Zinc Pest (Mazak Rot); The Affected Models List

[Going Spare]

That is not a standard Hornby A1/A3/A4 tender chassis as none were rigid, the rear wheelset being in a pivoting pony truck.  Nor do they have what appears to be 4 traction tyres.  Could it be a Trix A2?

[Dunsignalling]

Whatever it is, I suspect the innards didn't start off in that outer casting. The latter has openings to accommodate outside bearings and the axles don't seem to line up with them.

 

John

[stewartingram]

I was wondering that myself. I have a tender drive A4 in the garage, I'll see if I can have a look tomorrow. I've also got a loco drive A3 and A4 for comparison.

[TimberValleyRailway]

No idea what model it is from, sorry.

 

I might be able to get a different view but that looks unlikely since I saw it in a shop.

 

Best wishes

[TimberValleyRailway]

Here you go.

[adb968008]

12 minutes ago, TimberValleyRailway said:

Here you go.

thanks, thats the Trix A2/A4 tender.

most probably Trix 1186 A2 525 AH Peppercorn.

 

 

Edited February 22, 2023 by adb968008

[stewartingram]

Thanks for posting that, I'll stop looking for mine now!

[RedgateModels]

On 10/02/2023 at 10:28, RedgateModels said:

Just had Hornby R2728 Royal Scot Class 4-6-0 46120 "Royal Inniskilling Fusiliers" in BR Green with late crest come through my hands. Clear signs of rot to the chassis above the front bogie. Gears are slipping on the motor so there's also a good chance that the motor mounts etc are affected too. I'll take it apart soon to confirm.

so here’s the chassis in all it’s sorry glory

 

 

[robertcwp]

On 23/02/2023 at 21:02, RedgateModels said:

so here’s the chassis in all it’s sorry glory

 

 

I have a 46120 in store as a spare, bought second hand as I thought it was free of the pest. I shall check to see if it is showing signs of problems. I have written off two other Royal Scots and a Patriot already but my other two Scots and a Patriot seem fine. They are 46146, 46165 and 45535. I also have a 45531 which has been rebuilt but it's probably only a matter of time before it fails completely.

[BMacdermott]

Hello everyone

 

Forgive me if I don't trawl through all the previous posts.

 

I have just been speaking with some friends who have many of the same locos as me. Some of theirs have rot whereas none of mine do.

 

Mine are always in my railway room in my house which is always heated when cold weather demands. Does the rot affect those which have been stored 'cold' such as in lofts, garages etc?

 

Brian

[MikeParkin65]

4 hours ago, BMacdermott said:

Hello everyone

 

Forgive me if I don't trawl through all the previous posts.

 

I have just been speaking with some friends who have many of the same locos as me. Some of theirs have rot whereas none of mine do.

 

Mine are always in my railway room in my house which is always heated when cold weather demands. Does the rot affect those which have been stored 'cold' such as in lofts, garages etc?

 

Brian

My environment is pretty similar to yours apart from like most people this year the heating hasn’t been on as often as usual. I have several of the listed Mazak issues models but so far only the Railroad 9f has been affected.  This thread suggests Mazak rot is an unavoidable consequence of the use of certain unstable elements. That said its an interesting hypothesis that the inevitable can be delayed by some ‘environmental control’. That said I am going to learn to build Comet chassis in advance of when that day comes!

[Dunsignalling]

6 hours ago, BMacdermott said:

Hello everyone

 

Forgive me if I don't trawl through all the previous posts.

 

I have just been speaking with some friends who have many of the same locos as me. Some of theirs have rot whereas none of mine do.

 

Mine are always in my railway room in my house which is always heated when cold weather demands. Does the rot affect those which have been stored 'cold' such as in lofts, garages etc?

 

Brian

From my own affected models and similar ones belonging to friends, I suspect that environmental conditions may influence how quickly the rot becomes apparent, but if it's gonna happen, it's gonna happen.

 

There are also "lucky" examples of locos which usually suffer from it that don't. Presumably the impurities aren't always thoroughly stirred into the mix!

 

John

Edited April 4, 2023 by Dunsignalling

[TimberValleyRailway]

Just seen this over on the Hornby Forum: https://uk.Hornby.com/community/forum/0-6-0-chassis-quality-355782?ccm_paging_p=1#end-of-replies

 

[Manston]

I have a Bachman 31-460 Class C 0-6-0 No.592. Went to run it today having been in a display cabinet for several years and saw this under the front footplate. Seems to have spread over the paintwork. Is this the rot?

[melmerby]

Isn't that damp damage?

