My 7mm dabblings

mickoo

Western Thunderer
OK, here goes, a journey into the dark abyss that is S7 LOL

First a little history, I used to model 4mm OO ways back but gave up for other hobbies, got back into railways but with age found 4mm a trite small so moved up to 7mm with the purchase of three MMP kits, class 57, 56 and 60. I started the 57 but ran into a few issues, lack of skill/knowledge being one, and a general feeling that it wasn't big enough so moved onto 1:32. Blundered around 1:32 for about a year and started a scratch build a class 40 but came to the stark reality that in 1:32 you almost have to scratch build everything, at least in the projects I was interested in and that had two major downsides, time and interest retention. The class 40 still sits there glowering at me, daring me to continue, which I will one day.

So moving on went to a few shows and looked around and figured that 7mm wasn't so small after all and would probably suit my needs for a layout rather than static models, the added advantage being a large well stocked market of kits and parts which removes a large proportion of the time factor and thus increases the interest retention.

So what do I have? The MMP kits still sit ready for construction as well as two new ones from David Andrews, a Stanier Princess Royal and a Jubilee....fitting nicely into the WT scatter gun ethos! I also have a couple of Roxley 13:1 gearboxes a AGH S7 form tool (cheers Cynric) and a collection of 3/16th ball races.

Aims, simple build one or both to FS with as little compromise as reasonably practicable. I'd like suspension and at least ball races on the drivers, there's probably little gain to be fair but it might have some advantages for smooth running.

The kits, a quick check reveals a few areas I'd like to change, modify, I'm not a fan of laminated springs so need to source some cast ones (Laurie Griffin looks to stock what I need), also noted on the Princess that the motion bracket is also laminated etch so that might have to go as are all the rods and valve gear, I'd certainly like to replace the larger thicker ones with cast ones as a beginning.

The Princess also lacks any inside motion which is very obvious when looking through the frame holes at the front, thus additional cross heads and slide bars will be required as well as other sundry valve gear components and dummy cylinder castings as the front end looks very hollow at the moment.
The largest issue here is going to be the first axle replacement with a cranked variant to drive the cross heads, I think its a standard 90 affair but could be a 180 one....need to close check the drawings. additionally most of the kit spacers in this area will need to be adjusted or removed to allow the valve gear to pass through.
Regarding spacers, two trains of thought, simply etch new ones to the correct form and replace, though many on the Princess are not seen at all so simple L shaped spacers could be used.

Moving the frames out may well present issues with the running boards and splashers, especially at the front end where the frames poke out under the smoke box and the inside cylinder cover is, need to cross check the kit and see how David has modelled that area, some kits have a second set of dummy frames that solder on top of a solid footplate rather than the actual frames poking through as per 1:1 scale and there may be issues with the smoke box saddle as well.

I opted for the main series with combustion chamber firebox so that limits the choice of prototypes a fraction, I was hoping to do 205 (Princess Victoria...my youngest daughters name....as good a reason as any I suppose) but 205 has that hideous Y shaped outside motion bracket and Swindon valve gear linkages. The other loco could be 208 (Princess Helena Victoria) but that was painted in BR Maroon, hmm, still actual loco choice is a ways off yet.

Jubilee, overall and easier project, again opted for a long chassis with combustion chamber which fits it into the later production members and thus will probably carry a naval name as opposed to colonial, the only criteria her is that it will be a Crewe, Liverpool or Manchester shed loco as that's the area I'm aiming to model around 60-61.

Like the Princess Royal, laminated springs and valve gear will have to go and suspension with roller bearings is considered. Other than that I could not foresee any drastic issues except maybe the firebox, I initially thought I had a part missing, spent ages looking for the throat plate front ring white metal casting, not to be, reading the instructions requires soldering a flat face to the front, flooding the internal top corners with solder and then 'filing' the required radius, not much of an issue but in this day and age I'd of expected a white metal casting here as do many other suppliers if images I've seen on web are anything to go by.

Anyway, that's all the waffle out of the way, I know there will be lots more questions, trials and tribulations along the way, but here goes the road to S7.
 

Dog Star

Western Thunderer
If I may be so bold as to offer advice here... we have had several attempts to get a Finney A4 running in S7 and the road has not been easy. The difficulties have not been from lack of competence on our part, more a case of not knowing what compromises have been introduced into the design for whatever reason (I am not sure that the compromises which have caused us so much trouble have been down to catering for 0-FS and S7 standards). All in all we have got through three sets of slidebar etches... five crossheads... two sets of connecting rods and remade the original coupling rods more than twice.

