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Ron Heggs

Points Bridge, Hagg Bank, Wylam, Northumberland

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It is coming on well. It must be becoming quite rigid now. Are you doing the arches one at a time or have you all three on the go?

Edited by N15class

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It is coming on well. It must be becoming quite rigid now. Are you doing the arches one at a time or have you all three on the go?

Hi, Peter

 

Yes, the bracings are starting to reduce the arch flexibility and make it far more rigid. I can already see that the vertical rigidity will make the deck support/loading a reality

 

The arches are being built one at a time. This first one will be the middle of the three. The two outer arches are identical, and some of the cross-bracings are opposite-hand to those on the middle arch

 

Will have to increase the strip cutting time, to speed-up the build of this first arch, and attach it to the deck

 

Cheers

 

Ron

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All the main external braces fitted along with the relevant cross-braces -

 

post-10633-0-91491100-1334446516_thumb.jpg

 

Positioned, but not fixed, on the deck -

post-10633-0-90855800-1334446539_thumb.jpg

 

post-10633-0-85137400-1334446563_thumb.jpg

 

- internal braces and cross-braces next -

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I must thank all those members who are following this topic/thread for your continuing interest, and a special thanks for clicking on 'LIKE THIS'

 

Cheers

 

Ron

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Hi Ron,

 

Will you be fixing track to this before it is completed? Can't wait to see it finished with some stock staged on it. Also will this be going on to Manchester Central or is just a detour to keep you from getting bored other tasks!?

 

It is a superb build but everything you have posted on here is superb so would not have expected anything less really.

 

Steven

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Hi Ron,

 

Will you be fixing track to this before it is completed? Can't wait to see it finished with some stock staged on it. Also will this be going on to Manchester Central or is just a detour to keep you from getting bored other tasks!?

 

It is a superb build but everything you have posted on here is superb so would not have expected anything less really.

 

Steven

Hi, Steven

 

Eventually track will be laid, not sure whether before the challenge ends in October

 

The bridge will be used on part of the layout which will pass through the summerhouse, visually disconnected from the main part of the layout, which will be indoors

 

I do switch modelling tasks frequently, as you rightly say to reduce the boredom with tedious and lengthy builds

 

Thank you for your much appreciated comments

 

Cheers

 

Ron

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Another six internal braces/cross-bracings fitted this evening -

 

post-10633-0-62552800-1334530892_thumb.jpg

 

A brace unit ready to fit -

post-10633-0-49367000-1334530302_thumb.jpg

 

The brace unit threaded through the external brace member -

post-10633-0-29252100-1334530326_thumb.jpg

 

The brace unit fixed in its location -

post-10633-0-88107100-1334530347_thumb.jpg

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Some of you may have noticed that the last picture in post #53 showed a packet or two of Archer 3D transfers for rivet heads :O

 

Yes, I am going to try these out on the bridge before painting :rolleyes:

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Hi Ron,

 

You are making good progress with the arch, no surprise there. looking forward to seeing more pictures as you continue.

 

Colin

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Some of you may have noticed that the last picture in post #53 showed a packet or two of Archer 3D transfers for rivet heads https://www.rmweb.co.uk/community/uploads/emoticons/default_shok.gif

 

Yes, I am going to try these out on the bridge before painting https://www.rmweb.co.uk/community/uploads/emoticons/default_rolleyes.gif

That may well take longer than the construction. Looking very impressive with the arch over the bed.

Edited by N15class

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Somehow the "Like this" button seems totally inadequate.... amazing work.

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Hi Ron,

 

You are making good progress with the arch, no surprise there. looking forward to seeing more pictures as you continue.

 

Colin

Thanks Colin - there will be plenty more pictures to post as the build continues

 

Ron

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That may well take longer than the construction. Looking very impressive with the arch over the bed.

Hi, Peter

 

Thanks

 

You may well be right about the rivet head placements taking a little longer than the build

 

Ron

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Somehow the "Like this" button seems totally inadequate.... amazing work.

