S7 help please...!

Steph Dale

Western Thunderer
Don't panic guys, this works out to be a fairly specific request...:

I'm just looking at drawing up sets of patterns for details of SECR/SR moguls (and derivatives!).  I'm wondering whether it's worth considering the application of the parts (including brake gear sets and the pont truck) to S7 and so I'm wondering if there's a set of the wheel standards/dimensions available on line anywhere for me to look at and consider the implications.

Cheers,

Steph
 
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Simon Dunkley

Guest
Steph Dale said:
I'm just looking at drawing up sets of patterns for details of SECR/SR moguls (and derivatives!).  I'm wondering whether it's worth considering the application of the parts (including brake gear sets and the pont truck) to S7 and so I'm wondering if there's a set of the wheel standards/dimensions available on line anywhere for me to look at and consider the implications.
Not surprisingly, the Scale7 group has a website, and their standards are on this page.
 

28ten

Guv'nor
Steph, I suspect that you will find it hard to combine the two as its the difference between dead scale and erm not so scale  :) which is quite a lot in the chassis department
 

Steph Dale

Western Thunderer
Cynric,

You might be surprised; believe it or not I've been designing production tooling for over 20 years.  And these aren't exactly the first set of patterns I've designed or made in this scale!  :)

Thanks for the thought though.  Right, out with the calculator to see what will work.  Maths will out in the end  :headbang:

Simon,

Thanks for the links; that answers all sorts of questions, including the applicability of the standard...

Cheers each,

Steph
 

Dog Star

Western Thunderer
When one takes a 7mm kit which was designed for FS and then start to build the frame for S7....  one encounters all sorts of interesting problems and the biggest are often where a casting goes from one frame plate to the other frameplate.  As an example, and this ties in with your initial post, consider the brake hanger brackets and the break cross-shaft.

In some kits the break cross-shaft is often suspended from two trunnion brackets which are soldered to brackets cantilevered from the frame plates.  If the frame plates are placed at scale dimensions then those brackets are going to be in the wrong place, probably too far apart to support the cross-shaft.  Further, if the cross-shaft is a casting which includes levers for break pull-rods then often the levers are placed for pull-rods set to clear FS wheels.  So setting pull rods in relation to S7 wheels means that often changes are needed to the separation of the levers.  We have a Scorpio pannier tank kit which exhibits both of these issues....  resolved by [a] making a new shaft to (scale) prototype dimensions and suspending the shaft in accordance with how the job was done on the prototype.

The same kit has the break hanger brackets attached to the frame plates and place the hangers in line with FS wheels....  so setting the frame plates at a scale distance apart means that the hanger brackets (or the plates to which those brackets are affixed) need change for S7.

If you are thinking of making patterns for items which can be used for FS and for S7 then you may need to think about either producing FS- and S7- specific patterns or splitting the prototype item into non-prototype parts so that the castings can be assembled to the required dimensions. In the case of the cross-shaft above, separate castings for the two pull-rod levers, the handbrake lever and the steam brake lever (to be mounted on a rod of appropriate diameters) would address the FS / S7 difference.

regards, Graham Beare
 
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Simon Dunkley

Guest
Steph Dale said:
Thanks for the links; that answers all sorts of questions, including the applicability of the standard...
No problem, Steph, as I have a bookmark for the site and it was just a handful of mouse clicks to copy and paste it, but from your perspective a quick Google would have found the site very quickly, (put Scale 7 standards in as your search criteria and the group home page is the first site listed) and involved you with less typing.

However, that would have then denied the larger discussion which is opening up, which I find interesting. In the early years of the decade, I did consider adopting Scale 7 as my modelling scale, even getting as far a building a few wagon kits and scrtachbuilding the basic body of a dumb-buffered PO wagon. Whilst I was a member, I volunteered to act as a clearing house for putting together a list of kits that could be converted to S7 with reasonable facility, and those which required a lot more work. All I wanted was some feedback saying which ranges were more accommodating than others. The response was a deafening silence. It was not intended to be a definitive list, just a brief guide.

Having seen Graham's really useful comments here on brake hangers, I realise my idea was rather naive: I had assumed that all that was basically required was new frame spacers and relocation of splashers. Obviously there is more to it than that, so I am grateful that you did ask, believe me.

You may ask why I did not stick with S7? Well, the answer is threefold.
Firstly, I cam across a certain other Simon with models built to a certain other (larger) scale;
Secondly, I don't bother with things like scale rulers when working in S and One32, and can calculate measurements quickly using mental arithmetic, so I found 7mm scale somewhat difficult - fitting 12 inches into 7mm is not easy, well not for me when I am accustomed to building models in an imperial scale;
Thirdly, and I think this was a real downer for me when I started, one of the attractions was the idea that some models could be built quickly and get me started, things like common wagons especially. Unfortunately, I found some of the much vaunted "easy" kits to be poor: solebars with detail off centre, floors that didn't fit, corners that wouldn't meet easily, no interior detail, and so on. The upshot was that I spent almost as much time adding missing details, filing, filling and making corrections as if I had built from scratch, which rather defeated the one thing I thought 7mm scale had to offer me above S and One32: the ability to get cracking sooner rather than later, and I lost momentum. I should add that my interests in terms of prototype and period were rather specific, and that I am aware that there are many ranges which do not have the problems I encountered.

