Slow – Mo

Thu, 20 Jan 2011

I've had a few days of experimenting with lots of different ideas.

(That and taking #1 daughter to university interviews! She's hoping to study graphic design so we're carrying her huge portfolio case all round the country.)

One of the things I have been trying to do is recreate a sort of slow motion movement as demonstrated by astronauts on the moon. I have only a vague idea at the moment but I think I'd like to produce a model with an astronaut jumping up and down (slowly) next to a lunar module.

I thought I could fit a long pendulum into a box. Realistically, 17-18cm is the max length feasible.

After a quick calculation I reckon the period for a pendulum of that length should be just over 0.8 seconds. Just about right.

To utilise the movement I'll need a long arm sticking out sideways from the pendulum, the longer the arm, the greater the range of movement. The problem being that this means that the box with the model in will need to be both tall and wide. Tall for the pendulum, wide for the link arm.

To fit everything into a narrower box I'll have to wrap the mechanism up a bit. I reckon it should be possible using a bell crank. Although this should make the whole mechanism much more compact  I foresee a possible problem. There are now three joints which weren't there before, each of which will add a little friction to the movement. Perhaps if I use paper hinges rather than the usual card? More experimentation I reckon.

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Comments (4)

  • daveyboy January 21, 2011 at 3:41 pm

    I’m certainly not a paper

    I'm certainly not a paper engineer by any means but wonder whether a cam construction but with a reducing gear mechanism attached so the cam would move up and down much slower than it would if directly linked to the crank handle would be a possible alternative solution

    • robives January 21, 2011 at 8:44 pm

      Good point, a cam would work

      Good point, a cam would work well and I could use the worm gear to gear it down. What I was after was smooth movement where I could start the spaceman moving and he would jump up and down slowly for a few seconds after you have stood back to admire the model.

  • Nobledesign January 23, 2011 at 1:19 am

    Love the peep inside your

    Love the peep inside your process again, Rob. I don't understand a word of it but I like seeing you work it out!

  • daschwick January 22, 2012 at 11:22 pm

    Hey, i know I’m really late

    Hey, i know I'm really late with this(a whole year!) and you may have already trashed this project, but i came across this video a while back and it reminded me of this idea. Obviously yours would be on a much smaller scale, but it may suit your needs.

    Very nice! – RI

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