Forming the tumblehome

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David B
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Forming the tumblehome

Postby David B » Sun Dec 22, 2013 6:30 pm

On another forum I came across this very ingenious method of forming the tumblehome on a coach. Look about half way down the post where masking tape puts in an appearance. Do note that this is being done on a 7mm coach. See:

http://scalerail.phpbbhosts.co.uk/viewtopic.php?f=160&t=1515#p15196

martin goodall
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Re: Forming the tumblehome

Postby martin goodall » Mon Dec 23, 2013 11:23 am

That's a very useful idea.

Now, putting on my hat as a fully paid-up member of "Pedants-R-Us" :twisted: , I have to point out that it is not the tumble-home that is being discussed, but the turn-under. The tumble-home is the inward cant of the sides on some (but not all) coaches above the waistline. The inward curve of the coach side below the waistline is called a "turn-under".

The origin of the term 'tumble-home' is nautical, and refers to the inward slope of the sides of a ship's hull above the water line, e.g. on HMS Victory, to take a well-known example. [Switches off pedant mode :mrgreen: ]

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Paul Townsend
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Re: Forming the tumblehome

Postby Paul Townsend » Mon Dec 23, 2013 11:59 am

martin goodall wrote:That's a very useful idea.

Now, putting on my hat as a fully paid-up member of "Pedants-R-Us" :twisted: , I have to point out that it is not the tumble-home that is being discussed, but the turn-under. The tumble-home is the inward cant of the sides on some (but not all) coaches above the waistline. The inward curve of the coach side below the waistline is called a "turn-under".

The origin of the term 'tumble-home' is nautical, and refers to the inward slope of the sides of a ship's hull above the water line, e.g. on HMS Victory, to take a well-known example.


Gosh, thanks Martin.
So I and every other Railway Modeller have been using the wrong term for >80years!!!

[Switches off pedant mode :mrgreen: ]


How will your wife cope with unpedantry over Christmas or is it Saturnalia for you two?
You had better turn that mode on again PDQ :D

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grovenor-2685
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Re: Forming the tumblehome

Postby grovenor-2685 » Mon Dec 23, 2013 12:48 pm

Of course there is also this definition of "tumblehome" that might seem more relevant to our interests than the nautical version.
In railway design
Tumblehome can be seen where the carriage body attaches to the underframe in this photo of a North British Railway 3rd Class carriage from around 1900

The inwardly curving portions of railway passenger carriages at the point where the carriage sides join the underframes is also called the tumblehome. Tumblehome styling of railway carriages was particularly prevalent in the British Isles (or on railways influenced by British engineers or equipment builders) in the 19th century and "wood body" era of the early 20th century. This enabled the wooden step running the length of the carriage to remain within the dimensions of the loading gauge, while allowing maximum width for the main body of the carriage. Thus there was space to place a foot when entering or leaving the carriage.

Keith
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martin goodall
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Re: Forming the tumblehome

Postby martin goodall » Mon Dec 23, 2013 1:23 pm

Hello, "Pedants-R-Us" here again :twisted: .

Keith doesn't explain the provenance of the quote he has reproduced, but it was the railway companies themselves who referred to the inward curve of the coach body below the waist as the "turn-under".

Likewise, the railway companies themselves used the term "tumble-home" to refer to the inward cant of certain coaches above the waist line.

The fact that other writers, railway enthusaists, etc. have referred at various times to the turn-under as a 'tumble-home' (e.g. in Keith's quote) doesn't alter the fact that a vehicle builder in the carriage works at Swindon would have understood the word 'tumblehome' to describe the inward cant of a vehicle above the waist rail, and would have used the word "turnunder" to refer to the inward curve of the body side below the waist rail.

This is only one example of the misue of railway terminology by railway and model railway enthusuasts. Anaother frequently misapplied word is "footplate". The footplate was the area where the loco crew stood when driving the engine. The pieces of plating bracketed from either side of the boiler were the "running boards". The vertical stiffening plates suspended from the running baords were called "hanging bars". Thus what railway modellers often refer to as the 'footplate valances' should in fact be called the "running board hanging bars".

And another thing.................. [Oh, well, never mind. That's enough pedantry for one day. :D ]

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Will L
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Re: Forming the tumblehome

Postby Will L » Mon Dec 23, 2013 3:07 pm

Strangely Keiths quote comes strait of Wikipedia which also admits the nautical derivation.

