Conflat P - in 4mm Scale by Filament 3D Printing ?

Discussion in '3D Modeling Projects' started by Jim Freight, Jan 25, 2025.

  1. Jim Freight

    Jim Freight Full Member

    Messages:
    1,562
    Likes Received:
    1,318
    Joined:
    Sep 9, 2019
    1 - Introduction

    Well, this is my next mission impossible, typically, 3D printing your own wagons is restricted to 7mm scale as the smallest size practical for fine detail, and using resin based 3D printing techniques.

    So what on earth can I achieve in 4mm scale with a filament printer?

    Defining the Terms of Engagement
    1. Firstly I model in 4mm scale, I have seen some simple models designed and printed this way on YouTube, i.e. Sam's Trains, so within tight limitations, like 1960's Tri-ang plastic chassis mouldings it can be done.
    2. Secondly, I am not getting into resin printing, the thought of using toxic chemicals in a domestic environment or even in a shed, especially as I get clumsier is a recipe for disaster.
    Having read with interest the exploits of those on P1 MRC who have mastered it in 7mm scale and achieved amazing results I admire their skills and patience :thumbup:

    However the amount of work, okay, let's be quite frank here, the hassle of preparation and post processing looks tedious and messy, I have not got the patience and that assumes one manages to print something worth post processing.

    Then there is the buying and disposal of the chemicals :facepalm:

    The first step is to set a realistic target of what I am trying to achieve.

    Target

    1. Create a model of something that is not commercially available r-t-r
    2. Keep it simple to run with my 1960-70s loco fleet

    The wagon that comes to mind first and foremost is a Conflat P to run with my Dublo Co-Bo locomotives as a Condor express freight.

    There is what appears to be an excellent metal kit available from Judith Edge of which I bought one to examine last year, but whether I am capable of building it now, let alone at least 10 of them is open to question and doubt.

    Whichever way the wagon is built it is probably more cost effective in time to buy the containers.

    So, what if I can print what is really just a chassis to the same detail standards of a Dublo Co-Bo which is quite low by todays superb injection mouldings?

    To be continued ...

    Jim :)
     
    Last edited: Jan 28, 2025
  2. Jim Freight

    Jim Freight Full Member

    Messages:
    1,562
    Likes Received:
    1,318
    Joined:
    Sep 9, 2019
    2 - Getting Started

    First I need a design, well luckily there is one available on Thingiverse, here

    https://www.thingiverse.com/thing:5968262

    This provides my starting point, I credit Jonny (IronMink) with the original design and STL files he has shared via Thingiverse.

    Attribution License

    https://creativecommons.org/licenses/by/4.0/

    From Thingiverse two STL files are downloaded, the wagon chassis and the separate brake lever.

    Buffers are not included although others are available from the originator on Thingiverse.

    Importing the files for use in SketchUp

    I use the free SketchUp Make 2017, this version and maybe others are inefficient at importing an STL file, it takes a very long time as I found out for myself when I imported a 3D scan of a die cast 4mm lorry chassis as the basis of a skip truck (really must get on with that too).

    Admittedly I generally do my CAD on an elderly VAIO laptop c2010 running Win 7 so this time I tried a different route, i.e. a different format.

    Spin3D Plus from NCH Software can convert various formats and what was a common one worth trying was .3ds an old format still in use.

    https://en.wikipedia.org/wiki/.3ds#:~:text=3ds is a binary file,well as the data itself.

    This is an import option for this format available in SketchUp.

    After conversion the .3ds files imported into SketchUp on my old laptop quickly, not like an hour plus I had loading the truck chassis scan in STL format*. Good start.

    *Units in STL format: An STL file is dimensionless so be careful how you import it to ensure that the STL units are translated correctly. If the units are defined as equal to a mm, when the STL file is written you must import it as mm otherwise it will not load at the desired scale, in this case full size.

    Ultimately It is always better to create models of small objects, e.g. 4mm scale parts, larger than full size in SketchUp, otherwise rounding errors occur and the model breaks and can be difficult to fix. SketchUp appears to have originated primarily as a civil engineering tool, long before domestic 3D printing of small parts, so working down to 3 decimal places of millimetres is always one step away from a broken CAD model.

    So to reduce problems the .3ds file was imported full size where one STL unit = 1 mm, once cleaned up then re-scale to e.g. 10x the size of the printed object, this makes editing the model easier and keeps you further away from an unstable CAD model.

    Wood for the Trees

    When such a file is imported into SketchUp it is a straight conversion, by which I mean it is totally composed of the triangles that was encoded into STL format, this is generally unusable to edit. Let me demonstrate.

