Need some help from the auto-rotating monitor experts...

[nitz]

OK, after sitting on the parts for a few months, I'm finally getting a start on this and I'm stoked, but also pretty lost.

I'm one of those guys who can do the software side of things no sweat, but give me something like this and I feel a bit like a monkey working on a math problem.

I have all the parts from DNA Dan's shopping list in reply 13 of this thread http://forum.arcadecontrols.com/index.php?topic=112424.0. (Well, I don't have the hinge and the casters yet, but I may not need them as I'm planning a pacman style laydown monitor setup.)

I've looked through the documentation on the Pololu site, but I'm really lost as to how to wire this baby up. Also, it sounds like I need an external power supply...I was hoping it could just run off the PC's power via usb.

So if any of you rotating monitor gurus out there (*cough* TopJimmyCooks *cough* DNA Dan *cough* DaOld Man ) could help me out with some step-by-step instructions, that would be great! And don't be afraid to dumb it down to me - I'm a total noob at this and am probably really gonna need stuff spelled out.

[paigeoliver]

There is NO WAY you are gonna rotate a monitor using teeny amount of 5 volt power you can pull from a USB slot. I have read nothing about the setup you are doing, but you are gonna need more power than a USB slot can provide.

[Nephasth]

There is NO WAY you are gonna rotate a monitor using teeny amount of 5 volt power you can pull from a USB slot. I have read nothing about the setup you are doing, but you are gonna need more power than a USB slot can provide.

Well, that was helpful.

So if any of you rotating monitor gurus out there (*cough* TopJimmyCooks *cough* DNA Dan *cough* DaOld Man ) could help me out with some step-by-step instructions, that would be great!

Definitely the guys to ask on this one!

Your motor controller will be connected to your computer via USB, but you'll also have to bring supply voltage to the controller's "VIN" terminal, most likely 12V from a molex connector from your computer's power supply (yellow wire), and hook up ground (black wire from the molex connector you took 12v from) to the "GND" terminal of the controller. "OUTA" and "OUTB" on the controller to the the motor terminals.

Software wise... you'll have to wait for the powers that be to chime in.

[nitz]

There is NO WAY you are gonna rotate a monitor using teeny amount of 5 volt power you can pull from a USB slot. I have read nothing about the setup you are doing, but you are gonna need more power than a USB slot can provide.

I kind of figured as much as I know a usb port doesn't put out much power, but I don't see anyone else using a battery so I wasn't sure how they were powering it then.

Your motor controller will be connected to your computer via USB, but you'll also have to bring supply voltage to the controller's "VIN" terminal, most likely 12V from a molex connector from your computer's power supply (yellow wire), and hook up ground (black wire from the molex connector you took 12v from) to the "GND" terminal of the controller. "OUTA" and "OUTB" on the controller to the the motor terminals.

And now I see. This is why I need so much help...I would have never thought of this, and don't know how to do it. And, unless that's fairly idiot proof, I feel I might be better off powering it with a battery. I don't want to wreck anything, and especially not my PC.

This gives me some food for thought though while I wait for the powers that be to chime in...

[darthpaul]

It looks like you are going to need a 12v power supply with about 4 or 5 amps to play it safe, I'm using an Ebay special with no problems. I'm auto-rotating my 20" CRT using a windshield wiper motor. The Pololu motor controller I'm using is now out of production but the hook-up should be similar to yours. Since I am using DaOld Man's MRotate3, I had to use the PC printers port and a parallel cable for the auto-rotating feature. 

[nitz]

OK, the molex connector idea gave me something to go on, did some reading, and had a look inside my computer. There are some unused molex connectors in there. I see one with a yellow wire, 2 black wires, and (I think) a red wire. I was surprised to see 2 black wires...can I use either one for the ground? Do I need to cut the connector off, or would just sticking some wire into the connector work?

[TopJimmyCooks]

I think I tried to interchange the two black grounds but one ground is for the 5V, one is for the 12V.  Just make sure you get 5 or 12v when you complete the circuit with a tester. 

Because i had a small FF case with a wierd power supply on the pc, I used a separate ATX power supply for the motor, cab fan and marquee lights.  However, if I had an ATX power supply for the pc, a spare molex off of that would be plenty to pick up the motor as well.

The 131:1 pololu gearmotor needs between 12v and 18v, 12v works fine.  Nephasth explained how everything is fed through the pololu board, but if you need anything else, post.

[Le Chuck]

If one was using one of the LED screens with a Lazy Susan mount I don't see why a center mounted 5v servo wouldn't have the torque to muscle a 90 degree rotation.  You just need to isolate the support of the monitor from the force to move the monitor.  If you have a light monitor I think it is definetly worth a shot.  I'd be more worried about getting it to rotate slowly enough, you don't want the screen picking up momentum and stressing the servo. 

[TopJimmyCooks]

This is a wheel on wheel system.  The gear ratio given by the small wheel/tire on the monitor disc allows a tiny motor to be used, hence 12v 1/2A power supply to it.  Direct drive takes more like a windshield wiper motor with associated car amperage (3-4 amps or so?) or an Ond-style costly stepper motor.  Even then, there's still a geartrain.  It keeps the cost way down to use the robotics type motors, controllers, and their well developed software. The speed control can be set from 0 to max in increments ranging from 0 to 1000, so speed control may be finer than with a servo.  The servo with the horsepower and chassis to direct drive an lcd would be big bucks. 

I could see a servo that could do 900 degree rotation and accept a decent sized gear on the output shaft, interfaced with a larger gear on the monitor rotation axis (basically what Ond did) but the gear parts get so costly so quick its hard to be cost effective.  That's why the DNA Dan/Weisshaupt solution is so great, no expensive gears. 

[Le Chuck]

I am also a huge fan of the DNA Dan/Weisshaupt way but I definetly am going to explore the world of mid sized servos to direct drive a monitor, worst case scenario is I burn out a $20-$30 servo.  As for mounting if you're using a 3 or 4 inch lazy susan bearing it should be pretty staight forward to center mount the servo securely in the existing bearing support.  I know that Pololu has a beast that can move around 430 ozs at 12v but I don't know what the torque stall is at something like 5v.  

Edit:  Just found this servo that rocks 800 oz at 6vs for only a measely $300  

A bit better:  GWS S04 BBM can move 10kg at the post for the low low energy price of 4.8v.  The cost, under $20.  Totally trying this. 

[Nephasth]

Direct drive takes more like a windshield wiper motor with associated car amperage (3-4 amps or so?) or an Ond-style costly stepper motor.

Or a smaller monitor.

