Question Scratch build lattice girders - Gaviota Trestle

tiestvangool May 1, 2024

  1. tiestvangool

    tiestvangool TrainBoard Member

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    Hi there fellow z-scale modellers,[​IMG]


    I have changed my prototype from the Moffat Tunnel to the SP Coast Line depicting the Gaviota Trestle bridge. This to highlight the beauty of AZL’s SP Daylight passenger train consists. After having measured this bridge its length comes out to be 112cm (44”) in z-scale!

    As I am examining the bridge and its measurements I noticed the lattice girders and started wondering how to realize this in z-scale. Currently I am thinking scratch build these lattice girders by using styrene beams and manual handy work creating the lattice pattern. Does anyone have any other ideas how to make these lattice girders?

    Thanks in advance!
    -Tiest


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  2. spyder62

    spyder62 TrainBoard Member

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    I know they can be done on a laser as Rob Ray has done them before. But takes a lot of time to do right.
    rich
     
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  3. CNE1899

    CNE1899 TrainBoard Member

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    Tiest,
    I like the trestle, as it will really show off your consists.
    I plan on doing some lattice iron work for the locomotive works.
    One approach I was going to try was using a Circut to cut the patterns on black styrene sheet.
    The other approach was SLA parts, but I have yet to learn 3D modeling.
    Brass etching is also a possibility, either DIY our send out to an etching house.

    Scott
     
  4. rray

    rray Staff Member

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    Looking at the photos it look like laser cut would be the best way to go. You would have to hide the deck by sandwiching 2 to 3mm thick plywood between the laser cut ties on top and support trusswork underneath, then apply the bents, then cross bracing. I laser cut over 2000 pieces to make the trestle on the Timesaver Trestle module, and expect this would be a bit easier.

    You need to build the module and terrain first, then the deck span, then you could measure the height underneath to draw up workable trestle bents. I can lasercut them with your provided dimensions.

    Samtrees makes convincing palm trees like seen in that photo too, but they take a few months from order to delivery..
     
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  5. ed-n

    ed-n New Member

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    Seems like 3D printing should work (definitely want to minimize the number of supports needed). How high is the trestle in Z scale, and what size are the girders?

    The rust should make for a very interesting weathering project too. ;)

    Ed
     
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  6. tiestvangool

    tiestvangool TrainBoard Member

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    Robert,

    Thanks for the offer! I might take you up on it!!!
    I am expecting a book today called “ https://www.amazon.in/Closing-Gap-Bridges-Ventura-Counties/dp/0911773037Closing the Gap: The Coast Line and Its Bridges” by Nan Lawler.

    Second I am awaiting a custom module; currently being created by our TTZ friend Stuart Denniston.
    [​IMG]

    I am think to start a separate thread on this forum describing my endeavors, mistakes and learnings if that would be of intrest…
    I suspect this project will take me several months if not a year+
    Still got kids, my wife and a full time job that have my priority - in that order.

    Thanks again for your offer to help!
    -Tiest


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  7. tiestvangool

    tiestvangool TrainBoard Member

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    Ed,

    Based on documented measurements ( http://www.modelingthesp.com/Structures/Bridges.html), the Gaviota Trestle seems 69’2” high which equates to 991mm in Z scale.

    Forgive me for my ignorance but what do you mean with the ‘size of the girders’?

    I am awaiting delivery of a detailed booklet, see my previous post that hopefully contains more detailed measurements.

    Thanks!
    -Tiest


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  8. rray

    rray Staff Member

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    My laser can only cut 12" x 18", so some selective compression might be in order.
     
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  9. Curn

    Curn TrainBoard Member

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    No make the meter high bridge!

    I think your calculations are off. Height of 69’ 2” = 830 inches. Divide by 220 = 3.77 inches. 1 inch = 25.4 mm. That’s only about 96 mm.

    Should still be a cool bridge to build.

    -Matt
     
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  10. tiestvangool

    tiestvangool TrainBoard Member

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    Matt,

    You are correct; typo on my end. 1 meter high bridge would be something though!

    -Tiest


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  11. tiestvangool

    tiestvangool TrainBoard Member

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    Hi there!

    I am coming to the conclusion that my initial plan for this scratch build, using styrene beams and strips might not yield the detailed design I am looking for.

    I know [mention]rray [/mention], you mentioned laser cutting. What would be the benefit of laser cutting over 3D printing?

