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Galaxian Mame Conversion
csa3d:
Rotating Monitor Mount v3 - SUCCESS!
More work on the cabinet has taken place. For the third time, I've redesigned the rotating monitor rig. After two failed attempts, I've given into ways all ready proven to work and just accepted it. The only thing "new" here is possibly using skateboard bearings AS the wheels for the lazy susan. Here's how this went down:
I all ready cut out and painted the bezel and under bezel for revision two, and had also purchased all my parts from Solarbotics.com. I only blew up 1 logic chip, and decided it was cheap to just order a new HDrive and Motor. Since my last update, I only spent about $20 in new parts. After a while, you re-use whatever you have laying around etc. Who would have known I would reach this point in this hobby :dunno Also note that now that everything is working, a fresh sanding and coat of top paint could be used on my bezels after being installed and removed from the cab a bazillion times.
First, I decided to build a "box" this time around to house the entire lazy susan unit. My previous rig was a single cross brace mounted to the cab, which supported the monitor and under bezel. The upper bezel (square) was supported by brackets mounted to the sides of the cabinet and "floated" above the cross brace and monitor. This had a design flaw, in which a) the upper bezel was NOT adjustable which led to b) rubbing of paint from the under bezel hitting the upper bezel due to play in the center axis. This time around, I designed to go with the "lazy susan on wheels" idea and use adjustable pegs from dowels and clamps topped with Velcro to allow the upper bezel to flip open like a lid, while still being able to be adjustable if I needed to once mounted. Flexibility was a must given the fact that this is revision 3. This whole unit needed to be able to be pulled out and reinstalled many times, and with ease, if I needed to make adjustments to any one part of the unit until the design is truely bug free.
Secondly, this redesign permits the monitor cord connecting to the video card and the power cord to hang from the CENTER of the lazy susan, therefore more evenly distributing weight. The last setup failed due to improper balance around the center pivot. It was a goal of this build to eliminate that issue.
The above image is a result of the box, hinged upper bezel, and some wiring bits we'll get to shortly.
At the bottom of our base box, we need two wheels which will run along the side of the lazy susan circumference, giving bottom support to the platter on wheels. You can see these at the bottom of the image above. Also remember that my Midway Cab sports a 15 degree incline, so the lazy susan will not be held completely vertical.
I crafted two support wheels to allow the bottom of the platter to ride along the circumference seen here. I wanted to make sure the wheels I used had a LITTLE friction as possible due to an over abundance of friction in the 2nd installment of the rig. I therefore went with Swiss crafted Bones Skateboard Bearings, mounted to an "adjustable" 1 1/2" L-Bracket and a 1" L-Bracket. The insides of the skate bearings are 8mm, so I found some metric metal inserts from the Home Depot parts drawers which fit perfectly into the center of the bearings, making the whole through the center much smaller while preventing the bearing from rocking around due to the snug fit. Having the smaller center hole also allowed me to use much smaller metric nuts/washers, which worked out where I didn't need to drill out the holes of the L-Brackets larger. I knew that if I had to drill out the holes, I was again allowing for imperfection due to possible spacing mismatches. The inserts meant that this wouldn't be an issue at all. I also purchased some rubber washers which were smaller then the red section of the bearing, so that they didn't come in contact with the moving parts of the bearings, yet kept the nut from touching either.
If you look at the gold 1 1/2" L-Brackets, you'll also notice that I took a dremmel disk to the one side of each of them. Where there was one two screw holes, I fashioned out a slot. This slot allowed me to make a slide bracket with the silver bracket, meaning I could adjust the final height of the platter supports later if need be. This dimension was unlikely to change, but was one of those things I kind of made up as I went along. If you can fine pre-made slots, then get some. These have been elusive to me for some time. As a side note, when dremmeling your L-Bracket, do where saftety goggles and DO screw it down before taking 10000 rpm's to it. If not, it will fly out and you'll feel lucky it didn't hit you in the eyes or fly through the center of your monitor which you have laying off to the side of the work area. Just saying...