[TopJimmyCooks]

Edit:  Just found this servo that rocks 800 oz at 6vs for only a measely $300 

Dang, its on backorder.   

The issue with the lazy susan bearing is they're lightly loaded, but they're still being used at an angle they were never intended to do.  There's more resistance to rotation than you would think, especially when starting rotation from stopped.  The reason to use them is they cost $4.   

Had forgotten about the minibeast! 

[Le Chuck]

I thought there were some verticle force tested 4" bearings out there in the $10 to $12 range.  I'll see if I can dig one up.  Has anybody vertically stress tested the horizontal bearings?  They are rated in the 200 to 300lb range for horizontal.  At 5  to 10lbs for an LED monitor I'd think it'd be okay but would prefer to see some numbers behind that.  

Edit:  Found it. This bearing isn't actually a lazy susan bearing but a turntable bearing.  They do the same thing but are machined very differently.  I haven't been able to turn up the data sheet for it yet but most all turntable bearings have great verticle ratings as they are just small slewing bearings (think wind turbine or helicopter).  I'll be picking up one of these and putting it through some tests.   

[nitz]

Thanks Guys, some interesting discussion.

So I'm gonna go with wiring the 12V wire off a molex connector. Hoping to get a chance to play around with it on the weekend. If I get anything done worth sharing I'm gonna start a project thread.

EDIT: Could someone elaborate a little more on how I should do this? I was planning on using the same wire I'm gonna use for my CP which is 22 guage I think, or possibly 20. Should I try sticking this inside the molex connector, or is that a bad idea? Could it be dangerous? Should I just cut the connector off and wire that directly to my motor controller? Or would that be dangerous? Pretty clueless about this stuff, and definitely don't want to start a fire or damage anything.

[TopJimmyCooks]

5V or 12V 1/2A - no danger of "letting the magic smoke out" or messing anything up really so go for it.  paper clips, tinfoil, hot glue, do what'cha gotta do!

[Le Chuck]

There is no issue setting it up as a molex connection.  It would be a nice clean solution, but if you wanna start snipping ends and hard wiring there is not issue with that either.  I wouldn't just shove some 20g into the molex connector though, drop by radio shack and pick up some ends so you can do the fitting properly, you'll be happy with the result. 

[Nephasth]

I would recommend using bullet connectors for those inexperienced with wiring and wanting a connection that can be seperated at will. They only require standard crush type wire crimpers, no special crimping. Using male and female quick disconnects would work too, but I would recommend fully insulated connectors in this case.

ETA: When wiring a two wire connection like this, it is a good idea to alternate connector sexes on each end of the harness to help prevent connecting it backwards (i.e. a male and female connector on each side of the harness, so wire #1's male connector will only mate with its corresponding female connector, and wire #2 on the same side has a female connector installed so it will only mate with with its corresponding male connector on the other side).

Bullet connectors:


Fully insulated quick disconnects:

[TopJimmyCooks]

Nep, you're going to get into contract trouble if you're found recommending a non-Molex product.  It's not worth losing your endorsement deal over. 

  -the legal  department. 

[Nephasth]

 

Molex is always my recommended connector manufacturer to those who have the tools to properly use them.

[kahlid74]

Day late to this thread but you're on the right track.  Topjimmy knows his stuff so you should be all good with the above recommendations.  The only thing I'll warn you about is using a lazy suzy in this fashion can produce unknown results.  Those who have used it should know it's reliability but you are using it on a place it's not meant for, which Topjimmy stated before.

I plan to rotate a 42 inch LED TV in my showcase cab.  I plan to use Stepper motors with controls by Arduino's programmable interface and gears.  Topjimmy and Ond got me going in the right direction so If you're looking for another way to go Ond's build has a whole bunch of documentation.

Also, don't let Ond's method scare you.  The small Lbs*in torque required for a small LCD monitor can be accomplished with a small stepper motor/control.  So it's pretty cheap too.

[Le Chuck]

The only thing I'll warn you about is using a lazy suzy in this fashion can produce unknown results.  Those who have used it should know it's reliability but you are using it on a place it's not meant for, which Topjimmy stated before.

If you use a table top lazy susan you're right but there are thousands of bearings out there that are designed for rotational movement along a vertical plane.  The issue is that some lazy susans are thrust bearings (horizontal loads) and some lazy susans are radial bearings (axial loads).  Turntable bearings and slewing bearings do the same thing but are meant for industrial rather than household applications and are poured steel or iron rather than stamped aluminum yet are still commonly refered to as Lazy Susan bearings as well.  I did mention looking for vertical stress test data on table top lazy susans (thrust bearings) in an earlier post but further analysis leads me to conclude that this isn't necessary given the amount of affordable bearing solutions on the market, I have a good sized radial bearing lazy susan in the mail for $11 shipped.  What makes the "lazy susan"nice is that you don't need an axle as you have two fixed planes, but you sacrifice a lot of strenth doing that.  You can get flanged radial bearings in a 3/16 in diameter that have a dynamic capacity of over 300lbs.  They only go up from there, the trick at that size is finding an axle you can support the tv from.  Jump that up to 3/4 inch and you've solved the support problem for the axle and the bearing can support a midsized pachyderm. 

This was not meant as a rant but merely to clear the air about bearing application in rotation since I notice a lot of folks have written bearing solutions off and I think that they have a lot to offer. 

<significant edits for clarity>   

[nitz]

Thanks for all the help guys, I'm feeling a lot more confident about putting this together now.

[kahlid74]

The only thing I'll warn you about is using a lazy suzy in this fashion can produce unknown results.  Those who have used it should know it's reliability but you are using it on a place it's not meant for, which Topjimmy stated before.

If you use a table top lazy susan you're right but there are thousands of bearings out there that are designed for rotational movement along a vertical plane.  The issue is that some lazy susans are thrust bearings (horizontal loads) and some lazy susans are radial bearings (axial loads).  Turntable bearings and slewing bearings do the same thing but are meant for industrial rather than household applications and are poured steel or iron rather than stamped aluminum yet are still commonly refered to as Lazy Susan bearings as well.  I did mention looking for vertical stress test data on table top lazy susans (thrust bearings) in an earlier post but further analysis leads me to conclude that this isn't necessary given the amount of affordable bearing solutions on the market, I have a good sized radial bearing lazy susan in the mail for $11 shipped.  What makes the "lazy susan"nice is that you don't need an axle as you have two fixed planes, but you sacrifice a lot of strenth doing that.  You can get flanged radial bearings in a 3/16 in diameter that have a dynamic capacity of over 300lbs.  They only go up from there, the trick at that size is finding an axle you can support the tv from.  Jump that up to 3/4 inch and you've solved the support problem for the axle and the bearing can support a midsized pachyderm. 

