Leeloo
Posts: 22
Joined: Fri Oct 06, 2017 9:53 pm

advice from anyone with case printing experience

Fri May 25, 2018 1:01 am

Hello

Im thinking of making a case for my pi using software and 3d printing it, I would say I am somewhere between beginner / intermediate when it comes to making 3d models... at least with the ancient 3d modeling software I used way back in collage but it the only thing I really know how to use.

I don't have a printer and was planning to use an online printing service (when it's done TM) where I would have to pay something like $10 then wait to see if it came out right afterwards, so no real test prints to make sure things are lined up.

I managed to make a basic looking but accurate mock-up of the pi board but have few questions I am unsure abouts

1/scale, my software didn't like making things too tiny and wouldn't let me change the decimal place from meters :/ so for now my scale is set to 85mm = 0.85 meters (off to a terrible start but I figure I can scale it correctly in post using other software or the site )

2/any recommended (free) software I can use (blender does not like me)

3/suggest any good reliable sites that will print ? (I was thinking of trying one called sculpteo has international shipping and really the main one that came up when I searched for 3d printing online)

4/Im thinking of a much bigger case than the usual Pi ones but still think compact, i want it big enough so I can fit the board, a drive and guts that go with linking it to the pi, probably have the usb ports internal. generally how big is ok for 3d prints ? 16cm*10cm*2cm sound good?

5/would the build thickless controlled by the print or do I have to specify?

6/how sturdy are 3d prints ? should I be concerned about adding support structures?

7/will I also need to add temporary support structures too?

any other advice ?

probably going to be a hard project but will be fun to at try I think :D

Thanks

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Z80 Refugee
Posts: 358
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Re: advice from anyone with case printing experience

Fri May 25, 2018 9:36 am

I've not printed a case, but I have done a little 3D design and print.

> 2/any recommended (free) software I can use (blender does not like me)

I use FreeCAD. It takes a bit of learning and it helps if you have 2D drafting experience, but even then the concepts of extending that to 3D require quite a bit of new thinking. Use YouTube tutorials, or even better see if there is a local college doing on-off introductions to 3D (I found one very useful). You should not have any problem with scale, and I wouldn't recommend Blender for engineering jobs (it's more of an artists tool).

> 3/suggest any good reliable sites that will print ?

I have had work done through https://www.3dhubs.com/. Be aware that service providers may just be hobbyists at home trying to make a little money out of their domestic 3D printer, but professional outfits may well be a lot more expensive. If you can pick up somebody locally to you, you may be able to arrange to go and see it happening or have the odd trial-and-error.

> 16cm*10cm*2cm sound good?

Should be, but the larger it is the fewer providers you will be able to choose from and the more expensive the print will be.

> 5/would the build thickless controlled by the print or do I have to specify?

The design is not flat like on a piece of paper. The design files will explicitly state all the wall thicknesses, and that is what will be printed (there is a minimum thickness of course). You are designing the shape of a volume, and the volume has to be explicitly bounded form all directions (even from inside). If you miss something out, the design won't "compile" (ie produce a printer output file from the design file).

> 6/how sturdy are 3d prints ?

I have four holding the hub caps on the wheels of my car - I needed adapters when I changed the alloys but wanted to keep the original caps (which no longer fitted). Just don't make the walls less than maybe 2mm thick (3mm would be better).

> 7/will I also need to add temporary support structures too?

Only if you need overhangs. The item is printed from the base up, so any "horizontal" surface should be the first thing printed otherwise it will need something to support it. Typically you would design a box to be in two parts: the base and four sides, and then the lid (which you would print upside down). If you want to print apertures, you will need a support structure in them, but the compiler may add these for you automatically. This is where an introductory course comes in handy.

> any other advice ?

Yes: Don't dive in at the deep end. Start with something simpler. Alternatively, look around for an existing ready-to-print open source design file.
Last edited by Z80 Refugee on Sat May 26, 2018 8:02 am, edited 1 time in total.
Military and Automotive Electronics Design Engineer (retired)

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scruss
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Re: advice from anyone with case printing experience

Fri May 25, 2018 12:57 pm

Z80 Refugee wrote:
Fri May 25, 2018 9:36 am
> any other advice ?

Yes: Don't dive in at the deep end. Start with something simpler. Alternatively, look around for an existing ready-to-print open source design file.
Absolutely this. There are thousands ( > 3000) of Raspberry Pi case designs on Thingiverse. Maybe there's one out there that does what you already need. Try to choose a design that has lots of builds and positive comments. Many designs on Thingiverse are untested, so might be completely useless for printing.

Additional thoughts:
  • there are 3d models of Raspberry Pi boards on GrabCAD and Thingiverse. They are very helpful for sizing your design or even using as a subtractive part.
  • Design in millimetres. 3D printing assumes mm. Even files with no dimensions (= most CAD formats) are assumed to be in millimetres.
  • You can easily modify most 3d models in tools like TinkerCAD (online, decent if basic) or OpenSCAD (it's like a weird version of C crossed with Lisp but it's what I use)
  • Some materials change size as they cool. ABS (the first FFF 3D printing filament) is notorious for this. You may have to build that sizing in for some print vendors.
  • If you need toughness without the hassle of shrinky, stinky ABS, PLA+ prints easily and is much less fragile than standard PLA. It's a little more viscous than PLA, so you'll have to slow down printing outer layers.
  • It's probably worth seeing if a local library or makerspace has cheap access to 3D printers. Sending out to print bureaus is expensive when you're iterating a design.
  • I don't want to presume your financial situation, but the Monoprice MP Select Mini 3D Printer is a great 3D printer for not much money. It's got a small print volume (max dimension 120 mm) and isn't very fast, but will likely pay for itself in a few design iterations.
  • If you print things yourself, don't get carried away by the thousands of options available in slicing software and people's robust opinions on forums. Stick with learning the limitations of your printer and your material, and — unless there's something mechanically wrong with your printer — you'll get pleasing results.
‘Remember the Golden Rule of Selling: “Do not resort to violence.”’ — McGlashan.

