What motors do people typically use for small reciprocating animations? I saw what @Norton used for a swinging bell. I just don't need something that small.
This specific application will have a roughly 20" connecting rod. I don't know if that changes what motor should be used.
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It depends on what is being moved and how fast it moves. Remember the torque is related inversely to the gear ratio. Reduce RPMs by 100 times the torque is increased by nearly that much.
Pete
Depending on what you are doing, you might also take a look at linear actuators. They come in all shapes and sizes, and can produce much more elaborate motions than a simple motor--especially if the desired motion is not continuous. The downside is that it may be a bit more complex to control.
A search in Amazon for "linear actuator" will turn up a lot of interesting stuff.
@Norton I knew they were inverse but I didn't know that was the factor I was working with. Good to know.
@Avanti this is for a double bell system on a blast furnace. So the movement is just up and down. It's a very simple motion. But are those actuators moved with electricity? I'm thinking of the air actuators. I didn't know electric ones existed.
One advantage of gear motors is they can be had dirt cheap on the bay. Even big Pittman gear motors can be had for under 20 bucks, far cheaper than plain motors w/o gearboxes.
Pete
Billy,
I hope you will share with us the looks and mechanics of your final product. I am interested in doing things similar to this, using DC power, but don't want to just plunge in. (When I just plunge in, I end of up buying three times more things than I need, burning up at least one set of them, and butchering or throwing away another.)
It looks as if the gear motors only have a short metal drive shaft. Is there a ready source for a drive wheel that will attach to shafts like those, and some type of protruding stud or screw to mount on the outer edge of the wheel, so that one end of the connecting rod will go round and round, creating back and forth mechanical motion at the other end of the rod?
Mannyrock
I will share a cut away of the design later. I've been working on bench work all day.
It sounds like there's isn't exactly a specific sort of motor for this stuff. It's really based around application. I'm probably going to just go with what I have laying around. Tamiya makes small electric gearboxes with motors inside. I also have some little control boards that vary the speed of the motor. Both of these can be purchased from the store.
I was planning to 3D print my crank parts to get that reciprocating motion. I don't know the stroke length and whatnot yet. Depending on how common the shaft options are, I wouldn't mind making them available for a small fee to cover material and shipping.
I don't know how I'll get this to make a revolution every so often but I'll figure it out later. I have to make everything move before I worry about that part.
@BillYo414 posted:@Avanti this is for a double bell system on a blast furnace. So the movement is just up and down. It's a very simple motion. But are those actuators moved with electricity? I'm thinking of the air actuators. I didn't know electric ones existed.
Yes, electrical actuators are available in all shapes and sizes these days--with throws from fractions of an inch to several feet. The better ones come nicely sealed, like this:
https://www.amazon.com/High-Speed-Actuator-actuators-Cabinets-Automation/dp/B09X9GTLVN
but you can also get cheaper, open-frame ones like this:
https://www.amazon.com/Ladieshow-Linear-Actuator-Digital-Aircraft/dp/B08XXYFZ6K
This one uses a stepper motor:
https://www.amazon.com/Electric-Actuator-2%E2%80%91Phase-Position-Engraving/dp/B08QFLN4G7
Overkill for your purpose, but very handy for more subtle or extended motions.
I'm not sure if the video will play but you can see what I'm doing if it does play. This is a cut away view though. Plus I haven't bothered with the actual bells that would sit at the end of the vertical rods and seal the furnace shut. The motors with the cranks would sit in the bottom of the blast furnace (hence the roughly 20" rod). There are a lot of details to work out with axles and whatnot too but I wanted to figure out how I'm going to move everything before I start coming up with final dimensions.
@Avanti's actuators are looking interesting now that I see a few! I didn't know such a thing existed.
Pretty simple setup actually. Size wouldn't matter much. A motor the size of a smoke fan motor with appropriate gear ratios (20-30 RPM) could move those levers.
Pete
Bill, your animation plays fine and looks fantastic!
