4mm An EM Workbench: plastic steels

[AJC]

I've been in a soldering sort of a mood this week and so I've started working through something tiny but complex in the form of Southwark Bridge Models' GWR P7 hopper. Lots of really very small parts and a perhaps unnecessarily complicated mode of construction (compared to one of @jjnewitt's designs say), but all the bits fit so that's something. The really fun bit, the brakegear, is next...



Nice shot of the real thing at Evercreech Junction (the excuse for building one of these) here: GWR and Constituents | CH04986 - 'Herring' 20-ton ballast hopper No. W60274 at Evercreech Junction 24/10/59

I'll have to get one of Justin's Herring for comparative purposes.

Adam

 

[AJC]

P7 progress - I've made some decent strides over the last few days (following the boy's first birthday on Friday) and the hopper is assembled. This was relatively pain free and, I think, well-thought out using a disposable jig and a bending guide supplied on the fret. The two flanges fitted perfectly though the lower one required a little easing of the slots and tabs, just enough to take the cusp back a little. The rivet strips were a bit of a trial but the end result is about as tidy as the real thing which - without wishing to be unkind to Swindon - was a bit of a bodge and by the time I am looking at, somewhat tired. Yes, there is solder everywhere, but this is a wagon for which the usual financial point of comparison could be made...



Note that the hopper is not fixed yet and that there are lots more rivet strips to add before I contemplate the rest of the brakegear (which, as @Dog Star will tell you, is not for the faint of heart in 7mm, never mind the smaller scale).

All best,

Adam

 

[Dog Star]

P7 progress - I've made some decent progress over the last few days...

I do hope that this is not a race... there are some models here, yet to be finished, which were started more than forty years back.

... the hopper is assembled.... The two flanges fitted perfectly though the lower one required a little easing of the slots and tabs, just enough to take the cusp back a little.

The same with the 7mm model, the dry run showed that the lower flange around the upper side panels was held away from the panel because the tabs did not go home fully. We reduced the length of each tab until the flange sat tight against the body side.

The "T" section flange is a made from (1) an upper rivet strip, (2) a flange strip which is tabbed into the body and (3) a lower rivet strip. Each of those parts is supplied in two sections with joins on the end of the body (no option with the flange because of the tabs on the ends) - could the rivet strips be fixed to the body side with their joints staggered relative to the joins in the flange strip? Please post a photo of the end of your model.

Most of the prototype photos that I have found so far show just two panel joins in the upper sides. I have seen one prototype wagon with the central join and that is in the 607xx series so choosing a running number may require care, have you a number for your model? We have chosen 60005 and 60027 for our first two P7s.

Note that the hopper is not fixed yet... and that there are lots more rivet strips to add before I contemplate the rest of the brakegear (which, as @Dog Star will tell you, is not for the faint of heart).

Your warning is appreciated!

Can the wagon be made as two parts so as to ease painting and lettering (many of the hoppers are written on the sloping side of the hopper)? I think that I can sort the tie-bar rods which run from solebar to solebar and pass through the botton of the hopper.... the operating levers can have removable pins for the bottom joints... what I have yet to resolve is how to incorporate a secure fixing of the hopper to the underframe after painting.

regards, Graham

{ps - as your model is for Evercreech, and the YMRG layout (Evercreech New) is 7mm scale, how are you going to upscale your efforts?}

 

[AJC]

Hi Graham,

What you see is what there is rivet-wise. The ends are the next job and I expect that I shall have to ease the slots there, too. When I've done that, I'll take a few pictures. The one thing I will say about this kit is that it lends itself to my current capacity to model: a few iterative details little and often work well around work and childcare. I think the approach you suggest might well work but we'll have to see. I guess that post-painting assembly is also possible, but I have a couple of concerns (and would not try it in the smaller scale).

1. The best place to add the join is at the bottom of the various supports (at least, if the interior is to be visible, if not, you obviously have more options). How big would the surface area for fixing be? What would you use? Epoxy perhaps?
2. Attaching vac' pipes and the various bits of hopper door gear might well be more of a fiddle than lining up letters...

No plans to do a 7mm one, the scale just doesn't float my particular boat (and yes, I've tried the odd wagon). Add that to the fact that I'm not back in Somerset at all often and, the way things are, it may be that the next time I'm down there will be a full year, near enough, after I was last there (which is utterly depressing, to be honest), so there's relatively little connection with the progress on Evercreech New, though I gather that it's going well.

Mine will be W60274 per the photo at Evercreech. There are pictures of rakes of Herring all round the area, including on the Lyme Regis branch so at some point, by various means, I hope to replicate this on my fictional Ilchester branch. My earlier Herring model supplements my late-'60s ballast rake so won't be appropriate here, but this one with a small shoal of Herring and something like an O2 or M7 at the head of the rake should look well, I think.

