Lee Bertolone's Merkur-Built Meccano Blocksetting Crane

Lee writes: "Hi Doc: I am sending you pictures of my recently completed blocksetting crane built with two plus Merkur M-8 sets. I have always wanted to build one of these iconic Meccano models (it seems like its a rite of passage for British Meccanomen) but price and availability kept me from doing so. The long out of production (with the exception of limited edition commemorative sets) #10 Meccano sets were alway a rarity in the U.S. and complete ones in good condition that periodically show up on E-Bay are typically bid up into the thousands of dollars so that wasnt an option for me. After building a few models using Merkur sets I realized that a blocksetter could be built with them. To me Merkur is a high quality product and the M-8 is a large complete set that is available and affordable. If someone wants to undertake this model I recommend that they Google "blocksetting crane" and browse the many websites that come up. Most are of Meccano models but 5-6 have interesting pictures and information about the prototypes.

Building any model for me is a history lesson. If I'm interested enough to build it I want to know as much as possible about the prototype and the internet is a wonderful tool for this. Some of the Meccano models are amazing in terms of detail and prototypical correctness. Some are quite large weighing over 70lbs and in one case a builder gold plated the parts that went into his model. Mine ended up weighing 15lbs and the dimensions are: height 20", width of base 10" and overall boom length of 45". The Meccano model uses one beefy motor in the back of the cab (looks like it runs off house current) that powers all four functions (travel over the tracks, boom rotation, travel for the boom trolley and lastly the hook). Mecanno developed an ingenious and complicated gearbox full of sprockets, chains, gears, detents and levers (probably much like the original steam powered prototypes). After a long look (plans are available as free downloads on a number of Meccano Web-Ring sites) I took the easy way out and decided to power each function with its own motor (I rationalized that this may actually be prototypically correct for the later cranes that I assume were powered with electric motors).

I used Merkur motors for the boom trolley and the hook but they arent a good choice for the other two functions. They don't have enough torque to power the crane over its tracks and there isnt enough room in the base to build a reduction gearbox. Polks Hobbies sells a small (I think its a Mabuchi 380) motor/gearbox combination that works perfectly here. The motors have 4 very compact mix and match planetary gearboxes and with all 4 in place you end up with a 360x1 reduction. This allows this small motor to produce quite a bit of torque and its enough to move the crane down the track.

I also used reproduction meccano sprockets and chain. They provide a secure positive link with no slippage between the motor and wheels. Another advantage of these motors is the prototypically slow speeds they provide and that why I used one for the boom rotation. I discovered that 1/4" ball bearings will fit in the races of the boom turntable and while the boom will work without them it rotates more smoothly and is better supported with the bearings.

Power and control is provided by a Tamiya 4 function corded remote box. It's designed to use two D cells but the 3 volts they provide arent enough to drive the Polks motors. A 4 cell battery box for AA's will fit in place of the 2 D cells and the 6 volts it provides works well with all the motors. At some point I plan on radio controlling this model There is plenty of room in the back of the boom thats directly below the cab for batteries, a receiver etc.