    Overall view as imported into SketchUp

    1.jpg


    Closer view

    2.jpg


    Close up, just look at all the triangles around the buffer mounting holes and the dense meshes between the rivet/bolt heads.

    3.jpg


    For this to be editable by me I then manually clean out all the surplus lines which are only there to triangulate the whole model, there may be software out there to do this but I haven't found one I can understand how to use so I plod through it manually.

    Not too difficult when you get going, but save regularly with numerically incremented file names in case some actual detail inadvertently disappeared that becomes obvious later on.

    It is fairly easy to spot these triangles on a flat surface and delete in bulk using the eraser tool, short cut key 'e' and sweep across swathes of them, a quick Ctl Z when a surface breaks, when whoops the deleted line actually defined shape.

    After a couple of hours, well on the way, I haven't tried removing all the triangles from the holes and rivet/bolt sides, that is way beyond brain numbing!

    As can be seen the shape of the wagon chassis stands out much better than in the first image above. This also loads into SketchUp much quicker now.

    4.jpg

    Next, I move on to de-cluttering below the solebar.
     
    Andy_Sollis and gormo like this.
  3. gormo

    gormo Staff Member Administrator

    Messages:
    6,369
    Likes Received:
    4,900
    Joined:
    Dec 5, 2015
    G`day Jim,
    I`m just wondering about the images above, especially the last image, the perspective looks to my eye to be out.
    The right hand end especially does not seem to be quite right.

    [​IMG]

    Probably a 2D elevation check would confirm all is good.
    Sorry....but that`s just what it looks like in the pic.
    :tophat:Gormo
     
  4. Jim Freight

    Jim Freight Full Member

    Messages:
    1,562
    Likes Received:
    1,318
    Joined:
    Sep 9, 2019
    Hi Gormo, the CAD model view is in a parallel projection mode, not perspective so it can look a little odd when viewed out of square from an elevation or plan view.

    I am just used to it, except when mentioned by somone, then I do notice it, we naturally expect it to taper into the distance.

    The framing also adds a slight optical illusion to distort appearance too.

    Jim :)
     
    Last edited: Jan 31, 2025
  5. Jim Freight

    Jim Freight Full Member

    Messages:
    1,562
    Likes Received:
    1,318
    Joined:
    Sep 9, 2019
    Hi Gormo, here is a perspective view, generated from the next episode, hence clean below the solebars, working in perspective mode is messy, so normally I work in parallel projection mode, forgot to change the view for this thread.

    4a.jpg

    Jim :)
     
  6. Andy_Sollis

    Andy_Sollis Staff Member Moderator

    Messages:
    4,385
    Likes Received:
    4,347
    Joined:
    Aug 4, 2018
    Why are you cleaning up STL files ?
    they are meant to look like that and ultimately, its an STL file you will use with nearly any printer for slicing before printing??
     
  7. Jim Freight

    Jim Freight Full Member

    Messages:
    1,562
    Likes Received:
    1,318
    Joined:
    Sep 9, 2019
    A very good question Andy.

    Here is my answer.

    There are several reasons why I am not just applying this STL file directly to my printer via my slicer as the originator intended.

    1) As I mentioned above the STL file is for printing a wagon using resin printing techniques, a process that I am not going to use.

    2) The nature of supports for filament printing are inferior to those you have with resin printing.

    Supports by default I have found to be useless during the Arkitex project because they don't actually touch the overhangs, usually a layer or two short, they only catch a droop from an overhang. Okay for large objects but useless when parts are only a few layers thick. If they do touch they become a part of the print and need cutting off, the materials used in filament printing do not lend themselves to snapping off, they vary from flexible to tough.

    3) If I cannot provide supports that contact the printed object with my dual extruder filament printer using a water soluble material (which I shall be outlining in the next episode), then I will have to break the model down into a kit of parts. Too complex to do that with the imported STL file.

    4) I want to modify the method of mounting couplings, fit brass wheel bearings, and possibly simplify details I cannot print, almost impossible using the imported file.

    Summarising.

    So I imported the STL file and cleaned it up so I have a CAD model from which to modify the design to suit my preferred printing process, the triangulation lines in holes, bolts and rivets have been left in place as I do not need to change those, besides it would be madness, even for me, to remove those :hammer:

    The much improved clarity of the model can now be seen by comparing the before and after images.

    In one sentence, I required a clear editable CAD model to enable efficient implemention of design changes, so I cleaned out most of the model triangulation lines, this I have completed.

