Thursday, March 18, 2021

SP Jawbone Branch (Part 16) - Brackets, Pits, & Diagonal Joints

During the last month I've been working on getting the layout module structures assembled.  The more basic modules have been good practice for the lead-up to the more complicated Owenyo #1 module which will have the removable wye.

Owenyo Yard in place without track... yet.

Much has happened in the last three weeks since my last update post on construction, so let's have a look at what has been built.

Fun with Mock-ups

Mocked up view of the Owenyo #2 with the skin sheet of Owenyo #1 on top before I dismantled the shelf.

The next major step that is required before really mocking up the layout will involve removing is building the wall mounting brackets.  Also I'll need to move my small bookcase back to my mid-room desk from the desk that is under the east end Owenyo.  This is very annoying because only a week or two before I moved this bookcase between these same two desks.

Wall Brackets

One of the biggest challenges of this build is the wall-mounted brackets.  While many layouts are cantilevered off of the wall, the walls in my shop are metal with horizontal 2x2s as the only thing that I can screw into.  They're not on consistent centers.  Also I added ~2" of insulation foam paneling and then 1/2" drywall to finish the walls.  So trying to find the few vertical studs under that is a pain.  Also the nearest horizontal stud, is about 4" above the roadbed at Owenyo... so can't use that unless I want to move the whole layout in 3/4" and shift the backdrop to allow the brackets to come above roadbed level.

CAD drawing of wall bracket concept. - Jason Hill, 2021

My main concept with the layout sections is to keep them with their weight vector vertically down into the support structure.  I don't want to have the actual layout sections taking the shearing cantilever forces.  The small lip at the rear edge to catch the module's frame rails is only to keep the modules from sliding too far away from the wall and possibly falling off the brackets.  (Earthquake territory, it is a possibly).

Bracket arms cut from 3/4" Plywood.

Pilot holes drilled and counter-sunk for 3-1/2" long screws from the back side into the arms.

The brackets are glued and screwed together.

A pile of brackets fabricated

The wall base plate is 3/4" plywood.  On several of the brackets I've later refitted them with additional 'sisters' of 3/4" ply at the wall-arm joint for increased strength at the point of maximum stress.

Stack of five 2x2 Risers for holding the front edge of the upper level layout modules.

The 2x2 on the top of the pile here shots the bracket arm slot at the left and the 1/4" notch at the right for the front rail of the module to sit on.

Bracket 2nd from the West end of Owenyo, west of the western window.  The plate against the wall is stood off 3/8" to catch the layout's rear frame rail.

The 2x2 riser is slotted at the bottom currently for easy adjustment and removal.  As I found installing the first mock ups of the layout modules in place... the wall isn't vertical!  Ah yes... second hand material sheds with 2.5" of stacked insulation and finishing material.  Great, but sometimes not exactly square.  Shimming will be needed to get the layout sections level compared to the brackets.  The 2x2 risers will eventually be screwed in place through the bracket arm once I'm sure everything is in alignment.

Mojave West in place with the brackets and risers.

I double checked the height of the brackets as I was installing them.  Targeting 57" for the top of the upper deck, 2" thick sections.  The top notch in the base plate should be at 55".  The bracket arm should be at 51", maintaining the 6" separation between decks.  This was somewhat tricky to do as my workbench has a 1/4" thick sheet of material in the main work area, which one of the wall brackets will land on.  I would like to have the bottom of the wall brackets land on the work bench where possible to keep loading forces vertical into structures below.  The lower bracket arms come out at a nominal 13" above the base plywood work bench.  I literally checked and rechecked this dimension a dozen times.

Testing stacking of West Mojave with Owenyo #2.  So far it hasn't fallen down!

Several brackets had to be modified as they landed under support structures of the layout modules or other extenuating issues, like the wall not being straight!  The great ideas of putting 1/8" backdrop panels in behind the upper layout sections will have to be looked at again as the wall actually pinches this planned 1/8" gap in several places.

Customized Bracket

Special off-set bracket is needed for the east side of the east window under Owenyo #1.

As I started working on the brackets for Owenyo #1, I found that the bracket attaching right at the edge of the window could easily be adjusted to support both end-walls of Mojave Mid & West modules.

This customized bracket is placed to have the ends of the Mojave staging modules land right on it.

Of note here, the end pieces are 2" high, therefore the bracket needs to be 1/4" lower than normal and the top slots should be 6.25" for this bracket.  Note this bracket has the sister 3/4" plywood block attached and additional screws to keep everything together.

A panel of 2/4" ply is screwed to the east wall of the shop.

I decided to not try to attach a normal wall bracket at the far east end of the room.  A larger chunk of 3/4" plywood will work instead.  The lines on the wall are marked with a level to keep track of the heights.  I'd rather not put additional brackets on the wall in this area, as I'll be wanting to put a custom book case in over the desk to avoid the curve coming out of the Mojave staging yard.

Cutting Out Pits - Owenyo #1 (East Owenyo Module)

SPNG "Pit" Track

Far east end of Owenyo #1, which has SPNG ramp down into the fuel & oils transloading "Pit".

