Printing Multiple Scales from a single 3D model

[oorail]

I model in OO scale, but I thought I would do some experiments to see if I could easily print some of my OO scale designed 3D models in other scales, and how to go about that easily.

 

I had some pretty good results,  so I put together an article that details the math and a video showing the time-lapse which you can find at https://oorail.co.uk/one-model-many-scales/

 

The formula to use is:

 

(original scale / new scale) * 100

 

So to convert a OO scale model to HO scale, you would use 76.2/87 * 100 = 87.586%. You then drop this percentage into the scaling option in your favorite slicer, and you now have converted the print to your scale.

 

Obviously the quality of the CAD model will determine your mileage with it, but I was able to use the speed restriction sign designed for OO scale in O scale and all the way down to N scale on a Creality Ender 5 printer with Hatchbox PLA.

 

Thought this might be of interest especially for folks who can't find something in their desired scale.

[JimFin]

Done that with some Swiss buildings, HO down to N and it largely works. Need to be careful with fine detail e.g. window mullions and even wall thickness to ensure they translate with a simple % reduction. Needs a little tweek occasionally. Would expect the same is treu scaling up, some detail may appear a little course and need to be refined. Having adjusted in the slicer, its worth checking the layer view to make sure you get all the detail you expect and may need to adjust the model before checking again. 

 

HOm (1913)

 

 

Nm (Current)

 

[Arun Sharma]

There are a few aspects of rescaling you might need to consider if you are producing say, masters for resin casting. Rescaling will naturally also rescale wall thickness and not just length etc.,  Many resin casters will advise a minimum wall thickness of say, 1.5mm which if reducing a model from 1/76.2 to 1/87 may require some walls to be selectively rethickened.  Similarly, grooves and panel lines may cause a surface to be significantly weakened and begin to flex when the surrounding structures are thinned. This is obviously more of a problem if reducing from 1/43.5 to 1/76.2

 

Devices that are inherently thin castings such as tram bow collectors may need to be redrawn as non-prototypically thicker as they might not survive the printing process. It may be necessary to print such reduced scale parts as FDM prints rather than acrylic resin parts. Similarly, rivet detail in 1/43.5 scale where you have rivets that are 0.45mm dia and 0.3mm tall almost vanish when scaled down to 4mmm scale.