Hey Engineer Types... If I wanted to build a gear...

[TimC]

This doesn't fit anywhere else, at least until I figure out what it is I am trying to accomplish. So bear with me if you can help.

I thought about joining reddit in this pursuit for knowledge but I don't need more interweb presence. However I did find a good glossary of reddit jargon which leads me to declare ELI5. For other non-techies that stands for "Explain Like I'm Five"

The engineering problem...
If I have a small high torque motor and I want to have it be able to turn a table that weighs about 30 lbs. What are the first steps I should look at to build a geared drive system? I will go into more detail of this "system" later so I'm hoping to just hear about transmission, gears, torque. Those kind of things. For instance do i need a gear reducer or a speed reducer? I was originally thinking a drive like a bicycle would use to lower the need for torque.

Some technical stuff
Rated torque 0.25 (NM), 2.21269 inch lbs, 0.18439 ft lbs
DC, 6 volt, 10 rpm, 0.3 amp rated current.

The specs on the motor state in Greek "The torque size depends on its speed and voltage. Please take parameters above as reference before purchase". Ha! To late for that nonsense.

[twisted lines]

At 10 Revaluation per minute (RPM) and 2 .21 Inch pounds of tourqe I would Say it has a plastic gear reduction. not capable of cracking peanuts
I have a slow treager auger gear reduction but it's 110, fan spins like crazy, then gear drive for torque, and they seperate i guess, there are screws.
yours if it would help, but a new one might be cheaper then shipping.

with fan.jpg (36.31 KiB) Viewed 551 times

[TimC]

At 10 Revaluation per minute (RPM) and 2 .21 Inch pounds of tourqe I would Say it has a plastic gear reduction.

I'm going to stick with this 6v, 10 RPM gear motor. I'm hoping for advice on how to make it work. If it turns out it won't work I'll deal with it.

According to the manufacturer... "DC Mini Metal Gear Motor, ideal for making robots. Light weight, high torque and low RPM. Fine craftsmanship, durable..." We shall see if that is the case.

I'm interested in how to build a gear/transmission to allow the motor to turn a table of approximately 30 lbs. I imagine a low resistance bearing and a system of gears to multiply its torque to allow it to work. The mechanism will not build much inertia when turning as it will only turn about one degree at a time. Maybe an aluminum bike wheel, driven by a belt, driven by a sprocket, attached to the motor shaft.

[QueticoBill]

The dead simple way is put a rubber tire on shaft and mount under turning table. The closer to center the driving wheel is, the faster it goes. Pretty simple to calulate speed, size of driving wheel, etc. Also nice that if something goes kaka, the driving tire will slip. Makes for a lot of options for the turntable bearing.

Maybe too simple.

[twisted lines]

Worm drive, That E place had some for 15.00 buck's
That will slow things down and add lots of tq, but stopping at 1 deg ?
Button with adjustable timer may come close enough.
Stepper motor can be adjusted very close. but $

Good luck.

[Pmullen503]

The dead simple way is put a rubber tire on shaft and mount under turning table. The closer to center the driving wheel is, the faster it goes. Pretty simple to calulate speed, size of driving wheel, etc. Also nice that if something goes kaka, the driving tire will slip. Makes for a lot of options for the turntable bearing.

Maybe too simple.

I agree. Unless you need precision control, that's a good way to go.

Just finishing up a CNC hotwire myself. If you do want to go the stepper motor route, there are simple, cheap boards with a pot to control the speed of a stepper motor.

[pchast]

A bigger question is how fast do you want that table to turn. What kind of bearings take up the friction and weight of the table.

The weight is the greatest factor with stopping and starting, Inertia or Momentum...

With a pressure mount under a supported table that motor is likely to work when you help start the rotation. As stated a mount closest to the supported center would provide almost the 10rpm. If you have an adjustable power supply you could apply slightly greater voltage for marginally higher rpm but chance shorting the motor.

[TimC]

Some good info there. Thanks. I'm trying to create a solar tracking system for a 17 lb solar panel (plus the necessary mounting kit required.)