In a way this is a shame, as 0 gauge models are of a really nice size: a small tank loco feels just right in the hand. They roll well (or should do - this does not seem to be the case on some 0 gauge layouts at exhibitions) and have a good presence without requiring the enormous amounts of space demanded by One32 layouts. I did consider working in 1:48 scale, i.e. Proto:48, using some bits and bobs from the US, but for a British prototype I would have been ploughing a very lone furrow, and not been able to run on other people's layouts.

I suppose ultimately, for me, 7mm was a compromise between S and One32, and for some would therefore be the ideal scale to use. But I don't like compromise: in the end, you get the worst of both options. (I also don't like win-win. Sometimes that is possible, but on times when it isn't, then either win the whole way, or lose the whole way, and learn to live with it!)

I'm rambling again, aren't I?
 

adrian

Flying Squad
Simon Dunkley said:
Having seen Graham's really useful comments here on brake hangers, I realise my idea was rather naive: I had assumed that all that was basically required was new frame spacers and relocation of splashers. Obviously there is more to it than that, so I am grateful that you did ask, believe me.
I think it depends on the kit to be honest. The Connoisseur Jinty I've recently finished to S7 only needed a couple of mods mainly wider frame spacers but I also had to skim down the thickness of the sandboxes. With the narrower wheels and tolerance there was less room between the frame and the back of the coupling rod, enough for the coupling rods to foul on the sandboxes as supplied.

I'm sporadically building a MOK Std4 - the S7 version. Even with this kit I've just found one omission. The front pony truck has been widened, including all the castings to make it to S7 widths, the difference is quite significant. Unfortunately when I soldered on the front guard irons these over hung the gauge by a small but noticable margin. Presumably spot on for finescale but on S7 needed a little tweaking.

Adrian
 
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Simon Dunkley

Guest
Hi Adrian,

Interesting feedback - exactly the sort of thing I was looking for before, but no one came back to me. The idea was not be definitive in anyway, but provide a list of kits which had been built to S7 standards with the comments from the builders, to give interested parties an idea of what might be involved.

But it's more fun (and possibly less futile) to try to persuade Neil of the benefits of DCC.
 

adrian

Flying Squad
Simon Dunkley said:
Interesting feedback - exactly the sort of thing I was looking for before, but no one came back to me. The idea was not be definitive in anyway, but provide a list of kits which had been built to S7 standards with the comments from the builders, to give interested parties an idea of what might be involved.
It would have been useful and I dare say we lost a few potential S7 recruits from the lack of one. The Connoisseur Jinty was quite easy to convert, I've listed the few modifications required on my website www.cherryclan.com/locos/jinty/s7mods.html. I've just bought a JLTRT 3F and a quick look in the box wasn't encouraging. The chassis is a one piece etching to be folded up into a U shape, so it's going to be a bit more of an effort to convert to S7.
Simon Dunkley said:
But it's more fun (and possibly less futile) to try to persuade Neil of the benefits of DCC.
You could always buy him a years subscription to MERG!! The latest journal has dropped through the letterbox today and there is mention of using DCC over radio control.
Adrian
 
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Simon Dunkley

Guest
adrian said:
You could always buy him a years subscription to MERG!! The latest journal has dropped through the letterbox today and there is mention of using DCC over radio control.
An interesting and cruel suggestion!

re radio control, it's not exactly a new idea, but it has its limitations. I have discussed this elsewhere, which I refer to not out of vanity but laziness: there are a few links in there and I can't be bothered to copy and paste them all.
In browsing the web, I have since discovered none of my suggestions are new: other people have been putting forward the same thoughts for a few years now.

I would say that this is more possible in larger scales as there is more room to accomodate equipment and batteries, but really with high-efficieny motors and gearboxes, it should be possible in 4mm and below, without resorting to permanently coupled rolling stock. (That's my vague attempt to get this back to the OT.)
 

Steph Dale

Western Thunderer
Guys,

This has indeed turned out to be a very interesting discussion.  And I say that as someone who's trying to ignore Scale7; as some of you know I'm involved with a large F/S project with a number of other guys.  There is no way that I'll be going S7 in this context, but it would seem silly to me to ignore the finer approach, if I can easily produce a set of patterns that can be used to either standard.

I'm not doing this professionally (well not any more anyway!); it's just a way of getting the parts I'm interested in 'out there' in the belief that if I want them and put the research in then other people will be interested too.  And if I'm lucky I get free castings...!

There are a number of issues that have been raised here which I will happily take away and consider when I start working out my cutting lists.

Cheers,

Steph

Steph
 

Scale7JB

Western Thunderer
Interesting thread, though I'm not sure i have too much to add just yet...

Got a great picture of the K2 in the S7 society mag though...!

JB.
 

7mmMick

Western Thunderer
I agree i'm keeping a close eye on this one and the picture does look the buisness :bowdown: :bowdown:

Best regards Mick  :wave:
 
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