Hornby class 31 mazac chassis disintegrating

[Dungrange]

1 hour ago, kevinlms said:

A friend of mine does and it isn't a question of storage, as someone else raised earlier. My friend has other models from Hornby of the same age and they are stored side by side with the Class 31 in the original packaging, with none of the others showing any sign of the rot.

 

The 'rot' is caused by impurities in the casting alloy and is not caused by storage conditions or age.  However, some of those with the same model as I have, found that their model had 'rotted' within a couple of years of production (ie back around 2010), whereas mine took over a decade to show any signs of an issue.  Matt (Foden) indicated that his model of the same vintage was okay a couple of years ago, when he bought and fitted a new chassis.  Why therefore did some of the faulty Class 31 models rot quickly, whilst others have rotted more slowly?  The most likely explanations are either than some batches of Mazac were more contaminated than others, or storage conditions play a part in how quickly a faulty model rots.

[melmerby]

On 24/12/2019 at 18:33, AlexHolt said:

 

I know but the worst and most documented cases are with Hornby models.

Check out Mainline.

My 57XX literally crumbled to crystaline dust, My 43XX warped beyond recognition.

My Manor strangely seems so far unaffected. All three were bought new around the same time from the same retailer and kept in the same storage conditions.

However two original Airfix 14XX from the same period seem fine.

 

It all depends how much contamination was in the batch of Mazak that was being produced.

Edited December 27, 2019 by melmerby

[tomparryharry]

4 hours ago, Dungrange said:

 

The 'rot' is caused by impurities in the casting alloy and is not caused by storage conditions or age.  However, some of those with the same model as I have, found that their model had 'rotted' within a couple of years of production (ie back around 2010), whereas mine took over a decade to show any signs of an issue.  Matt (Foden) indicated that his model of the same vintage was okay a couple of years ago, when he bought and fitted a new chassis.  Why therefore did some of the faulty Class 31 models rot quickly, whilst others have rotted more slowly?  The most likely explanations are either than some batches of Mazac were more contaminated than others, or storage conditions play a part in how quickly a faulty model rots.

Agree, but temperature humidity, etc, can be contributing factors for Mazak decay. If the zinc base is gained by using scrap, such as old vehicle batteries, then you're on a loser before you start. Copper (Cu) has a much higher value, so, surprise, surprise, used as little as the smelter can get away with. Even with ideal conditions, too high a temperature in the melt will start to burn off the zinc, so any old scrap will go in. I can't imagine a scrap vehicle battery will be ideal, being immersed in acid, and then chucked in a Furnace.

 

The best Mazak I've seen thus far has been a Palitoy /Mainline pannier chassis. It's just a pity that the wheel muffs break down across the axles.

 

Cheers,

Ian.

[andyman7]

25 minutes ago, tomparryharry said:

Agree, but temperature humidity, etc, can be contributing factors for Mazak decay. If the zinc base is gained by using scrap, such as old vehicle batteries, then you're on a loser before you start. Copper (Cu) has a much higher value, so, surprise, surprise, used as little as the smelter can get away with. Even with ideal conditions, too high a temperature in the melt will start to burn off the zinc, so any old scrap will go in. I can't imagine a scrap vehicle battery will be ideal, being immersed in acid, and then chucked in a Furnace.

 

The best Mazak I've seen thus far has been a Palitoy /Mainline pannier chassis. It's just a pity that the wheel muffs break down across the axles.

 

Cheers,

Ian.

As has been documented in these pages, this is a complex subject. I have 1930s Dinky and Hornby O gauge early mazak castings that have distorted but are now stable - we are talking 80-90 years old. Others though crumbled to dust. The problem with the recent (past 20 year) occurances is that they are inevitably in models with much finer tolerances so any distortion proves unworkable - a Hornby O gauge coarse sclae model with mildly fatigued wheels can still be used.

[melmerby]

41 minutes ago, tomparryharry said:

 

 

The best Mazak I've seen thus far has been a Palitoy /Mainline pannier chassis. It's just a pity that the wheel muffs break down across the axles.

 

Cheers,

Ian.

Read my post two above.

