic below shows less than you need)

• Lightly sand all the sides of 'framebracket2' and then push a M3 hex nut into the back of each. Push them in fully. Make sure they are flush or below the surface.
• Screw two 'framebracket2' to each sorboholder feet with two m3 12mm screws. Don't fully tighten them. Don't attach the adhesive sorbothane yet. Again, you need six of these total not four.

Repeat these steps for each end (short end and then long end) of the frame:

• Slide the stock/gray/existing Prusa feet towards the middle of the frame four inches from each end, and do not remove them
• Slightly loosen one end of the frame plate by loosening the eight large screws. Once they are all loose remove them fully.
• (see pic) Lift the frame up and slide in the assembled sorboholder/framebracket2 assembly for the both feet on that end of the frame. Loosen the M3 12mm screws if needed

• Leave the old feet in for now. Once they are in reattach the eight frame screws and screw them back in to reattach the frame end.

• Slide the new feet into the desired position, and firmly screw in the new feet into the frame.

The short end has one assembled sorboholder/framebracket2 assembly and the long frame end has two, for a total of six. The pics below are incorrect as they only show four. Their should be 3 along each side of the printer, two at the ends and one in the middle on each side. 

When all are in:

• Finally, attach the new adhesive Sorbotane domes and remove the old Prusa rubber feet. 

• Use the wood protect pads under the domes as well as an option

(Fusion 360 file included for remixing.)