MiniBeast - Nano Style w/ Monitor Rotation (Concept Phase)

[Nephasth]

THE MINIBEAST - CONCEPT PHASE



Another project that is to be started from simply acquiring one part. I picked up a couple of 7" LCD monitors with RGB input from KLOV with the intent on making a compact JAMMA test station with one of them. I decided to make a "one for the road" MAME machine with the other, and the idea of the MiniBeast was forged.

LCD with protective film still on the screen. These were just refurbished this month.


Back of the monitor showing the power and signal headers.


These are 12V LCDs and run a "widescreen" format. One awesome feature with these is that if you supply 5V to one of the signal pins, the LCD will letterbox a 4:3 "normal" format. More info on these can be found in this thread on KLOV.

Since the display is so small, playing vertical games with the monitor in a horizontal orientation would pretty much suck, and vice versa with the monitor in a vertical orientation. So I thought it would be best for the MiniBeast to have a rotatable display. Due to the small space I'm working with, as well as the small size of the monitor, I figured it would be easiest to have it rotate manually. You can see the part of the plate/wheel/disc protruding from the top, and that is where I will be able to turn the monitor assembly.

I had the basic design thought out, which is very close to what I have modeled now. I drew some inspiration from the Nanocade and made a few adjustments to the design. Pulled up Sketchup and started messing around. This was the first model I have ever created with Sketchup, and I struggled with it for a while, but it got a lot easier towards the end. This model is EXTREMELY rough, about the only thing that is exact is the monitor size, everything else is approximate until I start getting some parts together to figure out the exact dimensions. The width will stay close to 12". The sides and bottom will be MDF. The front 3 surfaces, and the top will be one piece of stainless steel sheet metal (just like the CPs on the Two-Headed Beast), the back will be a separate piece of stainless steel. I'm hoping I will be able to get my friend, DMEN, to manufacture the metal panels like he did for me on the Two-Headed Beast. The MiniBeast will be running a Mini ITX board. I've got a spare ArcadeVGA that I will most likely use since the monitor requires an RGB signal, but I may go with Soft-15KHz though. For controls, I will either go the U360 route with its nice I/O feature, or a MagStick Plus with a 1 player interface (like the Xin Mo). Buttons will be black standard size concave ILs, and the joystick top will be black as well. Control layout is the same spacing as players 1 & 2 on the Two-Headed Beast minus the 7th button an buttons rotated for comfortable play on a table or desk.

Still plenty of tweaking to do with the design. The actual build will be held off until the Two-Headed Beast reaches a respectable ratio of completeness and playability.

[yotsuya]

Keep us updated!

[Vidiot]

I love this idea. Please post progress updates.

[TopJimmyCooks]

Nep,
You can't do it without motorvating your rotation!  It would be easy.  You could use a tiny motor/wheel combo and direct drive against the edge of the disk the monitor is mounted to.  the drive motor could be at the top corner of the monitor which will be hard to use space anyway. 

Pololu simple motor controller: $30
micro gearmotor $15
Wheel $5
usb cable- already have
2 microswitch limit switches - already have
+12V - from itx power supply - already have
rotation bearing - already have.
Molex ninja skills - already have in spades.

If you decide to, I would be more than happy to help with sketchups for your rotation wheel with cord ports/channels, limit switch accommodations, lightening/ventilation.  I used a sketchup model to package everything in switchcade and get it as tight as possible without clearance issues.

wheel layout for fullsize monitor:

[Nephasth]

To be honest, the rotation is going to be the hardest part of the whole build for me to engineer. If there is an easy way to set the rotation up automatically, I'm all for it. Any help is greatly appreciated and I am very open to any suggestions on the rotation.

Molex ninja skills - already have in spades.

[TopJimmyCooks]

Frontend?
Mala- plug and play rotation - plugin already done by DaOldMan. recommended.
Hyperspin - not rotation friendly since the FE themes are horizontal only.
maximus, gameex, atomic, wah, etc - not sure but could be checked out. 

the interface is just command line calls and can be done via batch files or autohotkey scripts.  I just used batch files and left AHK out of the loop.  It's easy, i did it and I am a GC, not an IT type. 

I feel it's just as easy to motorize than to figure out a good human interface where part of the rotation is actuated from outside the cabinet.