The motor is this
https://www.ebay.com/itm/JGY370-High-Torque-Gear-Motor-DC-6-12-24V-4-160RPM-Mini-Electric-Slow-Worm-Motor/284524536090?var=586101280555&pageci=2b01baf3-b80f-4cd1-84b6-b92cea62d7f4&redirect=mobile

And the brains to control the motor
https://www.ebay.com/itm/5V-Solar-Power-Panel-Automatic-Tracking-Sensor-Module-Single-Axis-Circuit-Board/143652397324?pageci=44c1fb44-ccb7-4b7a-a50d-6c9144447d9d&redirect=mobile

The control board and motor will follow the sun. They are typically used for very small solar tracking systems but I hope with some ingenuity it will allow tracking of a 17 lb panel mounted on a turntable.

So it's movement will be very slow in very small increments. I hope inertia isn't a problem. The control is supposed to have a delay built in that minimizes jerky movement.

[Pmullen503]

That helps a lot. Your system is very low power but also very slow moving.

The "wheel on the motor shaft" rubbing on the table is good. Mount the motor as far away from the pivot as possible to lower the start up torque for the gear motor.

[TimC]

Thanks for the input folks. I'm beginning to formulate some ideas to make this work. Just to be clear, I don't need 10RPM. The lower the RPM the better according to the tracking board manufacturer. To follow the sun I believe it will move just a fraction of an inch every few minutes.

When I receive the materials I will put together a prototype and see how well it goes. I'll update this when I get a start on the build.

Instead of a bicycle wheel I might create a large wooden wheel that would double as the mounting table similar to Mattias Wendel's bandsaw wheel design. https://www.youtube.com/watch?v=ofxbo1b9OFg My version won't have to stand up to the side pressures, torque and high speed balancing that Mattias' version requires so it should be easier to build. I have some 1/8" lauan that would work well if I can waterproof it with The Mix. I'll be able to provide some underside support bearings with caster wheels or something similar to keep the table stable. I'm was originally picturing a Lazy Susan type bearing but I'm not sure they have low enough resistance to qualify.

[Tomterrific]

I did not read a reason for the rotating table. At first I thought you wanted a fancy serving table. But now I bet it is to maximise solar cell output by following the sun. What is the purpose of the table?
You may be able to adapt a telescope mechanism to track stars if You need precision.

Tt

I see you already found the tracking electronics. I didn't know such things existed.

[TimC]

...

I see you already found the tracking electronics. I didn't know such things existed.

I just discovered that there was such a device/controller as well. I knew that tracking controls existed but they seemed to be either for the large arrays ($$$$$ and high maintenance costs) or for the tech crowd that likes to play around with the little computer controls (Arduino? and solar sensors). For large arrays it seems that dual axis tracking no longer makes sense as PV panels have come way down in cost/watt and those tracking devices are high cost and high maintenance. Throw on a few more panels which require little to no maintenance and you have the same production as tracking systems provide. Some single axis tracking is gaining in popularity for commercial installs that are limited in space.

I was actually looking at a simple tracking system using only a 12v gear motor and two 5 watt PV panels.

https://www.youtube.com/watch?v=Oj1E7o7J3qc

I thought that is an interesting method. I was searching for small 5 watt panels when I noticed the tracking board that I eventually ordered. It uses a 6v gear motor instead of a 12v motor. The two small panels, or the cells to build the two panels, were costly compared to the control board I am going with. I think $30+ for two 5 watt panels vs less than $9 for the control board. The motor is another cost for either but are less than $10 each for either 12v or 6v gear motors.

The system I hope to build will be cool (IMO), fun to create and yeah, probably totally unneeded. Sorry, I like to tinker... It will track the sun in a campsite that doesn't allow my roof mounted solar to produce much. I can lay out my 100 watt panel mounted to the "table" and it will track the sun so I don't have to babysit the panel as the sun moves across the sky. My fear is that it will be so cool that I'll be looking at it all day to see it pointing correctly.