    Jim :)
     
    Andy_Sollis likes this.
  8. Andy_Sollis

    Andy_Sollis Staff Member Moderator

    Messages:
    4,385
    Likes Received:
    4,347
    Joined:
    Aug 4, 2018
    Makes sense, although I’d say, by the time you have cleaned that up to make edits, you could well have drawn it from scratch.. and yes, before you say your not that skilled, have a go, it’s not that hard. That’s just as I started.

    it just seems a lot of work, but if it’s getting you to where you want to be, that’s good. I know it will differ from system to system, although I’m not sure what you’re saying re support? That should be in your settings in the slicer before printing, so maybe you need to look at the settings there??

    having done both FDM and SLS it’s always a guess work to what supports you need where and how much.

    regardless, the wagon was looking good when you had cleaned it up. I know there will be some hours worth of work in that!
    Andy
     
  9. Jim Freight

    Jim Freight Full Member

    Messages:
    1,562
    Likes Received:
    1,318
    Joined:
    Sep 9, 2019
    Hi Andy, probably about 6 hours, which included running the Inspector tool add-in on SketchUp a few times because I unleashed a Pandoras Box of broken surfaces and openings which took a hour or so to unravel amongst the dense meshes half way through cleaning up.

    I have no problem about drawings I started my working life as draughtsman in a design and development office when we used crayons, plastic film and microfiche back in '73.:whatever:

    From what I gather getting a drawing of a Conflat P is not easy, unless you know which of the plate wagons it was derived from.

    My only drawing reference source at this time is a Datafile article written by the BRHSG (British Railways Historical Study Group) in the 1983 Model Railway Constructor Annual which even there only shows a BR outline drawing.

    Besides I found this STL file on Thingiverse, so it was probably quicker to reverse engineer an STL as the images shown there indicated it was good enough for me and may need to be simplified, and modified for filament printing anyway.

    I would not try and do this for much else, especially if a r-t-r model was available, and building a Judith Edge kit x10 would probably take me much longer, once I have worked out how to print it then I can let the printer spend hours creating them.

    Parts I shan't be 3D printing and will buy, are wheel sets, bearings and buffers, the latter are much easier bought as whitemetal castings, some from Lancashire Model Supplies look promising, not quite what the source data indicates, but close enough.

    Regards supports, it's as I said above, very different to the snap off ones you can create with resin prints, I went into that in depth when developing my Arkitex parts, so I am pretty sure about the limitations with filament printing and slicer settings for supports. If anybody can offer me an alternative approach to expensive water soluable supports I would like to know about it. But then again, on the web I see very little regarding printing with a 0.2mm nozzle let alone using dual extruder machines to print tiny functional parts.

    Speaking of which whilst trying to DCC convert a Mainline J72 I think I have found a subject, a geared drive axle variant (not available from Peter's Spares) to try and print in Nylon, mission impossible #3 coming up, I am not to be deterred by no one else doing it :headbanger:

    Jim :)
     
    Last edited: Feb 2, 2025
  10. Andy_Sollis

    Andy_Sollis Staff Member Moderator

    Messages:
    4,385
    Likes Received:
    4,347
    Joined:
    Aug 4, 2018
    Very true.
    I also have a dual nozel FDM, but not used it in probably 4 years. Still sat on the desk next the computer gathering dust. I never quite mastered the two colours. Mine needed to be calibrated and just couldn’t spare the time.

    I also tried (and still fitted) the .2 nozzle after seeing a guy print Z gauge loco bodies.

    all sounds good and fun and look forward to your progress..

    I seem to find the more expensive the machine the better the results, but isn’t that true of so many things in life?
     
  11. Jim Freight

    Jim Freight Full Member

    Messages:
    1,562
    Likes Received:
    1,318
    Joined:
    Sep 9, 2019
    They do need more extensive calibration than a single extruder machine especially when you use both heads on a single job, e.g. printing in two colours of PLA which I succeeded in doing with a 0.4 nozzle, using one for the object material and another with a dedicated support filament using a 0.2 however will be more challenging.

    Well, my R3D E2 IDEX is quite solidly built so squeezing (excuse the pun :facepalm:) out finer prints than what seems be done normally with FDM has been my aim ever since I bought it and it has surprised me what it can do once the multitude of slicer options are tuned accordingly. :hammer:

    Out of curiosity what make/model is your dual machine, there's not many dual extruder machines around?

    Jim :)
     
  12. Andy_Sollis

    Andy_Sollis Staff Member Moderator

    Messages:
    4,385
    Likes Received:
    4,347
    Joined:
    Aug 4, 2018
    Ctc bizer
     
    Jim Freight likes this.

Share This Page