First design of a complete novice, MS Surface Pro holder

[LambdaFF]

...
I think it would be great if you could just, you know, open the Cura Manual or read a bit about print prep.

The total shell thickness is linked to 2 parameters (in FDM printing) : the diameter of the printer nozzle and the number of shell-paths. Say you have a 0,4mm diam nozzle, you print at 0,45mm width and you decide to have 3 shells : total 1,35mm. It is the max external paths thickness on any horizontal slice (layer).

The infill % is basically for any slice of your part the % of surface that is filled vs the total available surface.

If at that point you're wondering why I said slice in the above sentence, please follow advice number one and find some data on slicers.

The software also allows you to decide how many layers are completely filled at the bottom and top. This is how you get to decide the shells on the vertical axis.

Now, as you can see, you set a discreete number, there is no scaling. This is not part of the design either, this is set in the print prep software, generally called slicer.

If I read you correctly, you intend to do a 1,5mm thick support ? I'm sorry but seriously, I don't need to open a Finite Element model to tell you that it won't sustain the weight of a 1kg Surface, unless you just want to use it as a shim ? Even an aluminium sheet would probably bend noticeably.

I may err on the side of over-engineering but give considerations to the dimensions I gave you. Unless of course, you just want to raise the tablet, not actually support it ?

[MysteryAlabaster]

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.

For most printers, if there is no room for the number of selected shells AND infill, the printer will print as many shells as it can, basically rendering the object 100% solid.

Also, if you'd like I can help you out with prototyping.

[dmehling]

...
I think it would be great if you could just, you know, open the Cura Manual or read a bit about print prep.

The total shell thickness is linked to 2 parameters (in FDM printing) : the diameter of the printer nozzle and the number of shell-paths. Say you have a 0,4mm diam nozzle, you print at 0,45mm width and you decide to have 3 shells : total 1,35mm. It is the max external paths thickness on any horizontal slice (layer).

The infill % is basically for any slice of your part the % of surface that is filled vs the total available surface.

If at that point you're wondering why I said slice in the above sentence, please follow advice number one and find some data on slicers.

The software also allows you to decide how many layers are completely filled at the bottom and top. This is how you get to decide the shells on the vertical axis.

Now, as you can see, you set a discreete number, there is no scaling. This is not part of the design either, this is set in the print prep software, generally called slicer.

If I read you correctly, you intend to do a 1,5mm thick support ? I'm sorry but seriously, I don't need to open a Finite Element model to tell you that it won't sustain the weight of a 1kg Surface, unless you just want to use it as a shim ? Even an aluminium sheet would probably bend noticeably.

I may err on the side of over-engineering but give considerations to the dimensions I gave you. Unless of course, you just want to raise the tablet, not actually support it ?

I must remind you once again that I do not have my own printer. I will be using a printing service. I do not have the technical expertise to even begin to know how to do it myself. Most of what you have said about shells and infills and slicers is like a foreign language to me. Furthermore, none of the printing services I have checked will let me fine-tune things the way you are describing them.


The 1.5 mm support I was describing was apparently not at all what you were referring to. What I do know is that in the case of aluminum, I have a laptop tray as a reference point. It is able to support well over 5 pounds and it appears to be less than an 1/8 inch. Instead of four rectangular empty spaces, it has circular cutouts, but it's mostly the same amount of surface area as the design image I shared. This is only for reference. I know that nylon would not be as strong, but if I had some idea of the differences in specific strength between the two materials, I would be closer to understanding if my idea would work.

[dmehling]

For most printers, if there is no room for the number of selected shells AND infill, the printer will print as many shells as it can, basically rendering the object 100% solid.

Also, if you'd like I can help you out with prototyping.

I would definitely appreciate some help with prototyping. I should have realized how complicated my idea was, considering I am not an engineer.

[curious aardvark]

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

That is industrially strong !
Made a 5mm pla bar the other day. 4 shells 20% infill. Could just about flex it a mil or so, no chance of breaking it.

For strong stuff I use 2mm - for really strong stuff I use 4-5 mm.

Got a large plant trough with extendible legs - that's 4mm walls, It'd take a sledge hammer to damage the things.

To give you some kind of idea how strong 2mm pla is (and most other plastics are at least as strong).

The white thing on the drill in this video has walls made from 2mm pla, and yeah it's also pretty flexible, don't believe half of what these guys tell you about pla ;-) :



5mm I could jump up and down on.
I did stand on the plucker to test it's strength. About 90 kilos on the hoof.

Surface pro's don't weigh much.

And I don't get how a flat piece of plastic is a holder.

The answer to your dilemma has already been mentioned.

Find someone local to you on: www.3dhubs.com. They should be able to help you with the design and also print way way cheaper than someone like shapeways.

[dmehling]

Here is a better design that also illustrates better what I am needing to know: http://www.thingiverse.com/thing:395373


I will be attaching this mount to an articulated arm with a tripod style connector. 90% of the time I will be using the tablet in an upright position, so most of the weight will be on the bottom edge. The rest of the time, it will be rotated up. So I need both the bottom section with the holes and the bottom edge to be strong enough to support the tablet. I was able to open the STL file, and the thickness of the bottom section appeared to be 2 mm. Would that be enough if I was using nylon or PLA?

[dmehling]

Any thoughts?

[curious aardvark]

yes - read previous posts and find someone local to you on 3dhubs.

At least talk to them and go see a 3d printer in action. And handle some printed bits.

Nylon is completely different to pla - tougher but an awful lot more flexible. And a bastard to print with unless it's on an sls machine.

Pla should be fine. For that design I'd probably use 3mm for the base and 2mm for the side walls, maybe 1.2 depending on how much they'd need to flex.
But go find a 3d printer and you'll answer most of your questions much easier :-)