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New readers may want to begin here. See also more photos, videos, and additional links below.

25 November 2018

An Edwardian car

Leafing through Constructor Quarterly for modeling ideas, I came across this beautiful old Edwardian car (apparently a 1908 Panhard et Levassor). It was originally described by the late Keith Cameron in Constructor Quarterly #1, and rebuilt by Graham Jost, who in a letter in CQ #112 said he "did not find the instructions particularly easy going".  No more did I...

Here is what I had after the first burst of building activity:



I came close to giving up at this point, because I could not for the life of me figure out how the steering column was meant to be supported.  And also because I knew that I had prose like this to look forward to:

"The rear side panels of the passenger compartment are made from two 3-1/2" Strips, formed in their lower 1-1/2", two 2-1/2" Narrow Strips, and a 2-1/2" x 1-1/2" Plastic Plate, all held in place by 3/8" Bolts and four Washers spacing them from Obtuse Angle Brackets (slightly flattened) secured to the first and fourth holes of the 3-1/2" x 2-1/2" Flanged Plate."

But I persevered, and reached a point where all was done but for the passenger seat and motor.  A good point for a photography break:
    

I made one improvement to the model as it came to me: the doors open!


Here is how I mounted the steering column. It passes through an elongated hole in the footboard and then through a 2-hole coupling bolted to a short axle rod, which is held in a 3-hole coupling to its right, which is bolted directly to the footboard.  By rotating and sliding this short rod in its coupling, the 15-tooth gear's orientation and pressure on the contrate gear can be adjusted at will (up to the limits imposed by the elongated hole's size):



The remaining problem with this arrangement is that the 15-tooth gear can "wander" and climb off the contrate if enough steering pressure is applied.  I don't know how to fix that without major changes.  Using a simple coupling where the orthogonal axles meet to hold them in place won't work because the small contrate doesn't allow enough room for one; but there's no room for a large contrate in this design.  I decided to let it be and rely on the driver not to apply superhuman force to the steering wheel.

14 November 2018

The joys of eBay

Recently I won an eBay item entitled Antique Meccano Erector Set with Wood Box.  The parts are quite varied, some from the nickel era (pre-1926) and some from the dark green/red era ('26-'34), with a few Erector interlopers mixed in. The box is not marked in any way, but its compartments are well proportioned to take Meccano parts, and I have a feeling it is indeed a Meccano (perhaps Gilbert Meccano?) product.  I am putting these photos here in hopes that an expert may shed some light on the matter.

The box is quite beautiful, to my eye.  Front, back and side:
      

The first sight of the open box is quite spectacular.  The lid has a stiff board with the keyholes used in Meccano stringing cards, and a set of parts still wedged in some of the holes.

 

The box contains three removable trays, two of which have a cutout designed to make room for the Boiler part 162.

  
  

The set in all its glory:

The sprockets, eccentrics, gears and other brassware were a fairly good haul for the price:


And finally, here are the interloper parts, mostly Erector if I'm not much mistaken.


Thank you eBay for satisfying my acquisitive mania once again, and helping fill my poor house to the bursting point with heavy rusty metal of dubious resale value!

8 October 2018

The Hoberman sphere

Recently I picked this up in a charity shop for a few dollars:
 
A very nice Hoberman sphere - or something like it, since the original Hoberman sphere was apparently an icosidodecahedron, whereas this one has 24 identical kite-shaped faces that meet at 18 4-way junctions and 8 3-way junctions.  If you know what such a thing is called, let me know.

The entire thing is made of just 6 types of part: the 4-way junction cap, the links that meet there (male and female versions), and similarly for the 3-way case, in which the links are slightly shorter.

When I got home I could hardly fail to start tinkering with Meccano and see what might be possible.  I did not find any prior art on Meccano Hoberman spheres (although I have found plenty since; after 100+ years there is little new under the Meccano sun).  I started with a basic expanding linkage:
   
Note that for the whole circle to collapse satisfactorily, the strips must be joined at points that are offset slightly from their center, here achieved using fish plates.  The next step was to use curved strips to achieve the same thing:
 
This was a very pleasing model in itself, fun to fiddle with, but I could not stop there so I made the obvious 3D version.  It came together easily enough, given the patience to attach 96 bolts and 96 nyloc nuts.
 