[Manston]

Don’t think so, it’s been in an insulated shed, min temp is 10C. I’ll see if a soft brush removes any more. No other engines appear affected by this, but I noticed that the C class wasn’t on the list.

[34theletterbetweenB&D]

On 04/04/2023 at 11:36, BMacdermott said:

Does the rot affect those which have been stored 'cold' such as in lofts, garages etc?

Yes is the short answer. The 'rot' is a change in the crystalline structure of the alloy from that which it  assumed when cast to a slightly less compact structure, which is more stable at lower temperatures, so the progress of the change is accelerated by lower temperatures. (The difference in volume between the two crytalline structures is what causes the fragmentation.)

Edited August 14, 2023 by 34theletterbetweenB&D
corection of factual error

[adb968008]

1 hour ago, Manston said:

Don’t think so, it’s been in an insulated shed, min temp is 10C. I’ll see if a soft brush removes any more. No other engines appear affected by this, but I noticed that the C class wasn’t on the list.

Looks like oxidisation not mazak rot, especially if it brushes off. You cannot brush off mazak rot.. it will crumble like a broken biscuit (dont try it by the way as the pieces can be very sharp).

 

water vapours condensate to colder surfaces and corrodes the surface.

 

good news is if you brush it off, and keep it in the house warm it should be ok.

 

[sandwich station]

11 hours ago, Manston said:

Don’t think so, it’s been in an insulated shed, min temp is 10C. I’ll see if a soft brush removes any more. No other engines appear affected by this, but I noticed that the C class wasn’t on the list.

 

This is what Mazak rot looks like. Funny enough this is the front bogie off of 34070 Manston. :) 

[Dunsignalling]

9 hours ago, sandwich station said:

 

This is what Mazak rot looks like. Funny enough this is the front bogie off of 34070 Manston. :) 

My Manston (R.2260), dating from the end of 2002  went just the same way when about five tears old. At the time I was fortunately able to source a spare bogie.

 

The later release, with the high-sided tender (R.3249) is not affected TTBOMK.

 

John

Edited August 14, 2023 by Dunsignalling

[34theletterbetweenB&D]

On 04/04/2023 at 17:54, Dunsignalling said:

There are also "lucky" examples of locos which usually suffer from it that don't. Presumably the impurities aren't always thoroughly stirred into the mix!

Many possibilities for this outcome in the casting process. If for example the casting shop is producing relatively small batches, and only some are made with a contaminated melt, it's a lottery.

 

Seen it happen with component castings in 'an alloy'. Vendor shifted production from 'long established' to 'new location' without informing the customer, and when the problem became evident years later, a large tonnage of what were planned to be 'indefinitely recyclable' parts all had to be sent as scrap for reprocessing, no practical way of tracing, or alternatively determination by test, which components were good. (Major row over 'who pays', vendor caved when their contractually indefensible action was proven.)

[melmerby]

It's ridiculous that this is still happening decades after it was first found.

Mazak/Zamak are a group of tightly specified alloys with a rigid list of constituents that if adhered to and certified as such will not suffer from the dreaded pest.

The fact that it is happening suggests that short cuts (presumably cost driven) are being made in its production.

 

It's silly because if it manifests too soon after production the manufacturer is lumbered with replacement costs for the duff items, possibly wiping out any profits made.

1 hour ago, 34theletterbetweenB&D said:

If for example the casting shop is producing relatively small batches, and only some are made with a contaminated melt, it's a lottery.

I bought three Mainline models when first introduced, 2 of the three succombed completely some years ago, a 57XX & a Mogul, the Manor is still intact!

[Dunsignalling]

23 minutes ago, melmerby said:

It's ridiculous that this is still happening decades after it was first found.

Mazak/Zamak are a group of tightly specified alloys with a rigid list of constituents that if adhered to and certified as such will not suffer from the dreaded pest.

The fact that it is happening suggests that short cuts (presumably cost driven) are being made in its production.

 

It's silly because if it manifests too soon after production the manufacturer is lumbered with replacement costs for the duff items, possibly wiping out any profits made.

I bought three Mainline models when first introduced, 2 of the three succombed completely some years ago, a 57XX & a Mogul, the Manor is still intact!

Different countries. Different standards.

[34theletterbetweenB&D]

8 minutes ago, melmerby said:

...suggests that short cuts (presumably cost driven) are being made in its production...

That's the one! Decisions to reduce cost now with no competent technical advice sought of consequences. I could provide a long list from my own experience from the nations that initiated and lead the industrial revolution, before even thinking about those that came later to the party.

[Mark Saunders]

Never mind the quality feel the width! 
 

I suspect the same poor quality was a problem in the Uk at the beginning of the industrial revolution!