kernowtim Posted February 10, 2019 Share Posted February 10, 2019 Just dug my warship out of its storage box to find the chassis somewhat banana shaped, never heard of this affecting this model! Link to post Share on other sites More sharing options...
John Tomlinson Posted February 10, 2019 Share Posted February 10, 2019 It would be helpful if you could post details onto the List in "Modeling questions, help and tips". I think D804 in blue has been recognised as a victim . Have you found it in time that the body is undamaged and could be put on another chassis? John. Link to post Share on other sites More sharing options...
RMweb Premium Gwiwer Posted February 10, 2019 RMweb Premium Share Posted February 10, 2019 Is this the early ex-Mainline D804? I thought that might be early enough to have escaped the plague. Mine is already on a new chassis because the drive shafts on what was a second-hand loco to me were both completely stuffed and one gear tower had been affected by a crude attempt to glue the shaft in. I had a weathered 802 which I was unhappy with because the weathering over coloured plastic made it appear pink. A quick swap of the guts means that D804 is now happily running with almost-new innards from 802 which loco is now a heavily-weathered and rusted scrap-siding non-runner after being attended to on my "dirty" bench and acquiring D804s chassis. Link to post Share on other sites More sharing options...
kernowtim Posted February 10, 2019 Author Share Posted February 10, 2019 This is the reworked ex mainline one, the plastic chassis moulding appears undamaged and would probably straighten out. I was going to sell this on ebay with a long dead unpowered mainline version, I may transplant the works into the mainline Plastic chassis instead! Link to post Share on other sites More sharing options...
RMweb Premium Gwiwer Posted February 10, 2019 RMweb Premium Share Posted February 10, 2019 Following up on this I have inspected the chassis-swapped D802. It does indeed have a very slightly warped ex-D804 chassis though as explained above it is already a non-runner. Link to post Share on other sites More sharing options...
kernowtim Posted February 10, 2019 Author Share Posted February 10, 2019 4 hours ago, John Tomlinson said: It would be helpful if you could post details onto the List in "Modeling questions, help and tips". I think D804 in blue has been recognised as a victim . Have you found it in time that the body is undamaged and could be put on another chassis? John. Have added to list, plastic components and mechanism seems unaffected so far! 1 Link to post Share on other sites More sharing options...
trevor7598 Posted February 11, 2019 Share Posted February 11, 2019 With the increasing use of mazak in models to add weight, increases the onus on manufacturers to make sure the Chinese factories check the purity of the mazak used in our very expensive models. The time it takes for impure mazak to rear it's ugly head, will ensure that the warranty is long expired. Pre-war Hornby Dublo and Dinky toys suffered badly from mazak rot, but post-war models were fine, so they eventually got it right. 3 Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted February 11, 2019 RMweb Gold Share Posted February 11, 2019 This impinges on a fundamental problem with the Chinese production model. The castings are not made in one individual factory where conditions and materials can be closely monitored, they are made in many small foundries scattered about that huge country, to CAD specifications available online from the co-ordinating agency, so quality control is a particularly difficult issue. The raw mazak itself will come from many different suppliers, compounding the situation. The attraction of mazak to the trade is that it is cheap, easily obtainable, easy to cast/mould, and heavy; vital in models that need all the help they can get with traction. Lead is cheaper, easier to work, and heavier, not to mention not suffering from rot, but there is a resistance to using it in anything that might be sold through a toy shop. Mazak is fine so long as the quality is up to the mark, but there are people in China who want to make a fast buck out of inferior materials just as much as there are here, or anywhere. Link to post Share on other sites More sharing options...
atom3624 Posted February 11, 2019 Share Posted February 11, 2019 I can never understand why its considered 'heavy', considering the majority is Zinc and Aluminium - both very light metals - with some Copper thrown in. I suppose it is considerably heavier than most plastics at least. Al. Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted February 12, 2019 RMweb Gold Share Posted February 12, 2019 It's about as heavy as cast iron or steel, which is problematic in models because it picks up magnetism from the motor, and because it rusts; it is also comparatively expensive and difficult to work. Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted February 12, 2019 RMweb Premium Share Posted February 12, 2019 18 hours ago, atom3624 said: I can never understand why its considered 'heavy', considering the majority is Zinc and Aluminium - both very light metals - with some Copper thrown in. I suppose it is considerably heavier than most plastics at least. Al. Zinc is not light! It has a mass of 65 which is more than copper or iron. Lead is more than three times the relative mass, Tungsten which is non toxic is just under 3 times but is somewhat more expensive. I t can be bought in ready made blocks of various sizes, if you are considering using it as ballast. Link to post Share on other sites More sharing options...
RMweb Premium 3rd Rail Exile Posted February 12, 2019 RMweb Premium Share Posted February 12, 2019 1 hour ago, melmerby said: Zinc is not light! It has a mass of 65 which is more than copper or iron. Lead is more than three times the relative mass, Tungsten which is non toxic is just under 3 times but is somewhat more expensive. I t can be bought in ready made blocks of various sizes, if you are considering using it as ballast. Atom for atom I'd agree with you (you've quoted the relative atomic mass of zinc at 65) , but it's the density that matters... Zinc 7.14 g/cm3 Copper 8.96 Iron 7.87 Lead 11.3 Tungsten 19.3 Mazak 3 6.7 (there are actually a variety of grades of Mazak, with densities between 6.4 and 6.8 g/cm3) I guess cost, plus ease of casting and working are the main factors... 1 1 Link to post Share on other sites More sharing options...