I found this one quite photogenic, so here are some more pictures:
          

In retrospect, this would have been a perfect time to stop, but I did not.  This model expands, but only by about 20% - nothing like the original, which also has far more vertices.  I had to go on!

To make a very long story shorter, I ended up with this:

  
  

It is 16" in diameter when closed and 35" when open.  It uses 288 curved strips part 89, which I had just enough of, thanks to the 2003 Ferris Wheel sets that keep turning up in said charity shop (hence the unfortunate colors; all zinc would be nicer).  It also uses 528 bolts and 1056 nuts, all lock-nutted in pairs (I did not have enough nyloc nuts for the job).  It took dozens of hours to make, of which 10% were fun design and tinkering and 90% were entirely menial.  I have never lock-nutted so much in my life, and I never will again.

So I honestly cannot recommend this as a Meccano project for any sane human being.  It was mind-numbingly repetitive and fiddly.  If however you still want to give it a shot, read on and perhaps you can benefit from my research and mistakes.

Detailed construction notes


What polyhedron is my plastic toy based on?  I did not find it described online.  Though the faces all have the same trapezoidal (kite) shape, there are two types of vertex, one where 4 edges meet and one where 3 do, and two types of edge, as the ones that meet at 3-way junctions are necessarily shorter than the ones that meet at 4-way junctions.

The vertices are not hard to model, except that the 3-way ones need angle brackets opened out to an angle of 120°.  Here is a close-up of both types of vertex:

  

The two types of edge are a little harder.  For the longer type, I used three "scissors" made from pairs of 11-hole curved strips lock-nutted at their central hole:

  

But the shorter edges need to be shorter by a very exact ratio, which I just about managed to calculate using spherical trigonometry as 0.78365.  Not easy to achieve in Meccano.  I found an ugly way to make an edge that is 0.73333 smaller by chopping down some of the curved strips like this:



This 7% inaccuracy is a hidden advantage.  The perfect ratio would allow the sphere to expand fully, making it extremely hard to collapse again without 3 people manipulating it at once.  This inexact ratio constrains the sphere to a maximum size that collapses again without effort.

Nothing else about the construction was especially interesting.  The main remaining question, as always, is what to do now with this big unwieldy hunk of metal.  Somehow I don't think my children will want it in their inheritance...

There is a ton of fascinating further reading about 3D expanding structures online.  I will link to just one: 3-dimensional Expanding Structures (pdf).  These MIT lecture notes cover a lot of the subtleties in a way I have not seen elsewhere.

26 September 2018

Additional photos

Here are larger sets of photos for some of the Meccano projects documented here, as well as photos of some projects yet to be written up.

Meccano Madness
Meccano Display Cabinet, 2016
Meccano Braiding Machine
Meccano Braider II
Meccano Plate Rolling Machine
Meccano Walking Hat
Meccano Menorah
Meccano-Compatible Grub Screws

And some more photos in my gallery on the NZMeccano site.

2 January 2017

The walking hat

Fast forward to autumn 2016. A Christmas Challenge competition had been launched on Spanner: to build any model from the classic Set 4 manual and improve upon it without altering it beyond recognition. A brilliant theme, but not too inspiring to me as I don't tend to build from plans and I am unfamiliar with those manuals.

But then Edward Lupton of MeccanoSpares.com fame issued a competing challenge! Not intentionally, of course, but it grabbed me straightaway. The idea was appealingly perverse: to create a model that somehow found a use for the 25 most useless Meccano parts ever made, as judged by Edward. Here they are:


So off I went. I laid out the 25 accursed parts on a table. I stared at them, poked them, jiggled them, arranged them in absurd ways. Many hours later I agreed violently with Edward's assessment. It was maddening to try to shoehorn all these things into a coherent model.

After a few evenings of this, rationality went out the window and my fevered brain roamed further afield. Until finally this presented itself:

Basically the same thing, no?

Behold the pilgrim's hat or capotain! It is one of the ugliest hats ever to encase a noggin, but it has the right mix of concavities and convexities to make use of all those odd curves in the required Meccano parts.

Now I just had to find a rĂ´le for the centre fork, the rack strip, the slotted strips, the ratchet and pawls and so on. I wanted them to be mechanically justified, not just bolted on willy-nilly. But here I hit a second brick wall. If any reader can think of a mechanism that might sensibly use these parts, I'd love to know of it. (Of course one could argue that a mechanized hat is not a very sensible proposition to begin with.)