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Z80 Refugee
Posts: 358
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Re: advice from anyone with case printing experience

Fri May 25, 2018 9:30 pm

scruss wrote:
Fri May 25, 2018 12:57 pm
MP Select Mini 3D Printer
Nice! And once you have a basic 3D printer, you can use it to print parts for your next 3D printer.
Military and Automotive Electronics Design Engineer (retired)

For the best service: make your thread title properly descriptive, and put all relevant details in the first post (including links - don't make us search)!

Leeloo
Posts: 22
Joined: Fri Oct 06, 2017 9:53 pm

Re: advice from anyone with case printing experience

Sat May 26, 2018 2:33 am

wow I hadn't imagined I would get such great feedback, answered everything I wanted to know! then answered something I thought about asking but didn't post, I considered mentioning budget 3d printers and had previously looked at a delta printer as an option the MP Select seems even better priced.

I checked Thingverse thought it had exactly what I wanted, small computer style case that i can fit the pi and a bunch of other bits and pieces inside but wasn't exactly as planned as it turned out to be miniature and really could only fit the pi board.

I think I was jumping in the deepend, Thingverse suggestion got me thinking I can probably find existing project files as a good starting point for the board mounting and port positions and to help figuring out how I can make the top and bottom join up and modify as needed.

thank you so much for the responses :D

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bensimmo
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Re: advice from anyone with case printing experience

Sat May 26, 2018 8:31 am

As above.
Base your design on Thingiverse designs.
I've not edited a lot for 3D printing, but some 10 years ago I did use TrueSpace and some 3d programs for various things.
and I did use to program in G-Code for micro-machining.
Unfortunately, a lot of 3d printing is trial and error, so do find someone local, maybe pop you general location up and someone here may have a 3D printer you can go and be 'taught' on.
Maybe a MakerSpace is near you if you are lucky or a School/College where you can learn or use them.

This is probably the best one to start with, it's tried and tested over the years and has been modified by many to their own designs.
https://www.thingiverse.com/thing:922740

Read the comments and you'll probably learn more than I know about printing a case out.
I use a Kossel style (3 rods and a static base), it's fun but getting things to stick to the base due to the cooling is a pain. I need to reprint a new workpiece duct, but I only have PLA and well they keep melting when in use ;-)

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Imperf3kt
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Location: Australia

Re: advice from anyone with case printing experience

Sat May 26, 2018 9:21 am

Note: all prices in Australian dollars

3D printing a Pi case will cost you a lot more than $10 if you use a professional online service - last time I looked, the cheapest SLA service I could find wanted 15 cents per cubic cm (measured in volume, not material used. It is called bounding box.
That was of course, with a lead-time of ONE WEEK. (aka, one week before they even START to print your project)
For a Raspberry Pi case, you need:
85.60 mm × 56.5 mm × 17 mm (3.370 in × 2.224 in × 0.669 in) (taken from wikipedia) plus a few mm for the case. Lets say you print the side walls at 1.5mm thick (any less might be too soft/flexible)
88.6 x 59.5 x 20 mm
So we have 105.434 cubic cm. At 15 cents per cubic cm thats 105.434*0.15 = 15.8151
so you're looking at almost $16 for just a rectangular box with 1.5mm walls and presumably cutouts for the ports. Then you need to pay for shipping (probably around $7)


For the software: Blender actually will not do the job - you need CAD software, which Blender is not. Sure, you can design your case in Blender, but you will not know how big it will print, for that you need the accuracy of CAD design tools.
I use FreeCAD myself, and its very easy to learn after an hour or so of fiddling and having a quick look in their forum if you get stuck.
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MarkJ62
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Location: Sydney, Australia

Re: advice from anyone with case printing experience

Thu Jun 07, 2018 2:10 pm

I just paid a professional company to knock up the design on mine. I provided them with the mechanical schematic from somewhere on here so they had the details of the Pi. I didn't have the time or any CAD experience so I turned up with paper drawings and spent an hour with the designer getting it into the software. Of course they charge by the hour for their time so that wasn't cheap. I think it was well worth it as they suggested changes and as I had fan holes in the case got the details for that so they were a perfect fit.

One of the advantages of using a professional company is they tend to have industrial grade printers so can print larger objects. I was able to get 3 cases out of a single print run. My cases hold 4 Pis side by side and are approx. 33cm wide. They have a top piece (white) and a bottom piece (red) so really it was 2 runs, one for the top and another for the bottom. That got the cost down to $177 (AUD) for each case.

The finish isn't that great with 3D - you can see the lines where the printer has been and there were blemishes where it started or finished. Injection moulding produces a smoother finish.

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