Appropriate Motor/Shield/Power for 1st timer's Lazy-Susan

Hello. This is only my second post, so please excuse my stupid questions. I am new to working with electronics and Arduino as well as motors and gears. I have done quite a bit of research and experimenting and even almost blew myself up one time, but I am still struggling with this project. Please review the brief description I have - I will gladly welcome any tips, advice, and general knowledge any of you may offer. My main concerns involve the proper torque (I am completely overwhelmed by all the formulas and gear ratios, etc), powering, and overall size.

Project: Motorized Lazy-Susan with ability to control speed and direction with the use of an Arduino Uno R3

General Info:
I am a visual artist - I do light show projections on bands while they play and provide a creative, dynamic form of ambience in other situations. I am looking to automate with control, the rotation of a clear lazy-susan which I use with a Canon RE-350 (document camera much like an overhead projector - http://www.usa.canon.com/app/pdf/projector/re350_manual.pdf) illuminating objects on the lazy-susan turntable from above and below. The image is sent to my computer where I manipulate it with various software effects, mix it with other visual content, and send it all out to a projector to display the mixed content.

I have just recently got an Arduino Uno from Sainsmart and have motor shield on order. I also have a decent digital multimeter and soldering iron, all which I am just learning to use - via tutorials and experimenting.

Other various info regarding the project:
Input via MacBook and/or iPhone and possibly MIDI
I currently use a MacBook with an Oxy8 MIDI controller. It would be great if I could manage the motorized turntable in the same program (Arkaos VJ- older, outdated, yet still functional VJ software) I use to manipulate the video, but if that’s even possible, I can save that for a later project once I’ve achieved the basic part of this project - motorizing the lazy-susan.
Being able to control the device with an iPhone would be best to start with as my computer will be in use at the time I would need to send data to the driver, unless I incorporate analog knobs/fader, which is completely acceptable.

Equipment Specs:
Lazy-Susan**
Diameter: 12" (9" base, 12" turntable)
Material: Acrylic - As sold by Tap Plastic
http://www.tapplastics.com/product/plastics/acrylic_displays/revolving_display_bases/355

**Must be clear and unobstructed to allow light to pass through underneath

Desired Functions:
360º Rotation
Variable Speed: 1-10 RPM
Load Range: (approx.)
Minimum: 8g (eg. overhead transparency)
Maximum: 1,800g (eg. tray of marbles, glass dish)

So, at this point, I know I need a high torque motor, but am not sure if there is such a motor that can handle the range in load and speed I am looking for. I tried a mirror ball motor, but it was not appropriate as I could only get it to go one speed - too slow.

I tried to make a variable speed controller from a dimmer switch, but no luck. I was going to try a turntable motor someone gave me, but I blew it up before I could even test it with my set-up.

I really was hoping to repurpose a scavenged motor due to my extremely limited funds. That would be ideal, but so far, I have not had much luck and am hesitant to purchase something that wouldn’t work or that I might destroy by accident.

As you can probably see, I really don’t know what I’m doing.

There are certain limitations here as well - such as the motor must be offset in order to preserve the clear lit projected image however, I was looking at these robotic motors and wondered about the feasibility of attaching them directly to the lazy-susan turntable overhang (approximately 1.5" around), but then wouldn’t the power and Arduino/shield also need to be connected there as well?

http://www.banggood.com/Robot-Smart-Car-Wheel-Deceleration-DC-Motor-For-Arduino-Smart-Car-p-907973.html

This actually poses a number of questions should I be able to use these.

Anyway, like I said, any help offered is greatly appreciated. Thanks so much for taking the time to read through and reply should you choose to do so.

Desired Functions:
360º Rotation
Variable Speed: 1-10 RPM
Load Range: (approx.)
Minimum: 8g (eg. overhead transparency)
Maximum: 1,800g (eg. tray of marbles, glass dish)

The below servo modified for continuous rotation (very easy) and the bottom lazy-susan might form the basic platform you need.

http://www.homedepot.com/p/Shepherd-6-in-Lazy-Susan-Turntable-9548/100180572

zoomkat:

Desired Functions:
360º Rotation
Variable Speed: 1-10 RPM
Load Range: (approx.)
Minimum: 8g (eg. overhead transparency)
Maximum: 1,800g (eg. tray of marbles, glass dish)

The below servo modified for continuous rotation (very easy) and the bottom lazy-susan might form the basic platform you need.