atom3624 Posted February 12, 2019 Share Posted February 12, 2019 (edited) QED as I would say - I am a chemist by trade btw .... The RD, as mentioned isn't that light, but it's hardly dense. Comments go for the easily worked, limited toxicity variety, etc ... that rules out Pb obviously. It isn't that reactive either, which would help. Mention within the infamous Wiki states Mazak rot set in through poorer grades of Zn being used. When respected, maintaining at '4 nines' (99.99%) or above if possible, then it's fine. W would be nice, just a little hard and expensive ... but where there's a will, and a decent production set-up, there's a way. Al. Edited February 12, 2019 by atom3624 1 1 Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted February 12, 2019 RMweb Premium Share Posted February 12, 2019 From what I've read, it seems to be unwanted lead that seems to be the undoing of Mazak. Relative atomic mass: Schoolboy error as it's literally 30-40 years since I did anything to do with metals and have forgotten everything. Zinc is still not light though, as your figures show, it being in the same region as iron and copper. I've used zinc sheeting in the past and it is way heavier than aluminium/aluminium alloy sheet. I It was being used as a substitute for lead sheet for roof flashing at one time but lead is back in fashion. Link to post Share on other sites More sharing options...
Gibbo675 Posted February 12, 2019 Share Posted February 12, 2019 5 hours ago, melmerby said: Zinc is not light! It has a mass of 65 which is more than copper or iron. Lead is more than three times the relative mass, Tungsten which is non toxic is just under 3 times but is somewhat more expensive. I t can be bought in ready made blocks of various sizes, if you are considering using it as ballast. Hi Kieth, Tungsten carbide cutting tips used for machine tools make excellent weights for models especially if you are on friendly terms with a machine shop that will let you have their worn tips for free. Similar density to gold but rather cheaper by weight ! Gibbo. 1 Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted February 12, 2019 RMweb Gold Share Posted February 12, 2019 Truth is that mazak is a rubbish material for use as ballast or cast chassis blocks in model railway locomotives, but that everything else is worse in terms of suitability, or cost, or ease of use, or environmental/health and safety issues (lead). So, for any foreseeable future, we're stuck with the stuff and can only be grateful when it doesn't rot! Success depends on a level of quality control which the Chinese production model cannot guarantee to offer, and given the past failures of the British model we have no real right to complain. Some Hornby Dublo models, and not a few Triang ones, were notorious for mazak rot and the issue pervades the British die cast industry. Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted February 12, 2019 RMweb Gold Share Posted February 12, 2019 1 minute ago, Gibbo675 said: Hi Kieth, Tungsten carbide cutting tips used for machine tools make excellent weights for models especially if you are on friendly terms with a machine shop that will let you have their worn tips for free. Similar density to gold but rather cheaper by weight ! Gibbo. But too expensive and difficult to work to use in RTR mass products. But you are definitely on the right track here, Gibster... Link to post Share on other sites More sharing options...
JSpencer Posted February 13, 2019 Share Posted February 13, 2019 Accurascale will be using Tungsten in their Deltic and Class 92 models. So no fear of mazak rot there. My only concerns are: 1/ we will need to wear steel toe protection boots when we play with model trains now 2/ the packaging will need to be really secure to ensure that the loco does not suddenly burst out like the baby Alien in the Alien movies when it gets delivered 1 1 Link to post Share on other sites More sharing options...
RMweb Gold BR Blue Posted February 13, 2019 RMweb Gold Share Posted February 13, 2019 I think one of the motivations for Accurascale's use of Tungsten was to create space for speakers so they would presumably need to use less material as its heavier. 1 1 Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted February 13, 2019 RMweb Gold Share Posted February 13, 2019 The best material is Unobtainium, found in the centre of black holes. 1 3 Link to post Share on other sites More sharing options...
JSpencer Posted February 14, 2019 Share Posted February 14, 2019 On 13/02/2019 at 11:21, BR Blue said: I think one of the motivations for Accurascale's use of Tungsten was to create space for speakers so they would presumably need to use less material as its heavier. Another one seems to have been to give their locos some internal details without reducing weight. 1 Link to post Share on other sites More sharing options...
JSpencer Posted February 14, 2019 Share Posted February 14, 2019 23 hours ago, The Johnster said: The best material is Unobtainium, found in the centre of black holes. At several hundred tons a spoonful, I'm sure material from a white dwarf would easier to obtain and perfectly suffice for model railways. 1 Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted February 14, 2019 RMweb Gold Share Posted February 14, 2019 I agree that compacted star stuff of this sort would serve most model railway needs at a push... It'd certainly put a new light on model railway civil engineering; no more card bridges! 2 Link to post Share on other sites More sharing options...
RMweb Gold tomparryharry Posted February 15, 2019 RMweb Gold Share Posted February 15, 2019 (edited) The problem with Mazak is the copper content. Copper is an ideal constituent to stabilise Zinc. However, copper is more expensive.... So, out goes the copper. I can't remember the exact alloy content (I need to look it up) but we did know that the zinc content breaks down when copper is removed. Zinc Oxide is capable of 'growing' , rather akin to the skin of aluminium oxide when left to the elements. Once it starts to expand, it's got to go somewhere! Back to metallurgy class for me. A good chemist and a rigorous QC will sort that out pretty quick. Have a great weekend, Ian. Edited February 15, 2019 by tomparryharry Keyboard misdemeanour, since corrected. Link to post Share on other sites More sharing options...
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