Adam

 

[AJC]

Ok, the next instalment finds the hopper all but complete ready for the supports to be added. This has entailed much tacking and sweating and capillary action, but the result is not at all bad considering the fiddle factor involved.



For Graham's benefit, here's the neater of the two ends.



You can see that there is a blob of solder at the base of the T section which I need to attend to and on the top L section I have failed to make the ends meet and again, this is something I must sort out. I would note, however, that the rivets are etched in such a way that there are gaps in the run where the corners fall and thus all the joins for rib and rivet strips must be in the same place so staggering as @Dog Star suggested isn't really viable. The next job concerns the internal hopper bracing and then, I suppose it's another round of struts...

Adam

 

[iak63]

Fiddly bugger this one Adam?
How are the fingers?
Kit design has definitely evolved for the better...

 

[AJC]

Fiddly bugger this one Adam?
How are the fingers?
Kit design has definitely evolved for the better...

One burnt thumb so not too bad. There may be better ways of doing the hopper, but with riveted construction of the real thing and the tricky angles I'm not sure that there are many. It works, the detail goes on nicely, you don't have to emboss any rivets and it's square without stress.

The chassis is a bit of a mess and leaves too much to chance though that said I managed to put it together right first time. There are a lot of tiny bits. The brake push rods, shoes and especially hangers are not really fit for purpose in 4mm. Half etched brake hangers with no backs to them are not really on. Ivan isn't available for comment following his untimely death and to be fair to him, the brake variations on this are many, varied, and made even worse than the usual Swindon norm by the retro-fitting of vacuum cylinders but that shouldn't have made it past the test etch. As already noted, I'll have to get one of Justin's Herring for comparative purposes. His approach to the hopper is a bit different, having seen the instructions, but the chassis is to his normal method and I know that works and works well.

Adam

 

[Dog Star]

This has entailed much tacking and sweating and capillary action, but the result is not at all bad considering the fiddle factor involved.

For Graham's benefit, here's the neater of the two ends. You can see that there is a blob of solder at the base of the T section which I need to attend to and on the top L section I have failed to make the ends meet and again, this is something I must sort out. I would note, however, that the rivets are etched in such a way that there are gaps in the run where the corners fall and thus all the joins for rib and rivet strips must be in the same place so staggering as @Dog Star suggested isn't really viable.

Good work to achieve those overlays for the 4mm model. Your photos expand on the drawings in the instructions and I shall refer to them when we start the overlays of our model. The rivet strip overlays are in numbered plastic bags at this time so your comment about gaps in the rivet spacing is timely, thank you.

 

[adrian]

One burnt thumb so not too bad. There may be better ways of doing the hopper, but with riveted construction of the real thing and the tricky angles I'm not sure that there are many. It works, the detail goes on nicely, you don't have to emboss any rivets and it's square without stress.

That's coming along nicely - a little burnishing and I think it'll look great. I've mentioned it before but I highly recommend Alligator Tape as it does provide a level of insulation for your fingers.
Alligator Skin Finger Protection Tape, 90ft Roll

 

[AJC]

That's coming along nicely - a little burnishing and I think it'll look great. I've mentioned it before but I highly recommend Alligator Tape as it does provide a level of insulation for your fingers.
Alligator Skin Finger Protection Tape, 90ft Roll

A good tip - the burnt thumb wasn’t holding the model at the time though!

I’ve got some brackets still to add before I do some serious cleaning up, and they’re really small.

Adam

 

[Mike Garwood]

Nice work. Where or what is this destined for?

Mike

 

[AJC]

Nice work. Where or what is this destined for?

Mike

Thanks Mike - at this point it’s mostly just for the challenge. In time it’ll form part of a short ballast train for my developing Somerset branch line (link in the signature). I already have a late ‘60s ballast rake of Dogfish and Catfish (the latter borrowed from the LMR) so this will be the earlier equivalent. The wagon modelled was in traffic in ‘59 and there’s evidence that some others survived to ‘63.

Adam

 

[AJC]

Coming on, I think it's mostly the brakegear from hereon. I think I understand how that goes together (though I haven't a clue how the safety loops are supposed to be fitted as yet). Anyway, underneath: the brake cross shaft isn't necessarily mean to go like that, but there are a couple of extra 'V' hangers that are present on the real thing and not on the etches or instructions so I guess that Ivan simply missed those. These must be anchored to the hopper sides above the door. I'll trim the shaft back to these once I've restored the alignment. The rather fragile nature of the half-etched ribs on the bottom are evident. This is a problem elsewhere on the model as we'll see...



... here, in fact.



Note the slightly wavy edge of the top of the solebar, I'll have to straighten that out before painting, along with the left hand spring stop. Despite the amount of solder sloshing around - poor technique, I know - I should add that all the bits went together accurately and as intended, once I'd ground away some of the ribs around where the wheels go: if you will model something like this in EM you're going to have to live with that. The same may well be true in O 'finescale', of course.

