Saturday, January 20, 2024

SP Jawbone Branch (Part 40) - OwlMtModels 3d Printed Transfer Ramp

 My current project is starting on a couple of the buildings and structures for the facilities at Owenyo.  The rail transfer ramp, used to load narrow gauge cars onto standard gauge flatcars is the first structure I'm working on.

South-west corner of the ramp with Code 40 rails and wooden retaining boards installed.

The research for the structures at Owenyo has been progressing. In the mean time, I've sent the proof drawings for the Owenyo Transfer Track Ramp or OTTR over to the 3d printer as a proof of concept or test for all the trestle related projects. Can we make them? Will they be good enough?

Newly drafted Owenyo Transfer Track Ramp used to load Narrow Gauge equipment onto Standard Gauge flatcars.

One of the smaller structures at Owenyo, but still very much a signature cornerstone of the railroad facilities to support the SP Narrow Gauge operations was this little ramp for loading the narrow gauge steam engines onto the standard gauge flatcars for their annual trips to visit the Bakersfield shops for heavy servicing and regular repairs.

Prototype Photos & Research

Owenyo SG-NG ramp - Rich McCutchan  - owensvalleyhistory - slim rails63_sml

The ramp is drawn to go down into the sub-grade and after reviewing the photos of the prototype, I'll be modifying my module to fit the changes to the ground profile.  I know of no drawings for this structure, but I have managed to find five or six photos, which taken together with my research of the much larger Owenyo Transfer Trestle, at the south end of town, I believe I've worked out the dimensions of this smaller structure.

First Test Pre-production

Early test print, several minor changes to come before we get to 'production' level quality.

The new year continues the Owenyo Structure's project for OwlMtModels with the first prototype 3d print for the Owenyo Transfer Track Ramp (or abbreviated OTTR).  Note that this print still needs some minor cleanup on the bottom of the main beams, and the bents aren't in final position at this point.  Two of the support beams are doubled up at the left end of the trestle to make it more level for this photo.

There were scaling and some guesses that turned out to be wrong in this version... so I revised the drawings after this first print.  The main stringers were deepened, and the Bent 2 was also beefed up to larger size timbers.

Second Print - Revised Version 2024-01-14
The underside showing the 1/16" magnets installed in bents and caps connecting to the stringer magnets.

I want to be able to remove this ramp deck section from the Jawbone layout modules when it needs to be moved or worked on upside down.  The magnets will also allow me to make fine adjustments to the grade of the ramp as I'm installing it on the layout, while not breaking any glue joints between the stringer beams and the bents.

South-west corner of the ramp with Code 40 rails and wooden retaining boards installed.

This model needed two wooden scale 2x10 strips cut to a scale 9ft long to be installed on the dirt side of the Bent 2, which forms sort of a second abutment at the south end of the 'ski-ramp'.  The strip wood was pre-stained by wetting the wood with water, then stained with Apple Barrel Burnt Umber, followed by a wiping with a paper towel.  Then a repeat with Pavement (dark gray-off black) and wiped off.  I also pre-painted the 3d printed Bent 2 part with similar colors and darkened the end of the main stringers.

South-east corner of the ramp with rail and wooden strips for retaining boards installed.

The Code 40 rail sections are glued in place with thick ACC cement.   About 1/8" of rail extend on the abutment end, which will be fitted with half-rail joiners.  The transferring southern end extends about 1/4" past the last tie, which matches the prototype photos, allowing it to span to the deck of the flatcars.

Test Fitting!

The ramp is dry fitted on the layout, which has a 1/4" depression for SG track.

Time to check it against the layout!  Prototypically installed ramp would be partly buried in the ground at the left end and the Standard Gauge track in the pit to the right accounting for the height of Bent 2 at the right end.

Here a F-70-10 flatcar spotted against the ramp to check the relationship.

The whole OTR will need to be sunk into the layout surface another 1/8" or so, including dropping the SG pit another 1/8" as well, maintaining the spacing height of the top of the OTR and SG track.  Sinking the ramp into the layout will help me get the ski-ramp track down to ground level to meet up with the NG that goes down into the NG pit track at the north end of town.  I may also take the opportunity to cut away some of the other bits of MDF material to smooth out the shape of the ground here, possibly putting in some pieces of pink foam and carve it down to shape to match photos.

In Closing

The short test print section of the Owenyo Transfer Trestle with wooden decking and Code 40 rails.

I'm hoping to be able to start working on the layout more, but I'm being delayed by the cold weather now and another lingering injury from October.  Got to stop getting hurt!  It seems that over half the time since I started the Jawbone Branch layout in 2021, I've been down to heal up from various things keeping me from get back to having fun with the hobby and building the layout!

Jason Hill

Related Articles:

SP Jawbone Branch (Part 28) - Laying Out the NG-SG Rail Transfer Pit - Making the first steps to building the OTR area of the module.

This project is also planning to be released by OwlMtModels on a limited run, reservation basis, these blog posts are covering the R&D process developing these planned kits.