Apr 20, 2021, 02:14 pm

News:

New, New TardisBuilders!


The 2012/Pickwoad Console Whirligig

Started by davidnagel, May 06, 2017, 07:48 pm

Previous topic - Next topic

davidnagel

Silly question because I feel I should know the answer, but how would one go about reproducing the way the whirligig operates?

The three tiers operate different directions (well the middle one does) but what sort of mechanism would achieve this?

Your thoughts welcome.
Kind Regards,

David

www.spiffinglyniceguy.co.uk

galacticprobe

May 06, 2017, 08:19 pm #1 Last Edit: May 08, 2017, 10:30 pm by galacticprobe
Quote from: davidnagel on May 06, 2017, 07:48 pm
Silly question because I feel I should know the answer, but how would one go about reproducing the way the whirligig operates?

Not silly at all, David. (Remember my uncle's saying about the question that never gets answered because it never gets asked? ;))

Quote from: davidnagel on May 06, 2017, 07:48 pm
The three tiers operate different directions (well the middle one does) but what sort of mechanism would achieve this?

I wish I could remember where I saw this, because I did see this. I can't remember if it was in one of the Doctor Who Magazines, or a YouTube interview with the builders/designers of this wonder, but it was when I saw this that my eyeballs almost popped out because until then I thought the whirligig's movement was CGI. This article/interview explained and showed that it was a real mechanical thing, and not CGI. And since I can't find it (probably because I'm looking for it), I'll try to explain as best I can what I can remember from what I saw. So... here goes.

The tiers rest on wheels, with each set of wheels resting on the top of the tier below. Those wheels are fixed so they can't just roll around. That is, the wheels are stationary on the ends of axles, but they spin (like roller skate wheels or car wheels). One motor operates one of the tiers (I can't remember which tier, but I want to say it was the largest, top one).

When the top tier spins clockwise, the pressure it puts on the wheels makes them turn with it (like how a roller skate wheel rolls under your hand when you push your hand along it). This makes the bottom of the wheels turn in the opposite direction, sort of like this:

----->
  O
<-----

This causes the middle tier to rotate in the opposite direction (anticlockwise) because the bottom of the wheel is rotating in that opposite direction. So we have the middle tier pressing on the next set of wheels below it and you have this:

----->
  O
<-----
  O
----->

The wheels between the middle tier and bottom tier are rotating in the opposite direction than those between the top tier and middle tier, which makes the bottom tier rotate in the same direction as the top tier (clockwise).

--> TOP TIER ROTATES -->
---------------------> - direction of top of wheel between Top and Middle Tier
      O (wheel)
<--------------------- - direction of bottom of wheel between Top and Middle Tier
<-- MIDDLE TIER ROTATES <--
<--------------------- - direction of top of wheel between Middle and Bottom Tier
      O (wheel)
---------------------> - direction of bottom of wheel between Middle and Bottom Tier
--> BOTTOM TIER ROTATES -->
---------------------> - direction of top of wheel between Bottom Tier and whatever it rests on
      O (wheel)

That's about as much as I can remember from what I saw of it. I'm not sure how the bottom tier is set on its wheels, but since nothing below the bottom tier rotates, I would guess that those wheels are free to roll with the bottom tier, and are not on fixes axles like the other wheels are.

I'm sure others would have seen this, and hopefully know where to find it again so it can be elaborated on.

I hope this helps a little.

Dino.
"What's wrong with being childish?! I like being childish." -3rd Doctor, "Terror of the Autons"

timewomble

On the set tour, we had a Runner from the show who said the whirligig is really, really noisy, and if they film a scene with it moving then they will definitely have to redo the audio later. We definitely got the vibe that it was regarded as an impractical pain in the ass.