What would the best way to open a 4 sided pyramid. With or without arduino - Page 1
Forum section: electronics / beginners

author: Astaldoath
author_rank: Contributor
timestamp: January 20, 2018, 12:47:02 am
content: Say I have pyramid and i want all 4 corners to open outwards (and inwards when i want it to close) What type of system do you think would be best. I know this is beyond my scope of experience at the moment but im hoping someone can point me in a direction to experiment with and maybe figure out something that will work. I was watching a youtube video where a guy has a motor and an arm mounted inside the box and when powered the motor spins and the box opens and closes, its a fairly large one, I imagine i will only need like the toy motors for mine. Im not sure about linking them up in a way to provide slow steady and even movement of the top 4 parts of the pyramid opening and closing. I dont expect anyone to do all this for me or anything if someone could point me to a website or a book to learn about this that would be great, even a book a library may have to take out if not something free online.Thanks guys.Oh PS. I dont want the motors to be visible inside the box and also another motor will lift a center platform up to the top level of the pyramid flush with it. Its going to be like a motorized stand if that makes sense. There is no rush because like I said I have to learn a bit more before I can start working on this.Up and down for the acrylic or plastic shelf seems easy, maybe a motor with gears on each side the rotate and lift it up and stop when it reaches either a sensor, or after a number of turns of the motor/gears

author: danadak
author_rank: Super Contributor
timestamp: January 20, 2018, 01:09:55 am
content: Assuming the pyramid is hollow a wire or tiny cable that bisects each side terminate toapex, other end in a box underneath pyramid attached to servo motor. Strain put on wirewould make the side rotate to vertical. Note the wire / cable goes thru eyelet at base ofeach side so when tension is applied the forces are translated to apex to rotate the apex.Eyelet constrains base movement azs well.Regards, Dana.

author: Richard Crowley
author_rank: Super Contributor
timestamp: January 20, 2018, 01:18:11 am
content: Can you add some depth to the "base" of the pyramid to hide the mechanics?Else where were you imagining that they could be hidden?We have no clue what is the size/scale/weight your project? Ounces? pounds? Tons?Or how fast you want the gadget to open/close? Or how much power is available?Or what budget or timetable, or access to components, etc. etc.If some sort of platform will raise up out of the open sides, can you simply push the sides away with the edges of the platform as it raises? Then you would need only one motorized mechanism.

author: Astaldoath
author_rank: Contributor
timestamp: January 20, 2018, 02:11:27 am
content: Yeah sorry about that, the base will probably be 4-6 inches tall so mechanics can be hidden under there. The total size is gonna be estimating of course around L x W x H8 inches, 4-6 inches, 6-8 inches(btw these are estimate i havent mocked anything up yet to see what ill need room to fit)I need to have it also more of a rectanglular pyramid (maybe on this, not completely sure) or else it would need to be much bigger to fit the object inside, which will be a lightsaber handle, the kind you get from ultrasabers, forcefx ect.. I believe they only weigh 1-3lbs so it wont be a lot to lift. The entire unit will be made out of acrylic with either a tint applied or laser etched and painted to look like a Sith HolocronSomething like this but not exactly, that only dispenses a book, it doesnt open but that is the basic shape, with my own designs, sith writing, my own button which will play a sound, while its open i plan on having 4 leds light up either either cree rgba so the colors can be mixed or just a circuit board with like 5 red high output leds so its bright enough, those will be hidden in 4 small acrylic boxes in each corner and i believe have those etched too or frosted or maybe an opaque plastic or acrylic so the light is diffuse and you cant see the parts if you look inside.BTW im not stealing anyones idea i thought of doing this ever since i noticed all the lightsaber sellers dont have a good display stand for them and whats better than a sound playing, light up motorized holocron on your table

author: IanB
author_rank: Super Contributor
timestamp: January 20, 2018, 02:54:40 am
content: Quote from: Astaldoath on January 20, 2018, 12:47:02 amThis is the kind of question I find very difficult to comprehend. If I am faced with this kind of question I construct designs in my mind and visualize how they work. It is an almost trivial exercise to construct mechanical simulations in my head for such things. There is no question to answer.Which leads me to wonder: for what percentage of the population is this question trivial, and for what percentage of the population is it hard?A straw poll, if you will. Answers below?

