Mazak rot on Hornby class 31

[roythebus]

I've just started to run my Hornby 31 without headcode boxes and found the cab end about to call off due to the well known mazak rot. Is there a replacement chassis block available for this?

 

I sent Hornby service dept an email to see if they can help. and yes, it's one of the locos on the list of mazak rot locos.

 

Incidentally, one of the lads at the Folkestone club thinks they've found out what causes it. One of the quality control manage ladies went to China and found that in the mazak casting shop of one factory when the metal was spilt on the floor it was put back in the melting pot to be re-used. This was probably what has been causing the problems over the years.

[Foden]

There’s no replacement chassis available, you’ll have to find (a non rotting) second hand one if you wish to swap it over.

 

You’ll also not get any help from Hornby regarding warranty replacement if that’s what you’re seeking, I’m afraid that ship sailed some time ago, which is fair enough.

[andyman7]

To be fair, the affected models are now all around 14 years old.......

[Fat Controller]

50 minutes ago, roythebus said:

I've just started to run my Hornby 31 without headcode boxes and found the cab end about to call off due to the well known mazak rot. Is there a replacement chassis block available for this?

 

I sent Hornby service dept an email to see if they can help. and yes, it's one of the locos on the list of mazak rot locos.

 

Incidentally, one of the lads at the Folkestone club thinks they've found out what causes it. One of the quality control manage ladies went to China and found that in the mazak casting shop of one factory when the metal was spilt on the floor it was put back in the melting pot to be re-used. This was probably what has been causing the problems over the years.

Remelting spillages has been common practice since the year dot; it has been widely suggested that the problem has been lead contamination in the ingots supplied to the factory. It's not a new problem, but elsewhere has been reduced, if not eliminated, by testing and quality control.

[kevinlms]

53 minutes ago, roythebus said:

I've just started to run my Hornby 31 without headcode boxes and found the cab end about to call off due to the well known mazak rot. Is there a replacement chassis block available for this?

 

I sent Hornby service dept an email to see if they can help. and yes, it's one of the locos on the list of mazak rot locos.

 

Incidentally, one of the lads at the Folkestone club thinks they've found out what causes it. One of the quality control manage ladies went to China and found that in the mazak casting shop of one factory when the metal was spilt on the floor it was put back in the melting pot to be re-used. This was probably what has been causing the problems over the years.

Probably a lot worse than a spillage of metal from the floor.

 

More likely they used a batch of 2nd hand material, from who knows where and what was mixed in it.

[roythebus]

Oh well, seems like it's only fit for stripping for parts unless I can work out a way to repair it. Someone elsewhere suggested using a Lima chassis with the Hornby motor, is that feasible?

[LNWR18901910]

I guess you can say it's the Sound of Mazak. The Hornby Class 31 was based on the Lima 31 as we all know it. Heljan do actually produce a more detailed and (hopefully) reliable model in good ol' 00 gauge so maybe worth saving up for perhaps. Even I do the same when it comes to saving up for models old or recent unless there were clearout sales.

[Corbs]

If it’s any use, I have used cheaply available Airfix class 31s combined with mazak rot-affected Hornby ones to build into one good model. 
If you click on ‘Corbs and Chris’ Clinic’ in my signature it will take you to the thread. 
The first one used the Airfix body and chassis frame with Hornby drive train but I’ve also used the Hornby body on the Airfix chassis frame.

[Foden]

Depends what your budget is for repair. Sometimes the DCR 31s come up on eBay for relatively cheaper prices than searching for a replacement chassis.

[Dunsignalling]

9 hours ago, LNWR18901910 said:

I guess you can say it's the Sound of Mazak. The Hornby Class 31 was based on the Lima 31 as we all know it. Heljan do actually produce a more detailed and (hopefully) reliable model in good ol' 00 gauge so maybe worth saving up for perhaps. Even I do the same when it comes to saving up for models old or recent unless there were clearout sales.

The Hornby Railroad 31 is basically the old Lima model fitted with Hornby's newer non-ringfield motor bogie.

 

The main range one was redesigned from the ground up, with centre-can motor and flywheel drive to both bogies. It's (some of) those that rot.

 

Heljan do 31s in O Gauge, but not (so far as I am aware) in OO.

 

John

 

 

Edited February 10, 2020 by Dunsignalling

[cheesysmith]

Fitting the super detailed bogies and parts to the Lima/railroad chassis I easy, having done a few myself. Just needs some 30thou plasticard iirc, a drill and a blade. Bits from the old body can be useful, like exhaust ports to fit into a Lima body, or the buffer beam surrounds for back dating a non HGR loco.

Edited February 10, 2020 by cheesysmith
Photos

[cheesysmith]

[rob D2]

Keep an eye on eBay.

replacement chassis ARE available and I’ve seen a vendor who’s sold several recently , they seem to come up from time to time ....this guy. Might be worth contacting see if he has anymore .

Edited February 11, 2020 by rob D2

[34theletterbetweenB&D]

On ‎09‎/‎02‎/‎2020 at 22:26, roythebus said:

...one of the lads at the Folkestone club thinks they've found out what causes it. One of the quality control manage ladies went to China and found that in the mazak casting shop of one factory when the metal was spilt on the floor it was put back in the melting pot to be re-used. This was probably what has been causing the problems over the years.

