Dished side



The hub assembled using the smaller 'cheese-head' bolts near the boss allow the strips to move slightly closer to the centre. This will reduce the circumference slightly allowing the side to be assembled without stress resulting in a flat side.


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20th August 2008
Ferris wheel - Sorted

Ferris wheel set
The finished wheel - at last!

Back at the last TIMS meeting at the end of June, it was muted that large models would be the order of the day for next years exhibition to be held over the bank holiday weekend at the beginning of May.

Sue and I decided that it might be a bit of fun to build a large Ferris wheel of some kind. The basic Idea is to have a central hub with spokes supporting an outer ring into which the gondolas would be suspended. I digress because neither of us have ever built anything like this before and that is way we thought we would start off small. The current production Ferris wheel set seemed like a good starting point - little did we know at the time how much hassle that decision was going to be!

Flat or not...

I found a set on ebay and duly won the auction. The set arrived and Sue set about building the Ferris wheel. She had not got very far when she discovered that it was impossible to build the sides of the wheel flat. It seemed that the geometry was wrong. I had a go and got the same result. Hmmm… A post on Spanner II led to a small debate. Some were saying that they had no problem with it, other were offering ‘fixes’.

You can see just how much paint is on the new stuff. The yellow in the hole is the paint on the strip below.

I decided to build one from ‘old’ Meccano. Guess what? It worked. The powder coating was the first suspect. This was underpinned by the guys on Spanner II who also felt that this could be the culprit. I ‘reamed ‘ out all the holes in the end of the curved strips (Part 89’s) and proceeded to put the thing together again. Still no joy.

It was then pointed out that the holes in the strips should be 11/64 inch (4.365mm) the drill bit I had been using was only 4.1 mm. In round figures that is about 1/4mm too small. That’s it! Problem solved. I rushed out to the workshop and found an 11/16 drill bit. That is too big to fit into the boss of a standard wheel so while I was out there I set the bit in the chuck of the pillar drill and opened up the hole in the boss of a 1 inch diameter pulley wheel (Part 22) so that, with a tyre fitted, it would make a convenient 'handle'.

Should I get out more?

Back to the Meccano and feverishly put the side together with high expectations of success, only to find that the side, although less so, still had to be dished to get the last bold in place. Well, to say I was devastated was an understatement, all that and it still did not want to play the game and lay flat. (At this stage even I am thinking I should get out more…) This is really bugging me now. In fact it was bordering on obsession.

I decided that life was too short and put the whole lot to one side. It was still bugging me and I think the guys on Spanner II were getting bored with me going on about it…

… a couple of weeks elapsed and I had nearly let it go when I saw a new Ferris wheel set listed on Amazon for a reasonable price and they were offering free next day delivery. That was it. I could not help myself. Tap tap, click click, … bought another one.


The new one arrived today. I opened it up and proceeded to build. By now the instructions were irrelevant, I know how to build those sides with my eyes shut.  It went together fine. No dishing just fine…

OK, so what is different? At first glance nothing. Then on closer inspection I noticed that the new one had the cheese-head hex bolts and the original one had round-head hex bolts. So what?

The heads of the bolts are different sizes - 7 or 8 thou makes all the difference.

Well, call me obsessed but I decided to measure the diameter of the screw heads. The round heads are (give or take a couple of thou.) 7 or 8 thousandths of an inch larger than the cheese head ones. Using the larger headed bolts will hold the strips fractionally further away from the boss of the face-plate when all eight strips are bolted to it. This means that the curved strips have a greater distance to span than they should have resulting in the wheel side becoming dished.

I replaced the bolts on the original wheel side and eureka! It worked… I can now sleep at night!


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A flat side - at last!