It's hard to beat the lazy susan bearing from Lowes for a rotation hardware solution.  just test spin it by hand before you buy.  one size is much more smooth and silky than the others.  Then, you can just work backwards through your stack of thicknesses to figure out the system:  say 1/4" for glass, 1/16" for clearance, 1/8" bezel mat, the lcd thickness, the monitor disc thickness, 5/16" or whatever for the LS bearing, then you're at the face of your monitor support.  Considering how small/light the display is, I would make the monitor disk and monitor support out of 1/4" plywood, plenty strong for that span and load. 

[Nephasth]

I've really been wanting to try out Mala, and that is what I will be going with on this one (even got it on the sketchup). I might want to make the disk out of 14-16 gauge aluminum (maybe even stainless steel) since I somewhat have access to a laser CNC. I was thinking of maybe just some smoked plexi right on top of the screen, or paint some clear plexi/lexan black leaving a clear window for the monitor, no bezel. Lots to think about and consider for sure. I'll work on making an accurate sketchup of the monitor and we can get a better idea of what will work best. Thanks.

[Nephasth]

Well Jimmy, you've definitely got me going in the direction of motorized rotation! I've been doing a little research on motors, and ran across something that I think will work while using fewer parts.



I believe, since the monitor is so small and light weight, that a motor set up like this will be able to be bolted to the center of a mounting plate for the monitor. No bearing, no wheel, no disc. And it would only protrude 2-3" from the back of the monitor. They say the motor will begin rotating with voltages as low as 1V. They also say their 131:1 motors run at 80 rpm at 12V. I wonder how slow it rotates at lower voltages. Thoughts?

About $41 for the motor and hardware...

[TopJimmyCooks]

It could definitely work.  I have that 131:1 motor and it's a stout piece, It's very possible it could bear the entire weight of the monitor.  The best way to be sure is to get the bits and do a mockup.  if you decide to go back to the disc rotation you could reuse the same stuff.  that motor is way more than you need to spin a 7" disc, though. 

[DaOld Man]

Another rotating monitor project! Sweet!
And a miniature one at that! Double sweet.
Good luck with your project, I for one will be following it.

[Nephasth]

I made a sketchup of the monitor today. Things went a lot quicker once I figured out how to use the guides effectively. 





The holes in the sides are threaded and I will most likely be using those for the mounting bracket. I have also attached a .rar file of the sketchup for those who are interested.

I'll be making sketchups of the motor and mounting bracket soon. It will be nice to see the assembly put together, and also give me a much better idea on how deep the MiniBeast needs to be. The design process is my most favorite part of any project.

Another rotating monitor project! Sweet!
And a miniature one at that! Double sweet.
Good luck with your project, I for one will be following it.

Blessings from the godfather of monitor rotation! Thanks!

[Nephasth]

Sketchup of possible mounting bracket. Might decrease the clearance between the LCD and the bracket. We'll see what total depth looks like with the motor first. Right now clearance is 1/2".



Sketup file attached.

[Nephasth]

Monitor and motor assembly. Looks good. The one thing I might be worried about is the weight of the monitor (although it's not much) hanging off the end of the motor's 6mm shaft. If I need to, I may have to make a disc for the monitor, and have it rest on wheels/bearings to support the monitor's weight.

Total depth: 4.6"

[javeryh]

You could reduce the depth if you mounted the motor at a 90 degree angle to what you have now and add some sort of wheel with a grip to generate enough friction to turn everything... if space is tight or you don't want a deep cabinet.

 

[Nephasth]

At its current depth it fits with about 2" of clearance in the original model.

[TopJimmyCooks]

Looks good.  One area of concern-- that motor mount from pololu is pretty flexible at the 90 degree bend - you can bend it with your hands.  You might want to test it and maybe back it up with some reinforcement if it can't keep the monitor in place securely where you want it or if it vibrates. 

Another concern- cable managment - make sure you've got a little area for your monitor cables to move around and uncoil without getting caught.  even the weight or stiffness of the cables can affect the rotation on a bigger rig (don't know that this would be a concern with the direct drive, you have a ton of torque with the direct drive)  DNA Dan and I routed our cables right at the center of rotation to minimize the movement.  you won't be able to do that since the motor is at the center. 

something else- start thinking now about where your limit switches might be.  might be easy to hang tabs off your monitor mount bracket and bend them to make stops/switch tabs. 

Excellent job on the modeling - it really helps avoid crappy surprises later in the build.   

[Nephasth]

DMEN came over last night and I showed him the models. He was super excited about it and said it wouldn't be a problem for him to make the pieces. I think when he does, he'll be making two of everything to have one for himself.