Worst by far was my Mainline 57XX, there was literally nothing left of the chassis apart from some very small pieces and crystalline dust.

I got it out of storage and the wheels were solid and wouldn't turn, seeing it was distorted I started to separate the halves of the chassis and it just broke up, once the screws were out what looked like complete pieces of chassis just dismembered themselves. You could crunch it up in your hand like a sugar cube.

The 43XX bought at the same time was just extremely distorted but did not break (The body strangely was not damaged). The Manor still seems reasonably OK and is a runner.

[thaddeus]

The oddest metal fatigue fault I have seen was in a Mainline J72 one half of the split chassis was completely serviceable with no defects and the other half had turned to powder. The wheels also were riddled with rot and crumbled just looking at them.

Edited December 27, 2019 by thaddeus
stuff

[adb968008]

Gosh ive been lucky with Mainline locos... never had a rotter yet.

ive handled a lot in my time.

 

Most frequent issues ive had with mainline locos is the plastic axles, which can be replaced, or motors just becoming unclean and needing servicing.

 

Performance though the J72 ive always found poor, even 30 years ago. Std 4MT wasnt much better.  I still run some Mainline panniers, though admittedly I swapped chassis on them 3 decades ago.

[kevinlms]

2 hours ago, thaddeus said:

The oddest metal fatigue fault I have seen was in a Mainline J72 one half of the split chassis was completely serviceable with no defects and the other half had turned to powder. The wheels also were riddled with rot and crumbled just looking at them.

Which makes absolute sense, given the two halves were from different batches.

[GWR-fan]

On 27/12/2019 at 11:13, cheesysmith said:

...........................................................

All mine are packed away due to house move, but has anybody got some of the first chassis with the broken ends who can check if the centre section has disintegrated further? ...................................

 

Some years ago I converted a Lima class 31 body to an affected Hornby chassis (original Dutch livery model)  in which the ends had disintegrated.  To fit to the Lima body I narrowed down the chassis to fit inside the Lima plastic chassis to aid chassis install/removal.  Quite a bit of material was ground away to slim it down and it did require some force to refit the motor but the main part of the chassis still seemed intact.  I recently checked the loco and all seems well,  with it running like a Swiss watch.

[thaddeus]

9 hours ago, kevinlms said:

Which makes absolute sense, given the two halves were from different batches.

well good for you for pointing out the obvious. Oddly enough with all the mainline chassis I have thrown in the bin (a lot) both sides seem to rot at an equal rate. yes, I do realise that separate parts can be made at different times from different materials to different tolerances, as it has been the only one I have personally seen this happen to I thought it was a little unusual, pardon me for sharing.

[kevinlms]

1 hour ago, thaddeus said:

well good for you for pointing out the obvious. Oddly enough with all the mainline chassis I have thrown in the bin (a lot) both sides seem to rot at an equal rate. yes, I do realise that separate parts can be made at different times from different materials to different tolerances, as it has been the only one I have personally seen this happen to I thought it was a little unusual, pardon me for sharing.

No thank you for sharing, it's an important statement. Sorry if I worded my reply badly.

It certainly puts paid to the suggestion some have put forward, about a storage problem.

[pheaton]

On 27/12/2019 at 08:58, Foden said:

Just to throw this in there, I have one of the affected batch (31110) that has had the body removed and replaced onto a later chassis. This was done in advance of any signs of rot as a rescue mission to re-use the loco, rather than a cure after the rot had set in as it were.

 

The chassis was binned after it was relieved of everything useful, but it never showed any signs of rot. This was in 2017.

 

The model in question was dry stored in its box from new, having come out only a few times for a few minutes, I’m wondering if these storage conditions played a part in its condition.

Not all 31110s were affected, afaik there has never been any published batch numbers, i have a 31110 stored in less than ideal conditions and it show none of the signs that preceed the rot. 

Edited December 29, 2019 by pheaton

[kevinlms]

5 hours ago, pheaton said:

Not all 31110s were affected, afaik there has never been any published batch numbers, i have a 31110 stored in less than ideal conditions and it show none of the signs that preceed the rot. 

Unlikely to be batch numbers, as it isn't food or medical goods.