Restoring Meccano

Try the hammer. You can fix everything with a hammer!

I agree, a ball peen hammer and a wooden 'anvil block' should work for straightening bent panels, and give the students some experience in 'cold metalworking.'

Let them learn how to make minor repairs and adjustments. Also, let them learn that Life does not always give you all your parts 'up to spec,' and sometimes you need to finish a job yourself.

GA! An old chopping block/cutting block is commonly lower in the middle from all the little pieces that got chopped out over time. That's a good thing for straightening. Remember that, due to springback, hammering or pressing down to a flat surface does NOT result in a flat piece. You must hammer or press beyond flat to end up flat.

Now when you (OP) say bending in a vice does not work, you must not know how to do it. You need three shims; the best shim thickness depends on the "springiness " of the material to be straightened. I'd start with something around 2mm thick. You open the vise wide enough to be able to insert one shim at the peak of the bend, and the other two shims at equal distances away from the peak, and on the opposite side of the part to be straightened. If this isn't obvious, I can provide a drawing...

Now you tighten the vise until the bend has passed beyond straight. Experience will tell you (and your students) how far you have to go beyond straight, to end up with a straight bar, for a given kind and thickness of material. If you go too far, you just flip it over and repeat the process, using less force.

Clearly, it helps if the vice is large compared to the part being straightened, and it does need smooth flat Jaws. A 6" machinists vice is excellent for this job. If you don't have one available, go to most any machine shop that's been around for a long time. They probably have several that have gotten damaged or oxidized, and have been stashed away in some corner. When you explain what you are trying to do, I'll bet they'll give you one or more. The last time I did that, it took me a large portion of a day and a good bit of elbow grease and WD40, working the handle back and forth to get the vice to open all the way, but once I did, it has worked just fine for several years (keeping it lubricated).

Thank you. I do have a suitable vice (I think made as an apprentice's test piece) and I'll hunt up some shims. Simple hammering against a piece of kitchen work surface has been quite successful so far, but at the cost of the paintwork.

"Simple hammering against a piece of kitchen work surface has been quite successful so far, but at the cost of the paintwork."

That is why woodworkers and craftsmen came up with things such as the 'bench hook' and 'sacrificial surface,' to PROTECT workbench surfaces and kitchen work surfaces.

Sorry, my confusing wording. The kitchen work surface is a plastic and has not suffered at all. The damage is to the paintwork of the Meccano piece being hammered. I shall now follow up the suggestion of using wood rather than plastic as a working surface.

With older samples of painted metal, the paint is likely to chip and flake off as the metal is bent and flexed; it's just the nature of the paint used back then. More recent paints are more 'supple' and able to deal with a flexing surface without cracking and falling away.

I would suggest a 'cushion block' of wood between the hammer and the metal part to reduce the effect of the hammer blows on the paint. Even something as simple as a piece of '2x4' (framing lumber) between the hammer and metal will provide protection.

When checking the metal fenceposts every spring for 'uprooting,' I use a wooden block between the 'acorn' top of the post and the hammer to protect the paint (and to avoid the dangers of striking a kind-of-pointy metal fencepost top with a metal hammer.

I suspect you will want 3 or 4 hands to hold everything in place while you tighten the vise.

Building Meccano models is sometimes like that anyway!

"GA! An old chopping block/cutting block is commonly lower in the middle from all the little pieces that got chopped out over time."

Even a 'fresh' piece of wood will grow a 'bowl' quickly if you're pounding on it with a hammer. Again, it's a learning experience for the kids, and an object lesson as to why you use a Bench Hook or other form of sacrificial surface between the part your pounding on and the workbench supporting the part.

That last part is actually the more important lesson, as many craftsmen and woodworkers pride themselves on the 'lack of damage' their workbenches have. They love that their workbenches are as flat, smooth and level as the day they built them. (All those features make is a good 'reference surface' for building precision projects, such as cabinetry, upon) You do NOT want to be the person who puts the first gouge or bowl into that craftsman's beautiful workbench.

Not just panel beaters, but the original "boiler makers". Before the invention of mechanized bending, everything was done with a hammer. Repeated blows formed the shells. I have dabbled, with some success, in forming various curvatures using only a ball peen hammer (with no heat) on an anvil. Methinks I would need a few more years practice to perfect the technique though.

Using a vice will get you close to straight but hammering will get the final little kinks out. You might need a surface with a slight depression if the pieces have significant spring back.

Similarly, one can use shims and a vise (not vice) to overbend a little for springback allowance.