Eventually I decided that my hat's prime directives would be to fend off threats and flee from danger. To this end, the two long slotted strips serve as channels for little rotating claws (pawls) that scrabble madly forwards. The rack strip is a sort of cowcatcher that saws the air and slices up any enemies in the hat's path. Behind this are some spikes mounted on slotted strips, rattling about threateningly. The ratchet and centre fork are used for lateral self-defence. The threaded crank serves as an on-off switch.


This is the ridiculous contraption I ended up submitting, and it won second prize! Truly a glorious achievement.

Some more photos can be seen here.

The first flush

For Christmas 2014 I gave my 7-year-old a modern Meccano set, vaguely hoping it would interest her in gadgetry and mechanics. It was the Multimodels Super Construction Set #0570, 25 models, 640+ parts, ages 8-88, $79.99.

It did not immediately seize her attention. But one sunny spring day an unseen psychic force pulled me towards the dark closet where it lay, and I opened it. It was a nice surprise to see how many Meccano parts had survived unchanged from the glory days, and painful to see how many had been replaced by barely usable plastic and rubber.

The manual was ludicrously drab and unappealing, but I picked a random model and it came together well enough. I have absolutely no idea what it is meant to be... If you do, please let us know in a comment!

Unidentified moving thing, from page 52 of this manual

At this point some echoes of the childhood thrill came back. I wonder if I could still have turned back? But alas, I did not.

Over the next few months I cajoled my daughter into various joint efforts. She is far more creative than me and loves making things, but the mechanical aspects (and the torture of endless nutting and bolting) did not appeal to her. So the Meccano gradually became "my thing" and I dropped any pretense otherwise.

But I soon found myself hamstrung by lack of parts - just like my 10-year-old self. Here are two models I did manage to make, barely:

Working cable car or ski gondola thing

Demonstration of a Schmidt coupling

Finally I fell into the arms of eBay.com, which kindly reminds me that I made my first order on July 28, 2015: one lot of "Meccano Erectror Set Pieces Gears Wheels Axles Screws Washers Tools" for $8.50. This must have opened the floodgates: I appear to have bought 342 more Meccano-related items on eBay since then... not to mention the odd unmissable deal on Amazon, Craigslist, or shopgoodwill.com... ouch. I did not until this second quite take stock of this situation. I am on a Meccano diet, effective immediately! There's my resolution for 2017.

And thus began the golden age, subject of a future blog post.

1 January 2017

Introduction

Meccano is a legendary, beautiful construction toy system created in 1901 by Frank Hornby in Liverpool, England. It spread worldwide and was for decades a shared language and culture embraced by millions of children and many adults. It is documented in great detail by many excellent websites; www.alansmeccano.org is a good starting point. This blog is a chronicle of my own Meccano experiences. I hope that some of them are helpful or encouraging to other burgeoning Meccano nuts.

I had some Meccano growing up in Spain in the 1970s. Meccano was already long past its heyday (it struggles on to this day, in a debased form, but the less said of that the better). Nonetheless it made a very deep impression. I particularly remember one display model in the now defunct Galerias Preciados in Madrid: a 2-foot cube, as I remember it, full of mechanical assemblies and contraptions chugging away to no discernible purpose other than transfixing passing 8-year-olds. But Meccano was expensive and hard to find, and I never had even a fraction of the parts needed to replicate such a marvel. I continually dreamed up gadgets to build and continually ran out of parts a quarter of the way there, and gave up by age 12 or so.

Following an apparently common trajectory, Meccano crossed my mind again 32 years later and I was delighted to discover that it was still going strong as an adult hobby. There are great websites (www.nzmeccano.com, meccanoindex.co.uk), a lively mailing list (Spanner), thriving Meccano clubs in many countries, and impressive yearly exhibitions (Skegex, Magic of Meccano). There is a worldwide community of Meccano fans full of knowledge and eagerness to share it. Not bad for a besotted father's brainwave on a train more than a century ago.

So here we are, the passion burning unabated after two years. It is very hard to describe quite why Meccano gives me such satisfaction. It is little more than bits of metal with holes, and the maker movement has gone far beyond what is possible within the confines of pure Meccano. I'll have to ponder its particular appeal and romance more deeply. But enough for now.