[Capebuild]

Hi Tim. Just saw your post.
The motor (with gear box) shown in your link you purchased looks like a typical toy motor (thus the seller's comment about being used for robot building). The motor itself probably outputs about 1700 to 2000 rpms or as high as 3000 rpms (depending on input voltage). The attached gear box will reduce the output to whatever the specs note through the gear box reduction. It may work for your project. I'd probably want something a little more robust but again, this may work for your intended purpose. There's nothing wrong with adding additional gearing mated with the output from your current motor/gearbox. If you build something and grab the final gear, stopping it or putting a strain on it, you know you've got to get more torque/ and or power/further reduction from your setup, or if the final thing you're driving is "well balanced" and rotating very slowly, again... all may be good. Using one smaller output(gear or wheel) going to a large gear or wheel driven via a belt could provide a slip clutch action should there be an issue with the output being hindered (as a previous poster mentioned). That's one way to do it. Another is to add a slip clutch (and this can be done in a variety of ways). Personally, from what you describe you're after, I'd look into developing a gear train, either off the motor/gear box you purchased... or some other motorized source. You may also want to consider having a large internal gear as your final output, putting a table on top of that to carry your solar panel(s). Maybe the large internal gear is teamed up with a lazy susan setup that way the weight is kind of centered on the final output gear (if that makes sense, I can do a drawing for you). This would give you an easy starting point to try this out. Let's say your final output on your setup is (I think you said) 10 rpms. Let's say you put a 20 tooth spur gear on your output axle and mate that with, say a 200 tooth internal gear. For every 10 rpm coming from your source output (the 20 tooth gear X 10 rpms causing the teeth to move 200 teeth on your internal gear), your internal gear (attached to the table holding your solar panel) will make one complete revolution. This is a very simplified way to thinking about all this... but you can now start to do the math and "creative thinking" about how fast (or rather, how slow) you need your final output. Obviously you might want the internal gear to be 3000 teeth (just using as an example as 3000 teeth is probably not realistic).... so you have to slow your motor's gear box down so maybe it's not outputting 10 RPM.... but maybe half an RPM.... or your added gear train to the gearbox can also provide a gear reduction (and potentially more torque) to slow things down. Look at how a clock works and what the gearing does to slowly move the hands.
So, there's a number of variables that can affect your final output. Speed of your source, the reductive gear train you develop, the input voltage which is going to drive your motor, and there's probably a few other things. If you're using an Arduino you could probably set up some sort of PMW (pulse width modulation) to control the output speed coming from your motor.
Not sure if this all helps or not..... but good luck!
John

[TimC]

Hi Tim. Just saw your post.
... but good luck!
John

Hey John, thanks for the input. I've been spending a good deal of time researching as the temp this morning was 11F with a wind chill of -6F. Spring is not making much headway this week!

I kind of understand what you're getting at. I was just looking at a YouTube video of a drive system a guy built. It gives me some additional ideas for gearing and idler pulleys.
https://www.youtube.com/watch?v=qLJ4XSAUR2U&t=2s

He used a 3D printer drive pulley on his gearmotor rig. It might be a good start for me though in just a few minutes of searching I don't see any of that type of toothed pulley near the number of teeth you are describing for the final output. Not to say a drive belt like that won't work on a homemade pulley of some sort. He is also turning a flexible PV panel and very light weight frame with a 12v gear motor. The control board I have coming only operates at 5 to 5.5 volt and the gearmotor is a 6 volt.

I don't know how RPM of the motor will effect the outcome of this. I'm not looking for speed of rotation as being an issue. If it takes one second to turn the panel a degree or two vs five seconds I don't think it matters much. Once I have the board and motor in hand I can experiment with what it will do and like you mentioned, try to design a system with the final output gear attached to the table to mount the panel. I think you are spot on that the final can be big enough to hold the panel in place even though the final pulley, sprocket, whatever attached to said table can be considerably smaller than the table.

From the little bit of reading I've done so far it seems the critical issue for this type of drive is it shaking back and forth. In other words if the inertia takes the panel too far the brains compensates by reversing immediately and then if that move over compensates the other direction another cycle starts. The manufacture says to remedy that scenario by angling the sun sensors away from perpendicular to the panel to. Basically trial and error until it behaves.

BTW, when I say "table" I just mean some sort of rotating surface or frame that the PV panel will mount to. The rotation probably only needs 90 degrees of travel for my purposes. Let's say southeast to southwest. After that in most locations trees or other obstructions will block direct sunlight.

[TimC]

Speaking of toothed pulleys I found the source below that offers a variety of GT2 (3D printer type) pulleys. Not sure how the gear ratios work but I'm guessing a 16 tooth pulley on a 10RPM gear motor that drives a belt to a 64 tooth pulley would reduce the RPM by 1/4 (or to 2.5 RPM). Am I thinking correctly?

Again... ELI5 (explain like I'm five) : )

https://www.ebay.com/str/powgesynchronousbeltsandpulleys