O Scale Modular Tunnel Portal for Lionel or MTH Trains

thingiverse

This is a tunnel portal for O Scale Model trains like Lionel or MTH. The exterior dimensions are based off the MTH single and double track tunnel portals, while internal dimensions have been expanded to give more room for trains when installed near curves. A modular design allows printing on smaller 3D printers like the Davinci Mini. Assembled internal portal dimensions are: 217mm double track width or approximately 8.5 inches 127mm single track width or about 5 inches 146mm height or roughly 5.75 inches Base pieces and rear connectors can be printed without supports, while upper sections and keystone need supports for printing. I used a .2 resolution with 15% infill on my Davinci Mini and achieved good results in about 20 hours. After printing, assemble parts with gorilla glue. Connectors snap in well but may require gluing for added security; the keystone must be glued into place. I updated the keystone_blank.stl file by removing personalization and recessing it instead of making it protrude. This design improvement enhances overall appearance. My printer lacks a heated bed, resulting in top-right and top-left files pulling up during printing. Rafts are optional for these parts if excessive pull-up occurs; I can live with the minor imperfections. Update 3-16-2017: I added an alternate double portal top that integrates the expander into top left and right parts, eliminating seams when using the keystone. These new files are solid. After experimenting with several prints, I found that printing at .2 resolution with a 10% honeycomb infill reduces warping significantly, using nearly the same amount of filament as before. New file names include: top_left_double_solid.stl top_right_double_solid.stl Based on my experience printing two singles and one double portal, I recommend printing connectors and bottom pieces at .2 resolution with 10% infill without supports. Top portions require .2 resolution with 10% infill and supports due to curved surfaces and cavities. For the keystone, a .1 resolution with 10% infill and supports is recommended after adding text. Print Settings: Printer: Davinci Mini Rafts: No Supports: Yes Resolution: 0.2 Infill: 10-20 Parts needed for a single track portal: 2 bottom (repaired).stl pieces 2 connector_small (repaired).stl pieces 1 connector_big (repaired).stl piece 1 top_left (repaired).stl piece 1 top_right (repaired).stl piece 1 keystone_blank.stl piece Parts needed for a double track portal: 2 bottom (repaired).stl pieces 2 connector_small (repaired).stl pieces 2 connector_big (repaired).stl pieces 1 center_expander (repaired).stl piece 1 top_left (repaired).stl piece 1 top_right (repaired).stl piece 1 keystone_blank.stl piece