This was not meant as a rant but merely to clear the air about bearing application in rotation since I notice a lot of folks have written bearing solutions off and I think that they have a lot to offer. 

<significant edits for clarity>   

Le Chuck, can you give me some examples/links to Axis/Bearings able to hold 30Lbs?  I've been doing some rough looking in my area and haven't found what I'm looking for yet.  Then again I'm new to this stuff so I'm not 100% sure what I'm looking for.  I would PM for this but I thought it would be good for others searching on this to find it.

[Le Chuck]

Le Chuck, can you give me some examples/links to Axis/Bearings able to hold 30Lbs?  I've been doing some rough looking in my area and haven't found what I'm looking for yet.  Then again I'm new to this stuff so I'm not 100% sure what I'm looking for.  I would PM for this but I thought it would be good for others searching on this to find it.

Sure thing.  Depends on what you're wanting to do and how you're wanting to hook up so I'll put a few solutions:

Axle based solution:  Both of these and pretty much any like them have a tolerance of several hundred pounds.

Flangette Collar Bearings - These are great because they have set screws in the collar so your axle doesn't just pull out.  Available in two bolt and four bold models. (tolerance of over 7 KNs on this model!)   

Pillow Block Bearings - similar to the above but they mount differently.  Many of these are not self lubricating so come with a grease zerk.  For arcade use you'd likely never have to lubricate.

There are also regular collar bearings and rod end bearings and all kinds of others that come in a variety of sizes a good price.  Just watch for key words like ceramic and surgical because prices will climb exponentially. 

Turntable based solution: Much lower weight tolerance but still around a 100 lbs or so, a data sheet should be coming with the sample I ordered and I'll update.

Aluminum Turntable Bearing - Right now this is the only axle free solution that is remotely affordable (various sizes available).  When I was in Germany slewing rings in the 100mm to 200mm range were commonly available at Einhaeupl's but they are harder to come across in the states it seems.  I've heard that you can get them at tractor supply stores so hit that up if you have one near by.  Other than that I'll keep searching for a steel supplier as you lose a lot with aluminum. 

[TopJimmyCooks]

. . . a data sheet should be coming with the sample I ordered  . . .

Got a rotating monitor project coming up?


I would have used that VXB turntable bearing if I had known of it before going with the LSB.  That is awesome and a great price. 

[Le Chuck]

Got a rotating monitor project coming up?

I would have used that VXB turntable bearing if I had known of it before going with the LSB.  That is awesome and a great price. 

I'm percolating for the kid's cabinet I'll be doing for their Christmas.  I'm getting the stuff now though because I really want to do a proof of concept on a 4.8v rotation using a robotics servo and that turntable bearing.  Once I get the pot issue sorted (or fail miserably) on my caanoo hack I'll be using the first linked flange bearing to support the scaled yoke. 

[kahlid74]

Thanks for the bearings examples.  I also saw that first site had shafts as well.  I got my motor and primary voltage controller today so I'll be rigging it up here in the next few days especially when I get my Power supply.

[kahlid74]

The question then becomes what type of shaft to use and gear vs pulley.  Anyone have any thoughts on one versus the other and what to look for specifically with shafts?  I see a lot of shafts rated for linear motion but what about rotational motion or are they the same?

[Le Chuck]

Most shafts you get that have a sufficient linear rating will have a sufficient radial rating.  This has to do with the basic shaft design (round and all) but there is variance if you're working at high rotations... which we aren't... so it doesn't matter.  If the shaft can hold the load and fits the bearing you'll be fine. 

As for gear and pulley that is more determined by what sort of drive you want to use.  There is no reason to even have gearing if you have a strong enough motor or servo to connect directly to the axle.  If you need to offset though I am still a huge fan of the wheel and roller from the DNA Dan builds.  (Same type that Darthpaul just used on his automation opus... and I think that Switchcade used it as well)

[DNA Dan]

Go for it Nitz! You can do it! I've been around, but just now saw your thread.

What I did for the pololu motor controller is I bought an actual molex pigtail so you can plug directly into the power supply of the computer. This way you have a plug and play design that is fool-proof. You want to use the 12V rail for this. The USB connection is strictly for communication to the software. I purchased the board already assembled because they have a nice terminal block on it for the power. You can extend the pigtail to reach the controller, but I would use similar wire, not some cheapo thin stuff. For the limit switches, I actually bought connectors from pololu for this so I could plug into the board easily. Check out --> http://www.pololu.com/catalog/product/1901 they even make the wires precrimped if you don't want to spend the extra time making your own http://www.pololu.com/catalog/category/72  If you have to solder any joints, just make sure they are well taped, shrink wrapped, etc. You can also install a connector in there, but I typically prefer to have a solid wire with only connections on the ends. The design of your cab will mostly dictate this and only you will know for sure where it might help to be able to break the wire and pull the motor controller out. For mine, I made a complete run with no other connections and put them in a harness. I also ran coin door, marquee light, top fan, etc, all in the same harness so the interior guts are nice and tidy.

The connections to the board will be 2 wires for power (Screw down terminals) and 4 connections (2 each) for the limit switches. That's it. The rest is all USB mini plug for the communication. Almost forgot, there are also two wires for the motor leads.

For the rotation, I actually prefer the axle design. I think that offers the least amount of drag and deflection. The issue with all these approaches is getting that axle mounted in the center of the monitor setup so it doesn't rotate lopsided. Remember, any lopsidedness with become evident when you try to make the bezel. One orientation or the other will not be perfectly centered top to bottom or left to right.

[DNA Dan]

For the molex computer stuff I used www.frozenCPU.com Be careful though, you could spend and entire paycheck here!

If you're concerned about ventilation, I used this for my fans up top http://www.frozencpu.com/products/9389/bus-202/Manual_12V_Variable_Speed_Controller_-_4-Pin_Molex_Connector_to_Dual_3-Pin_Fan_Connector.html?tl=g47c17s285

That website has a lot of good parts for using PC molex power supply connection to do whatever you really need.

[nitz]

Awesome, thanks DNA Dan, this makes things pretty clear.

This is what I love about this forum...ask for some help with something and get it in spades. Since coming here I've learned/done stuff I probably never would have attempted otherwise.

[DNA Dan]

Same for me dude. I am just paying it forward to keep the community alive.

