MEEP: A Minimal Mini-VPin Project [Completed!]

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markc74:

--- Quote from: jeremymtc on August 24, 2024, 03:46:00 pm ---Thanks, Mark! I actually owe you a debt of gratitude - your Polybius Mini has probably been the single greatest design influence for these projects :cheers:

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Thanks! Bizarrely I'm actually working on that today to upgrade it to a Pi4 and a 10" screen - it was supposed to be a Pi5 but that doesn't work well with the controller hat I'm using (annoying!) but it's a great little toy and I don't really play high end games on it anyway

--- Quote from: jeremymtc on August 24, 2024, 03:46:00 pm ---I do have a question for you, and/or any of the other experienced vpin builders: For monitor positioning, do you think it's better to have it mounted near-flush to the top rails of the cab, or recessed at a slightly greater depth? I had planned to have the playfield overlay mounted near-flush to the rails but with maybe about 1" separation between it and the playfield monitor.

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On my Flip cabinet I've mounted the monitor flush but I'm not sure I like it like that. It definitely makes the tables feel flatter and lack depth. Could be that I need to tweak the angles in the table but I'm not comfortable enough with VPX yet not to screw everything up!

Anyway - progress is looking really good!

jeremymtc:
Thanks for the input on the monitor! That was exactly my thinking on having it recessed to give it a little more apparent depth and appearance of parallax, especially since this one's 1080p and the PC driving it is no graphical powerhouse. I've played with the Z-depth and view angle/view distance settings a little bit in VPX, but find that the results are just a little weird-looking on my setup. I think that maybe they're tailored more for use in VR or for headtracking than for a physical cabinet, where the cabinet itself gives some perspective effect at least as far as how the shape of the playfield appears.

If you do want to mess around with the perspective settings, you can do it without fear of ruining anything. Just delete the table's .cfg file (just like in MAME) and it'll regenerate a default.

Glad to hear that you're still tinkering and having fun with your mini cab. It really is a neat little toy!

jeremymtc:
I haven't made a ton of progress on this cabinet over the past week, mostly because I'm waiting for delivery of a few parts that will necessitate woodwork before the cabinet can be cleaned up and finish work can start. Nonetheless I've chipped away on some things.

I've decided to go with a different LCD display for the DMD panel than originally planned. The original one was chosen simply because I already had it on hand and would have been workable, but it was a compromise - it would have needed to be mounted vertically, and there were some scaling issues with it within the PinMAME/ES/Batocera software when oriented in portrait. All of that was rendered moot when I shorted something on the LCD controller while relocating the input panel during a test session and the panel went into an irretreivable burn-in mode. A happy accident, as far as I'm concerned as it forced me to buy a more suitable display. The new one is a 7" 1024x600 HDMI panel which can be installed in its normal orientation and shouldn't run afoul of the scaling problems that the old one did.

I had been thinking of how I wanted the lockbar to operate for a while. The easiest solution would have been to simply screw it down into an internal crossbrace, but I really didn't want to have any visible fasteners anywhere. I came up with a very simple solution which looks like it's going to work out fine - the concern here is not for security as in a real commercial cab, but just for fast access and a way to keep the playfield display and glass locked into place securely:

The lockplate is bonded to an interior insert (really just a crossbrace) which carries a stud/carriage bolt that can be engaged by a camlock mounted through the bottom base of the cabinet. The insert prevents the assembly from being able to walk or twist relative to the cabinet, and the cam lock prevents it from being lifted upward.

The playfield-facing edge of the insert does two things: it acts as a longitudinal stop to locate the playfield monitor, and it has a slot cut in it which accepts the front edge of the playfield glass:

The carriage bolt was countersunk through the insert piece prior to gluing, and has a nut and washer on the underside to keep it retained tightly and help prevent it from torquing or walking if someone tries wrestling with the lockbar. The two nuts locked together at the bottom of the stud are what the pawl of the camlock will engage with to prevent it from being pulled up vertically:

In the cabinet's final form there will be edge molding running in a continuous strip around the cabinet profile and rails, and the lockbar will actually sit on top of the molding, adding 2mm to its height. The material I'm using for the molding is fairly soft and has some squish to it, so when the lock bar is engaged it should have a pretty positive clamping effect but with some 'give' to it.

I've installed some placeholder buttons to test, check and verify that everything in this crowded area of the cabinet can coexist peacefully. Switches and wiring loops are present so that there are no (or more likely, "fewer") surprises later.

I've also added a couple of small, pivoting ledges into the rear of the cabinet to retain the playfield monitor. These double as ledges for the playfield glass to perch on to give it some separation from the top of the monitor. The molding trim which will mount to the rails has a 2mm lip which overlaps the edge of the rail and will prevent the playfield glass from coming free of the cabinet. For removal, the monitor slides forward with the lockbar removed, and once the monitor bezel passes the center pivot of the moveable ledges can be tipped up a few degrees and pulled away. The playfield glass will be masked and painted to "hide" the bezel and ledges, and all of the theoretically visible area of the insides of the cab will likewise be painted black.

