MegaGRRL Desktop - Real Hardware YM2612 VGM Player - Casing by Voodle

Last crawled date: 3 years, 1 month ago

MegaGRRL - YM2612 VGM Player
The MegaGRRL is an ESP32-based, hardware Sega Genesis / MegaDrive VGM player. Using real YM2612 and YM3438 FM chips to play back music from games like Streets of Rage and more. It's designed by Kunoichi Labs, details and video here: https://hackaday.io/project/169129-megagrrl-desktop
This is a housing for the Desktop version, with a 2.4" LCD. You can read more on how to make your own here: https://git.agiri.ninja/natalie/MegaGRRL_Desktop
The casing is optimised for FDM 3d printing, made up of multiple separate parts for the best finish and to securely hold the buttons and d-pad in place. All of the MegaGRRL's functions and ports are available with the case fitted.
Printing Overview
These are my recommendations for printing them, parts have been oriented into their correct printing orientation in the .stl files before uploading, so there's no need to re-orient anything.
The upper body of the case is assembled as two separate parts for two reasons:
I think the heat from the voltage regulator heatsink could warp / melt PLA plastic around it, so the vents / screen cover is printed in PETG, which has a much higher glass transition temperature. My first test print was in PLA though and that has been fine, so it seems the vents are doing their job.
It allows for the best looking surfaces around both the buttons and the screen, with minimal support material required.
Requirements
Some components are very close to the edge of the board where the casing goes, specifically the 74HCT595N at IC2 must be fitted directly to the PCB and not socketed, to allow the case to close properly.
This case design fits the 2.4" screen size only, and is clearanced only for the versions without touchscreen. This is the part used: "2.4" 240x320 SPI TFT LCD Serial Port Module+3.3V PCB Adapter SD ILI9341"
You will need 4x 3mm wide (m3) x 10mm screws to hold the upper & lower case together. I use m3x10mm Thread forming / self tapping screws because all of my m3 thread screws are too short. The maximum head size for the screw is around 6mm
The D-Pad requires either an m2x8mm screw, or superglue and some 1.75mm printer filament, I prefer using a screw for initial placement, then glue can be used once it's all fitted together nicely
Supports
Most parts print without any supports needed. The Upperbody-front-buttons part is the only one that requires supports, and the suggested support locations should be visible in the .3mf file
Printing The Parts
Small PLA parts
Recommended 0.2mm layer height & 0.4mm nozzle:
A Button-v4-printable.stl
B Button-v4-printable.stl
C Button-v4-printable.stl
D-Pad-ControlArm-v6.stl
FMLED-LightGuide-v1-printable.stl
PowerLED-LightGuide-v1-printable.stl
Power-Switch-Arm-v4-printable.stl
Upperbody-retainer-v5.stl
Fine Detail PLA parts
Recommended 0.1mm layer height, or variable layer height & 0.25mm nozzle, or resin print - the detail in these is best seen with a smaller nozzle, they will still work just fine if printing with a larger nozzle though
DirectionalPad-v7.stl
Power Switch-v3.stl
Large PLA parts
Recommended 0.2mm layer height & 0.4mm nozzle:
Lowerbody-shell-v2.stl
Only print one of these, not both:
Upperbody-front-buttons-v7.3mf
Upperbody-front-buttons-v7-printable.stl - same as the .3mf but you'll need to specify the overhangs for supports to be generated around the power button and the
Clear PETG Parts
Recommended 0.1mm layer height & 0.25mm nozzle, should still work with 0.4mm nozzle though. I recommend to enable Ironing in the slicer for best light transmission
FMLED-4 LED-v3.stl
FMLED-7 LED-v3.stl
PowerLED-3LED-v2.stl
Large PETG Parts
Recommended 0.2mm layer height & 0.4mm nozzle:
LCD-Arm-v2-printable.stl
Upperbody-rear-vents&screen-v7-printable.stl
Assembly
Clean off support material around the power button slider and FM chips, the power button slider part of the Upperbody-front-buttons
Clear any drooping bridges from the Upperbody-rear-vents&screen where the tabs for the upperbody-front-buttons will be inserted
Push the Upperbody-front-buttons & Upperbody-rear-vents&screen together lining up the mounting tabs and the ridge for the screen.
optional screw the two parts of the upperbody together with 2x m3x4mm screws, longer screws could damage the casing. Otherwise I think superglue could hold these two together. There's enough holding the two parts together with the pegs that this step is optional
Buttons & D-Pad
Push the power-switch-arm into the Power-Switch so that it clicks into place to check fit, then un-clip it and do the same again with the power-button installed in the Upperbody. Check the "MegaGRRL-Construction.jpg" picture for part orientation, the slider and arm can only fit in correctly in one orientation
To test fitment, attach the D-Pad to the D-Pad control arm to check that they fit together, aligning the peg with the screw hole. They can be securely attached with an m2 8mm screw, or shorter if you have a countersunk screw. If you don't have a screw available, 1.75mm filament can be used instead, but don't glue / screw them together just yet
Put the Upperbody-Retainer over the D-Pad control arm, then put the D-Pad on top of that so that it lines up with the control arm. Now you can either screw the D-Pad parts together, or use filament & glue
Check that there's no extra plastic or 'elephants foot' on the buttons. Then install the A, B, C buttons into the Upperbody, make sure they're the right way up and move freely
Install the Upperbody-Retainer over the buttons, clipping it into place. Clipping one side into place first then the other is easiest
LED Parts & LCD Prep
Install the transparent LED lenses into the holes in the upperbody, Use a bit of superglue to hold them in place if the fit is loose. The LED lenses need to stay in place when the Upperbody is the right way up
Place the FMLED & PowerLED LightGuide parts over the LEDs on the MegaGRRL player, those will just rest in place and don't need to be secured.
Install the LCD-Arm so that it's securely holding on to both the PCB and the LCD. You will need to bend the 0.1" PCB headers that the screen installs into, to get the correct angle
Final Assembly
Now that the buttons are installed in the Upperbody, the LED lenses and lightguides are installed, and the LCD is securely held at the correct angle, the Upperbody can be installed.
Remove the nut & washer from the volume dial potentiometer

Slide the Upperbody into place, starting from the Volume dial's arm, then carefully over the LCD. Possible parts that will get stuck are:
The transistor next to the voltage regulator heatsink, bend it over a bit if needed
The power switch, move the slider into position to match and it should fit into place fairly easily
USB port - just get that lined up
Audio jack - bend the back of the Upperbody out slighly so that it can fit over

Turn it over and fit the LowerBody into place. Use a screwdriver to clear out the structural extra filament over the screw holes.

Line it all up, then install 4x M3 x 10mm screws, either with machine threads or thread forming (better for plastic) type

Check that the buttons and D-Pad move freely, then check that the power switch is working. That should be it :)