Prusa Enclosure Square Feet Bracket

The problem

As the proud owner of an original Prusa Enclosure and MK4s, I felt that the bottom plate of the enclosure didn’t provide much support to sustain the weight of the printer. In addition, the vibrations caused by the printers’ movements are transferred to the rest of the enclosure because there’s no damping. So, I set out to design a bottom plate support for the enclosure that would address these issues.

I was inspired by the solutions provided by:

• Ricochet: https://www.printables.com/model/1042657-extra-feet-for-prusa-enclosure
• AE: https://www.printables.com/model/264693-snap-in-sorbothane-mount-for-3030-extrusions

These were really good & elegant solutions but I felt that they could be combined and improved upon. 

So…yet another solution to reduce the vibrations of the original Prusa Enclosure! 

The solution

I decided to design a rectangular bracket that would slide underneath the bottom plate. This bracket rests upon 4 sorbothane hemispheres on each corner to dampen the vibrations caused by the printer. The bracket would be positioned underneath the printer in such a way that when the print bed moves back and forth, its vibrations will be distributed among the four hemispheres.  Basically, this means that the centre of the bracket should be positioned in such a wat that it aligns with the X-axis of the printer. Since the printer has a substantial part of its mass located both at the front and the back (the power supply), this positioning roughly provides a 50-50 weight distribution on the bracket.

This Prusa Enclosure Square Feet Bracket is designed for maximum strength & support, as well as making sure that the vibrations are directed to the sorbothane hemispheres. There, the vibrations will be damped by the visco-elastic properties of the sorbothane. The bottom plate will be thoroughly supported by the cross-bracing of the bracket, essentially eliminating the deformation of the bottom plate and providing a very stable platter for the printer to rest upon. It’s a very sturdy design but I’m an engineer who likes things to last…and I tend to be a bit on the conservative side 😉.

To facilitate easy placement underneath and making sure the bracket latches on to the bottom plate, I included nine magnetic strips in the design. I selected these magnets for this purpose:

https://www.amazon.com/dp/B0B6PQPBP1/ref=pe_386300_440135490_TE_simp_item_image?th=1

Since the sorbothane hemispheres will cause stains, I added a coaster design to prevent your bench/cupboard/what-have-you from it. 

So which hemispheres to use?

I used the following hemispheres from IsolateIt:

https://www.amazon.com/dp/B0042U6ZDU?ref_=pe_386300_442618370_TE_sc_as_ri_0

These are the 1”, 50 Duro, Sorbothane hemispheres version and this design uses 4 of them. However, these have a maximum load of 4 LBS and the total printer/enclosure/filament spool assembly weighs about 19,2 kg (or 42,3 LBS).

Since 4 of these 50 Duro 1” hemispheres would only be able to handle a load of 16 LBS (max), that would not be sufficient. That why this design is to be used together with this design:

https://www.printables.com/model/1291797-prusa-enclosure-damping-extension-bracket

This design uses 8 additional 50 Duro 1” hemispheres, combining to a total of 12. The 42.3LBS is then spread across 12 hemispheres, which comes down to 3.5 LBS per hemisphere. This is well below the 4 LBS maximum rating.

If you just want to use the 4 hemispheres for the Prusa Enclosure Square Feet Bracket, I would advise to use the 1”, 70 Duro version (allowing a maximum 32 LBS load in total).

Print settings

I used Prusament PETG Prusa Orange (I love that colour 😁) with the following settings:

• 0.20 mm Structural
• 30% Gyroid infill
• 5 perimeters
• No supports

These settings are definitely aimed at strength while keeping printing times to acceptable levels. It will take about 10:hr42 to print the design. I’ve added an automatic Pause Print command (M601) at 3.2 mm: this allows you to insert the magnets. Don’t forget to hold them in place with a drop of superglue underneath, otherwise they will pop out and cling to the printhead! It also prevents possible rattling of the magnets. Wait for a few moments for the glue to dry and then continue the print.

I used an inside brim of 10 mm which wasn’t necessary: the model sticks well enough to the printbed and the 9 magnets also prevent movement.

Assembly tips

Note: If you have the LCD attached externally to the enclosure, make sure you lift the front-end first and place the damping extension bracket. You don’t want to crack the support and possibly demolish the display by lifting the rear end first! After this place the Prusa Enclosure Square Feet Bracket. 

I used these very handy little things to lift the enclosure (the 42-62 mm versions):

https://www.printables.com/model/920145-adjustable-height-support/files

So how does it all work ?

Well, pretty good actually! For starters, the noise levels have dropped substantially, something I definitely didn’t expect. My whole setup (printer & enclosure) is very silent now. The support for the bottom plate makes for a much sturdier enclosure and that results in a more silent setup.  Although pretty sturdy, the enclosure has a number of parts that are easily made to vibrate and rattle. I never considered my printer “noisy” until I implemented the sorbothane hemispheres…They do a great job in addressing these isuues.

The vibrations also decreased significantly: the items placed on top of the enclosure used to wobble a lot but not anymore. Sure, there are still vibrations but the whole setup is much more dampened now. The bracket directly place underneath the printer does an excellent job in dampening the vibrations caused by the printbed moving back and forth. The 4 damping extension brackets on each corner handle the vibrations of the enclosure very effectively.

So, very happy with the total package!

Have fun with this design and let me know when you use it. Love to see those pictures!

Happy printing!