Radio Control Planes, Drones, Cars, FPV, Quadcopters and more - Hobbyking

http://www.homedepot.com/p/Shepherd-6-in-Lazy-Susan-Turntable-9548/100180572

Thank you for responding, zoomkat. I already have the lazy-susan - it's just like the one I linked in the original post. I would like to try this servo, but I don't really have much time before my next gig to order a different one if it should not work out. Zoomkat, Are you fairly confident that this servo will meet my torque needs - I know it's impossible to calculate without the turntable friction force torque factor, but I know that gearing down it should be about the right speed.

And I guess it should work fine with the Arduino and the L293D motor shield I have on order?

Thanks again. I will order it later today unless I hear back from you otherwise before then.

I’d suggest a look here for motors, wheels, mounting brackets - you’re going to have a spinning wheel driving the lip of the lazy susan, yes? So you’ll need a method to hold all the bits together.
http://www.servocity.com/html/wheels___tires.html

CrossRoads:
I'd suggest a look here for motors, wheels, mounting brackets - you're going to have a spinning wheel driving the lip of the lazy susan, yes? So you'll need a method to hold all the bits together.
http://www.servocity.com/html/wheels___tires.html

Yes, that is correct. I currently have a piece of medical tubing going around the lip of the turntable which I just slit down lengthwise (though quite unevenly) to fit it. I have had success testing it with various tools fitted with a rubber grommet.

If I do order the servo as suggested by zoomkat, it has a gearbox, so it would just be a matter of attaching the right sized grommet or such to the output shaft, no?

CrossRoads:
I'd suggest a look here for motors, wheels, mounting brackets - you're going to have a spinning wheel driving the lip of the lazy susan, yes? So you'll need a method to hold all the bits together.
http://www.servocity.com/html/wheels___tires.html

Wow, that does indeed look like a fantastic resource for parts. Thank you for pointing me there. My limited budget has me trying to use as much stuff I have laying around as possible, but if I can get the 'prototype' to work well and do what I want, I will eventually want to rebuild it with proper parts, and when I have some money to invest in it properly. I love all that kind of stuff. I was initially thinking about turning my lazy-susan turntable into a meshed gear, thinking that would be most efficient, though again, limited by budget. Perhaps I could find a rubber lip that could fit the turntable better than my unevenly cut, and did I mention bulky, medical tubing.

If I do order the servo as suggested by zoomkat, it has a gearbox, so it would just be a matter of attaching the right sized grommet or such to the output shaft, no?

Yes, hot glue is quick, easy, and generally removable if needed. Below is how I modify the servo for continuous rotation. After modifying the servo, send a 1500us command signal to the servo and tweek the pot until the servo stops. Pot a little dab of glue on the pot shaft so it doesn’t drift, then reassemble.

edit: If you send the 1500us command and let the servo position prior to disconnecting and opening the servo, tweaking of the pot might not be needed if you are careful with the output gear/collar removal.

zoomkat:

If I do order the servo as suggested by zoomkat, it has a gearbox, so it would just be a matter of attaching the right sized grommet or such to the output shaft, no?

Yes, hot glue is quick, easy, and generally removable if needed. Below is how I modify the servo for continuous rotation. After modifying the servo, send a 1500us command signal to the servo and tweek the pot until the servo stops. Pot a little dab of glue on the pot shaft so it doesn’t drift, then reassemble.

edit: If you send the 1500us command and let the servo position prior to disconnecting and opening the servo, tweaking of the pot might not be needed if you are careful with the output gear/collar removal.

Thank you for the details and the graphic, zoomkat. It should be much easier for me to have this as a reference. I talked to a guy yesterday at a nearby hobby shop, and he explained the process, but this is definitely what I needed to see.

I will go ahead and order the servo then. Just wondering what other small parts may be needed that I haven’t thought of, to make my order worth the cost of shipping - extra or various sized shafts or possibly couplers? And will the Arduino be capable of powering this servo or do I need to consider an additional power supply?

I’ll check the servo/wheels dealer CrossRoads suggested as well - maybe they have a similar priced servo (though hobbyking’s is pretty cheap) and then I could get a precision wheel to attach to it. I’m just not sure what size that would need to be yet.

Thanks so much for your help. Really appreciated.

You need a power supply for the servo, the arduino will only supply the control signal.
I wonder if you could also locate a long cogged belt & glue that to the outside of your turntable, then could experiment with different gear sizes.