Thanks for pointing out those concerns, especially the one about the Pololu bracket. I'll have DMEN make one out of some steel that won't flex. Cable managment shouldn't be an issue. As far as the stop switches, I'll be putting together a model of the whole thing with all the components inside this week, that should give me a good idea on how to tackle that issue.

[Nephasth]

Inside is the mobo, AVGA, power supply, 60mm fan, 2.5" HDD, U360, buttons, smoked plexi, monitor assembly and mounting brace. I have the sides translucent right now to see inside. A little groove will have to be routed out for the microswitch of button 4. I may not use a U360, but I chose to put the deepest joystick option in the model. There will also be a small speaker mounted on the back panel above the power supply. Everything fits, but just barely. These are the actual dimensions of the first model, with the exception it is a 1/2" taller to accomodate the U360, and the bottoms of the buttons. Still drawing a blank on the stop switches, I'll have to do some reading on the other rotating projects. The .zip of the model is too big to attach...

Time to focus on the Two-Headed Beast.

[TopJimmyCooks]

Wow, all metal! sweet.  Was that motherboard in the 3D warehouse?

[Nephasth]

Yup. I searched for "mini itx" in the warehouse and found a few. Found the hard drive in there too. I also used a pci-e card I found in there to use as a template to match the AVGA dimensions.

[Nephasth]

Determined the best solution for the motor angle bracket would be to get rid of it. In doing so it would also get rid of any potential for any flex. This is the new motor bracket, it goes from wall to wall. Also came up with a fairly simple solution for the stop switches. The brackets for the stop switches will have spacers between them and the motor bracket. Also, the screw/bolt holes for the switch brackets will be slotted to make adjustments to the position of the switch.

Horizontal stop switch with monitor in horizontal position.


Vertical stop switch with the monitor in the horizontal position.


Horizontal stop switch with the monitor in the vertical position.


Vertical stop switch with the monitor in the vertical position.


View of the assembly from the back.

[TopJimmyCooks]

happened to have sketchup open: 



I messed around a little bit with microswitches that had actuator arms combined with separate stops.  In the end, it was much simpler and easier to get rid of the switch arm and let the switch housing itself be the stop.  these arcade microswitches are robust and have done fine for me used this way.  you can slot or enlarge the bolt holes in the mount plate for adjustability of the monitor angle.  Angle the switch so the bracket hits it squarely.  the motor at this gear ratio will hold tight to the closed switch to keep the monitor steady.  also, since the time for rotation is very predictable at a given speed, it's easy to slow down before you hit the stops if you want.  I am getting ready to experiment with this. 

It would also allow the mounting arms for the switches to be the same metal as (or bolted directly to) the monitor bracket, which i showed.  just some thoughts. 

[Nephasth]

Food for thought, for sure. So does that motor spin by hand? Or is it really stiff unpowered? I was thinking I would have to add some stops with magnets to keep the monitor stable when not powered up during transportation.

[TopJimmyCooks]

With the SMC board, the motor is always on when it's on, regardless of speed.  You can adjust the braking force when the speed is 0 to suit your needs via the SMC board software.  It won't return to the same absolute position like an RC servo, but it will expend power to keep the shaft from turning.   I have the braking set high enough to hold the rotating assembly in place against the stops without magnets. 

When the motor/controller are unpowered, you can turn it, but the high gearing is working heavily against movement.  usually if I have to move the motor while unpowered, I grab the shaft where it exits the back of the motor and turn it by hand, takes a while unless you get some momentum going. 

You could get some movement while moving the cab while turned off, but with the small weight of the rotating assembly, i suspect it wont be much. 

[Nephasth]

Stop switch revision.

Horizontal stop switch.


Vertical stop switch.

[Nephasth]

I've been playing with start and select (coin) button placements. I'm really liking them on their own panel in front. For those who are wondering about artwork, there won't be any printed. I'm hoping to be able to engrave (or etch) all the details into the stainless steel. I'm thinking fancy directional arrows around the joystick, detailing around the monitor window, "MiniBeast" on the monitor surround or the front panel, and maybe labelling the buttons A, B, C, X, Y, Z. I'll have to check into the capabilities of the local engravers.

[Raven..]

Oh my God!  That is one of the coolest ideas I have ever seen!  I knew these little monitors would be fun to mess with, but you are going off the chart with this one.

