How to Design and 3D Print Laptop Stand
by minhkhoitrannguyen in Workshop > 3D Printing
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How to Design and 3D Print Laptop Stand
I currently work as an Assistant at SUNY ESF - Office of Sustainable Operations and Facilities. As part of my responsibilities, I design and create this simple Laptop Stand to help my boss's laptop release the heat better and also to improve.
- The goal of this project is to work with tolerances in 3D printer better because my last project I did not do well on tolerances thing.
- Also the next goal is to applied the use of Force diagram into design process. As my future DIY projects will involve a lot of force calculation. Just wanted to prepare in advance.
- The final goal is involve the use of concept Design to Standard in simple project to prepare for future project.
Supplies
For this project, you need the following tools:
- CAD software, in this case I used SolidWorks.
- 3D printing machine, in this case I used Gigabot (for parts have dimension larger than 20 x 20 x 20 cm) and Maker Gear M Series (for parts have dimension smaller than 20 x 20 x 20 cm).
- Flowchart drawing software, in my case I used ConceptDraw Diagram software. Please make sure to download Physics (Mechanics) library from Concept Store. The purpose is to draw Forces diagram to visualize the forces acting on the Laptop Stand.
- Superglue to glue part.
Identify the Variables and Parameters in Your Design
So as you can see, the Laptop Stand I design and print has inclined feature, so there are several things we need to know:
- What is the best incline angle for incline Laptop Stand that still facilitate looking at the computer for a long time and also help laptop release heat good?
- What is the dimension tolerances for 3D printing, is there any difference between PLA or SLA? (I learned from mistakes from my last project, the 3D Foldable shelves, I did not have good tolerances there).
- The dimension of the laptop stand (mostly based on dimension of Laptop)?
The first question is already answered. Basically, the idea of incline Laptop Stand is not new, so there are a lot of information about it on the internet, including the incline angle. From the website I found, it is best to design the incline angle around 20 degree.
From this project, I also want to show you guys 1 engineering tip: When you design a project, try to do something that has features already been developed by industries. Because in the end, we just students, hobbyist, so we don't have enough time, energy and money to developed hundreds of prototype just to find the optimum solutions. By doing something industries have, you can easily look up for numbers, dimensions and make your design process go faster and reduced flaws. This concept in Mechanical Engineering called "Design to Standard".
Understanding Design to Standard
This is just an optional step for you to read for fun. I know about this concept when I was an Intern at TickLab (mech-eng lab) but I haven't have the chance to fully apply it into my project since this concept is only useful when you are involved in the manufacturing process.
Design to Standard means to design items with generally accepted and uniform procedures, dimensions or materials.
As you can see above are some examples of Design to Standard:
- For the 1st picture, you see PVC pipes have standards for inner diameter and even for length. So when you do design projects involving PVC pipes, you should follow these standard dimensions as all the dimensions are fixed, making your design process goes faster. If you try to create new dimensions, you will simply not buy it, you have to order a PVC company to manufacture new dimensions for you and it will be way more expensive because they have to change the whole production line to make those kinds of dimensions.
- For the 2nd picture, there definitely standards dimension for bolts and thread. One more advantage of Design to Standard is in SolidWorks there is a function called Smart Fasteners that if you design the holes in standard dimensions, it will automatically assign the correct bolts to that holes, saving you a lot of time.
Draw the Force Diagram
Because this Laptop stand will be manufactured by 3D printing. In 3D printing, usually you will not print a whole solid block, instead it's kind of hollow that has some infill matrix like picture above called Infill percentage. Usually the higher the infill percentage, the more force the 3D model can withstand.
Because of that, it is really worth drawing the force diagram to have an idea of all the forces acting on the structure. Picture of the diagram and top view of the design was provided below (I used my finished model just to help you guys easy to visualize, we will go to the design step next).
From my calculation, it seems like the vertical force on the Laptop Stand is around 3-4 N which is really light. So I think an Infill percentage around 15-20% is enough. To help you guys in future projects to choose a suitable infill percentage, I will include a link below, the 4th picture I took directly from that website:
What Is Dimension Tolerances
Tolerance is the total amount a dimension may vary and is the difference between the upper (maximum) and lower (minimum) limits.
Tolerance exists in every manufacturing, surface finishing processes such as CNC cutting, molding (used for plastic), casting (used for metals), 3D printing, laser engraving, welding,...
There are 2 types of tolerances:
- Dimensioning
- Fittings
The first picture I provide is the tolerances for dimensioning only.
Usually the tolerances is not a problem unless we create holes and cylindrical shapes for fittings and tightening. Imagine you want to do tight fitting between a cylindrical shape and a hole. The hole has inner diameter around 15 mm, and the cylindrical shape has diameter around 10 mm, resulting in a really loose fitting.
