Prusa Mini mount for Qube500

Before everything I would like to say that since im not able to make this project myself (as much as i want to) I cant truly call this a finished project. 

With that in mind.  If anyone looks at this project and thinks “damn that's cool and I want to make it” and serious about it, feel free to contact me and ill gladly help remix it to your own specifications and fix any unforeseen problems with the design that may rise during printring and assembly.

An interesting thought:

As with every design, it started with an idea.

I looked at my PC and thought: “If it was a Qube500, What could I attach to it that could make my life simpler?”

(picture for reference)

I pondered that for a bit. Then I looked again at my PC and my printer next to it thinking: “What if that was there?”

“all the things I could put under it”

“all the table space it could free"

“It's so cool, I want to design it!”
 

Haters gonna ask why not just put in on a stool and to that ill answer “maybe” and “you are boring”     

For me and I'm sure that in many other cases moving the printer to a mounted position suspended next to the table could free much-needed table space for other uses.

A few design constraints to start with:

1. The design has to be modular.

Every single person has an entirely unique setup, there is no way  I could have made a “one design fits all”, it has to be modular. 

2. The design has to withstand the weight of the printer with a healthy safety factor

The absolute last thing I want is for a part to fail and have an Innocent printer tumble to its doom.

3. The design has to be lightweight

As to not impede more on the balance problem stated earlier.

4. The design has to be simple to make

I usually design projects that are entirely based on stuff I have on hand, with this project I decided to work only with materials and items that anyone in the world could get cheaply and easily.

5. The design has to be simple to assemble

as any seasoned maker would tell you having a bunch of press-fit connections contradicting each other could be quite a pain to assemble. Designing (relatively) loose fits and a streamlined assembly process is key.

A question of balance:

The first problem that came to mind is one of balance.

Realizing a Mk3+ is not a suitable candidate for this idea, I switched gears to working around the Prusa Mini, being a small lightweight printer would make everything much simpler. 

The Prusa mini weighs 4.5kg (9lb) which is light but nothing to ignore. in order for this idea to come to life first I must quickly prove that in everyday use (baring a cat jumping onto the printer) it wouldn't tip over. 

a quick Google search shows that most PCs weigh around 9-18 kg already twice the Mini and assuming we are going to put the material spools on the case I felt pretty good moving forward with the project.

(worst case you can add counterweights in or the other side of the case which should really delete the problem)

The design 

I took inspiration from Alexandre Chappel who worked with broomsticks and 3D printed parts to make furniture. I figured working on a similar form of frame design would be the best way to achieve these constraints.

Just switched broomsticks with carbon fiber tubes readily available in Aliexpress which are dimensionally consistent and considerably lighter 

decided to use 14mm diameter tubes mainly because they looked better in scale next to the Qube500 and I have experience with 12mm and know for certain it could handle way more than the loads applied to it by a Prusa Mini's weight.


Ended up designing a modular system of connections for 14mm nominal diameter tubes, presented as a way to mount a Prusa Mini on a Coolermaster's Qube 500 PC case. 

features showcase :

In order the make the connection point to the qube500 easier to print I split it into 2 separate parts connected by a dovetail. this way both parts can be easily printed without support

All the connectors have a “crush rib” feature in order to get a more consistent tolerance on the tubes. having a 14.3 inner diameter creates a close running fit which makes the assembly process a lot simpler

using low-tolerance fits and minimal points of contact can go a long way in a matter of simplifying the assembly process. 

The connection point to the printer is a snap-on connector that can be easily attached to the printer's extrusions with printed M5 T-nuts and then the entire printer can just snap onto the tube frame simplifying assembly and making it possible to instantly remove the printer if necessary.

The bottom R connector of the frame isn't rigidly connected to the Qube500, this way the load distribution across the system is much more predictable and reduces load concentration.

And incidentally simplifying the overall assembly.

Because the connection between the case mount and the tube isn't rigid, direct loads don't transfer between the two. 

