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SJP.St18 On30 Southern Pacific narrow gauge 4-6-0 No.18

SJP.St18 On30 Southern Pacific narrow gauge 4-6-0 No.18

3D Printed Kit

Regular price $63.24 USD
Regular price Sale price $63.24 USD
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This is a conversion kit to turn the Bachmann On30 4-6-0 into a credible model of the SPNG #18. Because the Bachmann prototype was about 10%-20% bigger than the #18 it is not an exact model and some compromises were made to make it look right and still fit without cutting up the chassis.


This model includes a boiler, with domes and stack, smokebox front, air tanks and cab. It reuses the drawbar attachment and can use the original headlight mounting bracket and other details from the donor 4-6-0. You will need three M1.6x10 screws and nuts to mount the boiler. The cab (SJP.Cb07) can be mounted by reusing the original mounting screws or M1.6 or 0-80 screws.  There are provisions for 3/32” rods to stiffen and add weight to the boiler shell.


Also available is the matching cab (SJP.Cb07), an SPNG style pilot using On3 coupler height (SJP.Ax39), a correct length whaleback tender (SJP.Tn07), and an air compressor that fits the bracket on the boiler (SJP.Ax21), but many other air compressors should too.

This 3d printed kit includes the following parts:

  • 1x SJP.St18p4 SPNG 4-6-0 18 air tank L (ABS, 10.1 × 48.3 × 10.7 mm)
  • 1x SJP.St18p3 SPNG 4-6-0 18 air tank R (ABS, 10.1 × 48.3 × 10.7 mm)
  • 1x SJP.St18p2 SPNG 4-6-0 18 smokebox front (ABS, 33.0 × 7.2 × 33.0 mm)
  • 1x SJP.St18p1 SPNG 4-6-0 18 boiler (ABS, 58.7 × 167.4 × 71.9 mm)
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Made-to-Order Manufacturing

At 3DPT, every model is manufactured to order rather than pulled from warehouse inventory. This approach allows us to offer an extensive catalog while ensuring each piece is produced with the care and attention it deserves.

Most orders ship within 7-14 business days. However, larger models, complex projects, and high-volume orders may require 4-6 weeks or longer due to extended print times and production requirements.

While extended lead times are uncommon, they may occasionally occur during periods of high demand or due to circumstances outside our control. We appreciate your understanding as we continue our mission of preserving transportation history in miniature through high-quality, made-to-order models.