7mm At the Western End of F7

[SimonT]

Today's little adventure is to finally do something about the brake pull rods on the Western. As this loco gets to travel a lot it picks up damage to the brakes caused mainly by the rods being etched out a flimsy shim brass. The answer was to have my own rods etched out of 15 thou rod. So..
Before.


After


I shall be doing the same to the 37s, after i have touched up the chipped paint with more dirt .

Simon

 

[SimonT]

Newly arrived the some of the test shots for the Coil T steel coil wagon. I need a few for Aber and a couple of other people are interested in having some.

First the etches as received. There is one more sheet to come.



A couple of hours work saw the basic chassis assembled. The cradle will be built on top when the final etch arrives. The vehicle in intended to use Appleby castings for bogies, buffers, etc.


More pictures as work progresses.

Simon

 

[iak63]

Serious large scale wagon malarkey - mmmmmmmmmmmmmmmm

 

[AJC]

Interesting choice of prototype Simon. I have the beginnings of a pair of 4mm scale versions (actually, Coil Ks, the Ts are out of period for me) in a drawer somewhere...

Adam

 

[SimonT]

I might well do a Coil K as I would only need to 'adjust' the artwork for the cradle rather than start again. The Coil T can be built as either Vac or dual brake. The next wagon will be a Coil F. Standing further back in line are a Coil V and a Coil A (same underframe as the MDV that I need). Some of the Warflat derivatives would be nice. Then there are the iron ore wagons for the 9F to haul...... help!

Simon

 

[AJC]

All a bit big for my purposes! In 4mm the chassis is the easy bit, all those rivets apart, it's the cradle that I'm not looking forward to.

Adam

 

[john lewsey]

Any chance of a photo of one of these as I've no idea what they look like

 

[AJC]

Coil K and T:

http://paulbartlett.zenfolio.com/coiltferry

Not certain about the Coil F off the top of my head.

Adam

 

[Dog Star]

What is an approximate date for the last use of these wagons?

Where might the wagons be seen in this country? (I have looked at Paul Bartlett's web site so South Wales and Immingham feature plus some on the route through the Black Country).

regards, Graham

 

[AJC]

1966 in the case of the Coil K, a bit later, c. 1970, for the Coil T. Both were conversions from slab coil wagons which looked rather different. Not sure about their workings I'm afraid.

Adam

 

[Dog Star]

1966 in the case of the Coil K, a bit later, c. 1970, for the Coil T.

Paul's photos provide generally the location and date... most are in the 1980s and the most recent appears to be 1985.

 

[Steph Dale]

Looks good Simon, but I note the etchers have provided your top sheet on 0.5mm/o.o20" rather than the 0.55mm/0.022" that would seem to be indicated on the artwork...

Steph

 

[AJC]

Paul's photos provide generally the location and date... most are in the 1980s and the most recent appears to be 1985.

Reading what I wanted to read there, i.e., first use, sorry! Oops...

Some of the earlier Coil Vs lasted until the '90s so I would expect that these made it until about the same time before succumbing. As you might have gathered, this is not a period I know about.

Adam

 

[SimonT]

Not certain about the Coil F off the top of my head.

http://paulbartlett.zenfolio.com/brcoilplate

the etchers have provided your top sheet on 0.5mm/o.o20"

Worse than that Steph, it only measures .45mm. They have been told! Thankfully none of the slots in the cradle will be affected by this inaccuracy in the test build.

My understanding of the history of these wagons is that the original wagons were built at Swindon in 1961 as slab & coil wagons with a massive Heath Robinson structure on top of the chassis. Somewhere around 1964 to 1966 twenty were converted under Dia 1/408 to Coil K; the two cradles were placed on top of the chassis and the braking was modified. Some of these wagons were later modified under the same Dia to produce 10 ferry vehicles for the European traffic. Meanwhile Dia 1/417 & 419 converted the remaining Dia 1/408 to two further slab carrying versions. Finally Dia 1/453 and 1/458 produced the Coil T version; I don't know the differences between the two diagrams. Coil T were vac braked and Coil V were dual braked. Other than one that was withdrawn in 1966, they mostly lasted into the mid 1980s with periods in and out of traffic. If anyone has more information, please let us know.

Simon

 

[OzzyO]

Looks good Simon, but I note the etchers have provided your top sheet on 0.5mm/o.o20" rather than the 0.55mm/0.022" that would seem to be indicated on the artwork...
Steph

http://paulbartlett.zenfolio.com/brcoilplate
Worse than that Steph, it only measures .45mm. They have been told! Thankfully none of the slots in the cradle will be affected by this inaccuracy in the test build.
Simon

It really does make me wonder if people know about some of the sizes they are taking about?

0.002" is approx the thickness of the gummed part of a fag paper, when you go to the thickness of the fag paper with out the gum your looking at approx. 0.0015".

Then it's mentioned that the sheet metal only measures 0.45mm when it "should be" 0.55mm (what was used to measures it?) Think of the rolling tolerance for the sheet?

If all of the bits fit why worry, as by the time you have a coat of paint on them it will be about right.

In the old days (25 years back) I was told the cost of machining a job, and it started like this, these are all for milling (I was on £60 per week),

+ or - 0.010" Zero, the starting cost per hour,
+ or - 0.005" +£3
+ or - 0.001 + £8
Then when you get to grinding the job you times the cost by 10.

OzzyO.

 

[ZiderHead]

0.55-0.45mm might only be a fag paper but its almost 20% difference, or in engineering terms "miles out." For a well designed etch using slot/tab and grooves to tight tolerances, 20% too thin might mean a weaker but still buildable structure, 20% too thick means you have a sheet of scrap brass …

 

[Steph Dale]

Paul,

If the fret is toleranced for fit it would be enough to cause a foul-up though. It's a limitation on the technology.

And yes, I do know what 0.002" looks like:
1. The thickness of a green Rizzla
2. The difference between the ball races staying in or falling out of my gearboxes.

Steph

 

[SimonT]

The two sheets mic up as a variable 16.5 to 18thou and a consistent 22 thou. I did consider 28 thou for the cross members and the rails but subjectively, they looked too thick on the 3D model. Not having a prototype to measure, one inch plate seemed a sensible choice.

Anyway, here's the current progress on the cradle.


Simon

 

[OzzyO]

Paul,

If the fret is toleranced for fit it would be enough to cause a foul-up though. It's a limitation on the technology.

And yes, I do know what 0.002" looks like:
1. The thickness of a green Rizzla
2. The difference between the ball races staying in or falling out of my gearboxes.
Steph

Steph, I would expect you to know what 0.002" was, but some people don't know. As you say it's also a limitation on the technology as well.

The two sheets mic up as a variable 16.5 to 18thou and a consistent 22 thou.
Simon

Hello Simon,
this has got me a bit confused, how can the sheets be a consistent 22 thou. but then vary between 0.0165" and 0.018".
If the N/S sheet is 0.018" that is a standard S.W.G. size along with the 0.0165 IIRC these sizes are Nos. 26 & 27, by the sound of it your etcher stocks these as standard sizes in the two types of metal. If you want to have the consistency of thickness of the sheet you may have to go for only one type of metal and have all of the parts etched on one sheet.
IIRC the S.W.G. size for 0.5mm is No25 (0.020"). S.W.G. No23 maybe to thick at 0.024"

After all of this, it's looking a nice build of an unusual wagon.

OzzyO.

 

[adrian]

this has got me a bit confused, how can the sheets be a consistent 22 thou. but then vary between 0.0165" and 0.018".

I read it as being two sheets - one of which varys between 16.5 and18thou - the second sheet is a consistent 22thou.