Adam

 

[Dog Star]

Thank you Adam for yet another insight into the complexity of the construction process - I had not spotted that there might be missing supports for the brake gear shaft(s) although given that I am heading for a meeting with the vacuum-fitted DC3 brake arrangement then I may be faced with variants of what you have encountered.

Progress here is not at the same pace as you are achieving - I am pondering on the best way to fix the T-flange around the hopper extension so as keep a horizontal line.

regards, Graham

 

[AJC]

Progress here is not at the same pace as you are achieving - I am pondering on the best way to fix the T-flange around the hopper extension so as keep a horizontal line.

Hi Graham - I would just tack it in place from behind and then run some solder along the outside joint (small lengths of solder, plenty of flux) and the tightness of fit should do the rest. You can always tweak the thing with pliers.

There are quite a few detail variations on these - I've just noticed that the axlebox keeps are different on my prototype for example. Similarly the axleguards were either reinforced later or again, Ivan missed the detail. That's no problem as I have some spares from some Rumney Models kits that I can adapt. The big challenge will be in getting some weight into the thing...

Adam

 

[Dog Star]

The big challenge will be in getting some weight into the thing...

Just need some ballast .

 

[AJC]

Just need some ballast .

Where's the fun in that?

Adam

 

[Dog Star]

... once I'd ground away some of the ribs around where the wheels go: if you will model something like this in EM you're going to have to live with that.

Adam, @AJC , you may be able to advise on the above aspect of the instructions.

I have been progressing the wheels and suspension... and thinking through the three relevant sections of the instructions.

1/ packing the (Slaters) bearings from the suspension bearing carrier using the supplied full and half thickness washers (section 21);
2/ fitting the suspension carriers with spring wire (section 120);
3/ modifying end stanchions to clear wheel flanges (section 122).

I have used two full and one half thickness washers between each bearing and bearing carrier, so five full thicknesses per axle - is there any advantage in using (say) one full and one half thickness at one end of the axle with three full and one half thickness at the other end of that axle so as to shift our S7 wheels (and S7 flanges) to an off-centre position?

The instructions for the 4mm kit suggest 10 or 12 thou guitar wire for the wheel suspension - how does this compare to what you have used? (that is, is the suggestion realistic?).

Section 122 refers to end stanchions... without giving associated part numbers - I think that section 122 could be referring to the "headstock to hopper T-bars" (section 105). What is your take on this subject?

regards, Graham

 

[AJC]

Hi Graham,

I can't really answer the question about springing because, heathen that I am, I soldered the spring carriers in to produce a rigid wagon. I often do this because there's limited merit in springing a wagon with a wheelbase this short in EM and much associated hassle which I don't enjoy. In this case the clearances in so many areas are so tight, I wanted to reduce some of the variables that might get in the way of the thing running.* That said, 10 or 12 thou' sounds plausible, I think - it depends how much weight you add. The benefit of the system designed in - the spring carriers are similar to those Bill Bedford offers with his sprung W irons so you can change the gauge of the wire if you feel what you've fitted is not up to it.

Wheel spacing - an area where a bit of experimentation is probably needed. How many washers are needed to eliminate side play? You might find it easier to remove the axle keeps (do check if they're the right pattern - they're not for my later-era model) while you check that. I didn't find any washers were needed on my smaller version.

By 'end stanchions' in this context, I'm pretty certain that he means the T section reinforcement - I'm not sure whether this was an original fitting or something added when the sides were extended upwards. You may find, as I did, that the ends directly under the axle need the stem of the T ground away to allow free rotation of the axles. I'd be inclined to do that before fitting as a precaution: it's invisible and much easier to do at that point.

We're due an update on mine - I'm at the point where the last outstanding jobs are the vac' pipes and explaining why I've left most of the linkages off. Not easy on this one because they're quite visible...

Hope that helps?

Adam

* In 4mm, the tail of the spring is also expected to sit and survive in service in a rib supporting the hopper made from half etched brass sheet about 5 thou' thick. That's not tenable.

 

[AJC]

So here we are, almost all hot operations complete barring the upright vac' pipes which I think I'll have to make up from scratch. They're not a complicated shape but modifying a whitemetal one is likely to result in meltdown. Note the 'modern' pattern of kickstep, replacing the rather pretty, but I imagine a bit delicate, steps on a bit of rod Victorian version. The safety loops ended up mounted as I imagine the real thing was, attached to the hopper tierods: I'm sure Swindon did something more sophisticated than a blob of solder. Oh, and I've added journal reinforcements, tweaked from some Rumney Models spares.





So, vac' pipes, a variety of plates, a bit of filler, buffers, couplings, primer and transfer rivets and we're good to go. Hopefully the next etched thing I do will be a bit simpler.

Adam