Thank you - your comments are much appreciated

 

Ron

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The last of the internal braces with five cross-bracings -

post-10633-0-57220700-1334681115_thumb.jpg

 

post-10633-0-31881400-1334681344_thumb.jpg

 

The middle arch build so far -

 

- mounted temporarily on/through the deck

post-10633-0-14033400-1334681365_thumb.jpg

 

post-10633-0-13569200-1334681385_thumb.jpg

 

post-10633-0-75979400-1334681409_thumb.jpg

 

post-10633-0-98392300-1334681449_thumb.jpg

 

post-10633-0-76695400-1334681477_thumb.jpg

 

post-10633-0-50110300-1334681506_thumb.jpg

 

post-10633-0-87804300-1334681550_thumb.jpg

 

post-10633-0-68588000-1334681577_thumb.jpg

 

- now to complete the remaining internal bracings for the remaining 40% of this arch

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Stunning stuff. This is true model engineering - not the lathe-turned and paraffin-driven stuff you see at a typical model engineering exhibition, of course - but engineering of the highest order nonetheless.

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Couldn't post these photos last night as the site was off-line

 

The arch is complete and fitted to the deck -

 

post-10633-0-74826600-1334867382_thumb.jpg

 

post-10633-0-27244400-1334867411_thumb.jpg

 

The next step is to fit the suspension hanger/struts

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Stunning stuff. This is true model engineering - not the lathe-turned and paraffin-driven stuff you see at a typical model engineering exhibition, of course - but engineering of the highest order nonetheless.

Hi, John

 

Thanks for your comments - My model builds need to function in a similar way as the real structures - bridges need to be a real scale construction, not a facade - although these bridges couldn't really be constructed in any other way to represent the actual structure

 

Cheers

 

Ron

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So when is the first loco crossing? :sungum: Looks as if it will have no problems with the weight.

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The first two suspension/hangers fitted -

 

post-10633-0-37690200-1335299663_thumb.jpg

 

post-10633-0-05356700-1335299693_thumb.jpg

 

post-10633-0-24399700-1335299736_thumb.jpg

 

- another 14 to fit

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How does the tensile strength of the model plasticard compare to that of the full size steel ? I'm guessing the plasticard is proportionally stronger ?

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How does the tensile strength of the model plasticard compare to that of the full size steel ? I'm guessing the plasticard is proportionally stronger ?

Hi, Stubby

 

The answer to your question is in two parts -

 

1. Material Strengths

 

Styrene: Ultimate Tensile Strength is 40 Mpa (40N/mm2)

 

Structural Steel: Ultimate Tensile Strength is 400 Mpa (400N/mm2)

 

The actual bridge deck suspension hangers are 25mm x 150mm cross-section steel

The model suspension hangers are 0.5mm x 2mm cross-section styrene

 

Max Force (Load) = Ultimate Tensile Strength x Cross-sectional Area

 

Styrene: Force = 40MPa x 0.5 x 2 x 100 = 4kN

Steel: Force = 400MPa x 25x 150 x 100 = 150,000kN

 

Since the model scale is 1:76.2, the area ratio is 1:5806.44

 

This means that the scale equivalent scale Force would be 4kN x 5806.44 = 23,225kN, some 15% of that of the actual

 

2. Scale Equivalent Loads

 

Assuming a model loco is approx. 500g, then the scale equivalent mass would be 442,451g = 443kg = 0.443tonnes

 

Whereas, the prototype would be nearer 100tonnes. This makes the model loco only say 0.5% of the actual

 

In conclusion, the model suspension hangers have a greater equivalent model load capability some 30 times (15% / 0.5%) greater than the actual prototype, as the model locos, etc. are much lighter in scale terms

 

Hope I haven’t confused you too much

 

Cheers

 

Ron

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Ah, so what you're saying is : although the model is proportionally not as strong as the prototype, because the model locos are considerably lighter than their full size eqivalents, the model bridge is still well within tolerances for supporting said model loco.

 

Phew !

 

It's just that those hangers look very thin (mind you, I also said that about the real ones - what do I know ?)

 

Thanks

 

Stu

 

Edit : The other main difference, of course is that the real hangers are bolted to the other bits of the bridge at each end, where as the model is only glued together - which could result in weaker joints (except the glue is probably stronger than the plastic !)

Edited by Stubby47

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Hi Ron -

 

Been 'offline' for a while. Stunning progress! Two things - you say this model will go in a summerhouse? No danger of warping in the heat? Secondly - very early on it looked like you will building the intial structure over a plan. If so - how did you prevent the styrene sticking to the plan? I only ask because I've got to model the girder-work associated with the canopyof a platform at Brisol Temple Meads...

 

Regs

 

Ian

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