Sunday, June 22, 2014

Stone Arch Bridges, 3d printed, Down on the Farm 10

I saw some pictures of stone bridges, and thought it would be a good learning project for 3d printing.  Here are the two bridges I have done so far.

The back one was just to see if I could get something acceptable, and the front one I am using on my hog farm diorama.  I still don't know where I will use the back one. 

Here is a picture I uploaded in to SketchUp, then I scaled the picture to something reasonable, and used those dimensions to draw the bridge.  

The bridge had to be split in four pieces for printing.  

To get even a quarter of the bridge to fit on the printer, it has to be oriented at 45 degrees on the printer table.  This is a screen shot of the printer software showing a section of the bridge ready for printing.

I added texture to the surface of the rocks by mixing Aleene's Tacky glue to the paint.  That filled in any imperfections in the printed surface, gave the rocks some uneven surfaces, and put some color on at the same time.  The top course of stone was printed separate from the rest to adjust the width to fit the track ties.  I used Micro-Engineering bridge track, but won't add the guard rails until it is installed on a layout.

Down on the Farm #10
I have not been working on my hog farm diorama for some time, and really planned on having it done this week.  Some family things got in the way, but I still hope to have at least the buildings placed for next weekends KC Maker Faire (  I will have a table there displaying many of the items I have 3d printed.  I decided add train tracks to the farm, and since there is a stream through the farm, I was going to need short bridge over said stream.  
Knowing the stream width, I designed a bridge to fit the space.  I decided to add a cut stone with the railroad name to the face of the bridge.  Because the bridge is so small, I did not bother with rock detail under the arch, as it will not be seen.  Also the large bridge above is two sided, so it can be viewed from either side.  This one, because I think I know where it is going on the eventual layout, only needed details on one side.

Here is a screen shot of the Afinia printer software, with the bridge positioned on the printer table.  

The finished bridge except for installation in the diorama.  I added texture to the rock faces by mixing some sand in to some Aleene's Tacky glue.  I looks okay, but if it were a foreground model, it would be marginal.  

A little better shot of the cut stone lettering, and the texture.  The texture would have been better if I had used finer sand.  Next time!

All the Down of the Farm series of posts can be seen at this link:


  1. Nice job Kent. What are the smallest pieces you can make? How about tiny things like roof top vents for H0 Passenger cars?
    Peter B.

    1. Peter, I need some of those too! But the Afinia will not print all the slopes with a smooth enough finish. Hopefully, in about 6 months I will have an SLA printer,, and then I should be able to do them. Keep following my blog, and when I get the Titan 1 up and running, we will see what we can do. In the mean time you could have them printed at shapeways.

  2. what 3d program do you used


  3. Do you mean design software or printer software? I will answer both, but they are very different.

    For design work, I use SketchUp,. For hobby use it is free. Once done, the design must be saved as an STL file for my Afinia printer (and or most 3d printers), and there is a free add-on download available from SketchUp to make that easy. I will be doing a demonstration (teaching) SketchUp in a clinic at the National Narrow Gauge Convention this fall.

    The Afinia printer comes with proprietary software for slicing the object to be printed, and running the printer. I am not a computer geek, so that is why I chose the Afinia. I did not want to try and learn any programming code.