RTL-SDR dongle case & some design tips for FDM technology

RTL-SDR dongle case - Finished design

Finished design

I thought that you might like to see my “one day projects”, I’ve got mainly inspired by the Adam Savage “One day builds” series which are published on Tested (YouTube channel). So from now I will publish short posts like this one about my one day projects ,they will be tagged with [#One day projects] tag. I will also try to add something more to each of these posts. I hope you will like it  🙂

Today I will show with you a nice looking RTL-SDR dongle case which I’ve designed and printed in about 3-4 hours.

NOTE: This case fits only to the blue R820T2 based dongle with a SMA connector soldered at the bottom side of the PCB.

Some “features” of this design:

  • Improved air flow when comparing to the original one
  • It looks nice  🙂
  • Very durable
  • Easy to print and assemble
  • It fits to the SMA RF connector

Recommended printing settings:

 

RTL-SDR dongle case - 3D printing

3D printing

  • Layer height: 0.1 mm
  • Heated bed: 90 deg C or more
  • Printing speed: 40-60 mm/s
  • Filament: ABS/ASA
  • Infill: 25% (Grid) or more
  • Outlines: 2 or more
  • Top/Bottom 100% layers: 4 or more
  • Support: No
  • Nozzle diameter: 0.4 mm
  • Extrusion width : 0.4 mm

Links to .STL & CAD files:

  1. Grabcad [CAD]: https://grabcad.com/library/rtl-sdr-dongle-case-1
  2. Thingiverse [STL]https://www.thingiverse.com/thing:3093321

Assembly instructions:

RTL-SDR dongle case - Assembly instructions

Assembly instructions

RTL-SDR dongle case - Parts 2

Parts 2

RTL-SDR dongle case - Parts

Parts


How I’ve designed it:

RTL-SDR dongle case - Some dimensions

Some dimensions

I started with drawing a rough model of the modified dongle PCB. I’ve modeled all big components on the PCB that might interfere with the case. So that I can measure everything in the CAD software and adapt the case to the dongle very easily.

  1. I designed some tabs around the PCB that will hold it firmly after putting everything together. Of course every of these tabs sits in the place where the PCB has no soldered components,
  2. Then I’ve rougly outlined the shape of the case around the PCB which I modeled before,
  3. Then I created a assembly with these unfinished halves,
  4. After checking for some dimensions and clearances, I’ve added holes for screws,
  5. In this stage I’ve added some chamfers and fillets to improve overall external appearance and get rid of sharp edges that doesn’t print too well in FDM technology,
  6. Later I’ve shrunk the whole case around the PCB to reduce it’s size as much as I could,
  7. In the last step I’ve added: some text on the sides , vent holes to improve the air flow and a hole for the SMA connector of course.

And that’s it!, really nothing special 😉

RTL-SDR dongle case - Design process

Design process

RTL-SDR dongle case - Design process 2

Design process 2

RTL-SDR dongle case - Design process 3

Design process 3

RTL-SDR dongle case - Design process 4

Design process 4

RTL-SDR dongle case - Design process 5

Design process 5

RTL-SDR dongle case - Design process 6

Design process 6

RTL-SDR dongle case - Design process 6

Design process 6

RTL-SDR dongle case - Finished design 3

Finished design 3

RTL-SDR dongle case - Finished design 2

Finished design 2

RTL-SDR dongle case - Finished design

Finished design


Some design tips for FDM technology (without soluble support, one material) :

 

Probably most of these tips are quite obvious for more experienced people, anyway someone might find it interesting , so let’s start!

  • Avoid extreme overhangs
  • Always try to design the whole thing in the way that it can be printed without any support material
  • If you need to add some holes for bolts/screws always make them bigger if you don’t want to drill them to make them fit (for ex. add about 0.15 mm or even 0.2 mm to every 3 mm dia. hole)
  • Avoid thin vertical walls , It really depends on your printer setup but you shouldn’t go for single or double extrusion walls.  Usually these walls doesn’t look good, they are not durable either.
  • I found that the thickness of 3 mm of every vertical wall works the best along with the 0.4 nozzle and a 0.45 mm extrusion width (We need to have some free space for the infill, in my case I have about 1.2 mm of free space for the infll [4 x 0.45mm perimeters = 1.8 mm ]) If you don’t have some space for standard infill ,some problems with the pressure in the nozzle might appear (especially if you are slightly over-extruding)
  • Avoid vertical dimensions that can’t be exactly divided by the layer height
  • Avoid very sharp edges, they don’t print well in this technlogy , always apply some fillets and chamfers.The print will look nice and the risk of appearing any ringing or ghosting is greately reduced
  • Always add clearance in places that must fit other objects (For ex. I’ve enlarged the USB connector slot by 0.15 mm in the vertical plane)
  • I’ve found that text extruded 0.25 mm to the inside of the print (concave to the inside) works the best.

A few more photos:

RTL-SDR dongle case - Finished 3

Finished case 3

RTL-SDR dongle case - Finished 2

Finished case 2

RTL-SDR dongle case - Finished

Finished case

As always, you can post comments down below↓↓ (If you have any questions feel free to ask):