The playfield glass (acrylic in this case) will need some additional support down the length of the playfield, and I'm still deciding how I want to do that in a way that doesn't interfere with removal but stays invisible. One option is to glue stringers down the edges of the underside after masking and painting, but I'm not super enthusiatic about gluing to a painted acrylic surface. Another option would be to mount stringers to the top of the monitor bezel either by glue or self-adhesive velcro. I'm leaning toward the velcro option, as it would make them easily removable if there are any potential interference issues with the edge trim during playfield/monitor removal. Maybe some of those little plastic 'peg and hole' shelving supports might even do the trick..?

MiteWiseacre:
I too like to use up material around the shop :cheers:
Looking good, how do you plan to finish it?

jeremymtc:

--- Quote from: MiteWiseacre on September 17, 2024, 09:28:34 pm ---I too like to use up material around the shop :cheers:
Looking good, how do you plan to finish it?

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Thanks! It's a fun challenge to try to construct something cool from literal junk :cheers:

Regarding finish, that's a very timely question as I just came in from the shop after spending the afternoon on this blasted thing. Exterior finish is woodgrain vinyl, with acrylic overlays and black PVC edge trim - in finished state, it will appear similar to my "Project Jetsam" bartop.

Progress has been made!

During a lengthy delay while waiting for parts there wasn't a whole lot that could get done on the cab, but there were a few little things that I took care of. I filled and redrilled the holes for the flipper buttons, mainly for aesthetic reasons, but also because I noticed that my various press-ganged test subjects always placed their hands on the upper set of flipper buttons rather than the primary lower ones, and I figured that some additional depth/distance was called for. I also threw caution to the wind, and drilled the cooling fan, power button, and AC cord passages despite not having all of the hardware necessary to determine their fit in place. It's worked out well in the end though.

I also finished filling voids in the plywood and sanding, applied a coat of urethane varnish, and sanded it back level to prepare it for the surface vinyl application:

I ended up going with shelf supports to support the playfield overlay midway down its length, to prevent it from sagging while allowing for easy removal of it and the playfield monitor. This worked out great:

I finally received the 7" LCD panel to be used for the DMD, which had been the main blocker to progress on the cab. I couldn't finalize the playfield monitor position, playfield overlay dimensions, or lockbar setup until that piece was in place, as the design of the cab calls for each of those parts to "lock" the others into place for assembly and disassembly. To mount the speakers and DMD in the minimum of space allowed I concepted this setup to be built from acrylic sheet remnants and wood:

This 1/4" carriage bolt (countersunk through the top of the header panel), wingnut, and washer, hangs the assembly in place. A small bamboo dowel on the right indexes the speaker/DMD panel level relative to the cab. The mounting block for the module is slotted where it accepts the carriage bolt so that the assembly can be pulled free just by slightly loosening the wingnut, once the playfield overlay is removed. A lot of the cab's electrical and power junctions reside behind this panel, so quick and easy access for maintenance was important to me:

And this is what the lower half of the module looks like when fitted to the cab. Some furring strips were hot glued to the interior of the module to provide support for the outer overlay/reveal panel, and that panel is held in place by adhesive u-shaped edge trim which adheres to the furring strips. The HDMI and power cables for the display are also routed through the interior of this panel.

...And this is what it looks like, as an assembly. There will be steel mesh speaker grilles fitted into the reveal panel from the inside, but I don't have the grilles in hand yet. The playfield overlay snugs up to the underside of the DMD panel assembly, and in the final installation the edge trim that meets it and retains the reveal panel will fit a bit straighter and more uniformly:

Vinyl fitted, fan grille attached, playfield now properly located, and all the various motherboard connection breakouts/relay/buck converter/led connection nonsense is done:

The buttons in place are mostly placeholders for the ones I intend to use, however those will also be LED lit. The cab is now in a playable state though:

A bit of a rant here: Please allow me to say on record that mapping controls in Batocera/Emulation Station and VPX Standalone sucks sweaty hairy donkey balls. I level the blame mostly at Batocera/ES - they try so hard to simplify the process for the typical 'console gamer' installation, and make so many assumptions about the hardware users will be hooking up, that they end up making it umpteen times more difficult than it should be to do something so simple as mapping an encoder board. Rather than use the tried and true convention of labeling inputs as "button 1", "button 2", "axis 1", "axis 2", etc., everything is this horrible consolified "North", "South", "East", "West" garbage to describe button inputs. Maybe I'm just old, or maybe I'm just spoiled by how it's done in MAME or any other PC software I've ever used, but Batocera's system is just terrible to use for anything that's not a standard gamepad layout :banghead:

Whew.

Paint was drying on the lockbar and playfield overlay when I took the photos above, but they are now done too. The last things to do in construction terms involve parts that I'm still waiting to receive: edge trim, speaker grilles, desk grommets to finish the exterior amplifier knob and AC cord passages, and the power, flipper and front panel buttons.

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