It hasn't been a mystery for the best part of a century now, just poor practises, usually in the casting shop, of the sort described, (let's assume that the supplier has made the alloy right: the evidence suggests they have, it's infrequent specific batches of product that have this defect, it isn't 'everywhere').

 

Lead is the typical poisoning metal, and is unfortunately pretty ubiquitous. But it is now easy to screen out (QC) if the casting shop cannot control the process adequately to prevent the contamination at the melt and cast stage (QA). On receipt of the casting batch, hand held XRD's are now cheap enough to provide a quick non-destructive random sample test. Find any element in a casting that wasn't present in the specified alloy formulation, FAIL, return the whole lot to vendor.

 

That's how you drive it into a production operation that they do the job right, every time. And perhaps have their own XRD to check that the crew are conforming, every time. Because it may not only be the casting shop. One of my 'war stories' about a similar long standing problem of an (entirely different) alloy contamination was occurring in the transport and handling stages between supplier and goods inwards receiving. Man with fork truck occasionally punctured a barrel, or dropped it or backed into a stack, barrel fell off truck, you name it. Since it was expensive stuff and carefully weighed out and weighed in, and everyone knew it, spillages were carefully shovelled up. Damaged barrels were carefully substituted with 'good' empties (same contractor handled the shipping in and out)...

[roythebus]

It says out of stock on the ebay advert.

 

I mentioned the problem ay the folkestone club last night, a couple of lads there work at Hornby and may have access to something. Back to the club tomorrow night.

 

I see the 31 is back on the Hornby books but at abut £170 a pop is a bit outside my budget at the moment.

 

Mine is the class 30 anyway, the one without the headcode boxes.

[rob D2]

22 hours ago, roythebus said:

It says out of stock on the ebay advert.

 

I mentioned the problem ay the folkestone club last night, a couple of lads there work at Hornby and may have access to something. Back to the club tomorrow night.

 

I see the 31 is back on the Hornby books but at abut £170 a pop is a bit outside my budget at the moment.

 

Mine is the class 30 anyway, the one without the headcode boxes.

Yeah, I know.

thats why I said contact the seller and see if he anticipates anymore coming 

[davidw]

On 12/02/2020 at 15:58, rob D2 said:

Yeah, I know.

thats why I said contact the seller and see if he anticipates anymore coming 

I got one of these around Christmas last year. Transplanting the old to the new was quite a fiddle. Also make sure that you note the wiring layout. 

[Simeon]

To be fair to Hornby I contacted them in March 2022 to express my disappointment of the issue, my father had emailed them years ago to see if spares could be obtained, and they sent me out an equivalent replacement, D5627.  Considering I bought the model from new more than 15 years ago I think that's stunning customer service and more than I was expecting.  I've subsequently bought 2 more.  I've also ordered the Accurascale Class 31 too, I may have a problem.

[cypherman]

Hi all,

I am not sure if it would be an easy fit but could you not replace the rotten Hornby chassis with ones from the Lima class 31. I would swap out the original motor for a new cd motor as well. It was an easy swap to put a Hornby body on one of my class 37s

[cityofleeds]

If you have some Hornby Class 31's how do you tell if they have Mazak Rot.

 

If you leave them out for a few weeks will it become apparent

[34theletterbetweenB&D]

3 hours ago, cityofleeds said:

...how do you tell if they have Mazak Rot.

(Applicable generally to mazak castings.)

 

Initially, if the casting is painted, cracking of the paint because the effect of mazak rot is to expand the casting.

A close fitting plastic body moulding will initially be jammed on, then begin cracking.

Then visible cracks in the metal, and ultimately pieces dropping off, thinner sections are usually first to show these effects.

 

Specific to the Hornby 30/31 the cracks to the body shell mostly appeared behind the bufferbeams on the cab sides, and by the time this was noticed and the body was removed to see what was happening, one or both of the thin 'cab floor' elements at both ends of the cast chassis block would break off in the process. 

 

Interesting side note, the drive shafts to the bogies have a splined coupling in them. The effect of this is that those of us still running mazak rotted chassis have a slightly over scale length wheelbase under the model, but the drive shafts remain engaged between the flywheel and worm couplings despite the expansion.

 

[Southernman46]

3 hours ago, cityofleeds said:

If you have some Hornby Class 31's how do you tell if they have Mazak Rot.

 

If you leave them out for a few weeks will it become apparent

There is a link to a thread containing a file with the affected models here

https://www.rmweb.co.uk/forums/topic/123769-zinc-pest-mazak-rot-the-affected-models-list/#comment-2757031 

 

Also if your 31 has separation between the body & buffer valance with skewed buffers as circled below then chances are it is suffering.

 

I wouldn't worry too much - I feel a glut of cheap Hornby 31's to provide donor chassis' on the horizon soon 👍

 

Edited February 23 by Southernman46

[mcowgill]

4 hours ago, cityofleeds said:

how do you tell if they have Mazak Rot.

 

 

Damage/distortion/cracking around the cabs - most unprototypical https://flic.kr/p/2iX6pgH

[roythebus1]

I ended up getting a 2nd hand Lima model and grafting the Hornby motor and bogies onto the Lima chassis. Sadly the class 30 body was cracked beyond repair by the mazak breaking up. i'll put some pics on here when I get time!