    As I am researching the world of design software I keep coming back to Adobe Illustrator (Paid) or InkScape (OpenSource). Does anyone have any hands-on experience in any of this software?

    My main objective would be to design - structural elements - the bends, lattice girders etc.

    Thanks and good weekend all!
    -Tiest


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    Last edited: May 4, 2024
  12. CNE1899

    CNE1899 TrainBoard Member

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    Teist,
    Illustrator is my preferred tool for creating graphics and layout drawings.
    You can create some nice layout drawings with it, and the files have been used on the Cricut 2D cutter, and for helping to create 3D models for printing.
    I have tried InkScape as an alternative and have not had any success with it yet.
    Here is an example of layout in illustrator: Screen shot 2021-11-23 at 8.39.33 AM.png
    Scott
     
    Last edited: May 6, 2024
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  13. tiestvangool

    tiestvangool TrainBoard Member

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    [mention]CNE1899 [/mention] (Scott),

    Thanks for confirming my thoughts. I started to get hands-on Illustrator and looks very promising. The interesting and complicated process is the thinking in ‘layers’. I do realize more and more that laser cutting creates great opportunities to build our custom z-scale world.

    The example is exactly what I am looking for!! Couple of questions if I may:

    1) Is the picture you included in the example the laser cut beam reflected in the Illustrator design in purple?
    2) I assume the answer is yes, and would love to understand how this 2D looked on the laser cutter in 3D?
    3) How did you achieve the ‘3D’ depth - is this one complete piece or multiple pieces/layers that you ‘glued’ together?
    4) The lattice work depicted in Blue, can you share an example how that came out the cutter?

    Thanks a lot in advance,
    -Tiest


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  14. rray

    rray Staff Member

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    So it's true you could go 3D Print as well as Laser Cut, and both methods could yield fine enough and strong enough parts. The laser cut bents would have to be assembled from layers of flat parts, and it's strength would increase as each layer is applied.

    The same bents 3D printed in resin would be a lot more fragile, and if printed in filament would be stronger than resin but lumpy. Now that the size has been scaled to be 4" tall bents, I can say they would be pretty quick an easy to assemble each bent, then you just mount them under the trestle deck and apply cross bracing pieces.

    Here are a couple bridges I lasercut from Polybak paper that survived the years of wear at train shows on modules. Once assembled you can see the z bracing and detail that you can get on your trestle bents:

    [​IMG]

    [​IMG]

    [​IMG]
     
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  15. tiestvangool

    tiestvangool TrainBoard Member

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    [mention]rray [/mention] this is great feedback. Your examples show exactly what I am trying to accomplish, laser cutting it is. I am going to design these bents and subsequent lattice girders.

    Thank you much for this guidance!
    -Tiest


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  16. CNE1899

    CNE1899 TrainBoard Member

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    Tiest,
    The picture included is a MTL girder bridge that I will be using to model up the pink line work, it is an overhead traveling crane.
    Yes you can grow 3D parts with openings and detail, without layering.
    To Rob's point, I agree that the resin parts will be more fragile given the size of the bridge, but there are stronger resins and people have modeled big buildings using 3D resin.
    The lattice work depicted in blue has not been built yet, but I was planning on layering it either in card board or plastic sheet.
    The Illustrator will still be helpful modeling parts up for laser cutting.

    Scott
     
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  17. tiestvangool

    tiestvangool TrainBoard Member

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    Robert, Scott,

    You both have me convinced that lasercutting is the way to go for my project. After research and prior recommendations I am thinking to purchase xTool D1 Pro. There are 3 version 10W, 20W and 40W priced accordingly. Do you have any thoughts on what wattage to go with?

    @Scott: I completed the first sets of Illustrator tutorials, like it so far.

    Thanks again!
    -Tiest


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  18. rray

    rray Staff Member

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    I have a 30W CO2, and have found that things could be sped up with more power, so I would recommend the most power you can afford. Once you get used to using the laser, you will be able to make all kinds of great models.


    Edit: I would go with the 20W now that I read the specs, 40W is faster but the 20W has better fine line resolution, yet can still do the job.
     
    Last edited: May 7, 2024
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  19. tiestvangool

    tiestvangool TrainBoard Member

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    [mention]rray [/mention] ,

    Thank you I went ahead and purchased the xTool s1 20W. Let the journey begin!

    Thanks!
    -Tiest


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