It's been way longer than two weeks, but I do now have a prototype to show off.
I'll put this prototype in the functional category since I believe it is too busy to claim to be attractive. The intent of the prototype front panel is to show off the variety of switches, connectors and displays that the proposed enclosure solution is capable of.
So what's the point? I'm sure that many folks in these forums could design something similar. Polycase
will engrave panels for you and has a panel design tool. What is different about this solution is that it has integrated
- an easy to use enclosure design
- with circuit board design support
- including switches, displays and connectors that are validated to work with the system
- to give a wide variety of front panels all with a professional look
- at a lower target cost
- using free tools
- and all provided as open source
Going back to our earlier discussion, it took me two iterations to get the enclosure pieces right and I'm up to test #9 on the front panel. But now that I have this working I intend to publish (open source hardware) my results so that others can make use of it and have something that looks good and works on the first iteration. And although I have more hours than I care to count getting to this point, the next design I do will literally take just minutes. And it can be done by people without any skills at machining or mechanical design. I call this system StdBx and it is indeed a system, not just an enclosure or front panel.
In addition to the desktop-style box, I intend to also design a wall-hung version (think thermostat or sprinkler controller) that is based on the same design principles. I'm open to other form factors if there is an interest.
The process for using the system goes something like this: When designing the circuit board for your project use parts from the StdBx Eagle CAD
library. You can use any electronic parts you like but stick with the ones in the StdBx lbr for buttons, switches, displays and connectors. Add text to your layout for front panel labels and indicators. Once your layout is complete, click on the StdBx ULP to have the panel design files created. Send those files off to a laser cutting and engraving service like Pololu
. Have your PCBs fab'd
. Print the enclosure pieces or order them from Shapeways
. Once all the components have arrived assemble them into the enclosure with a screw driver and soldering iron.
Notice what is NOT in the process. There is no mention of entering a correct PCB or panel size to fit the enclosure. There is no mention of buying raw materials, marking, cutting, drilling, milling, silk-screening, sanding, painting or anything else to get things to go together. There is no mention of finding components that fit or having to get out the calipers because the datasheet doesn't have the info you need. Each library component includes vendor part numbers and is readily available from Digi-Key, Mouser and/or SparkFun. There is no mention of aligning front panel measurements to PCB measurements. The CAD tool does this for you. There is also no mention of buying yet another CAD tool. This solution builds on Eagle CAD. Everything you need is in the free Eagle version plus the StdBx add-ons.
Here is a list of the components shown in this sampler prototype.
- 3mm LED, clear (also available in diffused)
- 5mm LED, clear (also available in diffused)
- 8-digit 7-segment LED display (based on HP bubble display)
- SPST toggle switch
- SPDT toggle switch
- DPDT toggle switch
- momentary contact push button switch
- push-on/push-off button switch
- smaller push button switch (all push buttons available with round or rectangular caps)
- BNC connector
- Barrel Jack (2.1x5mm) connector
- Banana plug receptacle connector
- Potentiometer with knob
- Backlit textual indicators
Also available in the StdBx lbr but not shown.
- 16x2 LCD display
- 4-digit 7-segment LED display (20mm tall)
- Rotary Encoder with knob
- Rugged USB mini-B connector
As of this writing there are over 30 StdBx defined library components that represent over 80 real vendor parts. More are being added as they are needed. All parts are Through Hole technology. You DON’T have to be good at Surface Mount soldering to build with StdBx.
As you can see in this picture the StdBx system is based on a mechanical architecture similar to that used by the JYE Tech Function Generator
or any number of other instruments. There is an acrylic faceplate with a PCB behind it. The PCB is small enough to be designed with the free version of Eagle CAD, but can have a little over 8.5 square inches of circuitry. If that's not enough, the enclosure supports more PCBs on the back panel and floor of the enclosure for a total of 26.5 square inches of circuitry. And you can add even more PCBs if you want. You don't have to use that much PCB but it's available if you need it. The floor of the enclosure is also sized to fit a 4xAA cell battery holder for more portable projects. You can use standard panel mount connectors on the back panel instead of a PCB. The two shown are a barrel jack for power and a rugged USB-mini-B connector with FTDI serial converter.
I need to create a tutorial example that really highlights it, but I believe that this system addresses the "it's too difficult to design and craft" roadblock we've been talking about. The cost is not horrible, but still too high. I believe it can come down significantly. The custom acrylic front panel costs about $14 but I think that can be lowered to under $10, hopefully under $8. The simple black back panel costs about $4. The enclosure consists of two identical pieces which cost about $28 each from MakeXYZ or about $52 each from Shapeways. That puts the total at about $70 to $118 depending on vendors. Like I said, that's high, but it's in the same order of magnitude as a Polycase with a lot more customization and integration. If you have your own 3D printer the enclosure price comes down to just the cost of the plastic. If we could convince SparkFun or someone to do a run of injection molded plastics and sell a pair of them for say $20 then the total would ultimately come down to about $32. That seems pretty reasonable to me considering the quality of the result.
STATUS: This is NOT finished yet. There is a ton of documentation that needs to be done. To get the acrylic costs down I need to code up and test a new ULP. I have not yet approached SparkFun or anyone about manufacturing the enclosure. Most of the components work pretty well but a few need some additional tweaks (e.g. the bezel on the LED display in the photo needs to be thinner). Everything needs to be made "publish ready" and posted to GitHub. There needs to be a process established for validating new components. I’ve had a couple of projects in mind while I designed the sampler. I did this to keep things grounded as I imagined the design. I’d like to build these up as examples. Plus I’m sure feedback and more thought will turn up more things to get done.
None of the work I’ve listed to finish this off requires invention (well maybe the ULP) it just requires time and effort. I intend to continue pushing it along but given the level of response so far that's driven by my OCD. I do keep reading about folks who are looking for a better enclosure. Perhaps once people see this solution it will appeal to them and there will be more interest. Then again, maybe not. In any event I will keep at it for a while at least.
Your continuing feedback is much appreciated. Thank you! to everyone who has contributed to this thread so far. I'm enjoying seeing the attractive and creative designs others have done.
Good luck with your projects!
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