Board index Talking T Gauge Forum T Gauge Layouts

Post details of your T gauge layouts and the progress you are making.

Re: The Bridge

Postby tjejojyj » Sat Mar 29, 2014 10:46 am

Hi Doug

What source material did you use as the basis of you CAD model?
Do you find there is a maximum or optimal size and thickness of components you print?

I'm thinking that 3D printing would be a good way to make a version of the Landwasser Viaduct and Langwieser Viaduct for the Rhatishe Bahn layout I'm planning. It would be nice to make them to scale.

I'll add my 2 cents to say I eagerly look forward to seeing images of your completed layout. It sounds wonderful.
User avatar
tjejojyj
 
Posts: 21
Joined: Tue Mar 18, 2014 12:23 pm
Location: Sydney, Australia

Re: The Bridge

Postby dkightley » Mon Mar 31, 2014 8:48 pm

What source material did you use as the basis of you CAD model?

Everything I have so far has either been downloadable images from the internet...downloaded on the basis of "personal non-commercial use only", and three books on the subject of the bridge that I have purchased. Fortunately, lots of people have posted photos of the bridge...and a good "engineer's eye" can get a lot of information from a few pictures!!

Do you find there is a maximum or optimal size and thickness of components you print?
This is a simple question...to which I wish there was a simple answer! Alas, there isn't. The differing 3D printing technologies and systems have totally different printing capabilities.

Take a look at the design criteria for the differing materials available from Shapeways for example. The minimum wall thickness and detail tolerances differ wildly between the materials. And the minimum dimensions for the hot extrusion method that the Makerbot printer I have ( and all other similar printers) are actually different in each of the x-y-z axes. For instance, extruding through a 0.4mm diameter nozzle give an extruded bead of 0.4mm wide, so its impossible to have a vertical wall thickness of less than 0.4mm, whereas its perfectly possible to extrude a layer that is 0.2 mm thick! You have to be quite inventive on how to utilise the printing process! ;)

Perhaps forum members may be willing to pass on their experiences of 3D printing in the so-named forum section.


Gosh! What a subtle hint that was! :shock: :shock: ;)
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk
User avatar
dkightley
 
Posts: 915
Joined: Wed Nov 13, 2013 9:43 pm
Location: Nottingham, UK

Re: The Bridge

Postby dkightley » Wed Apr 02, 2014 11:38 pm

Another component drafted out. Needs detailing, hollowing out and a mounting insert designing...but we're getting there!
IMG_0975_red.JPG
IMG_0975_red.JPG (48.8 KiB) Viewed 4053 times

Let me see....I'll need thirteen of them. 8-)
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk
User avatar
dkightley
 
Posts: 915
Joined: Wed Nov 13, 2013 9:43 pm
Location: Nottingham, UK

Re: The Bridge

Postby dkightley » Sat Apr 05, 2014 12:32 am

After many hours of 3D detailing work, I finally have some textures on the viaduct supports. Here's the before and after...and the after version took a whopping three hours to print!!
IMG_0977_red.JPG
IMG_0977_red.JPG (62.67 KiB) Viewed 4024 times
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk
User avatar
dkightley
 
Posts: 915
Joined: Wed Nov 13, 2013 9:43 pm
Location: Nottingham, UK

Re: The Bridge

Postby Slarge » Sat Apr 05, 2014 9:23 am

Woah! :shock: you modelled all that texture? How?
Seriously how? Are they truncated pyramids or something?
Bricks are things we would never even consider modelling at this scale when making architectural models 3D viz, 3D for Printing or the Old school scalpel scored cardboard.
You just pushed the boundaries of modeling at this scale yet again!
Slarge
 
Posts: 30
Joined: Thu Nov 14, 2013 8:22 am

Re: The Bridge

Postby dkightley » Sat Apr 05, 2014 10:44 pm

Basically, I found out quite quickly that at this scale we have to design not for the detail....but for how the printer prints.

To illustrate this, here's what the model looks likes in my 3D package:
TextureDetail.jpg
TextureDetail.jpg (60.75 KiB) Viewed 3999 times


Compare the 3D model with the finished article. They're similar...but to get the end result, I have to exaggerate some of the surface shaping. And the rest is down to sheer trial and error!

And getting that level of detail for brickwork took hours and hours of repetitive dividing lines up and joining the dots! And then every sticking out node (forming the centres of the bricks) was moved out individually!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk
User avatar
dkightley
 
Posts: 915
Joined: Wed Nov 13, 2013 9:43 pm
Location: Nottingham, UK

Re: The Bridge

Postby tjejojyj » Sun Apr 06, 2014 9:21 am

That looks really good. From the first photo it looks like you have copied a 'block' pattern about ten times up the column.

(I was just thinking about asking whether such surface texture was possible at this scale as it is a facet of the Landwasser Viaduct.)
User avatar
tjejojyj
 
Posts: 21
Joined: Tue Mar 18, 2014 12:23 pm
Location: Sydney, Australia

Re: The Bridge

Postby martink » Sun Apr 06, 2014 10:53 am

What you are doing is very, very impressive. While 3D is pretty much essential for the complex ironwork, have you considered using more traditional modelling techniques for simple bits like the pillars? The old trick of sticking suitably embossed plasticard onto wooden piers springs to mind.
martink
 
Posts: 188
Joined: Sun Feb 09, 2014 3:13 am
Location: Melbourne, Australia

Re: The Bridge

Postby dkightley » Sun Apr 06, 2014 4:19 pm

With wanting to get as near to true scale as possible, I only thought of using 3D modelling to get the level of results I was looking for. And it also allows me to produce pre-production parts so I can make absolutely sure things fit together exactly how I want.

For example, with the tower "hot off the press", here's an example of all pre-production parts assembled together for the first time! And with the HST placed almost in the right place, it gives an ides of the scale of the structure.
IMG_0983_red.JPG
IMG_0983_red.JPG (54.66 KiB) Viewed 3975 times


There's four separate parts here...all of which are not in their final form, but knowing they fit together, I can press on with the time consuming detailing.

btw This tower is actually the largest single component volume-wise in the whole bridge! And it happens to be a key component in the design, as I now know exactly how high the track bed will be above the waterline...so I can now work on the roadway sections for the centre tower, which I have partly produced.

I had doubts as to whether I would be able to pull this project off. I'm starting to feel slightly confident that I might just succeed!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk
User avatar
dkightley
 
Posts: 915
Joined: Wed Nov 13, 2013 9:43 pm
Location: Nottingham, UK

Re: The Bridge

Postby peterg » Sun Apr 06, 2014 8:16 pm

Seeing the parts together...with the train, just confirms how great this will be.
I think we will be seeing you in a magazine with this one at some point!!
peterg
 
Posts: 47
Joined: Mon Feb 03, 2014 12:25 am
Location: Nr Rugby, Warwickshire

PreviousNext

Return to T Gauge Layouts

Who is online

Users browsing this forum: No registered users and 3 guests