[Ond]

I have been following along with this discussion, just some thoughts....  Stepper motors although more expensive than other motor types mentioned allow for simplicity of design.  With precise control of rotation you can focus on keeping the overall solution simple.  Someone mentioned that gears can be expensive.  I put a lot of thought into this and came up with a highly affordable but very robust solution in the form of toy helicopter Gears.  I looked up the biggest baddest model helicopter on the market and then sourced the spare parts from that.  The gear set uses a 'fishbone' profile that is very strong (think of the forces at work in a big ass helicopter model taking off) and also means zero slippage.  I've seen slippage issues with friction based rotating solutions.  From memory there was change out of about $35 for the gear set I bought so I bought a back up pair just in case.  The large ratio of these gears allows for high torque to play with.  I've yet to push the turning speed to see what I can get out of it, but that's next on my list.  Maybe rotate through 90 degrees with consistant precision stopping in under 1.5 seconds? (or shred the gears trying  ).

If you want bearing strength I recommend automotive bearings and bearing cages with a steel shaft to mount the monitor onto.

[DNA Dan]

For me the real appeal of a stepper motor is you could mount it AS the bearing itself. You'd need a beefy stepper, but the shaft could act directly as the rotation point with the monitor attached directly. You would save time and money on not having to screw around with the rotation parts so much, (lazy susan bearing, axle or whatnot) but the savings alone will not account for the cost of these industrial stepper motors. If mounting directly you'd probably want something 20mm shaft diameter or so and those can run hundreds of dollars. The other issue is the software interface. You'd have to use labview or some other software, something I lack experience with.

I like Ond's idea about a stepper with a gear ratio in there. This way you could have the cost savings of a smaller stepper. The issue again though is you need to create the rotation mech, unless the gearbox can handle this directly.

[kahlid74]

For me the real appeal of a stepper motor is you could mount it AS the bearing itself. You'd need a beefy stepper, but the shaft could act directly as the rotation point with the monitor attached directly. You would save time and money on not having to screw around with the rotation parts so much, (lazy susan bearing, axle or whatnot) but the savings alone will not account for the cost of these industrial stepper motors. If mounting directly you'd probably want something 20mm shaft diameter or so and those can run hundreds of dollars. The other issue is the software interface. You'd have to use labview or some other software, something I lack experience with.

I like Ond's idea about a stepper with a gear ratio in there. This way you could have the cost savings of a smaller stepper. The issue again though is you need to create the rotation mech, unless the gearbox can handle this directly.

The answer in short to your software interface is Arduino.  Arduino is easily coded and can control stepper motors who talk in "pulses"  It's been done with Arduino and "EasyDriver" which is a sort of small version of power/control for Stepper motors.

For my rotation, I'll be using a 428 oz*in torque motor that uses a 50 volt 5 amp controller with Pulse controls being powered by a 40v 5 amp power supply.  The 50 volt 5 amp controller then connects directly into Arduino.  Arduino tells the controller to execute X pulses and a direction.  Since my "box" will be 42" wide and 30 lbs, I'll have to use a gear ratio, but because gears are such a pain I'll be using a V-Belt to accomplish the same thing.  The V-Belt pulley's are super cheap along with a moderate V-Belt that is adjustable in size.

Ond's project originally was identical in design except where I'll be using the Arduino he used the KTA-190.  The KTA-190 is super simple to control but it's expensive compared to an Arduino and the Arduino can do a heck of a lot more to boot.

I should have all of my parts within the next week where I then will be building a test podium, mounting all of my parts and playing with the rotation.  Based on my success I'll create a new project thread for the machine.

[DNA Dan]

Which Arduino board are you using? I thought they were limited to 12-18v? Or is the motor powered separately?

[kahlid74]

Which Arduino board are you using? I thought they were limited to 12-18v? Or is the motor powered separately?

Motor powered separately by a 40v 5 amp Power Supply specifically rated for Stepper motors involved in CNC operations.  So it will work perfectly.

[darthpaul]

I know I'm still relatively new to this forum and no one loves gears and servos more than I do but isn't this all a little overkill, we are talking about an LCD monitor? I have done a rotating 21" CRT monitor using the friction method powered by a windshield wiper motor; simple, cheap and it works flawlessly. To control the speed, I am using PWM that is built into DaOld Man's MRotate plugin, no need for gearing.

[Le Chuck]

I know I'm still relatively new to this forum and no one loves gears and servos more than I do but isn't this all a little overkill, we are talking about an LCD monitor? I have done a rotating 21" CRT monitor using the friction method powered by a windshield wiper motor; simple, cheap and it works flawlessly. To control the speed, I am using PWM that is built into DaOld Man's MRotate plugin, no need for gearing.

Right but if you wanted to spin the monitor at 500 RPMs you probably couldn't... but they could.  That's the difference. 

[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]

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.

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.

[nitz]

No problem at all, I'm enjoying the discussion...even if most of it is over my head.

[Le Chuck]

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.

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.

I'm using a similar model minus the grease zerk for another application but those are fantastic bearings.  If I was doing an axle mounted monitor I'd go with a four hole just because I'd probably be working with a substrate that would need the added support. 

[DNA Dan]

I'm sure I could put some lighter weight grease in there if the drag seems excessive. I agree the 4 hole seems like a better strategy especially if there is some wobble in the rotation.

Do you think 6 seconds is too long for a rotation switch? The pololu linear actuators are nice because they have built in potentiometers for feedback if used with the JRK modules. Plus they're ~30% off right now.

[DNA Dan]

If I can get the double flange bearing with an axle shaft working it might be cheaper to just slap a sprocket on there with some chain and drive it directly. I could then get a motor with feedback position (how's that working out for you Jimmy?)

What I am trying to accomplish is a system that eliminates the need for limit switches and a tension type aparatus.

I just realized you have to center the rotation no matter how balanced or unbalanced the monitor is on the center point. Reason being is the bezel will be off in L/R or T/B if you offset the rotation to balance it. Basically you need to counterweight the aparatus once it's completed. I didn't have this issue the first time I did this because the mount was completely centered on the monitor and balanced perfectly. I am going to use a smaller monitor that has built in speakers I can cannibalize for sound which was a "leaner" type style, not mounted on a VESA compliant monitor stand. I am also going to make it "inset" in the disk to decrease the depth of the cab and make the bezel gluing easier.

I think I am in love .... http://www.robotmarketplace.com/store.html  Excellent place for the mechanical parts/gears/etc.

[Le Chuck]

Dan, kinda spitballing based on what you're saying but if you just use a second flangette locking collar bearing behind the first one spaced, oh, maybe 6 to 8 inches back and I would think that would take enough of the stress off the center collar to get your rotating smoothly w/out a counterbalance.  I think the $8 for a second bearing would be worth the trouble even compared to the price of free for a thick-ass peice of rusty iron you can bolt onto the ass of the axle to balance it out.
  
