Re: Showcase: Built With OnStep

Dave Schwartz
 

As long as we're showing off SHC's...

Here's our ESP32s-based SHC. Its now complete with PCB V1.01 and a 3D-printable case. While technically the .96" (SSD1306) display is supported, the bezel in this design supports only the 1.3" (SH1106) display. For the small difference in price and the much-improved readability, I don't see why anyone would want to use the .96" display but if there is enough demand, I will design a bezel for it.

The project page is at https://baheyeldin.com/astronomy/onstep-esp32-smart-hand-controller-shc.html and the assembly instruction document linked at the bottom has lots of pictures of how the 'guts' are assembled so I'm not repeating that here.

There are a number of these in the field now... four 'beta' models that I sent out completely assembled and a number of the kits without the modules that were sent as add-ons to STM32 controller kits.

All of these people are probably anxious to get the 3D-printable case I promised for it. I have been holding off posting this until I had completed development of the 3D-printable case and that's now finished.

The attached pictures show the design in FreeCAD (which I will be releasing shortly) and various views of the finished product (the one with the red case is an early version but the only one I have of the PCB in the case without the display or faceplate). That's not a display defect in the 'RA/DEC display... the camera caught it during the transition from a '1' to a '2'.

All the openings in the sides are 'knockouts'... they are 2.5mm deep pockets from the inside of the case, which has 3mm walls, so they are only visible from the outside as ghostly imprints but are easy to cut out with an Xacto knife if you want to use them. For example, many will want to open the RJ opening on the bottom but not many will want to open the RJ on the side yet (the passthrough port functionality has not been released by Howard) or maybe not ever. If you don't mind another opening on the side you can open the knockout for the USB so you can reflash the ESP32S without having to remove it from the case.

Depending on how accurate your printer is and what material you use, you may have to fiddle (file) the parts a bit after printing. For example, the clearance between the box and the faceplate is supposed to be .2mm all around but the clearance was just barely enough (almost zero) on the parts from my printer. Similarly, the openings for the button caps in the faceplate are 12mm and the button caps are supposed to be 11.8mm but I had to scale my button caps down to 95% before replicating them 6 times in the slicer before they fit perfectly (filing the posts would also work but was tedious so just reprinting at 95% is faster).

These 3D-printed button caps actually work better in this application than the supplied button caps... they stick up farther than the original caps (easier to feel in the dark) and can move a around a bit (the pocket on the bottom is larger than the switch's post) to tolerate assembly variances while still being vertical.

The way to assemble is:

1) open the knockouts you want to use,

2) prepare the bottom posts for how you want to hold the case together. The holes in the bezel and faceplate, as well as the PCB are 3.4mm so you can either tap the posts in the box for a 4-40 or M3 machine screw (the inside diameter of the lower posts is 2.4mm or 3/32 - sized for an M3 or 4-40 tap)  or finish drilling through the posts through the bottom to use a 4-40 or M3 machine screw and nut on the bottom. The latter may be better for some because if you tap, you need to use a finishing tap to thread all the way to the bottom of the post (but not through the case) and the threads are fairly delicate if you're a gorilla on the screwdriver.

3) lay the faceplate on a table with the posts up, put the button caps in the holes, making sure they move freely (lift the faceplate and let it back down on the table, if the buttons move up and down on their own, you have it right).

4) lay the inverted PCB, with the display module unplugged, on top of the faceplate posts with the button shafts in the button cap pockets and the posts aligned with the holes in the corners of the PCB. Put the box over that assembly in the right orientation, slide toward the edge of the table and pick it up to turn in upright.

5) The display module fits in a pocket on the underside of the bezel and then plug it into the header at the top of the big rectangular opening. The tab on the bottom of the bezel ensures you have it centered.

6) all that left is to fasten it together. I used 4-40, 1 inch machine screws with tapped holes. You may need to shorten the ones for the bottom corners because the hole is not quite 1 inch deep even after you used the bottom tap. The though-bolt may be easier to construct as long as you don't mind nuts on the bottom.

The STL files are on my in the public area of my Google drive https://drive.google.com/drive/folders/1kFKasl2IzegPsQQSOKps8zy5NTFplVp_

I would have put them in the files area of the group but I don't have privileges to create a subfolder or upload files.

On 2019-01-25 9:21 p.m., Khalid Baheyeldin wrote:
Very nice. Thanks for sharing.

Added it to the show case page.

I agree that the 0.96" screen is too small. That is why Dave recommends only the 1.13"
display for the ESP32 based SHC kit that he designed (details soon).

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