In the UK we keep good vices in the workshop as well as bad vices in our personal lives

"What were once vices are now habits."

Watch out--the vise squad is gonna come and grab your bench clamping tools.

Now that can be a trick, turning into .

Thank you. Funnily enough, I came across one of those on eBay just recently, but I don't think I have space for it.

An English Wheel makes curves by 'pressing' the metal between the rollers, squeezing it into a thinner, wider section. forcing one section into a wider surface area causes the surrounding metal to 'warp' to accommodate it. This is the same way that paper warps when part of the sheet gets wet, although with paper it's the swelling fibers that cause the 'spreading out' of the material.

You could, in theory flatten out a curved piece on an English Wheel, but you would be doing it by squeezing the metal until it starts to warp the sheet in the opposite direction of the original curve. Even if you managed to restore the sheet to 'flat' on an English Wheel, it will be thinner, longer, and wider. The mounting holes will not line up with other Meccano pieces anymore.

Lot easier just to buy old sets or ask for donations for old sets.....

http://picclick.ca/Vintage-1938-Gilbert-Erector-Sets-w-Lots-of-Parts-262579703430.html

Been there, done that. Although I have some very fine pieces for my personal collection, the cheap stuff I got for the youth club included some seriously bent items.

The Australian Ezy-Bilt alternative to Meccano had a 25 hole RIGHT ANGLE piece,
(see lower right, with round holes in one wing and elongated holes in the other wing of the angled section)
which added some practical commonsense to building many cranes, trucks, planes, bridges etc
that overcame the 'bending' 25 hole Meccano piece, needing lots of angled tabs
to achieve similar to the Ezy-Bilt solution.

It is indeed a very useful piece, but i have to report that Meccano got there first. It is number 8 in the Meccano parts list. My gold example dates from between 1934 and 1945.

None of my Meccano kits had such a useful item ... but my Ezy-Bilt kits did.
I will blame being south of the equator or some other silly excuse.

Is Meccano the same as Erector or a competitor? I had not heard of Meccano before CR4, and I had not heard of Ezy-Bilt before this thread.

I definitely spent many hours with the Erector Set I had as a kid in the '40s; I always wanted a set with an electric motor, but my parents couldn't afford it.

Meccano was the British originator of the design, Erector was the American competitor. Each had their own regional market. Erector was bought out by Meccano in 2000, and the erector brand name was retired in 2015.

This looks a bit like what I know as an Erector set. I think there's still a crane in the attic that I built as a kid, including the 4-wheel, 2-axle suspension that allows only one wheel to rise over a bump.

Try building a Meccano plate bender. Use larger diameter rollers, such as the wooden Meccano rollers. This should allow you to straighten the plates in a benign manner. I have seen it demonstrated at one of the SA Meccano meetings. The small diameter rollers should also work, just set the machine properly.

Yes, I have seen that machine before. It requires special steel rollers, so is not entirely in the Meccano spirit. What is also not clear is whether it can deal with a bend in the metal, as opposed to a smooth curve.

Meccano purists only use Meccano parts and are horrified at the thought of bending our precious Meccano pieces. Try using couplings as rollers. I can't test as I do not have a built up plate bender, nor any bent Meccano.

This idea has a good chance of success. Any roller small enough for the plate will do.

The trick is to roll the buckled piece into a curve beyond the elastic limit (so that it stays curved) - and then unroll it into a reverse curve - and back again - just enough so that it springs back flat - do this in both planes - probably two or three times both ways until you get it right.

Hammering the dent/bump spreads the metal in the dent/bump - and makes it worse.

Meccano pieces have a series of holes in the plates, which are equidistant, to permit them being screwed to other pieces.

If you hammer them, isn´t there the risk of deforming the plates and off centering the holes?

Regrettably, Meccano and precision engineering do not belong in the same sentence. There is always a fair amount of slop in a Meccano structure until all the nuts and bolts are fully tightened. Indeed the assembly instructions for the no. 2 chiming clock start by requiring the frame to be made up, after which comes "Later, when the interior mechanisms of the Clock are fitted into the frame, the positions of the axles in the frame can be adjusted slightly, as necessary, by slackening appropriate Bolts... and by then by moving the axles in the direction indicated ... to ensure free meshing of gears".

Building clocks in Meccano is a specialty with passions involved. As a junior doctor I was involved with treating a suicide attempt by the wife of a senior consultant, whose foibles included playing the piccolo very loudly and spreading the components of Meccano clocks all over the dining-room table. I met him later on in my career and my sympathies were entirely with his wife.

Well done colleague!