I like the linear actuator for rotation but I still think that a direct driving servo would be easier and faster.  I think 6 seconds would start to get one your nerves after a while.  The whole point is to get this as unobtrusive as possible and 6 seconds can be a long time, just ask a bull rider.  It's an untested theory but for $40 bucks the GWS Giant Servo should have the ass to do a CRT rotation condsidering it pushes 30kg at 6v.  Save you some dough over linear too.  When I do this I'm going to mill a collar that I can screw directly onto the servo output so I don't loose power through an actuating arm.

<edited to include example servo and adjusted cost> 

[TopJimmyCooks]

@DNA Dan:  the pololu motor feedback system is a quadrature setup, so it's really designed to give the actual speed under load v/s programmed speed for robots.  No positive position which is what we would be able to use,and what you get with a stepper motor, or to a lesser extent, with servo.  I'm not doing anything with it. 

[DNA Dan]

That sucks. So when they say "The jrk 21v3 motor controller is a highly configurable brushed DC motor controller that supports four interface modes: USB, logic-level serial, analog voltage, and hobby radio control (RC). The controller can be used with feedback for closed-loop speed or position control, or it can be used without feedback as an open-loop speed control."  

What exactly does "position control" entail? You can only offset values based on load that the board is receiving from the motor? The servo and stepper motors have their own dedicated boards, I assume with more logic chips on them.  It doesn't look like they support command line scripting for the stepper motors, just the DC motors and servos.

[TopJimmyCooks]

It's been a while.  I have the SMC board, not the Jrok.  I understood that the software could give position by counting quadrature pulses, but since my system, rather than being a low lash geared setup, was a friction wheel with limit switches, I surmised that counting 64 pulses (or whatever it was, can't remember, but it wasn't a big number) per rev would not work well for positive position with all the other factors.  Pulses may be acceptable once multiplied up by gear ratio, but the friction aspect/any wheel spin messes it up for me.  It's relative positioning, but not positive positioning in the way you get with a stepper. 

[kahlid74]

Quick question, how do I mount the shaft to the rotating monitor?  I saw on Ond's he used a metal contraption but I'm not to familiar with what part that would be.  I've looked at a bunch of parts but can't seem to find one that would make sense.

[Le Chuck]

Floor flange to VESA should suffice. Centering will take some work because center on a lot of mounts doesn't result in a centered rotation.

[DNA Dan]

Something like this http://www.vxb.com/page/bearings/PROD/Kit8299

or like this: http://www.robotmarketplace.com/products/0-HUB21225.html (This is probably what I am going to use.) I like the inset in wood approach because you will have a solid surface to which you can mount fiberboard for the monitor bezel to conceal the monitor/wood interface. I didn't do this with my first build and it was a real pain to glue a floating piece around the monitor's edge by itself.

Regarding the JRK board: You think if I used a chain and sprocket I could use this? There should be no slippage.

Centering: You should center the shaft based on the SCREEN. Don't center it by the weight distribution. When you rotate it, you want to have equal spacing in the bezel all around.

[Le Chuck]

Good links, Dan, I like both of those better than the threaded floor flanges.  Thanks 

[DNA Dan]

I'm telling you, that robot marketplace has some really good products for the mechanicals. Check out the sprocket section. Lots of custom sizes. (I am in no way affiliated with them, just stoked I found them!)

[TopJimmyCooks]

A well fitted drive shaft gear plus a motor shaft gear would be the best for positioning measurement.  A tight chain would be second best but I think it would work.  just build in an adjustable motor mount to set the chain tension.  If the motor is say, 50 to 1 geared with the 64 pulse per motor shaft rotation, and you use the jrock board then you can register 3200 pulses per full rotation, that's stepper motor territory.  should work fine, especially since pololu software can brake the motor at rest 100% like a servo.   

[kahlid74]

My stepper motor has an 8mm shaft, but I can't find any pulley's with that bore.  Any of you have any ideas?  8mm is right about 5/16's but no one seems to have them for pulleys.  I found gears for them, but no V-Belt pulleys.

Also, if I were to take a 1/2" bore what do you think would be a good way to "enlarge" the shaft on the motor from 5/16" to 1/2"?  Are there metal collars somewhere I can use?

[DNA Dan]

On a shaft that small I would use the timing pulleys if you can fashion one on the motor to mate it up with.

http://www.robotmarketplace.com/products/timing_pulleys_main.html

You're going to be hard pressed to couple those two. If you have a drill press you could drill out the 1/2" shaft and either slip or thread the 8mm shaft.

[kahlid74]

On a shaft that small I would use the timing pulleys if you can fashion one on the motor to mate it up with.

http://www.robotmarketplace.com/products/timing_pulleys_main.html

You're going to be hard pressed to couple those two. If you have a drill press you could drill out the 1/2" shaft and either slip or thread the 8mm shaft.

The problem with timing belts is you can't adjust the size.  So literally I'll have to create the mechanism the size of the belt and then get a tension-er.  With the V-Belt I've found an adjustable V-Belt that can do what I want. - http://www.amazon.com/Powertwist-Power-Twist-V-Belt/dp/B001BQDS8I/ref=sr_1_1?ie=UTF8&qid=1332267529&sr=8-1

Perhaps then I should use gears.

Also, trying to find a Floor Flange/Die Cast hub with a 3/4" bore is quite challenging.

[DNA Dan]

I think the belts with the teeth on them would be okay as long as the motor was able to be adjusted once the belt is worn in. Beyond that, there should be very little slack that develops in the belt with the speeds we are talking about. The rotation isn't a super fast RPM, it's more of a properly geared/torque issue. I am going to attempt the feedback motor for positioning, so I want something that has no possibility of slippage, which would be a sprocket. I just hope there isn't too much slack from the teeth once they are in the chain. I don't know whether this is better than the toothed belts in this regard. Although a toothed belt can slip, as long as there is some tension on the belt I think they are pretty solid and perhaps just as good as a chain drive.

The drawback to the belt is the size is fixed like you say. You should however be able to find one in the size you need to meet the mechanic design. In the long run, this may be an issue if the belt is no longer made. So maybe the old chain/sprocket stuff is more likely to be around in 10 years?I dunno, both designs seem to be industry standards that aren't going away.

For your 3/4" flange, I would buy the 5/8" one and drill it out. You only need to gain 1/8"

[TopJimmyCooks]

My stepper motor has an 8mm shaft, but I can't find any pulley's with that bore.  Any of you have any ideas? 

8mm drill.  can't get it at Home Depot but Grainger, McMaster, any real hardware store, even stateside.

