SP Jawbone Branch (Part 47) - Owenyo 3rd Module Construction

In the last couple posts I've been researching and pondering the finalized design for the modeling of Bartlett.  However the next step in construction really is building the frame for the Owenyo #3 module.  I've called this module Owenyo #3 in previous posts, as I was numbering the modules from the east-end of the branch.  This module is required to start working out the door-crossing removable module.  So eventually I'll need to get the other end of the removable section sorted out, and that will require Bartlett.  Those steps are still a little way down the road.

Constructing Owenyo #3 Module

Owenyo #3 Module CAD Test Assembly with OTT - 2024-01-28 with rough plan for the foam scenery.

I've been working out structural design for several months, really since almost 9 months ago, how I will be building this module.  This week, I finally started construction of the framing for the west of the three Owenyo modules.  For the back right corner of the module, which will go into the corner of the room, I lapped the two layers of 1/4" MDF, so that neither had a full butt-joint into the other frame strip.  When construction is complete, I can also glue in a section of MDF gusset or 2x2 to support the corner.

View from above, higher than normal viewing angle, but to show rough planning of the structure.

The other challenge is that I want to model a small culvert (bridge) just about the same place that the curve spiral is and the vertical easement into the 1.25% grade is.  That's really too much to ask the sheet of 1/4" MDF to do cleanly and smoothly with just riser supports.

So for this module, I'll be switching over to "spline" roadbed construction, but retaining the top cover piece of roadbed.  I believe that the spline-construction will allow me to 'sculpt' in the vertical transition to the grade and the curve, which is also going to have to be twisting in shear so that the rails are still cross-level after going through the nearly 90 degree corner, and establishing the 1.25% grade.

The underside of the planned structure - wire frame to show shapes without the shading.

The underside rendering of the design shows where the complexity comes it.  The spline roadbed will have to notch, or 'hop' over the front frame rail.  There will also have to be some fancy spline and grade work under the spur rolling over and forming the curve to align with the Owenyo Transfer Trestle structure.  For sake of my sanity in the CAD program, I only made the CAD drawing for the critical and weird parts of the construction.  I'm sure I'll be putting in more diagonal "web" bracing and stuff under there as well.

Cut & Glue Time!

This is the rear corner with the 1/2" plate (at right) abutting to the west end of the Owenyo #2 module section.

I'm returning to the previous method of using Gorilla Glue to bond the MDF sections together.  This is an expanding epoxy-type construction adhesive.  It requires clamping and holding the pieces until they dry.  I'm using the 90-degree corner clamps to hold the angles correctly.  In the later construction steps I'll be putting in corner gussets to support the joints, and when the module's done there will be foam scenery filling most of the internal area of the module.

This is the interior joint of the front frame member bonding to the right outer frame member, forming a T-corner, against the wall. - Top view

The structure is made up of a mostly standard frame-work like my previous four modules have used.  As this will be the first corner module, plus the transition to a 1/25% down grade, I'm having to work out the supporting structure, and keeping it square.  Every time you build a section or module and induce a warp or twist into the pieces that make it up, that piece will try, in return, twist the rest of the structure until the whole structure finds an equilibrium.  So all of that will have to be planned into the design, while at the same time correctly allowing the track supporting roadbed to twist and change to the grade, while on a 48" radius curve.

Back right corner, two layers of 1/4" MDF lapped and glued.

This back corner will also have to be secured vertically to the rear support bracket of the staging yard, while I still plan to have another bracket between the window and the door supporting the right wing of the corner module, I'd rather have it extra secure.  I also did the same thing, attaching the Owenyo #1 module to the wall, because of the weight of the extra supports and the cantilevered wye that can be attached.

The completed T-joint forming the front strip (left) and the right wall (right) - This is the bottom view.

This completes the basic four cornered 'box' frame which will be supported from below, as on the other Owenyo modules, and fit over the top of the Mojave staging yard below.

Always Planning Ahead

The frame of the new module is still rather fragile, without even any cross-members.

On the east end of Owenyo #3, I'm adding these small 1/4" MDF gussets to support the corner.

The final front strip will lap over the outside of the heavy 1/2" MDF mating plate to the Owenyo #2 module.  I can't really fit that strip, as it will be forming the front fascia of the whole module, curving and changing grade and also forming the terrain profile.  So I'd rather wait until much closer to the end of construction to install that piece.

Before I glued up the rest of the frame, I cut these slots for the future spline roadbed to mount to the end plate.

I'm planning to build the spline roadbed out of multiple pieces of 1/4" strips, so I made a set of 1/4" slots in the end plate for the spline ends to lock into.  Then I should be able to bend the strips into the desired spline shape with a couple other pieces to hold the shape I want.  There'll be a fairly short straight section, before the transition to the curve.  That should allow the bond between the splines and the end plate to be strong.

Mocking Up in Place

At this point I realized that the room is about 1/4" out of square at the long-wall window joint, so it introduces about 1/8" skew into this module's frame, which while annoying, isn't going to be a problem if I glue up the rest of the diagonals to hold it in this alignment.  Notice the clamp at the front edge of the mating plates at left.

For now an extra 3/4" plywood bracket arm is clamped to the right frame strip.

The clamp at the right side here is to help hold the module level and in proper position to start building the rest of the diagonal supports into.  

In Closing - For Now...

The outer framework over Mojave staging yard mocked up.

I think I'll leave the blog post at this point for now, and when I post on this again, hopefully I'll have more of the frame's diagonal supports and outer frame around the corner with the 0.65" grade change by the end of the module worked into it.

Jason Hill

Related Articles:

Jawbone Branch Layout Build Index - Master list of previous blog posts on my Jawbone layout.

SP Jawbone Branch (Part 46) - Printing Full-size Bartlett Template - Previous post in the series...

SP Jawbone Branch (Part 35) - Cutting Out Owenyo #3 Module - Last post on Owenyo #3 from 2022, on Aug 30!  Wow, that seems like such a long time ago.