Make Your Own Giant Servo -- Episode 442

Hello, i am currently doing research on building a mechanism similar to what you built in the vid. I am new to all this stuff but I could use something just like it for a purpose like when you did the test of it pulling up the container of water only a bit faster and would only need to hold a couple pounds really and I don't think I would need it as large. I dont know how to build this or the names of the parts i would need so any help would be greatly appreciated.

Hi Scott,

My design is actually quite terrible and the software was never properly finished, so I don't recommend using it for anything. Do you have more specifics for your build? How much does your water actually weigh? How fast is "faster?"

I can recommend different off-the-shelf servos or other actuators that may be what you need.

Cheers,

DJ

Thank you for responding,

I do not actually need it to be as large as your project was but the principal is the same as where you used water, I won't be using water but it will only be about 2 - 3 lbs so a lot lighter. As for speed, Yours was only doing half rotations so I am not sure how to figure the RPMs on that but the speed I am looking for I would say 120 - 180 RPMs (or 120 - 180 of the arm going to its down most position per minute) if that makes sense. So from the research I have been doing, i think I would need an electric motor obviously, a power supply (I'm assuming I will need an AC to DC converter), speed controller, and a body to hold it together but I can manage a body myself. A problem I have found is that I do not know what speed controllers and power supplies will work with any given motor. Sorry in advance as I am not that familiar with working in this area so that's why I am looking for help and advise.

Are you looking to move the load to known positions with a servo? It sounds like you want to move something that continuously rotates. How long is the lever arm of your design? 2-3lbs could be lifted by a tiny motor if it's only 1cm out, but things get much harder (i.e. more expensive) if you need to move something at a large radius. I wouldn't worry about specific motors/parts at this point. Right now, defining your objectives in detail will determine what parts/design can satisfy your goals. So:

• What is the maximum weight of any object that you intend to move? (Keep in mind the mass of the arm/wheel itself)
• What is the maximum distance of load from the axis of rotation?
• What is the maximum speed you need to rotate? (Does acceleration matter? Does is need to change directions at all or infrequently? How accurately does the RPM need to be kept?
• Budget?

So basically the object I need moved will continuously be moving up and down, bouncing pretty much like a bungy jumper. The lever arm does not have to be very long, I'd say a max of 6".

Weight would be a max of 7 lbs. but with the object bouncing, the force of it would add more weight so it needs to be able to hold that.

The rotation would not be a lot. if I was looking at a clock for example, the arm would have to be going back and forth between 1 o' clock and 5 o' clock. That part does not have to be exact. Give or take a half hour. haha.

As far as speed goes, I am not certain on how the speed could be measured but like i said previously, I need it to go down to 5 o' clock between 120 to 180 times a minute. I'd say a max of 300 times a minute. Since I am not 100% sure on that, is why I would need to be able to adjust the speed if needed. Once I have it adjusted to the desired speed, I would like it to maintain speed through the entire process. So no it would not need to speed up or slow down at all or change direction.

So all it really needs to do is the same continuous motion.

Lastly for budget, I would like to keep it under $50 but I am open if it requires more.

Thank you so much for this help.

"...Once I have it adjusted to the desired speed, I would like it to maintain speed through the entire process. So no it would not need to speed up or slow down at all or change direction.

So all it really needs to do is the same continuous motion..."

Sounds like a four-bar linkage (crank rocker) might provide a simple robust solution ?

Crank Rocker Four bar Mechanism - YouTube

Thanks for your responses! Give the mass of your object, the speed at which you need to move it up and down, and your budget, I think a pneumatically driven crank mechanism would be your best bet. A double-acting pneumatic cylinder and a 3/2 way solenoid valve would be the most cost effective way to create your motion.

Could I go into more depth about how to build this? Yes, but at this point I'm getting into the design-it-for-you stage, which is a professional service that I charge people for privately. I'm not available for this kind of work now or in the near future, but hopefully I've pointed you in the right direction to get started. Another member of the community may be able to help you more with your design goals.

Sorry for the delayed response, busy weekend. I completely understand about charging any further on a design. I think I should be able to handle that. I just needed help with what mechanisms to use.

So a pneumatically driven crank mechanism, A double-acting pneumatic cylinder and a 3/2 way solenoid valve should be all I need to make this work then? Do these things have proper names so I may find them a bit easier? Cause just a quick search on those terms and nothing specific is showing up

Thank you. I will consider this. if I can find one with adjustable speed then it may just work perfectly.

"...Do these things have proper names so I may find them a bit easier?..."

double-acting pneumatic cylinder

https://uk.farnell.com/w/c/automation-process-control/pneumatics/cylinders-actuators/prl/results?action=double-acting&so…

3/2 way solenoid valve

https://uk.farnell.com/c/automation-process-control/pneumatics/solenoid-valves?valve-function=3-2-way-closed

"...Do these things have proper names so I may find them a bit easier?..."

double-acting pneumatic cylinder

https://uk.farnell.com/w/c/automation-process-control/pneumatics/cylinders-actuators/prl/results?action=double-acting&so…

3/2 way solenoid valve

https://uk.farnell.com/c/automation-process-control/pneumatics/solenoid-valves?valve-function=3-2-way-closed

Sorry for asking as I mentioned before that I am not familiar with all this but from searching how these parts work and go together, it seems to me that they mostly rely on the work of an air compressor. I do not have access to one and was hoping to have this procedure a little more electric.

"...was hoping to have this procedure a little more electric."

The crank rocker mechanism suggested before could be powered by an electric motor.

Thank you. I will need to build one but that idea should work perfect. I will return here once completed to share the results.