"enlarge" the shaft on the motor from 5/16" to 1/2"?  Are there metal collars somewhere I can use?

It would be called a bushing.  That would be hard to find in that ID/OD - probably fastest to have one cut for you at a machine shop out of brass or aluminum.

The problem with timing belts is you can't adjust the size.  So literally I'll have to create the mechanism the size of the belt and then get a tension-er.  With the V-Belt I've found an adjustable V-Belt

Tensioning is best achieved by having an adjustment to the motor's distance from the axle rather than trying to have an exact belt length.  A powertwist usually goes on a 3/8" sheave/pully for woodworking equipment use.  They're designed to slip a little rather than positive grab all the time.  not recommended. 

Also, trying to find a Floor Flange/Die Cast hub with a 3/4" bore is quite challenging.

It's a standard NPT size, not a Home depot item but a real plumbing/gas supplier would have a bin of them.  It would be for 3/4" ID pipe, not od, though.  3/4" OD not sure there is such a thing if that's what you meant.  (like a 3/4" rod used as an axle.)

I think the belts with the teeth on them would be okay

Those are usually called gilmer belts.  They are hard to spec gears for but if you have any old inkjet printers they often have small ones, perhaps could be doubled up.  For this application you can shorten one by cutting 45 degrees on each end (aligning the teeth) and taping it back together.  Don't know the tape used but many of them are made with tape splices from the factory.  EditAll tape would work if you can find some. 

[DNA Dan]

Those are usually called gilmer belts.  They are hard to spec gears for but if you have any old inkjet printers they often have small ones, perhaps could be doubled up.  For this application you can shorten one by cutting 45 degrees on each end (aligning the teeth) and taping it back together.  Don't know the tape used but many of them are made with tape splices from the factory.  EditAll tape would work if you can find some. 

The belts are nice, but the gears for them are pricey and don't come in the size I want. I will be using the geared pololu motor maybe 100:1 with feedback so the chain system I need can just be 1:1 or slightly better. I think my cab now has the higher gear ratio with the friction setup and it's a little overkill.

[kahlid74]

Thanks Top Jimmy.  My Axel/Shaft is 3/4" diameter so I need ID bore to be 3/4".

So if I move to gears where is the best place to pick up an 8mm gear for the motor and a 3/4" gear for the shaft?

Also, what drill bit would I use to bore a 3/4" hold in a 5/8" or 1/2" Die cast hub/Floor Flange?  I'm assuming I'll have to drill it since no one seems to make one of 3/4" ID bore.

[TopJimmyCooks]

Here's a flange for a 3/4 OD rod. 

http://www.mcmaster.com/#structural-framing-floor-flanges/=gr9z9p

on the gears, those are large sizes so they'll be pricey.  Boston gear or mcmaster carr. 

[kahlid74]

Here's a flange for a 3/4 OD rod.  

http://www.mcmaster.com/#structural-framing-floor-flanges/=gr9z9p

on the gears, those are large sizes so they'll be pricey.  Boston gear or mcmaster carr.  

Okay hot Giggity Giggity that site is the beeznees.  I like to think I've got pretty good Internet Search skills but how in the world did I miss this site?  So They've got my floor flange, kicking.  They also have 5/16" pulleys.  So if I roll the pulleys the next question comes down to creating a tension-er for the belt system.  Where would I even start with this?  I'm going to do some searching to see if I can find some example but any Suggestions you guys have would be awesome.

What about this tensioner - http://www.grainger.com/Grainger/FENNER-DRIVES-Selfadjusting-tensioner-2ZRT8

[TopJimmyCooks]

Think more like sheet metal and make it yourself.  look at the alternator bracket on your car for ideas. 

[kahlid74]

Think more like sheet metal and make it yourself.  look at the alternator bracket on your car for ideas. 

I don't think that will work because I'm using the power twist belt.  It's not flat on the bottom of the belt but instead jutted.  So I would be worried about the outgoing jut hitting an alternator bracket.  Also, I just don't have a workshop where I can easily work with Sheet metal.

I'll go with the tensioner I posted before and we'll see how it goes.

[TopJimmyCooks]

I may not have explained well enough why you don't need both an adjustable length belt system and a tensioner.  I looked at that tensioner, it's 75$.  This seems crazy out of proportion for the job at hand.  mount the motor on a hinge and let the weight of the motor provide the tension.  I think that mcmaster rod flange was $25 plus shipping.  You're going to have more cash in hardware than in a display at this rate.  I think you've jumped the shark.  If your budget for rotation is $500, go read ond's thread ~page 7.  two pillow blocks is a better solution.  direct drive is better.  with a belt you'll lose your positive positioning and you'll be back to limit switches.  Consider before placing those orders Dude.  All my rotation hardware was $65 including a dedicated usb motor controller, after I sold some spares on to others. 

Can you tell its been a ---smurfy--- day for me?

[kahlid74]

I may not have explained well enough why you don't need both an adjustable length belt system and a tensioner.  I looked at that tensioner, it's 75$.  This seems crazy out of proportion for the job at hand.  mount the motor on a hinge and let the weight of the motor provide the tension.  I think that mcmaster rod flange was $25 plus shipping.  You're going to have more cash in hardware than in a display at this rate.  I think you've jumped the shark.  If your budget for rotation is $500, go read ond's thread ~page 7.  two pillow blocks is a better solution.  direct drive is better.  with a belt you'll lose your positive positioning and you'll be back to limit switches.  Consider before placing those orders Dude.  All my rotation hardware was $65 including a dedicated usb motor controller, after I sold some spares on to others. 

Can you tell its been a ---smurfy--- day for me?

No worries man.  I come here to get help and look for cool ideas.  Some stuff I'm all hands on and others I'm not.  Stuff like this is not my specialty of strong suit so where as for you to design a system to do what an auto-tensioner would do, I would prefer to save the time I would spend bumbling on something that was half ass and go with a rock solid part.  The door hinge is a cool idea but I know this would work the best.  I also had a 50% off coupon with grainger from a buddy at a machine shop so I got it for $35 with free shipping.

So here's the thing, I've gotten a bunch of great information but when it comes to moving 30 lbs at 45" across the consensus from all the motor experts on various forums I've been trolling say I need a metric ton of horse power.  So lots of oz*in torque.  To go with Gears like OND I would need a stepping motor with north of 1000 oz*in torque or a massive gear box.  Stepping motors/gears of that nature are insane expensive and big/clunky and want a lot of juice.  So, I'm just buying parts now to experiment.  As far as I'm concerned this is all throw away to me understanding how to actually build this right.

