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CMC Meeting, March 07

PLEASE NOTE: next month's meeting is on 13th April, as the first Friday of the month is Good Friday.

Last month's challenge

For the first time in a very long while, we had a 'competition' at the Christchurch Meccano club. The challenge was presented at the previous meeting in February, which was to build a model using no more than fourteen separate Meccano parts. However, the builders were allowed to use any number of part 37 (nut and bolt) and any number of part 214 (semicircular plate). The objective was to discover what new uses we could find for this very common part.

Models on display

First, the competitors for the challenge. Here's Hugh Aston's lethal helicopter. Powered by a No.2 clockwork motor, the main rotors fly out when the motor starts up, and are locknutted semicircular plates. The tail rotor is driven by a pair of bevels underneath the motor, and a contrate on the tail. Switching it off entails breaching all sorts of health and safety rules! Although there were some stray long bolts holding on the 'trim' that goes up the sides and along the edges, it was deemed to be legal as this trim was later removed and the model still worked.

Then this blocksetting crane, which works surprisingly well. Three movements are included (slewing, jenny travel, and hoisting/lowering). The hoisting is effectively braked by pushing the crank to the left, which jams the curved part of the crank in the hole. This model was inspired by the idea of using a block of 214's as a counterweight. Note the strange way the parts are bolted together with four sets of three plates in rotation (so that the entire job can be done using only part 37's), repeated across the width of the crane. The sides of the jib are surprisingly rigid. The blue legs curve out slightly, and are joined together at the bottom by a 3.5x2.5" flanged plate which bolts to the top of the ball race. The structure of the crane takes only two parts (this flanged plate and the double-angle strip at the end of the jib), leaving a further 12 to make the 'works'. In fact, only 13 parts were used in total. The counterweight balances the crane no matter where the jenny is, even though the entire model only sits on the ball race. Various tricks are used to save parts -- the cord is cut from one part 40, the travel and hoist both run through a double pulley block bolted to the end of the jib (avoiding the need for separate pulleys and axles). The single pulley block that is the lift is suspended on a 1" and a ½'' pulley, both bolted inside a cranked bent strip (saving yet another axle).

Dave brought this rubber-band-firing gun. Although there were some long bolts, again they were deemed unnecessary and thus the model was eligible for the competition. Certainly the most fun! I'm still not sure whether the semicircles at the end are a target or a sight, though?

Sue isn't actually a member of the club, but here's her entry anyway! It does go, and steers, and only contains fourteen parts (the Magic Motor is one, as is the rubber band). Considering this is only the second Meccano model Sue's ever built, it's not half bad!

Neil is winding us up here. A great model using exactly fourteen parts, but not a semicircular plate in sight! Exactly as the rules specify, you can use as many of these parts as you like.

Neil doesn't like them. And just in case you didn't get the message, he made another on the day of the meeting. Again, fourteen parts and no 214's. I can't remember seeing a 'simplicity' model using a 6" circular plate before.

Grace brought one of her favourites too, the 'rooster' simplicity model which is always a winner in my book!

Other models on show this month

Another nut and bolt cleaning device. Much more restrained and gentle, although I'm not sure whether it should be operating with a beer can. The drive uses a single eccentric turning one side of the bevel differential at the back. Sorry about the photo, this isn't really clear enough to see what's going on. But I can assure you it rolls the can gently to and fro a little more than half a turn, about once a second.

(more to follow)

The CMC Challenge - "Turning the Iron Lady"

Build a model in time for the next CMC meeting on the 13th April 2007.

The Challenge

Build a self-contained Meccano model (that is, one without trailing wires or controls), that will drive itself along the table-top at the club meeting, detect and avoid the end of the table, and return to the operator. The tables are a little over 2 feet wide and 6 feet long, although the model should ideally be capable of the same thing along the length or across the width of the table.

The Competition

At the CMC meeting in April, all present will vote for their favourite model amongst those that achieve the challenge (or the closest in case no-one manages this), and the winner will be the one with the most votes! In the case of a tie, the most senior disinterested club member present has the casting vote.

The small print

As usual, you can use any Meccano part ever made and sold as Meccano, or any reproduction part that is structurally identical to a Meccano part. Parts may not be cut or deformed such that they cannot be used for their intended function again. You can cut a 2 down into a 2a (it becomes a reproduction part), but not down to a 5" long strip (which has no Meccano equivalent).

Cord, driving bands, springs, and power supplies may be of any type. Motors, if used, must be genuine Meccano. Non-Meccano washers may be used in your model solely to protect the paintwork.