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xlchainsaw

mazak alloy

mazak is the alloy used by mamod in their castings. according to the mamod bible they first started to use it in 1953 replacing the more expensive brass flywheels. in my research ive come across an interesting article on the subject which may interest some members..........:::
Planes, trains and automobiles

Plastics are not the only materials affected by degradation. As the infantry crumbles, its air cover is disintegrating on the runway, grounded by "wing droop", a problem in 1930s model aeroplanes made by the Meccano company in Liverpool.

Equally affected were the company's early Dinky cars and Hornby trains. It's all down to "lead rot", a metallurgical problem. From the mid-1930s, Meccano began making toys from a zinc-based alloy called Mazak. The material moulded well, and brought out finer detail than the lead it replaced. By weight, Mazak contained 3 to 4 per cent aluminium and 1 to 2 per cent copper. But traces of lead as low as 0.008 per cent or cadmium as low as 0.006 per cent spelt disaster for the toys.

"They used to throw lead-contaminated shavings into the pot with the zinc," says Arthur Clapp, a restorer in the Wiltshire town of Warminster, who specialises in the repair of Meccano toys and trains. The lead atoms migrated to the grain boundaries in the zinc alloy, causing a change in the crystal structure, leading to a swelling of up to 10 per cent in these areas. Cracks appeared in the models as a result of this expansion, and ultimately they would flake apart, turning to dust.

According to Clapp, the planes were worst affected. "The wings would curl up," he says, a result of uneven grain boundary swelling. Cars made almost completely from Mazak turned to dust, as did Mazak wheels on Hornby trains built just before the Second World War.

"Hornby wheels literally disintegrated, but the superstructure of the locomotive was made from pressed tinplate, which was unaffected," says Simon Goodyear, a restorer of toy cars and trains based in Huddersfield. "I've had locomotives pristine in terms of their paint and bodywork, with wheels that had crumbled in the box," he says.

During the Second World War, Meccano was requisitioned to perform quality pressure die-casting for the Ministry of Defence. "Given the necessity to work to ministry specifications, there was tighter quality control and the company learnt how to craft Mazak to perfection," says Goodyear.

After the war, Dinky cars were made of Mazak or Mazak-like alloys, but lead rot was consigned to the history books through Meccano's newfound expertise in manufacture which, according to the company, persists to the present day. Understandably, intact models from the "lead-rot" period are unusually valuable, says Goodyear.

From issue 2061 of New Scientist magazine, 21 December 1996, page 38  
also ive found this mazak mender. has anyone any experience with it???
http://www.mazakmender.com/
Minor1PJG

Very interesting.  

I've not heard of the Mazak mender.  Thanks for posting this
igy569

Very interesting stuff!!   Always cool to learn something new!!
Mark-One

Interesting stuff.
xlchainsaw

when i was cleaning up some early te1 rear wheels i noticed small pinholes in the outer surface and on the spokes. i thought at the time that i must have been unlucky and got a bad one from mamod but idont know now. the wheels are getting on to  be nearly 45 years old. it appears from that article that 50 to 60 years is needed . i guess mr.malin didnt think his models would have lasted this long. little did he know. mr.malin always had very close business interests with meccano right from the beginning so i guess that is how he got organised with his castings.
tmuir

A lot of the Cranko locos suffer from this.
Bodywork in great condition axles in place but no wheels.
johnreid

Is this like an Epoxy?
Mark-One

johnreid wrote:
Is this like an Epoxy?



Slush metal, innit?

I remember a girthy Fleischmann on ebay where the flywheel was absolutely crumbling where it sat.

Evidently as big a problem back then as computer capacitors have been over the last 8 years.
Nick

Mister Occlusion wrote:
I remember a girthy Fleischmann on ebay where the flywheel was absolutely crumbling where it sat.

Same with Fleischmann lineshafts and pulleys. I've seen a few in that crumbling state.
Manxman

And the same problem with all Mastrand Rollers. You'll not find one with a good flywheel. They are all falling apart.
xlchainsaw

in the name of science liz donated to me a mamod rear wheel to melt down.  this wheel was on a model we wrecked for parts and had broken spokes ect but still!!! using a propane torch and stainless steel soup ladle i melted it! about a teaspoon full of crud (rubbish) was removed. it melted like solder. i liked the way it melted. if you can melt lead or solder then you can melt this stuff! so where can i obtain a cheap supply??? liz and i did a trip to a recycle depot and we found some chrome plated car door handles ,some bathroom fittings,and some window catches. so i melted them! fun this part! it was like squeezing melted chocolate out of it s metal wrapping. the chrome plate held its shape with liquid metal inside and you needed to pierce it to release the metal. pour this into a mold and there you are.this metal is everywhere in our lives and not just in our toys!
pauly

you should make a video of this process and post it on here it sounds very interesting
xlchainsaw

pauly wrote:
you should make a video of this process and post it on here it sounds very interesting
maybe someday . its not something that you can do and vid at the same time. maybe when i master a camera on a tripod with timer! i suppose i could get clinton to come over with his camera  
johnreid

No, I mean the mender stuff, it looks like it is supplied in a syringe
xlchainsaw

johnreid wrote:
No, I mean the mender stuff, it looks like it is supplied in a syringe
no i beleive it to be ground up metal in aflux paste as heat is needed to make the join/weld. i remember about 30 yrs ago a "miricle" pot mender in a tube on the market. as i worked in a hardware shop at the time i remember negative feedback about it! ive been thinking tho that if this stuff was used on an alumium pot no wonder it didnt stick. i tried to get mazak to stick to a peice of aluminium and it didnt stick! mazak to mazak no problems. i can see why they use it in pressure casting. that is to have parts roughly made up and place them in a die . heat the metal die ()like making a jaffle or toasted sandwich in a two peice iron)apply pressure and then the finished item comes out almost perfect.ill go to the hardware shops ect. im on the hunt   im going to try melting this stuff with a very big soldering iron that i will superheat ill let you know
alan2525

Aren't Mazac castings made by sintering the powdered metal too? Rather than pouring the molten metal, the metal is ground into a powder and then heated - the heating fuses the granules together, by it's nature the resulting casting is porous and a little fragile too.
bigal

Is this what they call pot metal?
johnreid

I think it is similar if not the same.
xlchainsaw

further to this post .ive just finished sanding back the paint work on two te and one sr. i noticed that the paint was loose in spots. this ive noticed before but this time i had a closer look. the metal had minute bubbles under the paint film thus lifting the paint off. i think this is why the paint on older models seem to chip very easy. this is like "rust" under the paint. this would be the result of the metal breaking down rather than the paint film loosing adhesion due to lack of primer or heat. mazak could be quite easily powdered or shaved ,placed in a steel mold and heated in a purpose built oven thus making the part like that.
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