Author Topic: James Ferguson's Mechanical Paradox Orrery  (Read 8103 times)

Offline raynerd

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James Ferguson's Mechanical Paradox Orrery
« on: December 30, 2015, 01:36:12 PM »
I've done no big projects for a few years now due to moving house and getting my machines in shape. I've currently got a clock build on the go which I will go back and complete but I wanted a new project for the new workshop and something a little different. I came across the concept of James Ferguson's (1710-1776) mechanical paradox several years ago and it took my attention.  It is quite amazing to watch  - turn the thick wheel and one of the thin wheels goes forward, one backwards, and one goes no way at all!

Original plans:


The story is also nice as well... Quote from John Millburn

Quote
One evening Ferguson went to a weekly gathering (probably a dining or drinking club), where one of the other people present, a watchmaker, 'began to hold forth against a Trinity of persons in the God-head, wondering at the impudence of the person who broached such an absurd doctrine'. Ferguson, who was sitting just opposite to him, 'gave him a severe frowning look', whereupon the watchmaker asked his opinion concerning the Trinity. Ferguson suggested that they should talk about the watchmaker's business instead, and asked him whether he understood how one gear wheel turned another. 'I hope I do, said he'.
‘Then, said I, suppose you make one wheel as thick as other three, and cut teeth in them all, and then put the three thin wheels all loose on one axis, and set the thick wheel to them, so that its teeth may take into those of the three thin ones; now turn the thick wheel round: how must it turn the others? Says he, your question is almost an affront to common sense; for everyone who knows anything of the matter must know that, turn the thick wheel which way you will, all the other three must be turned the contrary way by it. Sir, said I, I believe you think so. Think! says he, it is beyond a thought - it is a demonstration that they must. Sir, said I, I would not have you be too sure, lest you possibly be mistaken; and now what would you say if I should say that, turn the thick wheel whichever way you will, it shall turn one of the thin wheels the same way, the other the contrary way, and the third no way at all. Says he, I would say there was never anything proposed that could be more absurd, as being not only above reason, but contrary thereto. Very well, says I. Now, Sir, is there anything in your ideas more absurd about the received doctrine of the Trinity than in this proposition of mine? There is not, said he; and if I could believe the one, I should believe the other too.’
Ferguson then said that he could make such a machine, and would bring it along to show to the assembled company the following week. He did so, and asked the watchmaker to explain it. The watchmaker turned it to and fro, took it to pieces and put it back together again, and confessed that he was thoroughly perplexed. 'The thing is not only above all reason, but it is even contrary to all mechanical principles'.
‘For shame, Sir, said I, ask me not how it is, for it is a simpler machine than any clock or watch that you ever made or mended; and if you may be so easily non-plused by so simple a thing in your own way of business, no wonder you should be so about the Trinity; but learn from this not for the future to reckon every thing absurd and impossible that you cannot comprehend.’

You can google the way it works, basically the three wheels on the same axis have different tooth counts to create the paradox. This also doubles as an orrery which is surprisingly accurate. The error for the precession of the nodes is about 40 days out of 6793 and the error of the period of the apogee is about 20 days out of 3233.

There are a few builds online. A few plans for wooden sets but nothing for metal though there are three builds I have seen which are reasonably well described. I do intend to make plans for this at the end if it works.

I have been hugely inspired by Clickspring over the last months and I have tried to improve my video shots and narration. It isn't even in the same league but I'm reasonably happy with some of the shots even if my narration isn't particularly good. I also appreciate I am not a trained machines or engineer in any form so if anyone can provide improvements or corrections to my methods, I'd be happy to hear.



Hope that wasn't too bad.
Chris

RobWilson

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #1 on: December 30, 2015, 02:09:34 PM »
Very interesting Chris

It looks like a fair amount of work ,looking forward to following your progress .


8/10 for the video , much improved  :clap:


Cheers Rob 

Offline raynerd

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #2 on: January 01, 2016, 05:58:39 AM »
Cheers Rob, glad you think the vid is an improvement. I just finished making the first collet for each wheel. It's works nicely but I picked up what u thought was a piece of brass but it has a redder tinge to it and it more brittle... The chips seems to fall and chip off rather than gracefully fold off... Bronze, some odd brass composition. There is also a speckle of dark/black on the outside when examined closely. It's worked fine - I just don't know if I should continue to use it for the rest.

Offline raynerd

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #3 on: January 09, 2016, 03:57:15 AM »
Part 2 - Making the Collets


Offline DavidA

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #4 on: January 09, 2016, 09:07:31 AM »
Very interesting to watch your technique for this kind of work,

I look forward to the next video.

Dave.

Offline NormanV

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #5 on: January 09, 2016, 11:19:05 AM »
Chris, the videos are excellent, you make me want to try gear cutting, but. The music is distracting and even worster(!), those bloody superman shorts!!!!

Offline Andrew Wildman

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #6 on: January 09, 2016, 05:20:28 PM »
enjoying the videos.  Looks like a lot of work and will create a good talking point when done.  Only slightly overshadowed by the shorts!! :doh:

Offline raynerd

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #7 on: January 10, 2016, 02:43:54 AM »
 :D thanks guys...making no apologies for the superman bed pants, they were a present off the kids!! I must admit, I only get in my workshop at night and so they are frequently on :lol:

Thanks again, I'm looking forward to trying to fit it all together now but I expect it'll be another weeks of slow work.

Offline kayzed1

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #8 on: January 10, 2016, 08:35:43 PM »

Nothing wrong with those bed pants Chriss, i am 67 and Pat got me for Christmas:::::

Dennis the Menace bed pants :thumbup:
I still have other Dennis stuff from being a kid :doh:

Offline raynerd

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #9 on: March 25, 2016, 08:15:48 PM »
I have been massively distracted over the last 2 months as my ISEL CNC machine has dominated all my time. That said, it is going to be put to use in cutting the engraved ring for this orrery.

Off for two weeks and looking to make some progress. This is a short and perhaps somewhat pointless video but it was nice to see the telescopic tubing working as planned and the gears meshing with little friction:


Offline raynerd

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #10 on: March 28, 2016, 07:36:25 PM »
I`ve built a Perspex test cage and very pleased that the gears turn super freely! Need to cut it in brass now and tidy up the parts a little.

No music to the video as requested - hope that is better,
Thanks for watching




Offline DMIOM

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #11 on: March 29, 2016, 03:29:22 AM »
Thanks Chris, that's far more "watchable" and we can focus on what you've done / what you're saying.

Dave

Offline Alan Haisley

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Re: James Ferguson's Mechanical Paradox Orrery
« Reply #12 on: July 05, 2016, 03:37:29 PM »
It's looking great, Chris. Hope you get some more shop time soon.

Alan