CrossRoads:
I wonder if you could also locate a long cogged belt & glue that to the outside of your turntable, then could experiment with different gear sizes.

Yea, I was wondering if something like that existed - assuming I understand what that is, which I think I do. That would be a good idea to try. It would have to be around 38 inches I suppose. Anyplace you know of that sells that kind of thing?

I considered trying to make something like it with homemade sugru and opted against it due to the quick setting nature of the material and the length needed and my most probable lack of precision.

Note that different servos are built differently and might not be as easy to modify as the one in the picture. Note that the servos I was working with (below) came from Hobby Partz, but they appear to be the same as the hobby king ones. If you order from hobby king and can afford it, I'd get a couple of the servos in case you hose one up. Plastic bottle/jar caps of various sizes might work for the servo drive wheel.

belt material by the foot
https://www.servocity.com/html/timing_belts.html#.Uw1cHvldU4g

CrossRoads:
belt material by the foot
https://www.servocity.com/html/timing_belts.html#.Uw1cHvldU4g

Ask and you shall receive. Very cool, but I will file it away for a better financial time. Do you think it would be ok to try to splice it in half lengthwise? 3/8" is about or at least twice the depth of my turntable, but I’d be wary of making a clean, smooth and even cut .

That is a great site with all the options they have to build unprecedented ideas.

If you can slice the material in half - "Urethane with Kevlar cords" - I bet it would be fine.

Now that you know what to look for, might want to find something that is a better size match, or is more workable for trimming/size reduction.

CrossRoads:
If you can slice the material in half - "Urethane with Kevlar cords" - I bet it would be fine.

Yes, thank you. Duh.

CrossRoads:
Now that you know what to look for, might want to find something that is a better size match, or is more workable for trimming/size reduction.

Yep. Thanks again. Good to know something like that does exist. Now to find it (the kevlar aspect is appealing) in different widths...

Though ultimately, if I was to recreate my turntable thicker and as a cog wheel, would that be as or more efficient than using such a belt?

I'm thinking my rubber lip friction system should do well enough if the servo/motor can handle it, if that's the case. If so, do you think I'd be better off improving that system with precision rubberized servo disks like they have at servo city, or would I want to still go to a direct geared system over a pulley/belt drive?

I would think rubber wheel on servo pressed against the turntable could be fine, might be tough on the servo bearings being pressed sideways all the time.

Google "small pitch timing belts", all kinds of stuff comes up.

CrossRoads:
I would think rubber wheel on servo pressed against the turntable could be fine, might be tough on the servo bearings being pressed sideways all the time.

Would a servo with a 90º output shaft have the same issue?

I suppose if the one I ordered needed replacement from time to time, it's affordable enough to do that.

CrossRoads:
Google "small pitch timing belts", all kinds of stuff comes up.

Great, more overwhelming stuff to explore :wink: The project continues to fractal off into more and more fascinating new worlds...

It is hard to see the construction of the lazy susans, but you might see if the servo could be mounted on the underside to keep it out of view. Several possible ways to raise the lazy susan up and arrange the servo underneath, depending on how the lazy susan is built. Most display turntables are driven by a clock/timer type motor.

https://www.google.com/search?num=100&lr=&as_qdr=all&q=display+turntable+motor&oq=display+turn&gs_l=serp.1.1.0l10.28604.33906.0.36814.12.11.0.1.1.0.199.1271.7j4.11.0....0...1c.1.36.serp..0.12.1299.Faxyp8dRqtY

My servo is arriving today, but the motor shield coming from China has yet to come. Would I be able to to calibrate the servo's pot with just my Uno, and if so, what other components must be used?

And check out this video a friend shared with me. It is sooo simple - not even an Arduino needed.

I'm not quite clear though how the geared motor used in the video is different from a servo other than it does not have a built in pot/internal controller - that's enough I suppose. But how does, if at all, the use of an Arduino benefit if the control needs are as simple as speed and direction as achieved by the guy with the geared dc, pot and a 9v? Is about precision? - Could someone please clarify/explain? Thanks much!

Not sure what calibration is needed, or why a shield is needed. With servos, you supply them power, and a control signal from the Arduino.

Servo uses a PWM-like signal to control the position of the servo shaft - if modified to be free running, can be used like a motor. To change direction, the PWM is modified.
A motor uses a varying DC level, or a pulsed constant DC level, to spin the motor. To change direction, the current flow thru the motor must be reversed, using an H-bridge or a DPDT switch or relay.