Being relatively new to this, I would love some more information on how to actually employ those various motors. I have adapted a few of of the Lemax motorized accessories, but not quite the same, is it? 
Are there tutorials that teach how to actually utilize these motors out there?
Great question, I was starting to wonder the same thing as I plan ahead for some animations.
For animations that are not continuous, I noticed another modeler used this timer module to index through the animation steps. DC 5V 12V 24V Digital LED Display Infinite Cycle Delay Timer Switch ON/OFF Relay Module (DC 12V) - - Amazon.com
I have one of these. I have not used it in anything. I did not buy it on ebay but I found them there for reference. I liked that there is a gear box attached, and at 23 RPM preset I could work with it for something. Also, I liked there are 4 mounting holes pre drilled and treaded.
EBAY LINK REMOVED PER OGR terms of service
Thanks @Norton
As far as actually implementing this, I was planning to replicate the crank system we see on steam locomotives. I don't know all the technical terms so I hope someone does and will teach us. But I was planning to put a wheel on the shaft of a motor. That wheel should have a hole drilled out near the edge of it. The radius of the wheel should match the length of the desired stroke (aka travel) of the bell. Then a rod would be bent through that hole in the wheel at one end. The other end glued to the bell itself. That's what I planned to do. I'm fortunate because I can 3D print any size wheel I want with the appropriate radius. I would probably go after the actuators mentioned above if I couldn't do this. I may still go with the actuators if the wheels don't fit in the furnace body.
I don't believe there are tutorials @Rich in NOVA. In my case, I'll be splitting this into "initial testing" and "final product". The "initial testing" is just running the system constantly, as shown in the video (thanks for the compliments, by the way). This is to make sure it works because I've never 3D printed this sort of thing so I don't know what sort of tolerances I'll be looking at or if I'll need bearings/busing, etc.
Once I learn the details, then I'll come up with a "final product" that goes on the layout and is timed correctly. In real life, the bells wouldn't reciprocate nonstop, as shown in the video. They would run in cycles based on the skip hoist cars. My instinct is to program an Arduino to control the timing but a board like @EmpireBuilderDave mentioned would be simpler. The only benefit I see in using the Arduino is that I could control two skip hoist motors and two bell motors I think. We'll see. As I mentioned, I need to figure out the movement. Then I'll graduate to the more difficult stuff.
Unfortunately, I broke the 3D printer the other day. Parts are expected in less than a week. That REALLY puts a damper on things as I was doing the final prototype on the blast furnace body. Then I wanted to print these parts.
I'll check those out @Edmund Schwartzel 060518. Thanks!
You can make all this but you can also buy what you need for small money including motors with gearboxes with crankshafts. The place I got the micro gearmotor is pololu.com. Here are some of their gearmotors ready to go.
https://www.pololu.com/categor...motors-and-gearboxes
Pete
I would look into using a servo, These have incredible torque and cost very little. The only issue is you need to drive them with a raspberry pi or uno. I am in the process of using a raspberry pi pico w and trying to animate truck and things. Eventually I want to put animations on my layout.
It take some code but pretty simple if you buy one of the dev kits on amazon. I got this one https://www.amazon.com/dp/B0BJ...dt_b_product_details it comes with a stepper motor and servo in the box.
I used the Peco "Smartswitch" servo to animate my subway's platform extenders. But they don't automatically reverse at the end of their travel.
Allelectronics.com has a 6v dc 25 rpm gear motor, with an arm that rotates an offset axle in a 1" circle. It includes a mounting bracket and a slotted link rod, on clearance for $4.25. Item # DCM-470. Looks like it might be easily adapted to animation projects.
Lot of great suggestions here. I'm going to review them all.
@West Side Joe that's an impressive little animation! You should post about it and how it works if you haven't already!
You can read about it on page 2 of my thread about my subway station:
Looks like some good suggestions here but now add robotshop.com to your list. I have used their gearmotors with good results.
This has actually turned into a great thread of resources for this sort of thing haha I'm so glad!
BillY,
You are building some serious stuff. I cannot wait to see it in action.
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