Software Support > Automated Projects
Actuator Project ( Was MRotate4)
Le Chuck:
This is some great stuff man, nothing that is going to knock socks off immediately but it's exactly the stuff that makes some cockamamey ideal possible.
As for adding the fuse that is a really great solution. I ran into the same thing on my controller rotate with the servo hanging. I really fought with how to get it around it. The issue was that the servo was trying to push past the stop and wouldn't shut down at the right marker. Due to scale rather than try to fix with switches I just used a script to shut it down after one second (the process takes .5 second). It isn't a failsafe like the fuse tho, which really protects the system from unforeseeable failures. When I upscale I'll be hitting this thread up first.
DaOld Man:
Ok, I found a limit switch arm that I figured would work and look better than the hastily thrown together crank I used to test the actuator rig.
I had to drill the hole in the center of the arm to fit the 3/8" shaft.
The arm had a roller on the end, I removed it and bored that hole out to 1/4"
It is adjustable in crank length and rotation angle on shaft.
I am happy with the way it turned out:
Next I made bearings for the actuator pivot points.
I used brass pipe plugs (3/8"). I drill out a hole in the center for the pivot. (1/4", a little big but as close to pivot diameter that I had). I then filled the plug with wood putty. The putty set up pretty hard. I did this to keep oil from soaking into the wood and to help steady the pivot. Probably not necessary. Then I drilled out the wood putty (1/4") to the depth of the length of the pivot.
I then bored 1/2" holes in the wood supports and threaded the plugs in. It is a tight fit and I dont think they are going anywhere.
The actuator pivots a lot smoother and stays in line better.
Here is a pic of the backside of the bushing, showing the wood putty filler.
First pic of the new crank was with the monitor in vertical position. here it is in horizontal. (I dont have the mechanical stops or limit switches installed yet, its a bit past horizontal. You can see where I marked the stop for vertical (probably use a 1/4" bolt through the 2X4). There is a hole where I mounted the servo once upon a time. I plan to use this for the horizontal stop bolt.
I make the mechanical stops so the monitor can turn past the level vert and horz positions. This allows me some adjustment room on the switches, and if it hits the mechanical stop I will know because the screen will be crooked.
I then set up the rig to test for proper alignment. I ran small wirewrapping wire between the corners to find center of the screen. I then set up my camera tripod with a wood skewer for a pointer.
This pic shows monitor in vertical and pointer lined up on screen center.
And here it is rotated to horizontal. The screen is about 1/4" off center from vertical position.
Im going to have to live with this. I plan to center the monitor with the cabinet while in horizontal position, so maybe 1/4" to the side while in vertical wont be too noticeable.
And here is how I set up the centering guide. I ran the small wires (can be thread too) between each corner of the screen (not the monitor but the viewable portion of the screen). I scotch taped the wires to the monitor to hold in place. Where the wires intersect should be the center of the screen.
Next on my agenda for this project: Mount mechanical stops and rig up limit switches.
BadMouth:
Definitely "borrowing" that adjustable arm idea. :)
I know I'm not going to be able to get the screen exactly centered with my tools and ability.
My plan is to have a round logo displayed while rotating, and adjust the position of that until the picture is centered.
That will at least create an illusion of the screen being perfectly centered.
DaOld Man:
I have been experimenting with the adjustable arm.
I have found that the monitor turns faster on a short radius (arm adjusted towards center), but it is a lot "jerkier" so faster may not be better.
I am also experimenting with sliding a spacer over the worm shaft, which makes a very good mechanical stop for actuator retracting.
This actuator is so strong that it tries to bend the crank arm, so a extended mechanical stop will have to stop the end of the actuator screw, not the crank arm.
There is another hole in the actuator screw shaft on the opposite end, I thought about using that to make a mechanical stop for extended. But with the setup I posted, the hole in the screw end disappears into the actuator when extended, thats why I messed around with the crank radius adjustment, I did get the hole in the screw to still appear when monitor is just slightly past vertical. I put a finishing nail in the hole and extended the screw shaft. It bent the nail when it reached it, but it did stop the motor. I may have to move the actuator closer to the crank to get what I need. A nail is not going to work either. Like I said this actuator is pretty strong.
I like the way the monitor turns with the crank radius as in the pics I last posted. Much smoother. Will try to stay away from a short radius on the crank.
BadMouth:
--- Quote from: DaOld Man on May 01, 2012, 01:43:46 pm ---I have been experimenting with the adjustable arm.
I have found that the monitor turns faster on a short radius (arm adjusted towards center), but it is a lot "jerkier" so faster may not be better.
I am also experimenting with sliding a spacer over the worm shaft, which makes a very good mechanical stop for actuator retracting.
This actuator is so strong that it tries to bend the crank arm, so a extended mechanical stop will have to stop the end of the actuator screw, not the crank arm.
There is another hole in the actuator screw shaft on the opposite end, I thought about using that to make a mechanical stop for extended. But with the setup I posted, the hole in the screw end disappears into the actuator when extended, thats why I messed around with the crank radius adjustment, I did get the hole in the screw to still appear when monitor is just slightly past vertical. I put a finishing nail in the hole and extended the screw shaft. It bent the nail when it reached it, but it did stop the motor. I may have to move the actuator closer to the crank to get what I need. A nail is not going to work either. Like I said this actuator is pretty strong.
I like the way the monitor turns with the crank radius as in the pics I last posted. Much smoother. Will try to stay away from a short radius on the crank.
--- End quote ---
I've been planning on using the crank length to adjust the speed. I picture a square on the back of the monitor and I need to move one corner to the position of the next corner to get 90 degrees rotation. My actuator is lighter duty and rated at 1.5"/second, so I'd need a 4.5" square if I wanted the rotation to be 3 seconds. (slightly longer since the actuator isn't travelling a straight line, but close enough) ......at least in theory.
I'm waiting on a few more parts in the mail before testing. I thought about trying to get the length perfect so that it would hit the built in limit switches each way, but I'm not sure I'd be happy waiting that long for the monitor to turn. If I do go this route, can mrotate work without any input from limit switches?
BTW, I ordered the $7 motor driver from India that you linked to in another thread.
http://robokitsworld.com/index.php?main_page=product_info&cPath=73&products_id=15
Partially trackable and uninsured shipping, 7-15 day delivery was under $10.
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