author: floobydust
author_rank: Super Contributor
timestamp: January 20, 2018, 03:32:51 am
content: First, figure out your mechanics. For ideas on pyramid opening, like which sides to move where, I would search images for pyramid origami. That helps, to know what sides are moving in which direction. From there, you can select a motor and mech design. Need some hinges, is this plastic or wood or what.How did you want to trigger it? WiFi, or a pushbutton or ? That kind of selects the hardware platform.

author: amspire
author_rank: Super Contributor
timestamp: January 20, 2018, 07:00:24 am
content: A key starting point is the question how fast or slow is OK. How much margin do you want on these specifications? A solution that can handle 10lbs may not work at 12lbs. Perhaps designing for well over the weight is worth it.For example, if you are happy with 10 to 20 second speed opening speed, you can start of with very cheap and small geared stepping motors like these:https://www.aliexpress.com/item/5V-4-Phase-28YBJ-48-DC-Gear-Step-1PCS-Stepper-Motor-1PCS-ULN2003-Driver-Board-ULN2003/32803158077.htmlIt is not a bad way to get started as the cost is so low.You can go up from there through bigger stepping motors, geared DC motors to linear actuators.There is a lot of cheap hardware - largely thanks to 3D printer builders. Things like lead screws, belts, aluminium extrusions, T-nuts to suit the extrusions (nuts that fit in the grooves in the extrusions). If you look at videos on building your own 3D printer, or CNC milling machine, you will get some idea of parts that are easily available on eBay and AliExpress.Here is an example of a linear actuator. You will see there are lots of different models with different speed versus force combinations. The slower the actuator is, the more force it has.https://www.aliexpress.com/item/Electric-Linear-Actuator-12V-24V-DC-Motor-150mm-Stroke-Linear-Motion-Controller-500N-1000N-1300N-Max/32806865600.htmIf you buy one of those very cheap hand held luggage weighing devices, you can use it to test the actual forces needed to operate a idea you are testing. Many of the motors are rated Newton Meters or Newton- Centimeters. 1 Newton is about 0.1 Kg and so 1 NM means that if you attach a 1 metre disk to the motor, the circumference can pull 0.1Kg. A half metre disk could pull 0.2Kg.

author: paulca
author_rank: Super Contributor
timestamp: January 20, 2018, 02:57:06 pm
content: The brute force method would of course be 4 servos and an arduino.Define a start pos and end pos.Poll a button. If pressed cycle the servos from start to end pos with a slow down delay for effect.int closedPos = 30;int openPos = 100;int pos = closedPos;void loop() {if( digitalRead( THE_BUTTON ) ) {if( pos = closedPos ) {pos = openPos;} else {pos = closedPos;}}delay(1);}For the software PWM to control the servos on 4 pins you'll need an interupt routine, should be easy to google. There is an example servo sketch that comes with the Arduino you could borrow from, but it might use hardware PWM and I'm not sure you can use 4 pins as independent PWM. However it's easy enough to do in software at 50Hz for servos.To get the servos neatly aligned you might need open and closed positions for each one.To improve things you would probably want a mosfet on the servo power to switch them off and put the arduino to sleep, awake on button press to save power.EDIT: Hardware PWM works on pins pins 3, 5, 6, 9, 10, and 11. On an UNO or Nano.analogueWrite( servo_1_pin, servo_1_pos );

author: Astaldoath
author_rank: Contributor
timestamp: January 28, 2018, 10:12:08 pm
content: thanks everyone for your input, i have the thread bookmarked, you guys gave me great ideas and info so now i know some of what ill need to have and do to make this working. I appreciate it very much