I am sitting on a complete line of PCBs ready for production. These PCB all have the same height of 55mm. (and with height I mean the horizontal PCB size in PCBnew)
I am still working on ideas for making the enclosures. Using laser cutting service and make wooden or cartboard boxes (does not have to be extremely sturdy) is a viable option.
I have used PCB as front panels before. I liked the results with dem pritty silk layers. So I was thinking to make a complete enclosure out of PCB. If you order 30 side panels of 5 x 2 cm, the price per panel is already a few cents.
Front panel and main PCB would connected via bolts and the sides would be clamped in. Anyways were I to make something like this. So that PCBs properly interlock (while taking the 1,6mm thickness in acount)
What tollerances should I use here? I order at JLCPCB. Ofcourse I don’t want it too tight nor too lose I figured that I cannot possibly the first person who has thought of this. So I was wondering if people here did the same?
I also think it is good idea to order a trial batch with several tollerances in a single design so I can see what works best.
I also won’t order panelized boards because the mousebites would not be pritty.
You could have interlocking tabs (1.6mm long to align with 1.6m PCB thickness) and arrange pads/SMT strips at the intersections and solder them together . . . I’ve seen something similar done by a Maker with a LED dice/cube https://youtu.be/6NPTslF68Q0
Each PCB fab should have a mention on their site for the tolerance of PCB routing. A first guess would be a tolerance of about 0.2mm The machines are more accurate, but I guess it’s done “quick” and the router bit may flex a bit during routing.
I just measured the only PCB I had fabbed in the last few yeas
48.32 by 48.45 while according to the gerbers it should be 48.26 square.
Also, inner corners are never sharp and always have the radius of the router bit. For routing out of sheet material (plywood, plastic, etc) Mechanical CAD software often can add “dogbones” automatically to make corners in such cases fit.
Designing and making boxes this way is fun to do, but assembly for larger production runs can become a real chore because of the many parts to manage.
I also do not like the sight of the castellations. If you have just straight strips (of any material) then you can glue them to either the top or bottom PCB to make some enclosure.
There are also quite some (semi) DIY methods for making custom enclosures out of different materials with either a CNC router or laser cutter. And both these machines are quite affordable, and after a learning curve it’s just throw in a sheet and go drink some coffee (preferably black) until the machine is finished.
Thanks folks. That’s some interesting reading food. That LED cube is one laborous job though
I think I will make a test PCB and not forget to make those dogbones. JLCPCB does not seem to have listed how thick their tooling is. Gonna ask custommer support for that.
I got a proxxon multitool and a XY table. I am yet to use that one to mill those plastic enclosures. Without stepper motors I cannot make big round holes. + it gives a mess. I secretly do like the idea of getting me a laser cutter.
They also state they don’t support square inner corners:
My best guess is that if you draw square inner corners, they will silently use any bit to their liking, while if you draw a radius, their automatic tool changer will select a tool that can route that radius, and the minimum radius seems to be 0.5mm. Thinner tools are considerably slower in production, so they will have a preference for bigger tools.
One reason to prefer acrylic is because the material is cheaper so they offer more area for a nominal price. And lasers can make sharp corners, unlike milling bits. Here’s the one I saw a while back.
Colours cost more though. If you do a search you will find the fab that offers this price. I don’t want to advertise for them. It’s not one of the 2 majors in CN but they have done good PCBs for me in the past.
And here’s a project from Hackaday that’s often cited which can generate many shapes of boxes: Boxes.py | Hackaday.io 150k+ views and 400+ likes, that’s impressive!
If user has collection of Ideas on how to interface each PCB in the box, including Corner-Edge mating features/etc and knows enough about searching for Hardware to accomplish it (such as at McMaster-Carr) and can use FreeCAD (or other…) then, building the Assembly is easy.
Certainly, the details are important and, a good starting place may be in Kicad’s PCB, then loading the PCB in FreeCAD using StepUp.
Quick Example below… I did Not spend time to make Corner/Edge mating features but, doing it isn’t difficult - just need to decide what/how to make them. I left the Circular protrusions as-is (I could have taken care of this in Kicad or, Cut them off in FreeCAD).
Did not fully make the box but this may give you the idea… I left a slight Gap (in Kicad PCB so show the PCB are separate - without the Gap, the edges blend nicely in 3D-Viewer)
I’ll will do it in two steps. First I will order this PCB with SMT assembly alongside a frontpanel and backpanel. For backpanel I will use a front panel first. The only difference between the two are some holes and silktexts.
When I have the PCB working, I will carefully measure all dimensions and create the remaining side panels.
I want to connect front and back panels via bolts & nuts. These should clamp the side panels firmly. The main PCB will be held in position by the grooves in the side panels.
When I think the plan through in my head it seems solid
The worst thing I can think of is that the button and this hole may become a problem for a bolt. But therefor we superglue right?
And I did not forget the dogbones.
I’ll go design the front panel now. I’ll ofcourse post photo’s of me results.
The PCB in question has been delivered but I am still awaiting on some of the components to finish soldering. I do can start designing the side panels now. (+ I need to order new front panels as there is no solder mask due to my screwup)
Anyways I was looking at an older project on how the inner corners look. And I noticed that the manufactorer seems to use dogbones them selfes. I thought this was worth mentioning
I have received the assembled PCB and I did some measurements and I carefully divised the the front panel and all 4 side panels.
I have not yet made the bottom panel because… reasons. I may live without one. The design is however ready to accomade a bottom panel.
I used dogbones on all inner corners.
I used my own mousebite footprint to couple them all.
I enlargered the hole for the little knobs I put on the tactiles.
The inner rectangles are 1.7mm wide. I use 1.6mm board. But I believe this is sometimes more or less 1.65mm. My caliper has a dead battery so…
Now I need to do 2 things. See if my PCBs aren’t DOA at the first place and secondly pick a fancy color. I am feeling blue today but I haven’t done yellow or purple yet .
In another month or so, I can hopefully place a picture of a finished box.
Things that went south.
As I already knew the protoytype’s potentiometer is too high. I can cut of a few mm. But the following proto’s get smaller ones.
The bottom plate looks okay… if you look at this picture where it is resting on the RJ12
It is A too short, and B the cutout is not deep enough.
Unfortunately the top plate suffers the same fate. The cutout is too low.
An other problem and I really thought that I thought about it. The potentiometer is not just too high it is also sticking out at the top. I knew this from the 3D viewer but somehow I forgot something…
Despite the flaws are bit unfortunate it is not all bad. And I can re-order the top and bottom panels to finish (and sell) the prototypes. Meanwhile the main design is getting SMD switches and I will move the potentiometer about 1.5mm south.
And despite the mouse bites and the corners I do like the overal design. I was thinking to enlarge the ‘wings’ on the side to cover the entire length -2mm on each end to get a prittier topview.
A more practical note. I kept 0.1mm tollerances on all sides. That seems to be good. The PCBs don’t snap and are somewhat lose. This partcular design will need glueing. I am however yet to apply bolts and nuts. I believe that firmly pressing the controller board and top panel will clamp in the sides well enough. I will consider using SMD pads to make solder connections.
There are some tutorials on the 'net of making boxes from (bare) copper plated FR4. From what I remember, the panels were cut to size (no castellations) put at a 92 degree angle and soldered (which pulled them to 90 degrees) then the seems further filled, sanded and painted.
I did a short search but did not find what I really meant. I did find the hackaday article below, which is very similar to yours.