We followed the instructions and got a rolling frame with coupling rods and without connecting rods. When we added the connecting rods the frames made the occasional clicking sound and lurched occasionally. Eventually this behaviour was traced to the connecting rods hitting the bottom of the slidebars. At the same time we noticed that if we minimised the sideplay on the driving crank pin then the connecting rods were not parallel to the frames. If we set the connecting rods parallel to the frames then there was at least 60th clearance between the coupling and connecting rod on the driving crank pin. Time to go and look at a prototype. When we were working on the frame Bittern was at the Mid Hants and access was easy and with permission. So looking at the real thing... you could here the penny dropping from twenty feet.

On the prototype the connecting rod enters the slot between the lower slidebars and the inner edges of those slidebars are relieved to accommodate the connecting rod. On our model the "floating" connecting rod sometimes did what the prototype did and sometimes did not. Back to the workbench... study of the slidebar etches showed that the design of laminations produced a slidebar which was too narrow in overall width and too narrow at the open end (where the prototype has the relieved edges). Sorting that design compromise could be achieved with some work - however the question of why the connecting rods would not lie parallel to the frame plates still existed. Time to go back to the prototype - um, Bittern was now at Southall and access was no longer easy.

At this point Jonpaul (LNERJP) stepped in and provided measurements of the coupling rods and connecting rods of Sir Nigel Gresley (on the NYMR). More penny dropping. The rods as assembled from the etches were much too thin in respect of the thickness midway along the rod and of the thickness over the boss. So the rods needed to be made thicker... and then additional laminations added to each boss. For example:- the connecting rod as provided was two layers of etch whilst three layers was within a nats etc. of scale thickness. The big end of the connecting rod needed laminations on each side to produce a big end of appropriate thickness. Now we could see why the connecting rod had so much sideplay.

Why did we need five crossheads? The re-made connecting rods were 28th thicker at the little end and would not fit into the slot in the crosshead castings. In enlarging the width of the slot in the second set of castings one of the castings broke up... there is so little metal joining the gudgeon pin bracket to the slidebar slipper.

The moral of this story? If you are going to go down the route of S7 with big engines with outside cylinders then establish the clearances of the prototype and decide how the model stacks up against those dimensions. Mind you, nothing that I have written here was a consequence of S7 per se, I think that the problems which we encountered are just as relevant to 0-FS - just those compromises cannot be ignored in S7.

In getting to this point, we do need to acknowledge the continual support and assistance from Paul Penn-Sayers who was most kind in offering the use of the GER workshops to overcome the deficiences of the GWR works (closed since 1985).

regards, Graham
 

mickoo

Western Thunderer
Well step one, a little more research into Jubilees and tenders, I figured I'd start with a tender, so after two hours or more I'd worked out which tenders were plain on the locos I roughly wanted to model, I figured plain welded would be easier than the riveted one, brilliant, sorted all that and with excitement carefully unwrapped the tender etches from their protective tissue, bugga! the sides have half etched rivets, looks very nice indeed and very crisp, as do the rest of the etches but bloody useless for a welded tender.

So hours saved on potentially punching out rivets (hence the initial welded tender choice) and the risk of them not being exactly straight....and a tender side would show that in all its glory, but more hours required to research riveted tenders now LOL.

Graham, I feel your pain, moving the frames to the correct width is going to generate some lengthy head scratching in the valve gear dept that's for sure, hence my bent away from laminated rods to cast or milled, as you say, thickness is everything...or lack of in some cases.

JB cheers, will proceed forthwith in due course.
 

Len Cattley

Western Thunderer
Hi Mick, glad that your doing these models as I have been doing 4mm versions of the Jubilee, there is a lot of veriations of the Jubs so pictures of the era you are modeling is good. Sanspareil from Alan Gibson does parts for Jubilees (takes about 4-6 weeks) and for the Princess Royal Martin Finney does the crank axle for the Duchess's which should fit the Princess Royal class. I really think the frames do need to a bit wider as if they are like the Rebuilt Scot they are to narrow. I hope you are going to show your progress on these builds as I would love to see how you do it.
 

John D

Western Thunderer
Well step one, a little more research into Jubilees and tenders, I figured I'd start with a tender,

Depending on which loco you're doing bear in mind that a lot of the 'long firebox' engines were fitted with the small 3500g Fowler tenders which, to my mind, looks awful with them. I'm building an O F/S LF Crewe based BR Jub, 'Jutland' is my best bet though that was fitted with a Stanier 35oog tender which nobody seems to make a kit of (or perhaps DJH?)....yet;)
 

mickoo

Western Thunderer
Depending on which loco you're doing bear in mind that a lot of the 'long firebox' engines were fitted with the small 3500g Fowler tenders which, to my mind, looks awful with them. I'm building an O F/S LF Crewe based BR Jub, 'Jutland' is my best bet though that was fitted with a Stanier 35oog tender which nobody seems to make a kit of (or perhaps DJH?)....yet;)

John, hang fire I think Jutland was fitted with a 4000gal riveted tender, at work right now but will get back to you, pretty sure I noted that one in my lists of Cheshire/Lancashire 57-63 prototypes to consider.

