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Saturday 16 October 2021

Examples of mechanical linkages


 In an earlier video, we discussed key terms and some applications of linkage. 


Let us explore everyday examples based on linkage. 


Video here covers the following

.



Cloth Drying Rack


Wall Mounted Foldable Cloth Drying Rack is based on linkage. Mechanism can be better understood by simulating it. I used Linkage software for the same. Learnings from this activity can be used to build a small prototype as well. 


  1. Pantograph
  2. Folding chairs
  3. Elevator doors
  4. Bus doors
  5. Safety door
  6. Crane
  7. Pen Stands
  8. Stapler






Similar prototypes can be built for other applications as well using straws, needles, icecream sticks, paper strips and acrylic. 


Do give it a try.


Friday 1 October 2021

Sand Automata

Recently I did work on Automata. Sharing the same here.






Performance of this acrobat is powered by Sand. 




Many such old toys, driven by sand, always fascinated me. This is how I built one.


Instead of building a mechanism inside a rectangular box, I built this funnel and wheel from a cardsheet. This allowed me to test each step independently and make changes accordingly. 

Once I was happy with the movement of the acrobat, I placed this funnel inside a rectangular box and sealed it.



With a nice background picture, watching the performance of an acrobat was the best thing to happen.  Acrobat can perform for 30 seconds. To repeat this, I have to rotate the box clockwise to collect all the sand back in the funnel.


Now details about the build.


Cardsheet Funnel


Instead of building compartments in a box, an independent funnel is built with a cardsheet. This helps a lot in initial testing and finer adjustment. Triangle like shape is cut with each side - 15 cm. Sand will enter from this slot. A 6 cm extension on one side of the triangle will house the wheel. Large opening near the extension is sealed with paper with a small hole. 


Wheel


The Cardsheet wheel is made with a radius of 4 cm. 1 cm wide strips are pasted to form 8 small compartments. Toothpick acting as an axle is placed slightly off-center. This is important for two -way movement of the wheel. Larger wheel means more sand and hence acrobat can move full 

circle. 


Acrobat


Initially I made acrobat with PVC sheet, pins and blank refill. But this was heavy for the wheel I built. Hence I had to build another one with a thinner plastic sheet. 


Water instead of Sand


I tried using water instead of sand to power the acrobat. Wheel I designed was small. It could not move the acrobat as planned. 



Just  a Box


Initially, I built a mechanism in a used cardboard box. But testing and alignment was an issue. I also found that the weight of the acrobat was more for the wheel employed.



Tinkering


Try with other materials as well like these millets used in bird feeder. 


Enjoyed building sand automata. Sharing some versions which of course did not work to my satisfaction.


Thank You.