To make sure the loads are distributed evenly across as many members of the frame a “load spacer” is added in the assembly.

A spool holder is added at the top of the frame for convenience. 

The entire design is modular, so it is your decision to add this holder or any other. remixed into the design or connected directly to Qube500 itself.

It's important to mention that for balance reasons I recommend that whatever way the spool is held, it should be located on the top of the case.

Statics force analysis:

Disclaimer: Becouse of the amount of variables, getting an accurate value for each of the forces would require a Finite element analysis (or at least a more complax calculation then i knew how to do).

This chapter is mainly to visualise the force flow through the frame and to show that generally all the parts should hold under the prusa mini weight. 

If you feel these numbers dont statisfy you you can alwees add more connection points between the frame and the Qube 500 to distribut  the forces even more

Free body diagram overlay on the cad:

• A: The point just under the Prusa Mini center of gravity
• B: The point of contact between the truss and the case - acts as a roller support
• C: The front mounting point of the frame to the case, due to the direct contact of parts in the load direction - acts as a fixed support
• D: The front top mounting point of the frame to the case. The fit between the mount and the tube doesn't transfer loads - acts as a roller support
• E: The back top mounting point of the frame to the case, due to the direct contact of parts in the load direction - acts as a fixed support

Simplified equilibrium equations:

I am excluding points D&E in order to simplify the calculation 

including them would devide the load across more points which will enable us to declare a higher factor of safety. With the simplified version I found it to be good enough for comfort so I didn't feel it necessary to continue further

• The weight of a Prusa Mini according to the Prusa website is 4.5kg (9lb) meaning it exerts a force of 45 Newton (mg=45N) 
• The distance between points A and B is 110 mm (AB=110mm)
• The distance between points B and C is 270 mm (BC=270mm)

Finding (Fcx) via the sum of Moments around point B:

This force is divided across 4 base hook mounts integrated into the parts. Meaning the acting force on each mount is (18.3)/4=4.5N

According to Qube500's design guide, the base hook mounts were tested at a 2kg load. This means the allowed force per mount is 20N

Giving us for the simplified equation an initial value for the safety factor of the system of 4.4

In simpler terms all of this say that the system could hold the wight of 4.4 Prusa Mini's before beginning to fail

B.O.M:

All purchase links are a suggestion. They are not affiliates and it really doesn't matter where you get the hardware from.

*parts for the spool holder

**Leftover cuts from parts 12&13

Assembly instructions :

I chose to assemble the frame this way because in my setup having the printer suspended in this way can save a lot of space and allow me to have room under the printer for storage.

As mentioned in the first design constraint, every setup is different and I encourage you to remix the assembly to fit your needs and fill your imagination.

We are all makers here and I don't see any reason to guide step by step on how to assemble the frame like it is an Ikea furniture. 

Just a few keynotes on the way I think will be the easiest way to assemble.

recommended order of assembly:

For the load-carrying joints, I recommend using epoxy glue to make sure they won't come off under the weight and vibrations of the printer. mentioned in the guide with “Epoxy”

recommnded to dry assemble all the parts before. Then disassmebling and applying epxoy were needed.

1. assemble the printer's shelf as presented  

*Note that one side of the “R connectors” (5) has a deeper bore, make sure it is aligned upwards. 

**Epoxy the connection between parts 5 and 13 

**Epoxy the connection between parts 4 and 13

2. connect the mounting points to the Qube500 as shown:

*Note the orientation of the mounting points.

3. assemble spool holder (optional)

4. Use M5x20 bolt and M5 T-Nuts to connect 4x “Printer Connector” (8) to the Prusa Mini's base.

Using the assembled frame as a guide, tighten the bolts in the correct position 

5. Final frame assembly.

**Epoxy the connection between part 6 and 12 (printer side)

6. place the printer

Congrats! you now have a Prusa Mini mounted on a Coolermaster's Qube500 PC case. 

Have some Haribo gummy bears to celebrate! you deserve it!