Now that the lazy susan base has supports, we move onto the actual lazy susan itself, pictured here:
For the wheels for the disk bottom, I used 1" L-Brackets, and the same metal insert trick to bring the 8mm bearing hole down in side to the point where a small nut and bolt could be used to attach the bearing without drilling any new holes, which would more then likely mess up "factory alignments". My original plan with these wheels, was to go to the electrical department and pick up some 3/4" rubber grommets... ones used to keep water out of electrical boxes. Why? Because they slipped right over the bearing acting as a rubber tire! How bad ass! Unfortunately, that idea caused the bearing to spin ineffectively, and I lost a lot of movement. In the end, I decided to let the lazy susan spin direction on the bearings themselves.
To prevent over rotations past 0 or 90, I fashioned stoppers out of small L-Brackets and felt chair sliders. One gets screwed onto the bottom of the lazy susan, the other to the base upon which the lazy susan rests. These stoppers will ultimately trigger my limit switches, which you'll see later.
This is the result of the under bezel being Velcroed to the top of the monitor. The monitor is sitting on the 4 wheels we talked about above.
This is what it looks like sitting in the base, resting against the two lower support wheels we talked about above.
Wide shot to show the monitor in the base. If you look close, you can see scratches on the inner bezel from the first two implementations of rotation. When the unit is put in the cab behind the smoked glass, you cannot even see it. If my OCD kicks in hard enough, I'll likely hit it with a light sanding and final topcoat once I'm done taking it in and out constantly.
I knew I would be removing the monitor mount several times until I go everything right, and wanted a way to easily gain access to whatever I needed. I had a piano hinge laying around from an idea that I would be using it on my back access door. I cut it to size of the monitor box and mounted it to the 1/2" MDF lid using some spare plastic spacers. The reason for the spacers was because my screws were too long to the point where they would pierce the all ready painted lid if I was not careful. I didn't feel like counter sinking them from the top, bondo the holes, and repainting so I went this route. I learned that I therefore had to also knotch the base wall to allow the risers to fold under. Again, my dremmel tool came in handy!
Here's what it looks like with the lid flipped down, monitor removed.
Driving the rotating monitor is a Solarbotics.com gearmotor 2 (with faster engine) powered by a hybrid Secret Motor Driver circuit DaOldMan has been helping me design. Once we're solve a few minor issues, I'll post that here as well. The motor was mounted at the TOP of the rig this time, because the weight of the monitor pushing down in my last implementation caused too much stress on the tiny RC motor. I also dremmeled out the two holes in a 1 1/2" bracket again to create an adjustable slot, so I could slide the motor up or down slightly, adding or removing friction to the lazy susan as needed. Remember, the key here is being able to adjust things!
In the end, the gearmotor's wheel touches the lazy susan's edge, and the friction from the contact and the fact that the lazy susan is swiveling on 6 bearings make this unit turn like melting hot butter! I had thought the size of my monitor coupled with the extra weight from the birch disk would be worse then implementation #2, but I was far wrong. This way almost turned too easily! I found that I had to REALLY back down my gearmotor using Pulse Modulation. In hind sight, I probably DIDN'T need the extra powerful motor.
Here is a custom circuit DaOldMan and I have been working on. It's the standard red Secret Motor Driver H-Bridge, mounted to a breadboard. The breadboard is wired up to the the power, limit switches, and printer port. The switches are wired to look for signals going low on Pins 12 or 13 to stop rotation, while pins 2 and 3 control rotational direction. Pin 4 controls Pulsing, and pin 25 grounds our circuit. This setup completely separates the input pins from the output pins. More on this circuit in a few days.
Here you can see I used a connector to splice a junction between the circuit and the switches. This allowed me to reorder inputs, reversing rotation psychically without having to resolder. It also means I can switch out my limit switches if I have to down the road.
For limit switches, I used some coin door switches I ordered from Divemaster some time back. They actually never fit my Midway door, but came in perfect here. They have a wire that sticks out, which you can bend and adjust the point of contact. Based on how I decided to place my horizontal and vertical stoppers, you'll have to mount one of the swiches upside down. To do so, you'll need spacers to allow room under the switch for the swing arm to move properly. In this picture, you can see the switch, the limit arm unthrown, and the horizontal stopper.
This is that same horizontal switch, with the lazy susan mounted. In this shot, the monitor is rotating towards the horizontal limit, but has not yet reached. The two stoppers will eventually swing to make contact.
