A Tale of Two Serpents

[RichardG]

Welcome along Dave @daifly!

We have written lots about the floor but not much about the headstocks. The headstocks supplied do have holes for two buffers and one coupling, but their height doesn't match up with the GA. I am going to leave mine unfolded until I can see how to build the ends of the model.

And to save you five minutes of looking, part 1 in the instructions is labelled part 13 on the etch. It's the guide for the brake handle.

 

[magmouse]

Looking at the G/A there seems to be a reference to a further brake gear drawing for a vac fitted version. Are you Nick sticking with the unfitted version?

The annotation you refer to is in a different hand to most of the writing on the drawing, and refers to drawing 34028, so much later than this one (drawing 8209 of 1889). The NRM list shows drawing 34028 dated September 1907, and titled Either side brakes: goods carriage trucks - "serpent". The annotation on 8209 was presumably made at that time or later. Given this build is turning out to be way more involved than I had anticipated, I'm sticking with the unfitted version!

Nick.

 

[magmouse]

The headstocks supplied do have holes for two buffers and one coupling, but their height doesn't match up with the GA. I am going to leave mine unfolded until I can see how to build the ends of the model.

I think the headstocks are the right height, on the basis that only one of the etched lines is a fold line - see the drawing in the instructions. The GA gives the dimensions of the headstock as 3 1/2" x 12" x 1/2" (annotated at the left hand end of the plan view) - so 12" high, 3.5" wide, and 0.5" thick. Folded as per the kit instructions, the part comes out correctly as 7mm high.

What is then missing is the top flange. I intend to make this with some L-section brass soldered to the inside face of the kit part, though you could make it from something solid as the inside face of it will be hidden by the ramps and the floor boards. Or - if you are using the floor as provided, you can build the kit as intended, and the floor piece will meet the top of the headstock, so no need to represent the top flange separately.

I hope that all makes sense - these things would be much easier to explain with the kit parts and drawing in front of us, together with some arm waving!

Nick.

 

[RichardG]

Folded as per the kit instructions, the part comes out correctly as 7mm high.

Yes I agree.

But surely, the coupling hook and the buffer stocks are to be placed along the horizontal centre line of the front of the headstock? Unfortunately, all three holes provided end up too low after making the fold.

We have an unwanted fold line to fill, and the top flange is missing too. So I am verging on cutting out new headstocks. Otherwse the parts will end up like a patchwork quilt of alterations. Or, reduce the top and bottom of the headstock to leave the holes on the horizontal centre line, and add new flanges top and bottom.

 

[magmouse]

But surely, the coupling hooks and the buffer stocks are to be placed along the horizontal centre line of the front of the headstock? So all three holes provided are too low.

No - because the holes are centred a scale 4.5 inches up from the bottom edge, which is correct. The solebars are 9 inches deep, and the headstocks 12", with the extra 3" projecting above the top of the sole bars, so it makes sense the buffers and couplings are centred on the bottom 9" of the headstock. Does that make sense?

 

[Dog Star]

Nick,

Can you wave with longer arms?

 

[magmouse]

No - because the holes are centred a scale 4.5 inches up from the bottom edge, which is correct. The solebars are 9 inches deep, and the headstocks 12", with the extra 3" projecting above the top of the sole bars, so it makes sense the buffers and couplings are centred on the bottom 9" of the headstock. Does that make sense?

Okay, scratch that - Richard has directed me to actually look at the GA. I was assuming (!) the solebars were at the usual height above rail. The wagon designers have snuck themselves an extra inch and a half of height for the load by having the solebars lower than usual, so the buffers and couplings sit centred in the 12" headstock. We'll need to work out the consequences of this for the axle guards, etc...

Further study of the drawing required. Please hold the line, caller...

Nick

PS Another project that I thought would be a simple build with a few minor variations from the kit as intended....

 

[simond]

I'll hold that side order of springs...

 

[magmouse]

I'll hold that side order of springs...

Thanks! I’m about to do a comparison of the Serpent drawing with a drawing of a 4-plank from the same year, to see where the difference in height is accommodated…

 

[Tony Overton]

PS Another project that I thought would be a simple build with a few minor variations from the kit as intended....

Been there, done that, and recently too............

 

[magmouse]

Comparing the drawing for our increasingly poisonous-looking Serpent (8209W) with drawing 7925W of the same year, showing a 4-plank open goods wagon, we see that the solebars of the Serpent are a full 3" lower than that of the open. 1.5" of this is accommodated by having the buffers and couplings raised, centred on the 12" headstock. The other 1.5" is ... simply ignored. The buffer height of the Serpent is stated as 3'4", instead of the more typical 3'5 1/2" of the open wagon.

To make all this work, the axle guards of course have to be different, with a smaller distance from axle centre to top of solebar by 3" - the Serpent has 3'1" wheels, the same as the open. Possibly by design, an axle guard intended for 3'7" wheels is just right, so that's what we need for the model.

As it happens, I have a set of Slaters Midland compensated axle guards for fitted vans with 3'7" wheels, so that's what I'll use. I've also found some 7mm x 2mm brass channel, from which to make new headstocks.

That leaves the question of bearing springs, as Simon notes - these of course need a shallower curve, as the distance from the top of the axle box to the underside of the solebar is less by 3". I have some ABS whitemetal GWR axle guards from which the springs could be liberated and squashed to the right profile (the curve on them already looks suspiciously shallow).