- As you can see in the 2nd picture, this is my past project, the fitting inside the black circle was really really loose, and it didn't function well as tight fitting.
Another problem may arise is when your hole is around 15 mm but your cylindrical shape is 17.5 mm. At this point, you cannot fit the cylindrical shape through the hole anymore.
- Usually in professional engineering, they have a chart for tolerances in holes and fitting, usually denoted in letter. You guys don't need to know this as it is really rare for non-engineering major to used and really pain in the ass.
Believe me, when I'm in my Engineering drawing class, we have to study this chart and memorize it @@.
Sketches Your 2D Stand
For those who don't know, any 3D design first will involve the 2D sketches of your design. Usually you will start your 2D drawing with the most important features in the design. As you can see in my laptop stand, the incline is the most important feature in my design so we will begin to draw first.
- First step is to draw 2 sketch lines that create an angle of 12 degree like the first picture. These are construction lines to help you navigate and fixed your other dimensions.
- After that, just draw the other features.
Draw Your 3d Model
After that, just finishing with all your parts and assembly the model. Above is the picture of my complete model with and without the computers.
As you might wonder, actually I didn't design the computer, I download it from 3D CAD Model library. The next step is where we applied the idea of Design to Standard in Engineering design.
Take Full Advantage of Engineering Library Like Grabcads and Thangs
Usually, engineers don't often design every single part on their own. For me, if that parts I feel that it is so common, I will just go to 3D model library like Grab Cad or Thangs to download the file.
In fact, in my old projects like Compressed Can Machine, I download the DC motor from Grabcad.
However, do note that some people design model using the most recent versions of CAD Software. SolidWorks for ex, I used version 2018, so if someone design model using version 2019 or above, I cannot open that file.
So if you upload things on CAD library, please convert it into STL file, so that everybody no matters of version can open it.
Like an old saying: "If someone already inventing a wheel, you don't need to reinventing it again".
How to Find Tolerances for 3D Printer?
After you finishes your model, now you start to account for tolerances in your design:
So from what I understand, the printer we use is the 3D PLA printer. So the tolerances in those machines depend a lot on the tolerances of the filaments. For ex, look at the Novamaker filament, you see they have tolerances 0.02mm, it means that in this filament, the true diameter will be in the range 1.75 +- 0.02 mm. So if you buy 100 filaments of Novamaker, the true diameter will fall between 1.73 and 1.77 mm.
- Varying in diameter will affect the dimension of the object too.
- Of course, for each filament, they have different tolerances. So make sure to ask your 3D printing technician in advance to account for tolerances in the design. As you see, Hatchbox has tolerances around 0.03mm.
Understand more about 3D printing tolerances.
Another way for you to check for tolerances is via trial and error. Simply said, you have a hole with diameter 15 mm. And said you want to create small cylindrical shape that tight fit with this hole. You will start with 13 mm, if it's not fit then go for 13.5 mm, 14 mm and 14.5 mm until you feel the degree of tightfit is suitable for you. As you can see, I print several cylindrical with sizes from 13 to 14 mm just to see how it fits with the hole. Because I'm the man of realistic, I never 100% believe on the parameter provided by producers.
- As you can see for my 13 mm cylindrical shape, there are a lot of spaces, which makes it loose fitting while I want tight fittings. So I have to increase my size a little bit to reduces the spaces.
- For 14 mm shape, the spaces actually negligible, so I would say around 1 mm is the tolerances for this 3D printer machine.
Support Features in 3D Printing
Actually, from step 6, 1 reason why 1 mm is the good tolerance for my cylindrical shape is because of the bad surface finishing from support structures in 3D printing.
So Support feature in 3D printing is the added part that supports the overhanging structure that needs to be removed after printing. As you can see in the 2nd picture, when you have overhanging feature, due to gravity, the hanging feature will fall down, causing your 3D design to be incomplete.
Read more about support structures
For my cylindrical shape, because if it is printed in vertical direction, due to the ratio of height/ diameter is too high, the model will face overhanging, leading to distortion in shape. That's why they have to print it in vertical direction, adding supporting features. I did not take the picture of the supporting structures, so I draw a quick 3D models to let you know how the supporting structures look like for my cylindrical shape.
- After finishing my 3D cylindrical shape with supporting structure, that part needs to be cut away, thus it results in really rough finishing like this, which is why it affects tolerances a lot.
Note that for other manufacturing process, there are several ways to do finishing to make the surfaces of objects smoother. However, in SU Makerspace, we don't have that kind of machines yet.
Print the Model
At this time, your 3D-printed model is ready. This is really simple Mechanical Engineering project but I tried to incorporate some concepts that is really essential into this project just to practice and be familiar with them for future projects.