Will

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grovenor-2685
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Re: Forming the tumblehome

Postby grovenor-2685 » Mon Dec 23, 2013 5:55 pm

The meaning of words is derived from their usage, and changes with time as new usages occur, and is often different in different areas of knowledge, as Paul pointed out, the model railway usage has had ample time to become "correct" for our purposes.
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Keith
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martin goodall
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Re: Forming the tumblehome

Postby martin goodall » Mon Dec 23, 2013 5:59 pm

Will L wrote:Strangely Keiths quote comes strait of Wikipedia which also admits the nautical derivation.

Will


Wikipedia is a very useful resource, but it is not necessarily authoritative. It is a helpful first reference, but should be treated with a degree of caution, and used as first step from which more in-depth research can be pursued.

The description of 'tumble-home' in Wikipedia is a case in point.

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Paul Townsend
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Re: Forming the tumblehome

Postby Paul Townsend » Mon Dec 23, 2013 7:53 pm

[quote="martin goodall"]Hello, "Pedants-R-Us" here again :twisted: .

The fact that other writers, railway enthusaists, etc. have referred at various times to the turn-under as a 'tumble-home' (e.g. in Keith's quote) doesn't alter the fact that a vehicle builder in the carriage works at Swindon would have understood the word 'tumblehome' to describe the inward cant of a vehicle above the waist rail, and would have used the word "turnunder" to refer to the inward curve of the body side below the waist rail.

/quote]

Well, my wife's grandfather was a chippy in Swindon Carriage works!
Life's timings meant I never met him to ask :(

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Re6/6
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Re: Forming the tumblehome

Postby Re6/6 » Mon Dec 23, 2013 7:59 pm

An excellent method David. Well found.

It seems to be more effective than when I use my 12" GW rollers which always seemed not to apply sufficient pressure in the middle.
John

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jon price
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Re: Forming the tumblehome (in styrene)

Postby jon price » Wed Jun 09, 2021 5:13 am

the link at the beginning is now dead, but I suspect it was to a method for brass sides. Any tips on forming the turnunder (alias tumblehome) if sides are thin plasticard? I tried clamping the side between two boards with a profile outside the clamp and applying a hot air gun. Result: excellent turnunder, but hrrifically distorted side despite clamping.
Connah's Quay Workshop threads: viewforum.php?f=125

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David B
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Re: Forming the tumblehome

Postby David B » Wed Jun 09, 2021 6:26 am

The link in the first post is to a now defunct forum. However, I have found a similar post for the same technique here:

https://www.westernthunder.co.uk/threads/rob-ps-coaching-stock-workbench-kirk-twin-set-diag-105-125.2555/page-5#post-81160

You need to scroll down the post to the 5th image. As Jon guesses, this is a technique for etched sides.

Forming plastic is better done using warm to hot water than a hot air gun. the heating is more gentle and uniform.

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Lord Colnago
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Re: Forming the tumblehome

Postby Lord Colnago » Thu Jun 10, 2021 1:49 pm

Now that is really useful. Thanks David.

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Enigma
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Re: Forming the tumblehome

Postby Enigma » Thu Jun 10, 2021 3:32 pm

Didn't Teddy Francis form the 'shape' on plasticard sides by rubbing the back along its length with a rounded bone knife handle? The bottom edge supported on the edge of a ruler or similar? It'll be in his articles in old (ie 'ancient' - well to some of us anyway) issues of Railway Modeller (1970's?).

ralphrobertson
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Re: Forming the tumblehome

Postby ralphrobertson » Thu Jun 10, 2021 4:03 pm

A very simple and effective way is to use a wooden former to start the curve. A copy of a brief article I wrote some time ago is here:

Forming coach sides.pdf


I have formed lots of coach sides using this tool and the curve on the side is consistent through the length of the coach which doesn't always happen using other techniques.

Ralph
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Will L
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Re: Forming the tumblehome

Postby Will L » Thu Jun 10, 2021 10:42 pm

Enigma wrote:Didn't Teddy Francis form the 'shape' on plasticard sides by rubbing the back along its length with a rounded bone knife handle? The bottom edge supported on the edge of a ruler or similar? It'll be in his articles in old (ie 'ancient' - well to some of us anyway) issues of Railway Modeller (1970's?).

Pretty much they way I do brass ones, only I use a round Xacto Knife handle. I do think there is a tendency to overplay the difficulty in getting appropriate bends into brass sheet which I always find a deal easier to achieve than a lot of the advice you see suggests. I think it more a matter of being willing to chance your arm, that way you find its not as difficult as you thought it might be.


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