First design of a complete novice, MS Surface Pro holder

[dmehling]

I am a complete novice to 3-D printing, and this is my first project. My design is a holder/tray for a Microsoft Surface Pro 4. I have attached a very rough design that I created in Tinkercad. All of the dimensions are nowhere near correct, but this is intended only to demonstrate the actual shape of the holder, since there are so many different types out there. This is simply the base. I have yet to add in side supports. I will have supports on all four sides sides to hold the tablet securely to the tray. At this point, what I really need to know is what material I can use and what the minimum width and thickness should be of the eight "planks". I am wanting to make it as light as possible, yet strong enough to support my nearly 2 pound tablet and a couple of USB accessories that will be secured to the tray as well. I would prefer to use ABS or Nylon, but I have no clue if they are strong enough.

[LambdaFF]

The advantage of 3D printing is you can iterate as much as you want for a small cost.

Use good engineering judgment : make it 5mm thick, use 3 shells. For materials, use nylon or PETG. PLA melts too low, if the table heats a bit, you'd take risks. For a wide flat part like this ABS is not the best choice and might be tricky to successfully print.

If it doesn't work, try again ;-)

[ServiceXp]

For me, this is where all the fun is. I have no design ability but with low cost repetition I'm typically able to create a solution for a problem. Like LambdaFF says.. "If it doesn't work, try again".

[dmehling]

The advantage of 3D printing is you can iterate as much as you want for a small cost.

Use good engineering judgment : make it 5mm thick, use 3 shells. For materials, use nylon or PETG. PLA melts too low, if the table heats a bit, you'd take risks. For a wide flat part like this ABS is not the best choice and might be tricky to successfully print.

If it doesn't work, try again ;-)

I forgot to mention something really important. I don't have a 3-D printer. I was going to use a 3-D printing service since I don't have many projects planned for the future. So I need to have a better idea of whether this will work without being able to make and learn from mistakes.


So what are the vantages and disadvantages of nylon and petg, and which would be better for this project in terms of weight and strength? What is the problem with ABS?


Lastly, what do you mean by three shells? I'm not familiar with that term in this context.

[dmehling]

No response yet? I didn't think my questions were that complicated. What I really need to know is how thin can I make my tablet holder and how narrow can I make the perimeter section and crossbeam sections. I don't know if these are the best terms, but I think the picture makes clear what I'm talking about. I am considering nylon, but since my last post, I've also been thinking about aluminum. I did several Google searches, but cannot seem to find any info as to weight-bearing strength of these materials. Perhaps I don't know the right terms since my engineering background is essentially nonexistent.

[ServiceXp]

Your question, at it's core, is quite complicated. I think even for a material engineer there would need to be a lot more information required to properly answer you. I believe most users that frequent this forum are what I call trial-and-error makers, not professional engineers. We could throw out all kinds of guesses, that relate to what we've made in the past with the material and equipment we own, but I think the scope of that information may be too narrow, and could lead to a costly error for you.

I would try and get some help from the printing service you plan on using or an engineering forum.

[dmehling]

Your question, at it's core, is quite complicated. I think even for a material engineer there would need to be a lot more information required to properly answer you. I believe most users that frequent this forum are what I call trial-and-error makers, not professional engineers. We could throw out all kinds of guesses, that relate to what we've made in the past with the material and equipment we own, but I think the scope of that information may be too narrow, and could lead to a costly error for you.

I would try and get some help from the printing service you plan on using or an engineering forum.

Thanks for the suggestions. I didn't quite realize how difficult it was to make an educated guess. Is there a particular printing service that could advise me on my design before printing?

[ServiceXp]

Maybe one of the participants @ https://www.3dhubs.com/

[LambdaFF]

No response yet? I didn't think my questions were that complicated. What I really need to know is how thin can I make my tablet holder and how narrow can I make the perimeter section and crossbeam sections. I don't know if these are the best terms, but I think the picture makes clear what I'm talking about. I am considering nylon, but since my last post, I've also been thinking about aluminum. I did several Google searches, but cannot seem to find any info as to weight-bearing strength of these materials. Perhaps I don't know the right terms since my engineering background is essentially nonexistent.

As I already said ... ABS is not a good choice : as it has a high shrinkage ratio, it warps. Since you intend to make a flat wide part, it is not a smart material choice. Tritan, PETG and nylon are Ok choices, it's mostly about what you have at hand.

Regarding why we are not giving you a solution : the results depend on several branching choices you have not mentioned. You don't need to be an aeronautics engineer to know this : you can trade thickness (to a point) for infill rates, the number of shells weighs in, sharp corners create weak areas ...
But then, your requirements are somewhat blurry. What do you want it to stand to ? What is the max authorized static deformation ... ? What is the load case ?

So, unless you ask with proper engineering parameters, you don't get an engineer answer. ;-)

As a starting point, and given the the overall idea, I would advise you to :
- put a 5mm thickness on your "lateral supports"
- put 10mm on the base thickness
- put 1,5mm of shell thickness
- put 25% infill.
- add 5mm chamfers in all corners

I think there's 95% chance it will work. You want it slimmer & sexier : make iterations, ask with a clear specification or pay for a design. With the new surface 4 out the door, I'm pretty sure people will make stuff. I for one know I'll have to prepare something for my wife. Tell you in 2 months.

As for aluminium : good point but at this time, given your design, better get it machined than 3D printed. Also the cost compared to nylon won't be competitive, and compared to a plastic part that can be honeycombed, it will be heavier.

[dmehling]

I'm not that familiar with much of the 3-D printing terminology yet, so I don't quite understand everything you said. I have created another design where I have indicated the thickness of the sections, just to make sure that we are talking about the same thing.


As far as shells and infills are concerned, is there a scaling principle involved based on the thickness of the material? For example, I read an explanation of shells and infills, and based on the example pictures of a cube measuring 1 cubic inch, three shells appeared to be only a millimeter thick. And a 25% infill appeared to have chambers/cells that were about 2 millimeters across. Now, I can understand using three shells for my design if the vertical thickness is 1.5 millimeter, but with 25% infill, I don't quite see how that would work. So that's why I was wondering if the size would be scaled down. Maybe I'm misunderstanding something.