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Need some help from the auto-rotating monitor experts...
DNA Dan:
Actually I think I am going to use a linear actuator on a mini bartop I am planning to build. I also think I am going to use an axle with bearings.
darthpaul:
I'm curious to see how you are going to do that since I have a few of those laying around waiting for the next project.
DNA Dan:
I think as long as the rotation aparatus is silky smooth, not too much force should be required to move it with a simple ball joint anchored in the direction of travel. The trick is getting an actuator that is small enough for the small case size, but with a long enough throw. The distance of the movement decreases with decreasing the radius of the attachment point, however that greatly increases the amount of force you need to apply. I have a specific location I want to mount it for my design. Turns out they are on sale at www.pololu.com It isn't cheaper than the motor approach, but I am going for simplicity with this build. No motors or friction tensions involved.
RandyT:
I built a rotary mechanism for a 3D display a few years back. Used a geared motor with soft rubber wheel against a shaft held with "pin" bearings and it worked great.
A tiny motor can move a lot as long as the monitor is free moving, and the entire assembly is "geared" properly. Just adjust the ratio between the drive wheel and the part it is driving against so that the power of the motor is sufficient, and it will work. Obviously, the smaller the motor, the slower one would be able to turn the monitor, but that's something which needs to be decided by the builder. The simplest device I can think of is a round piece of MDF used as a monitor mount, with a shaft going to two bearings acting as an axle. This will turn very easily. Then use a small DC motor with a drive wheel (a softer skateboard wheel modified with some epoxy putty comes to mind as a possibility) positioned against the round monitor mount (wheel). Then use two limit switches which break the circuit to the motor when the monitor is in the desired position. This is how physical limit switches work in industrial machinery. Obviously, reversing the polarity of the motor will send it in the other direction. It shouldn't be too difficult to figure out how to wire the resulting mechanism to a manual switch, or controller for automated use. I can probably dig a little deeper into the wiring end if there's interest.
RandyT
DNA Dan:
--- Quote from: RandyT on March 17, 2012, 01:50:18 pm ---The simplest device I can think of is a round piece of MDF used as a monitor mount, with a shaft going to two bearings acting as an axle. This will turn very easily.
--- End quote ---
That is precisely what I had in mind. Looking for "light duty bearings" the flange mount typically only has 2 holes.
http://www.thebigbearingstore.com/servlet/the-1067/1-fdsh-2%22-Light-Duty-Two/Detail
That might be strong enough, but I was wondering if you think the 3 or 4 hole flanges are necessary? Also, these aren't "light duty" type bearings, they have thicker grease in them, do you think this is too much drag? Such as these: http://www.thebigbearingstore.com/fourboltflangebearing.html
Sorry for the hijack Nitz, just drop any questions if need help.
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