If it works, awesome.  If it doesn't, no big deal.  I'm at about $100 on parts right now.  Building the networking and virtualization of data centers, my job has put me in touch with a lot of people from many different fields.  I just called in a bunch of favors and got a lot of parts for either cost or %50 so for me it was a fun way to experiment.

In the end, I could have been smarter with what I purchased but honestly, I just want to learn this stuff and what better way to learn than just dive in and learn by trial and error.

[DNA Dan]

You've been warned, it's an addicting hobby! I am already planning my second...

[nitz]

Pulling this back to the original topic for just a moment...I got around to setting up the motor today and it worked great!!! I can't believe how easy it was...I just needed a push in the right direction.

Now I've just got to learn the ins and outs of the software and slap together my LCD, wood, and motor!

Thanks again guys!

[Le Chuck]

Pulling this back to the original topic for just a moment...I got around to setting up the motor today and it worked great!!! I can't believe how easy it was...I just needed a push in the right direction.

Now I've just got to learn the ins and outs of the software and slap together my LCD, wood, and motor!

Thanks again guys!

Shame on you for not posting a pic or video with this great news.  What a frickin tease. 

Glad it's up and running.   

[DaOld Man]

I agree...
 

[nitz]

Shame on you for not posting a pic or video with this great news.  What a frickin tease. 

Glad it's up and running.   

  Well, there's not much to see as all I did was wire up the motor and make it run. You better believe I'll be doing a project thread once I get some actual monitor rotation happening though.

[kahlid74]

Shame on you for not posting a pic or video with this great news.  What a frickin tease. 

Glad it's up and running.   

  Well, there's not much to see as all I did was wire up the motor and make it run. You better believe I'll be doing a project thread once I get some actual monitor rotation happening though.

Way to go man!  Post some pics for the rest of us to see!

[kahlid74]

Here's a flange for a 3/4 OD rod. 

http://www.mcmaster.com/#structural-framing-floor-flanges/=gr9z9p

on the gears, those are large sizes so they'll be pricey.  Boston gear or mcmaster carr. 

Hmm, so after closer inspection upon the received part (which I didn't really look on the page) the smallest OD floor flange was 1".  So these don't work.  I need 3/4" OD.  Any other ideas?

[kahlid74]

So here's a question, how do I get the shaft through the bearing?  Or better yet, how do I get the bearing on the shaft?  I've got a 3/4" OD Keyed shaft and a 3/4" Bore Pillow block bearing.  I can kind of get the edge of the shaft into it and if I push it goes in but not very far.  All jokes aside does anyone have any good ways of how to insert the shaft say a foot or two into the bearings?

[Le Chuck]

So here's a question, how do I get the shaft through the bearing?  Or better yet, how do I get the bearing on the shaft?  I've got a 3/4" OD Keyed shaft and a 3/4" Bore Pillow block bearing.  I can kind of get the edge of the shaft into it and if I push it goes in but not very far.  All jokes aside does anyone have any good ways of how to insert the shaft say a foot or two into the bearings?

Should go easily. Is your collar fully loosened?

[kahlid74]

The collar is fully loosened.  I got the 3/4" bore 6" diameter pulley on it just fine but the pillow lock bearings are just kind of being a pain in the butt.  I'm also not really pushing it all that far down it because I don't want to put it fully on until I have a test base assembled.  So yeah, still not really going on.

[DNA Dan]

It only takes 1/64th or less of an inch to make this an issue. I would take some superfine steel wool and work the rod lenghtwise. Wipe it down with mineral spirits and give it another go. If that doesn't work, use some super fine 4000 grit sandpaper and wetsand the rod lengthwise. Again, wipe with mineral spirits and try again.

Another possibility is the rod is slightly bowed at the point where it gets stuck. Not much you can do but shrink and smooth out the sides.

You could also try freezing the rod and taking a blowtorch to the bearing.

Whatever you do, make sure there isn't any shavings or dust from the rod when you try to press it in. Although small, they will build up and make matters worse with such a tight fit.

[Le Chuck]

The collar is fully loosened.  I got the 3/4" bore 6" diameter pulley on it just fine but the pillow lock bearings are just kind of being a pain in the butt.  I'm also not really pushing it all that far down it because I don't want to put it fully on until I have a test base assembled.  So yeah, still not really going on.

That sucks then.  I had to ask, I can't tell you how many times for me it's been something simple like that.  +1 to a light sanding and lube. 

[DNA Dan]

Where did you get the shaft from? Where did you get the pillow block from?

Might be a good idea to take some calipers to the ID and OD to see which one is off, then send the company an email.

[TopJimmyCooks]

What these guys are saying makes sense - something very common with rod stock is that its deformed where sheared/cut or possibly banged/dropped at the ends.  I would make sure you've got a slight bevel at the ends or use a straightedge to see if you have any bend or deformity.  you can get a good enough dial caliper at a hardware store to tell you whether one or the other diameter is wrong.  Get a $20 metal one rather than a $10 plastic one. 

good suggestions all.  make sure you know what's up before you do what i did one time:  laid the bearing over a hole in my drill press table, tapped in a recalcitrant bar with my BFH and surprise, didn't spin worth a crap.  That was a $2 bearing though, I think you've got something worth a little more $ to worry about. 

[kahlid74]

Thanks for all the suggestions guys!  The rod and bearings were from different places so it's entirely possible one is on and one is off.   I'll see what I can do.  Had the afternoon off so came home early and just finished the base.  I'm thinking it will hold a 30Lbs 42" TV just fine but we'll see once we mount it.

[darthpaul]

Do you think 6 seconds is too long for a rotation switch? The pololu linear actuators are nice because they have built in potentiometers for feedback if used with the JRK modules. Plus they're ~30% off right now.

I don't think this is a negative, I think seeing a monitor rotate is cool and should be played up. DaOld Mans MRotate has the ability to play a sound, when my monitor rotates, I'm playing the the Star Destroyer alarm sound.

[darthpaul]

I'm telling you, that robot marketplace has some really good products for the mechanicals. Check out the sprocket section. Lots of custom sizes. (I am in no way affiliated with them, just stoked I found them!)

For future reference for anyone, this is where I picked up my gears for my rotating control panels.https://sdp-si.com/eStore/

[kahlid74]

So I wound up building a prototype this last week/weekend.  My friend came over and we mounted the 42" LED TV to it.  It spun like a dream and the weight held fine on two pillow block bearings with 3/4" Keyed shaft.  We then tested the pulley's and like everyone said, at about 90% the pulleys started to slip, which is what my friend said they would do.  I kind of figured they would but I like trying stuff too.