And when they do, the limit switch is triggered, shutting off horizontal rotation.
This is repeated for the vertical limit switch. The only difference here is that this switch is mounted upright.
Here comes the rotating monitor! Switches not yet thrown..
Switches are thrown in this image for the vertical limit.
Blanka:
That's why I hope one day there will be 1600x1600 square OLED panels with 1:10000 true contrast and 180/180 viewing angles.
javeryh:
Holy. Crap. EXCELLENT JOB!!! Whenever I get back around to my rotating monitor project I will be using this as a guide.
So am I right in thinking there is no center spindle? You are just using the skate bearings on the edges to support and guide the rotation? Is the weight of the monitor an issue at all? What a great idea.
Have you interfaced this setup with MAME/MaLa yet?
Any chance you could sketch up a wiring guide for the switches, motor and parallel port? Freehand on a napkin would be fine as long as it is labeled!
:notworthy: :notworthy: :notworthy: :notworthy:
csa3d:
--- Quote from: Blanka on January 22, 2009, 12:25:15 am ---That's why I hope one day there will be 1600x1600 square OLED panels with 1:10000 true contrast and 180/180 viewing angles.
--- End quote ---
Yeah, I paid a pretty penny for my Viewsonic monitor. It has a pretty high contrast rate and really good viewing angles. Angles haven't been an issue for me, and I wonder if I could have gotten away with a cheaper monitor when it was all said and done. It's a great monitor, 4:3 aspect, and as large as I could squeeze in the cab. I'll ride the LCD train all day. They are fantastic to work due to their size.. plus I don't fear getting killed due to having to drain them first!
-csa
csa3d:
--- Quote from: javeryh on January 22, 2009, 09:22:11 am ---Holy. Crap. EXCELLENT JOB!!! Whenever I get back around to my rotating monitor project I will be using this as a guide.
--- End quote ---
Thanks man! I give credit to a bunch of rotators on the board for ideas. I spent endless hours looking for those stupid tiny Zebra wheels used by Psychotech, which led to the skate bearing wheel idea. Weisshaupts idea on the secret motor driver h-bridge make life easy for non-techies... but after my latest venture with DaOldMan, I might try crafting my own H-Drive next time if it were cost effective.
--- Quote from: javeryh on January 22, 2009, 09:22:11 am ---So am I right in thinking there is no center spindle? You are just using the skate bearings on the edges to support and guide the rotation? Is the weight of the monitor an issue at all? What a great idea.
--- End quote ---
There are two sets of wheels, 6 wheels in total. First you have 4 wheels mounted to the BOTTOM of the lazy susan at Cardinal Directions, turned so the wheels are parallel to the circumference of the platter. When flipped upright, those four wheels allow you top spin the platter easily in a circle when applying weight. The bad news is that those four wheels also allow you to slide the lazy susan up/down/left/right. To prevent that, you need another set of wheels. Look at this image:
Now draw a mental triangle from the bottom two red/gold wheels to the black motor wheel at the top. The platter is placed upside down in the middle of that triangle, allowing the four wheels in cardinal directions to support the monitor and allow the spinning. The two bottom wheels and the motor wheel prevent the disk from scooting left/right/up/down and sandwhich everything in place. Make sense?
--- Quote from: javeryh on January 22, 2009, 09:22:11 am ---Have you interfaced this setup with MAME/MaLa yet?
--- End quote ---
Yes, and DaOldMan has a new MRotate2.exe which is under development which works perfectly with Mame. We are working out some bugs yet, and hopefully Loadman is addressing some bugs in Mala with other non-mame emulator events. More news on this shortly.
--- Quote from: javeryh on January 22, 2009, 09:22:11 am ---Any chance you could sketch up a wiring guide for the switches, motor and parallel port? Freehand on a napkin would be fine as long as it is labeled!
--- End quote ---
Indeed. That drawing is mostly done. There's one more electrical issue I need to work out with the parallel port activating randomly upon windows bootup, and once I solve that, I'll report back with full drawings.
Make sure you bomb the Mala Forum and ask loadman to look at some of those rotation issues. :angel:
-csa