Nick.

 

[Dog Star]

To make all this work, the axle guards of course have to be different, with a smaller distance from axle centre to top of solebar by 3" - the Serpent has 3'1" wheels, the same as the open. Possibly by design, an axle guard intended for 3'7" wheels is just right, so that's what we need for the model.

Or the etch axleguard from the Slater's GWR 4 wheel coaches?

 

[Tony Overton]

Comparing the drawing for our increasingly poisonous-looking Serpent (8209W) with drawing 7925W of the same year, showing a 4-plank open goods wagon, we see that the solebars of the Serpent are a full 3" lower than that of the open. 1.5" of this is accommodated by having the buffers and couplings raised, centred on the 12" headstock. The other 1.5" is ... simply ignored. The buffer height of the Serpent is stated as 3'4", instead of the more typical 3'5 1/2" of the open wagon.

To make all this work, the axle guards of course have to be different, with a smaller distance from axle centre to top of solebar by 3" - the Serpent has 3'1" wheels, the same as the open. Possibly by design, an axle guard intended for 3'7" wheels is just right, so that's what we need for the model.

As it happens, I have a set of Slaters Midland compensated axle guards for fitted vans with 3'7" wheels, so that's what I'll use. I've also found some 7mm x 2mm brass channel, from which to make new headstocks.

That leaves the question of bearing springs, as Simon notes - these of course need a shallower curve, as the distance from the top of the axle box to the underside of the solebar is less by 3". I have some ABS whitemetal GWR axle guards from which the springs could be liberated and squashed to the right profile (the curve on them already looks suspiciously shallow).

Nick.

To save the fiddly job of liberating springs from your ABS whitemetal GWR axle guards, do you have a Slaters GWR cattle wagon kit in your stash? Are the springs with that the right size etc.?

 

[magmouse]

To make all this work, the axle guards of course have to be different, with a smaller distance from axle centre to top of solebar by 3" - the Serpent has 3'1" wheels, the same as the open. Possibly by design, an axle guard intended for 3'7" wheels is just right, so that's what we need for the model.

Or the etch axleguard from the Slater's GWR 4 wheel coaches?

Possibly - but I don’t have those, and I do have the Midland ones, so…

 

[magmouse]

To save the fiddly job of liberating springs from your ABS whitemetal GWR axle guards, do you have a Slaters GWR cattle wagon kit in your stash? Are the springs with that the right size etc.?

As it happens, I do have one of those. However, the ABS parts are going spare as I have already used the (separately cast) axle boxes for something else. Liberating the springs won’t be hard, and they are nicer than the ones that come with the kit, which would be the other option.

 

[RichardG]

The buffer height of the Serpent is stated as 3'4", instead of the more typical 3'5 1/2" of the open wagon.

For the builder who has chosen to retain and fold down the axleguards provided in the kit (this includes me), the buffer height with a corrected headstock is going to be

( wheel diameter / 2 ) + ( offset of bearing centre below solebar ) + ( half height of corrected headstock )

= ( 21.6 / 2 ) + 9.5 + 3.5 = 23.8 mm

Multiplying by 43.5 gives 1,035 mm, about 3 ft 4 3/4 inches. Half way between the two prototype dimensions, and good enough for me.

Well that's a relief.

 

[RichardG]

our increasingly poisonous-looking Serpent

On the bright side, the solebars seem to fit really neatly. The half-etched marks for the bolts and rivets are nicely small, so the punch is a snug fit inside them and a row of three indentations comes out in a straight line even for me.


Improvised folding bars. I also used these to fold up the sides of the lower floor.


For the side of the wagon without brake gear, there are two tiny slots in the solebar to be filled in. I struggle with parts this size so I solder in something overlength, then cut and file flush on the inside.


For the side with brake gear, I used the unwanted vee hanger to double up the thickness of the one retained.

Having put the solebars into place, I find it much easier to comprehend what the headstocks ought to look like, how they might attach to the model, and why the kit parts are wrong.

 

[Phil O]

Amazing , I was going to make a post saying that I couldn't see the photos and when I clicked the quote button, they miraculously appeared.

 

[Overseer]

Or the etch axleguard from the Slater's GWR 4 wheel coaches?


Possibly - but I don’t have those, and I do have the Midland ones, so…

But they won’t be correct. Check the space between the vertical legs of the axleguard where the axlebox slides. The Midland ones should be wider than most GW ones. Passenger axleguards will usually be wider overall than wagon axleguards. Some model interpretations are closer to the prototype than others, check the GA.

I thought about posting the old line “at least the holes are good” earlier in the thread, but they aren’t.

 

[magmouse]

But they won’t be correct. Check the space between the vertical legs of the axleguard where the axlebox slides. The Midland ones should be wider than most GW ones. Passenger axleguards will usually be wider overall than wagon axleguards. Some model interpretations are closer to the prototype than others, check the GA.

I've photographed the Slaters MR axle guards:



I've overlaid the photo on the drawing, scaled correctly, and the spacing of the 'legs' is very close to correct, as is the overall width. The angle of the angled parts is a bit steep, so they meet the vertical legs too far down. I might cut through at the meeting point, file a bit off, bend the angled part and solder back together. Or I might decide life is too short...

Nick.