Concur the Fowler tenders looks rediculous hence my opting for the Stanier kit variant. D Andrews does a 3500gal Fowler tender, not sure if he will consider it as a seperate kit, his etches are seperate for loco and tender, might be worth a call to see if he will consider just the tender etches for sale, I'm sure he does some, but as I say, at work so will reply this evening, and to you too Phil.

Kindest
 

Dikitriki

Flying Squad
Mick, I think you'll find that John was referring to the Stanier 3500 gal tender, not the Fowler one. It looks like a normal Stanier tender, just a bit smaller.

I have a vague recollection that Chowbent made one. I always fancied doing one just to confuse people.

Richard
 

John D

Western Thunderer
Mick , check out the line of rivets on the rear top edge of the body (right at the end) on the Stanier 3500G tenders there's quite an appreciable gap from the edge down to the line of rivets whereas the 4000g ones have the rivets just below it. Having said that there were so many tender swaps 'Jutland' may well have had the larger tender at some stage.
 

mickoo

Western Thunderer
Guys, ah that explains things then, saw 3500gal and assumed Fowler (bad hair day at work!), forgot about the Stanier ones, the information I have shows tender 4645 fitted from Jan/40. I will cross check my photo from 1963 to see if it is a 3500 or 4000 tender shortly, there may be more in my other collections, we shall see.
 

Eastsidepilot

Western Thunderer
Guys,
One of the first things to consider when building a steam loco to S7 is the the hornblocks/guides/bearings and the thickness of the frame material.
The hornblocks when fitted to the frames sometimes protrude through the frame and with a fixed dimension of the back to back this will all add up to determine the frame spacer size.
Every thing else can then follow, crank axle/s, cylinders, cross heads and brake pivots.

Col.
 

mickoo

Western Thunderer
Hi Mick, glad that your doing these models as I have been doing 4mm versions of the Jubilee, there is a lot of veriations of the Jubs so pictures of the era you are modeling is good. Sanspareil from Alan Gibson does parts for Jubilees (takes about 4-6 weeks) and for the Princess Royal Martin Finney does the crank axle for the Duchess's which should fit the Princess Royal class. I really think the frames do need to a bit wider as if they are like the Rebuilt Scot they are to narrow. I hope you are going to show your progress on these builds as I would love to see how you do it.

Len, thanks for the info, I forgot about Finneys Coronation cranks, will have to get one of those in due course.

Regarding photos, well you should know me by now, I like taking photos, so no fear of a lack from these models as i progress.
 

mickoo

Western Thunderer
Guys,
One of the first things to consider when building a steam loco to S7 is the the hornblocks/guides/bearings and the thickness of the frame material.
The hornblocks when fitted to the frames sometimes protrude through the frame and with a fixed dimension of the back to back this will all add up to determine the frame spacer size.
Every thing else can then follow, crank axle/s, cylinders, cross heads and brake pivots.

Col.
Thanks, it's the working out of which bit to do first that's the tricky bit LOL, sounds like bearings/ hornblocks or suspension system first and then work out your frame space width to suit the S7 wheels B2B.
 

Scale7JB

Western Thunderer
The Sudbury group is probably the most active S7 group in the country, so plenty of help on hand.

It's the Sudbury (east anglia group) Christmas party this Sunday if you're free Mick.

JB.
 

mickoo

Western Thunderer
The Sudbury group is probably the most active S7 group in the country, so plenty of help on hand.

It's the Sudbury (east anglia group) Christmas party this Sunday if you're free Mick.

JB.
JB, thanks, I've seen West Mersea mentioned here are they one and the same? I am free on Sunday, I hope, wife in for an op today but should be a day case so hopefully free, does one need to be a member? If so, how and where, and may I bring my camera?
 

Scale7JB

Western Thunderer
One and the same indeed..!

No need to be a member, though I'm sure Peter Hunt, our leader will try to convince you to sign up to the monthly newsletter, by all means bring a camera!

Probably best if you call Peter (also Perfect Miniatures) first just to make sure it's okay but I don't see any problem..

01787 375884

I'd probably leave about 30mins for the call though, Peter likes a chat... :D

JB.
 

BrushType4

Western Thunderer
Sudbury? Is there a significance to Sudbury, it's local to me I know but no Princesses or Jubilees there that I know of?

Mick, if you are going down the S7 route, you should be involved in the WM at Sudbury. Big S7 group as JB has said and more importantly, you'll be able to run your S7 locos on a decent length of track.

The price for that will be the occasional Sunday spent track building and natting about trains, beeching, politics, food, etc
 
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