[Nephasth]

Oh my God!  That is one of the coolest ideas I have ever seen!  I knew these little monitors would be fun to mess with, but you are going off the chart with this one.

Thanks! Definitely helps with the motivation on this one.

Later this week or early next week I will be taking my Lono out of my testing CP and installing it into the Two-Headed Beast. In order to still have a testing CP, I'm wanting to get a hold of one or two of these. Since I'm getting a new interface, I figured I might as well make a new testing CP. Since I'll be getting some metal work done soon, I figured I might as well make my new testing CP out of some metal!

This:


Will replace this:


And for the extremely rare occasions the MiniBeast will be played by 2 players, it will also give player 2 their own CP.

[Nephasth]

Flat drawing is complete for the test/P2 panels. The dotted lines show the locations of the bends. From top to bottom they are 15 degrees, 30 degrees, and 45 degrees. Just have to delete the dotted lines and save as a .dxf file and it is ready to be cut out by the laser.

[Rick]

Your work with Sketchup is amazing.  Can't wait to see more!

[TopJimmyCooks]

carriage bolts for the sticks - why not weld studs?

[Nephasth]

Your work with Sketchup is amazing.  Can't wait to see more!

Thanks man! Never constructed anything in Sketchup before this. I still think all my models are pretty crude, but they serve their purpose.

carriage bolts for the sticks - why not weld studs?

The laser places the cuts EXACTLY where I want them. Weld studs would be placed by human hands, and there is a higher chance for errors if you factor in humans doing the work. Also, weld studs may discolor and/or warp the stainless steel.

[TopJimmyCooks]

10-4 good buddy - forgot you were going with a brushed stainless finish.  Getcha some black chrome finished carriage bolts maybe.  Over and out.

[Nephasth]

MiniBeast flat drawing is complete. I will need to make the flat drawings for all the monitor brackets before I get these cut, just so they can all be done at the same time. Bends from top to bottom are 90 degrees, 45 degrees, -30 degrees, 30 degrees, and 45 degrees.

[Nephasth]

Monitor bracket flat drawing. This one took the longest to draw up. Moved the hub mounting holes to the center of the screen, the hub mounting holes were in the center of the monitor in the sketchup.



DMEN wants to make enough parts to do 4 or 5 MiniBeasts. But I told him the monitor supply has dried up at the moment, and the whole design of the MiniBeast is centered around these monitors...

No need to bump this, here's the motor bracket.

[Nephasth]

Racked up some rewards points at Sears buying the old lady a new washer and dryer. Routing is an essential step in the fabrication of the MiniBeast. I've never owned a router... So I cashed in the points for this router with table from Sears. After the points, and a $5 coupon for their merchandise pick up guy being slow, it only cost me $15! The table is... well, mini. But it's just the right size for this project.

[yotsuya]

Racked up some rewards points at Sears buying the old lady a new washer and dryer. Routing is an essential step in the fabrication of the MiniBeast. I've never owned a router... So I cashed in the points for this router with table from Sears. After the points, and a $5 coupon for their merchandise pick up guy being slow, it only cost me $15! The table is... well, mini. But it's just the right size for this project.

Let me know how it works out- I'd like to get a router table like that as well.

[TopJimmyCooks]

I have done a ton of table routing with an inexpensive benchtop router table that size.  You will like it.  Practice making some cuts before you throw your project on there.  Look out for dust buildup, getting trapped under the workpiece or between the workpiece and the fence.  It's also really easy to forget to clamp the router at the desired depth since it's hiding underneath.  I wrote "locking knob" on my table to help me remember. 

[Rick]

I have done a ton of table routing with an inexpensive benchtop router table that size.  You will like it.

Agreed.  I have the Ryobi version of this table.  Make sure you have it on a stable surface that's not too glossy - I had mine on my patio table, and it slid around on me, making my cuts difficult.  (I have since moved it to a work table.)

It's also really easy to forget to clamp the router at the desired depth since it's hiding underneath.  I wrote "locking knob" on my table to help me remember.

ALWAYS continue to check your depth, as even though the clamp on mine was set - it changed up to a 1/4" between cuts somehow, and caused me to ruin a piece I was working on.

[Nephasth]

Rick and Jimmy - Thanks for the advice! I'm sure it will save me more than a few headaches.

yotsuya - I don't have any bits yet, and it will be a while before I start messing with it. But Rick and Jimmy think it's worth having. You'll see what this one does once the MiniBeast reaches the build phase.