So he was thinking timing belts, I was thinking gears.  The challenge is the weight of the TV pulls the rod just enough where the gears would lose contact, but it's enough to "autotension" a timing belt.  So the next challenge is finding pulley's that are built for timing belts and have an 8mm bore and a 3/4" bore.

I took a bunch of pictures so I'll start a new thread in the Project announcement area and post it all there so we stop clogging up Nitz original thread with my antics.

My big challenge now is this cab or my Battletech VR 3.0 pod.  Fudge, I just don't have enough time.

[nitz]

And back to the original thread topic again.

I've got another question: how do I connect the limit switches? I think I know how to do it, but there are some pins on the motor controller where I'm supposed to wire it to...do I need some kind of connector here? I hope not 'cause I was all psyched to work on this today and it would suck to get delayed while I wait for that to show up in the mail.

Please advise...and remember to really spell it out for me.

[darthpaul]

I know this was probably the wrong thing to do but I just soldered the wires to the pins but if you are using DaOld Man's Mrotate plug-in, the limit switches get connected to the printer port's parallel cable.

[TopJimmyCooks]

Pololu board needs .10" molex connectors.  or you can bend the pins and solder to them. 

[nitz]

Thanks for the quick and helpful responses.

I'll likely go the molex connector route since I may be able to harvest some from an old power supply, plus I haven't soldered in forever and don't own a soldering iron.

[DNA Dan]

See my reply #29 "For the limit switches, I actually bought connectors from pololu for this so I could plug into the board easily. Check out --> http://www.pololu.com/catalog/product/1901 they even make the wires precrimped if you don't want to spend the extra time making your own http://www.pololu.com/catalog/category/72  If you have to solder any joints, just make sure they are well taped, shrink wrapped, etc. You can also install a connector in there, but I typically prefer to have a solid wire with only connections on the ends. "

I don't know what molex connection you're thinking of on a power supply, but these are super tiny connections; .10"

[nitz]

Thanks, this thread has gotten so long I guess I forgot about that post.

I actually did find a couple of the tiny molex connections on an old power supply and tried them out with some cherry switches. Worked great! It's not the prettiest or tidiest solution, but meh, when everything's inside the cab no one will see it anyway so I'm just gonna go with it.

Now to slap together some wood, lazy susan bearing, and my monitor...

[kahlid74]

Thanks, this thread has gotten so long I guess I forgot about that post.

I actually did find a couple of the tiny molex connections on an old power supply and tried them out with some cherry switches. Worked great! It's not the prettiest or tidiest solution, but meh, when everything's inside the cab no one will see it anyway so I'm just gonna go with it.

Now to slap together some wood, lazy susan bearing, and my monitor...

The cherry switches are an ingenious way to incorporate limit switches.  Very cool.

[darthpaul]

Just another option from DaOld Man

[kahlid74]

Just another option from DaOld Man

That arm assembly looks super elaborate.  Is that cheaper than a Rod/Bearings/Stepper motor process?

[DNA Dan]

Well since the linear actuator has already been done, I guess I won't be going that route. It does look complex.

[Le Chuck]

Well since the linear actuator has already been done, I guess I won't be going that route. It does look complex.

Not to be outdone DNA Dan's next rotation build uses a Star Wars Science Force Trainer hack to enable brainwave acutation of an electro-magnet zero friction hover mounted CRT monitor.  A nice side effect is his ability to... these are not the droids we're for... move along. 

[kahlid74]

Well since the linear actuator has already been done, I guess I won't be going that route. It does look complex.

Not to be outdone DNA Dan's next rotation build uses a Star Wars Science Force Trainer hack to enable brainwave actuation of an electro-magnet zero friction hover mounted CRT monitor.  A nice side effect is his ability to... these are not the droids we're for... move along. 

Don't forget that he will also incorporate a Neuro-Helmet into the mix so that his emotions can drive the rate of rotation.

[DaOld Man]

Well since the linear actuator has already been done, I guess I won't be going that route. It does look complex.

I really dont see where it is complex. (Or at least what I have done).
My rig is about as simple as you can get.
It has two pine 2X4's with a hole bored in the center of each. In the holes it has 3 brass bushings for bearings, and for a shaft it has a 3/8" round stock (bar). Add two more 2X4 blocks to properly space the other two 2x4s.
The only thing that might be complicated is the welding.
The lever arm (crank) I used was thrown together in about 10 minutes using discarded parts at work. (I had to weld it at work, since I dont have a welder. I didnt even take my time and weld it right, plus Im not a good welder.). I just used an old wrench that went to a worn out power tool (similar to a router collet wrench), and welded it to a nut. I then bored a hole through the nut and the shaft so a locking bolt could pass through both.
I did it quick and dirty because this is only a test. The test did work, so now Im in the market for a factory made crank, not sure what it will be yet, I may have to make another one out of key stock material.
The other perhaps complex part is the plate that attaches the monitor to the shaft. I had to weld it to the shaft
too.
This 2X4 rig was originally for a stepper, and I tried two different kinds, which explains all the strange cutouts in the 2X4's. (The steppers I tried did not work).
I may have to build another rig to document step by step how to do it.
The actuator I used is pretty simple too. Electrically, its just a DC motor. No special pulse drive needed.
The limit switch set up on this rig is also left over from the stepper trial. I used a special half gear on the first stepper I used. When it didnt work, I used that half gear to make the overtravel limits. I had to used a brass bushing to attach that half gear to the shaft. Im loosing that too, so even less complex.
My first goal on this setup was to use a stepper motor so I could exactly position the monitor through software. (Nice dream, but not truly necessary, my first rotator used limit switches and once you get the limit switches set, stop positions dont change on it.)
My second goal was to make it simple. (Trust me there is not much simplicity to a stepper drive and software.)
My third goal was to do it cheap, so others on a tight budget wouldnt be driven away.
When my steppers failed me, I shelved the rig until i saw DarthPauls project and how he used that actuator.
I thought, "you know that might work on my 2X4 rig".

Now as far as it already been done, dont let that distract you. The rotating monitor idea was here a long time before I was, so it had been "done before" when I got the urge.

Im looking forward to see what you guys come up with.
Keep the faith (and the good work) and some day everyone will be turning their monitor automatically, easily, and cheaply.

[DNA Dan]

Actually I am hoping for a complete single sheet of black glass that IS the monitor. Emulation would be able to be drawn in any direction with animated bezels and whatnot... I am hoping this whole rotation thing is a stop gap measure. Besides in another 5+ years there will be no more 4:3 ratios left.

DaOld Man, Really great job on the actuator! I love seeing what you come up with.

Nitz, are you rotating yet?