Modeling scale models to what scale?

Hi All

I may develop a plugin for model railroads, typically at H0 scale (1:87) but it could be at other scales too. Since I not very often do SketchUp models of scale models I wonder how you are doing this and if there is any best practice.

I’m thinking it may be easiest to draw everything in as if it was scale 1:1 in SketchUp. This way users could download buildings, trees, vehicles etc from 3D Warehouse without having to resize them and the plugin wouldn’t need to draw its object differently regarding what scale the users’ physical models are in. Also I suppose face creation is easier in this scale and perhaps other features of SketchUp works better in full scale too (clipping?).

The other option would be to draw in the model railroad scale which might be easier if users want to base the layout on the physical dimensions of their home. However I think it would be fairly simple to draw the room you plan to have the model railroad in, scale it up 87 times with the scale tool and base the railroad on that. Then everything could be scaled back to model railroad scale when exported/printed.

Thoughts on this?

Tricky one, this. I can see arguments for using both ‘real life’ and ‘scaled down’ dimensions when modelling in SU.

I’ve been helping a friend develop a model railway, in a process that has gone on so far for nearly three years.

It’s in the UK OO scale (4mm=1ft or 1:76.2, usually just approximated as 1:76) in which the gauge is the same as HO (16.5mm for 4’8 1/2" ‘real life’ gauge), but the other dimensions are to a different scale.

I modelled the room and baseboard construction full size. and overlaid images of the planned track layout (taken from the SCARM program by screenshot) in a mix of imperial and metric dimensions. I took dimensions for model buildings at their scaled-down sizes, measured directly in mm.

I didn’t really model any rolling stock in SU, but tried one locomotive, taking measurements from the model itself in mm, not ‘life size’ original dimensions. Ran into occasional difficulties with small faces in SU, but not many.

But I can see a case for a serious scale modeller who is making their own rolling stock, that they might want to make drawings with measurements taken from the full size original, then scale down afterwards.

I don’t see any likelihood of automatically working in the not-quite-to-scale OO, where the wheel spacing has to be adjusted separately from the main bodywork.

My main purpose in modelling the layout in SU was to plan the woodwork for baseboard construction (some of it very complicated), so I had no use for ‘original’ life size dimensions for the model rolling stock or buildings.

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I think it’s best to create them in 1:1 scale and let people scale to their needs.

Also will this be any different than your similar plugin?: Eneroth Railroad System (I have seen but never used).

That might depend on the purpose of the plugin.

The existing plugin Eneroth Railroad System (as I understand it from the description on the SketchUcation site) creates model layouts, track, rolling stock etc. If people using it would want to use the plugin it to plan a model railway, they’d want it created at the scaled down size, not original life size, I think.

And would probably be unlikely to change the scale afterwards, if it is to plan for a real scale model.

But if just to use a virtual model to run simulated trains on the computer, the scale may not actually matter, so long as things stay in proportion.

Julia, I’ve done some modeling for our N-scale layout. Since I am mostly working with real world objects, I model at real world dimensions and scale down afterward. That saves me the trouble of doing all the math required. I just let SketchUp do it. Working at real world scale also avoids the tiny face issue.

When I draw buildings for card stock structures, I don’t bother to scale them in SketchUp. I leave them at 1:1 and scale the viewport in LO for the PDF.

@filibis: The new plugin will be just for drawing tracks, not a full simulator. It will be used for a purpose I can’t disclose yet.

Though real world scale sounds attractive, mostly , on scale H0, it is almost impossible to make a real world station on scale, especially diameters. ( but perhaps, some have a very large hobby room ?) Most track building programs start with a manufacturer track-catalog with all available curves, tracks etc. the tricky part is the flexible track.
There are thousands different tracks-systems… Some decide to build their own… Would it be possible to define a certain brand, set, etc. in the extension ?
These tracks are ‘real-world’ scale, but if you want to import 3d warehouse items, I think one question : ( Is it real world size ?) would be sufficient ? Most of the time this 3d warehouse items aren’t real world size, so… Maybe a suggestion for a new extension ?

What is the benefit of modeling in a certain scale if SketchUp can do that for you? I may be misunderstanding the purpose of your plugin though.
The way I would approach this in SketchUp is to wrap the entire model in a component, =scale 1:1. This component gets layer1 assigned to it.
A copy of the component (the entire model) is scaled down 1:87 (or any other scale) and has layer87 assigned to it.
You can model in either the first at real scale or in the latter in scale 1:87 at any time. Whichever “model” you pick, the other will follow. You can setup various scenes for both scales to be used in LayOut.
Maybe I am simplifying things too much?

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When I draw track for a layout, I would draw it at 1:1. That is, I would draw it the same size as the track I would be laying down. Currently we’ve been using Kato N-scale track so I take measurements from the track to use for modeling.

XtrkCAD is handy for drawing layouts since it contains libraries for the various track manufacturers and also lets you make custom track sections. Then export the centerlines as DXF files, import into SketchUp and use Follow Me with the track profile to create a 3D model of the track.


At the moment it appears the plugin will use the scale of the model railroad. This way people can more easily build it to fit their home and layout tracks with a minimum radius they know their rolling stock can handle.


At first, I was thinking that you were talking about a component to model rolling stock and fixed items. But then I read the rest of the comments and it is clear your proposal is more directed than my notion. My experience is mostly modeling parts for eventual desktop printing. In that case, a scale larger than life is best—often 100 or 1000 to one. With what you’ve mentioned, to scale makes the most sense. Luck!

I didn’t do track design in SU, but do a lot of structures. SketchUp likes to work in 1:1. I don’t have Layout since I’m using SU Make, so to make scale drawings, I put it in parallel projection mode, present the views face on using the pre-set views, and screen print each view. I then import those images into Adobe Illustrator (can’t scale in AI) where I’ve preset guide lines conforming to the over all dimensions of the SU model where I do the 1:48 (O’scale) division. It works very nicely and gives me very accurate (worthy of laser cutting) images that I can turn into masterpieces.

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