Well it was back to the grind this week and while completing a rather repetitious engraving job today I had time to devote some time to the Trestle Project. The wing assemblies required some more refining and apart from the wing pile choice... I think we have nailed it. There is not a lot of small diameter timber dowel available and with the variations required for HO modelling some compromises are essential. The main thrust of today was to get the overall wing dimensions, batter and close fit of components right. With this achieved I attempted a trial fit to the main trestle assembly and utilised some commercially available basswood half rounds for the wing piles and while it was good to get a "prototype" completed... the choice of the half rounds has detracted from the overall appearance as they look too lightweight. I will construct a couple more differing trials and a decision will need to be arrived at so kit manufacture can then take place. I will try and complete the instructions this weekend and a small delay will then occur while we bring all other kits back into stock in particular the first bridge release, tank stands and station facing kits.
I must admit that I am looking forward to converting this finished trestle into a completed scene and again I will post the progress as this goes along.
Rod
Rod
ReplyDeleteWelcome back.
Looking nice, but I can see what you mean by the lightweight half round timbers. Never mind, life is full of compromises and those who feel inclined could always reduce larger timbers to half round if they wish.
Ray P
Ray,
ReplyDeleteI have some alternatives and will trial them out...And indeed I can split some larger sizes with the laser...This attempt looked acceptable until the camera was pointed at them....The Acid Test.
Rod
Rod,
ReplyDeleteSorry about two comments in two days but this one comes with a bit of experience.
In my days when I wore a green skin, I built a timber road bridge around Coonabarabran. It included retaining walls on each abutment. There was no hint of half timbers. We had to drive the abutment piles as far as the bridge pile sets. The abutment piles had to withstand the lateral soil load and we tied each pile to a 'deadman anchor'. Sorry, but a half pile is unlikely to withstand the pile driving and is very unlikely to carry the lateral soil load.
cheers Phil
Phil,
ReplyDeleteThanks for that...
Rod
Hi Rod,
ReplyDeleteI was looking at your wing walls and there was something not quite right with them and then it came to me - the timbers of the wing wall shoudl be horizontal - not at an angle. If they are at a angle the bottoms are mostly unsupported. I have picutres - contact me offline if you wish.
Cheers, Graeme
Graeme,
ReplyDeleteDuring extensive research for this project I became aware that there were examples of both types...Angled and Straight wing timber placements and within this are many sub variations. The decision to go with this style for this particular release was taken because of the ability to trace it to an original departmental drawing No8 / Contract No1 Cootamundra - Temora from the late 1800s. As this will not be the only trestle kit... we will follow up with different versions. Your post is timely as I am working on a Blog Post as to how we arrive at our designs and how people perceive these decisions & the research behind the reasonings.
Regards,
Rod
Rod,
ReplyDeleteMy research has also shown many different variations when it comes to the infrastructure. Looking at the angled design one in three boards are 'unsupported' at the base - the point where the pressure from the soil is the greatest. I don't really know (as I have not looked into it to any great extent) but it's possible that the these were first constructed with the angled design and subsequent constructions were of the horizontal desing - or it coudl have been the other way. More and more I find that as soon as you come to a discovery or conclusion you subsequently find something that disproves it. One more item to think about in the constadn voyage of discovery.....
Regards,
Graeme