LM2596 / LM2596S step-down converter with voltmeter – neat case / enclosure

These little useful PCBs are produced by many Chinese manufacturers, so the dimensions of the boards and the position of the components may differ sometimes slightly and sometimes significantly. Before printing, make sure you have the same version of the board. The dimensions of my board is 56.0x35.2 mm, the adjustment screw is shifted 2.6mm from the center to the right. Also look at the photos that I attached to compare the position of other components.

This model is designed for 0.4mm line width and 0.2mm layer height. Other values will result in less accurate print and may result in compatibility problems. I printed all the parts with PETG, but you can use any plastic you like.

Print with orientation like in STL files without support. The top part has a small built-in support near the voltage indicator that should be removed after printing by bending it to any side with your fingers.

If you need a one-color enclosure, then print just “top.stl” part. The labels will be engraved 0.2 mm into the top surface. You can use a permanent marker to make them more visible after the print is done. Then print the “bottom.stl” part and 2 “button.stl” parts.

If you need a multi-color enclosure, make it as follows:

1) The model “labels.stl” should be arranged exactly at the center of the bed (if it’s not, use “center selected” in Cura). Insert filament for the labels, print “labels.stl”. 

2) When the print is done, DO NOT COOL DOWN THE BED! If it is cooled down automatically, set it to 70 degrees at once to keep the printed labels glued to the bed, otherwise they may unglue before you start printing the top part.

3) The model “top.stl” should be arranged exactly at the center of the bed (if it’s not, use “center selected” in Cura). Now change the filament to the color of the top part and print it. The model should be printed in an ordinary way - from the Z=0. There is no need to change it to 0.20 because the model already has empty spaces exactly at the same places where the labels are printed on the bed in step 1. Finally you will get absolutely flat top surface with the labels of different colors inside it.

4) Don't go away from the printer while layer 1 is printed: you should control that the quality of the labels is good before they are covered with layer 2 and become unseen. The reason for it is that if you have bad adhesion to the bed, the nozzle can unglue the thin labels and the whole thing will be spoiled - you'd better stop the job at once and reprint it. At first I had such a problem and couldn't print the labels well, but I solved it by buying isopropyl alcohol to clean the bed and special glue-spray to improve adhesion - the small labels stick to the bed perfectly now as you can see on my photo. 

5) Remove the top part from the bed and print the “bottom.stl” part of the same color.

6) Change filament to the color of the buttons and print 2 “button.stl” parts. As they are very small, I recommend to print them separately to make their shapes more accurate. If you print them at once, you may have some shape deformations that will make them hard to use.

Assembly.

Put the PCB on the bottom part, put the buttons inside the holes of the top part, cover the top part with the bottom part. In most cases the assembly is complete now. However, depending on the printer you use, the connection between the top and bottom parts may be weak as I increased the tolerance for the pins because some printers don't print circles perfectly. I mean there is a chance that the case may disassemble by itself when you shake it. This model is designed to be in closed state with the help of friction only , but if friction is too weak, you can SLIGHTLY heat the tips of the pins on the bottom part with a gas lighter and SLIGHTLY bend them to opposite sides. Don’t push too hard, you only need to bend them 0.1mm and this will be enough to keep the case reliably closed. Alternative solution, if you don’t plan to disassemble it in the future, add a drop of glue on the pins of the bottom parts before joining it with the top part (do it only when you are sure that you are satisfied with the case and no other improvements like enlargement of holes with a file required). And the most tough solution is to cut off 4 pins on the bottom side, drill 4 holes in their places and use metal  screws to fix both parts together. But still I'm quite satisfied with the original variant without glue and screws because I can easily get the PCB out of the case at any time easily.

I share this model FREE for all electronics enthusiasts. The model and the prints made with this model are not for sale, however, you may print it to your friends and charge them no more that the price of the plastic you used to print it :)