Short hood test print

Did some work on the On30 road engine that Andrew Gillette and I are working on. Here I am test fitting a test print of a short hood. The cab is an Atlas O scale U23B.

The curves I used on the hood don’t match the larger curve on the chassis .. need to address that (#1 and #2). I also haven’t the curve right to match the opening in the cab. I think I will try scanning the cab opening and see if I can match that curve in Sketchup (#3). The opening at the front of the hood is for a O scale headlight cluster .. Used for SP and SSW locomotives, when full light cluster packs with gyro lights were still commonplace.“


Scanning worked. I tossed a towel over the cab to block the light and got an excellent scan. I then brought it into Sketchup as an image and then ‘traced’ the opening, resized etc.

Second Test Print

Fixed the problems with the earlier print .. and introduced some new ones. When I radiused the edges it thinned the walls. I’ll fix that by making the hood solid and then using MeshLab to hollow out the model.


Just for fun – for the techs/geeks into 3D CAD, here is the short hood .. call it V1D. I made a solid model and then pulled the base down 2mm (pmm) and exported as a STL. Imported into MeshLab and used Uniform Mesh Resampling – settings: Precision % I set to 1, check Clean Vertices and Multisample, with a negative 1mm offset which creates a copy of the mesh 1mm smaller on all dimensions. I then flipped the normals on the copy as this would be the inside and merged the two meshes. I exported to STL again, brought into Sketchup, resized back to the original dimensions (they get lost with all the exporting etc.) and sliced off that 2mm I had added earlier.
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3rd Test Print

Okie Dokie. Gonna post this last pic of the short hood (test print). It would I sprayed a coat of primer on so it would photograph better. You could use some filler and smooth out all those lines but really .. a resin print would be much better/easier .. but the FDM printer is great .. to prototype the pieces for printing on a resin printer better.

I just placed the SP cluster in place .. THAT .. was printed at Shapeways. The small wedge shape at the bottom needs filing off .. that was to fit the wedge shape of the hoods.

Next will start working on the long hood.


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