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Beginner's Guide (Inputs)

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JoeyJoeJo:
Is there an "MRotate for dummies" guide? I saw the video of the guy who selected his game and had his monitor automatically turn, now I know that I need one. The only thing is, I don't know squat about motors and whatnot. I've got a 23" 720p lcd tv that I want to use, but I don't know what motor to get or how to wire the motor to the computer. Can someone help out a newbie?

DaOld Man:
There are several posts on here showing how people rotate their rigs.
Since this is a LCD, the very first thing you need to do is test the monitor to see if it will display correctly.
Some monitors (not sure about LCD tv's), have limited angles of view from top of screen down.
The best thing to do is prop the monitor up on it's side and play a vertical game such as galaga or donkey kong, in it's native vertical mode.
While the game is playing, move to the left and right of the screen to see if the picture changes or blurs.
If this is going to be a two player cabinet, take into account the position of the players.

If this passes the test, the second thing you need to do is make sure you have enough room in your cabinet, if you already have a cabinet.
If you havent built your cab yet, you will need to size it for the monitor.
When the monitor turns, it requires more space than when it is stationary.
You have to measure the monitor diagonally from corner to corner (not the screen but the actual size of the case).
This is how wide the inside of the cabinet has to be, and also how much room from top to bottom you need. (Plus an inch or two may be necessary).
Also, take into account that the monitor's pivot point is the center of the SCREEN, and not necessarily the center of the case.
Some cases have an extension for buttons or what-not below the screen.
If you are not going to remove the screen from the case, then you may have to add even more to the measurement to account for the case being off center, due to the extension.

After these two initial steps, you will need to think about the hardware needed to actually hold the monitor while it is turning.

DaOld Man:
Most people attach the monitor to a disc, usually cut from wood (MDF or ply), simply because it is easier to cut and cheaper than metal.
On an LCD monitor, the disc can attach to the monitor using the vesa mount on the monitor, remember, you have to insure that the vesa holes are in the center of the screen, if not, the holes will have to be shifted to allow the center of the screen to be in the center of the disc.

The disc is usually supported by bearings or rollers. It's only necessary to have the bearings in the lower left and right "corners" of the disc, however I feel that two in the top "corners" add to the stability of the monitor, especially if the cabinet is to be moved.

The disc must be supported front to back also, to keep the monitor from tipping forward or backward.
Again, bearings or rollers are what most people use.
A metal shaft, in the center of the disc, ran through bearings supported by a block of wood could also be used.

A CRT monitor usually needs two discs, one for the front, with a cutout for the screen, and one in the back, making a "spool" with the monitor sandwiched between the two discs.
These two discs must be attached by wood struts or metal bars, to make sure both discs turn together.
You will need double the bearings for this, because the back disc will rotate also.

You also need to think about how you will attach the monitor bezel, to cover the ugly parts.
I used blocks of wood fastened to the disc, above top and below bottom of the monitor. The blocks extend out to be flush with the edge of the monitor.
I then cut a circle out of poster board, with the. center cut to fit the viewable part of the monitor screen.
This poster cut out attaches to the previous described blocks. This poster board turns with the monitor.
You can then cover all this with another poster, cut to fit the inside of the cabinet, side to side and top to bottom, with a circle cut to expose the screen so that all the screen is exposed when in vertical or horizontal position.
Some people have chosen just to use a smoked glass, but either way, the final cover is the glass (or plexi glass).

I know this is very sketchy, but without knowing exactly what you have, it's hard to say what you need to do, but maybe it will give you an idea how to start.

Next up, choosing a motor and attaching it to turn the disc.

DaOld Man:
The motor has to be chosen carefully.
You need one that has enough torque (or turning power), to turn your monitor.
Of course the heavier the monitor, the more power you will need to turn it. A CRT is usually much heavier than an LCD of the same screen size, just to note.

You can take a motor that turns fast and gear it down to decrease the speed but increase the torque. This is usually done by a gearbox "transmission" or belt and pulleys.
With either pulley or gears, the small gear or pulley attaches to the motor and the larger one attaches to the monitor disc.
If the gear on the disc is twice the size of the gear on the motor, the disc will turn half the speed of the motor, yet torque will be close to double.

If you attach two gears the same size, one on the motor and the other to a bearing that the disc rides on, then the diameter of the disc, compared to the diameter of the bearing, will determine speed.

You probably understand why torque is important, because you got to have enough power to turn the monitor in both directions without straining the motor or damaging it.
But why is speed so important?

Well, you really dont want a monitor to take forever to turn from horizontal to vertical. After the new has worn off, waiting for the monitor to complete a very long turn can seem like waiting for Windows to boot up.
However, you dont want the monitor to turn real fast either. You have to think about the centrifugal forces exerted on the monitor while it is turning. you dont want to damage anything inside the monitor that might work loose from repeated turns. Also higher speed is harder to stop, so you also can damage the monitor by "slamming" it against physical (or mechanical) stops. Think of it as traveling in a car and hitting a tree. The car stops but you dont.
This is probably an extreme way of thinking, but it's worth a little planning time.
In short, I would say 5-15 seconds of travel time is probably what you need to shoot for, however longer travel times certainly wont hurt anything. And remember, out of the 360 degrees of the disc, you are only turning 90.
(Except in some rare cases (of maybe a cocktail cabinet) needing 180 degrees of travel).

Lets stop here and come back to the motor later.

DNA Dan:
You've inspired me to do this on my cab. I am just starting a build around an HP LP2065. I have some good ideas already but I wanted to get some of the basics on how this is supposed to function. Do you have the software plugin on the front end so when you choose a game and it automatically rotates? What is all the USB and printer port connections for?

I could easily see the design of the circuit just being a powered motor connected to a relay switch. You hold the switch to power the motor in one direction. You hit another switch and it reverses the motor's polarity for rotation in the other direction. What are all the other connections I hear you talking about with the PC? Perhaps I am missing the point of the interface.  ???

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