Re: The birthday finally came around

[Pugsley]

The birthday finally came around

Thanks for revealing the, er, shall we say, issues, with the Presflo and other JLTRT wagon kits, I guess they don't ride very well?  ;D

I must admit, I'm a little bemused by the choice of whitemetal W irons for their kits, it seems like a backward step to me, and I was surprised when I discovered the their TTA chassis, again, exquisitely cast and detailed, was made out of resin.

 

[Pugsley]

The birthday finally came around

Also, so few of the original masters that many manufacturers use these days are in metal - they can't make 'em anymore!.

I thought that part of the idea of casting from masters was so that the master could be made from a material that is more easily worked than metal.  As long as it is made to high standard, to me it doesn't matter what a master is made of, are there any specific advantages to using metal?

 

[Steph Dale]

The birthday finally came around

Pugsley,

It's a question of process as to what the mould is made of - you can't use anything other than room-temperature vulcanising (RTV) rubbers if the patterns aren't metal because a hot-vulcanising process takes the rubber and patterns up to about 150degreesC (IIRC - it's been a while).  RTV rubber is not as resilient as hot-vulcanising so the moulds don't last as long - in essence (to go back to what David was saying) it's a 'rapid prototyping' technology, not really suitable for production...

I'm interested in the views relating to JLTRT; I've had a few bits from them which led to them rapidly being considered NQLTRT (Not Quite Like....).  I'd still like to build one of Malcolm Mitchell's kits though.  In my case it's an interest based upon the reputation of the kits, rather than the overwhelming desire to own (yawn) a (yawn) Great Western (yawn) 4-6-0 (zzzzz)... <Cynric, can I have a 'tongue firmly in cheek' smiley for when I'm being silly, please?>  ;D  The 43xx kit and a variety of their GWR tenders (the ones not covered by Martin Finney, for a start) would be suitable for the current project, even though Southern stuff will tend to get higher up the build order.

In any case I have no doubt that if JLTRT were to announce a model of the Southern diesel electric trio, then I would pretty rapidly change my view, probably three times over!

Steph

 

[Pugsley]

The birthday finally came around

It's a question of process as to what the mould is made of - you can't use anything other than room-temperature vulcanising (RTV) rubbers if the patterns aren't metal because a hot-vulcanising process takes the rubber and patterns up to about 150degreesC (IIRC - it's been a while).  RTV rubber is not as resilient as hot-vulcanising so the moulds don't last as long - in essence (to go back to what David was saying) it's a 'rapid prototyping' technology, not really suitable for production...

Thanks Steph, that clears that one up  8)

I'm interested in the views relating to JLTRT; I've had a few bits from them which led to them rapidly being considered NQLTRT (Not Quite Like....).

The diesel locos are pretty good IMO, but I'm not impressed with the bogies that come as standard.  I wouldn't expect all singing all dancing bogies, but etched brass has to be a far better medium than resin!

 

[djparkins]

The birthday finally came around

I thought that part of the idea of casting from masters was so that the master could be made from a material that is more easily worked than metal.  As long as it is made to high standard, to me it doesn't matter what a master is made of, are there any specific advantages to using metal?

Well I can only speak for two companies - ourselves and ABS Models [as they used to do work for me and I've known Adrian Swain since 1971].  Our masters are all machined/milled in metal and pinned as well where required so that they can stand repeated vulcanising straight to black rubber production moulds at very high temperatures and 20 tons of pressure. 

There is no RTV stage and so the production 'impression' is first-generation every time.  This gets the crispest casting possible - and with a much more reliable shrinkage rate - making that calculation when making the original pattern all the easier.  The other thing that I don't imagine a lot of mfrs. do is to cast up samples [possibly not from a final production mould] before the etched design work is done so that the interface between the etched & cast parts is not guessed at in relation to the casting shrinkage but is known at the point of design.

You can see some of the patterns for our upcoming Sprinter & Class 92 kits in the Birth of a Kit section on the Building O Gauge Online Web Site.  They are bright at this stage but are black after the first vulcanising due to the graphite powder used.

Of course I realise that the way we do things here is wrong and that all others do things the correct way!

David Parkins,
Modern Motive Power

 

[Dikitriki]

The birthday finally came around

The diesel locos are pretty good IMO, but I'm not impressed with the bogies that come as standard.  I wouldn't expect all singing all dancing bogies, but etched brass has to be a far better medium than resin!

Hi Pugsley

Attached 3 pics from the good old days when JLTRT did proper diesel kits ;D

Richard

 

[D1054]

The birthday finally came around

Very nice Richard Looks like it has come together very well....  it this a current project or a blast from the past???

 

[Pugsley]

The birthday finally came around

Of course I realise that the way we do things here is wrong and that all others do things the correct way!

Thanks David, that's very interesting, and it sounds like the better way of doing things to me!

Richard, thanks for the pictures, I had no idea the JLTRT kits originally came with brass bogies, it's a shame that they didn't persist with those.  That's a lovely looking loco  8)

 

[iploffy]

The birthday finally came around

I was told it was only the peaks and 40's that came with brass bogies

Ian

 

[Phill Dyson]

The birthday finally came around

Wouldn't the Hymek have brass bogies too, as it was the first JLTRT diesel ?  :scratch:

 

[iploffy]

The birthday finally came around

Dont know about that as I was just repeating what was said to me, Iwas told that the bogies under the 1co-co1 configurations changed  shortly after the kit was produced and not many were made.

Ian

 

[Jordan]

The birthday finally came around

Funny thing with those 'Peak' pictures is just how "right" the un-painted model looks with brass bogies... if that makes any sense...

 

[Dikitriki]

The birthday finally came around

Very nice Richard Looks like it has come together very well....  it this a current project or a blast from the past???

Thanks. It's sort of a current project (current being loosely defined as 'commenced within the last 5 years' ;D)

I grabbed it off the layout to take the photograph this morning. It was scheduled to be finished a couple of years ago, but I got involved in working on my layout and it has taken a back seat. It's about 6th on the list after 4 steam locos and 10001, all of which are pretty advanced. It came to a halt because I didn't (still don't) know enough about Peaks to do the final detailing, and the instructions are not good enough to identify, let alone locate, some of the detailing components.

Richard