For a little scenic interest I decided to slot the NG track as it hits the backdrop wall to drop into the SPNG "Pit" track.

Here's the roughed in SPNG "Pit" where it lands into the far eastern wall of the room.

This may be slightly too fast of a transition, but I can always fill it in a bit and adjust it.  Thankfully the SPNG is not going to be an operating set of tracks, but simply static operation scenery.

SPNG Loading Ramp Pit

Here's the SPNG to SPSG transfer ramp cut lines.

However the other "pit" at the east end of Owenyo is the loading ramp where the NG runs up a section of trestle and the SG is slightly depressed into a pit below normal 'grade'.  This will need to be in the range of 1/4" drop, so again I used the 'cookie-cutter' style cut with sabersaw.  I drilled a clearance hole which would accept the sabersaw blade into the middle of the sheet.

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

Here's the picture of the NG side of the ramp.  The SG track is down in a slight pit as well.

Here's the roughed transfer ramp.

At this point the SG pit is deflected by a piece of scrap styrene.  I'll be doing a more permanent method of deflecting it down as I build the structure for the section.  However, working further on this small bit will have to wait until later.

Structure for Owenyo #1 (East Owenyo Module)

A stack of the parts to assemble the bracing under Owenyo #1.

Several weeks ago I cut up the diagonal braces of 1/2" MDF along with the end plates.  I shaped the ends to match how they will mate up to the rest of the structure.

The main diagonal supports, sitting in place.

Owenyo #1 module differs from the other three panels basic I'm building in that Owenyo #1 will also need to support a module fully cantilevered off the front edge of the layout forming the wye.  

The diagonal braces will land into this heavier back block against the wall.  The marked area will be cut out to fit the "wye keel".

To support the removable wye, I'm planning to build in several heavier diagonal supports and a long "keel" beam which will slide in from the wye module.  This structure will require the front edge of the cantilever to be strong and have a hole for the keel to enter the Owenyo #1 structure.

Lap joint of the 1/4" MDF in the corners of Owenyo #1 module.

On the Owenyo #1 module, I've decided that it definitely needs extra strength.  I will be putting in a second layer of 1/4" strips of MDF along the length of the module.  Given the size of the layout I didn't want to buy a larger sheet of thicker material to make these thicker frame rails from.

The west end-plate of Owenyo #1 is slotted for two 1/4" frame rails of MDF to mount into.

There will be secondary bracing of the type that I've installed on the other modules, which will be placed on the guidelines.  I've laid out several arrangements for these, so there are duplicate lines.

Mock-up of the structure.  The diagonal joints are requiring some careful marking and cutting.

The front frame rail is split by the pocket for the wye keel.  This area will have a heavy plate added to the bottom of the structure to handle the forces.  The front frame rail is cut down to accept the plate underneath, which is 'top' in this photo.

Closeup of the diagonal joints

The diagonal frame joints have been cut so the frame rails will have continuous structure against the top skin, and the diagonal braces have the lower structure continuous.  Keeping the diagonal compromised at the upper side I believe is preferable, as they will be glued to the top skin for the entire length, which should hold the top-skin in tension.

Another view of the diagonal joints.

I plan to sister these joints with blocks of 2x2 like I do on the other modules.

Another view of the mocked up structure with the diagonals notched to interlace with the front frame rails.

Time to double check that everything is in order before I move to the next step.  Given my limit of five smaller clamps and five large clamps, I can't do large numbers of parts to glue at once.

Time for Gluing Up!

Everything looks good during the dry fitting, so it's time to apply the glue and clamp everything up.

Clamped up during the gluing of the front frame rail and diagonal supports.

I started by gluing up the doubled frame rail.  Then once that is starting to bond, I applied the glue to the eastern diagonal brace.

Sistering the front frame rail and clamping everything up while being glued.

Second diagonal being glued and clamped in place.

Now the eastern diagonal brace is glued and clamped, the western diagonal brace is also being glued and clamped.

Second diagonal being glued and clamped in place.

Well, nothing left to do again... just wait for the glue to dry....

Test Assembly of Owenyo #1

Completed diagonal and front frame rail glued in place.  The 2x2 is notched to accept the diagonal supports.

Surprisingly the structure of Owenyo #1 is actually quite strong already with the doubled frames and the diagonal 1/2" braces, but no additional 'normal' structure.  I certainly will be putting in the secondary bracing trussing, which will also support the SG transfer ramp pit.  The rest of the special supporting structure for the wye-keel still needs to be installed.

Closeup of the riser 2x2 notched for the diagonal support as this is the main structural member here.

The 2x2 riser under the diagonal turns out to be very strong, so I'll probably just be cutting the rest of the support plates to go around the riser so it can't shift.

In Closing

Owenyo #1 & #2 clamped together.

The next major step will be drilling and sleeves for the pins and bolts to hold the layout modular sections together.

The track materials are on order and I'm waiting for them to be delivered.  I am not going to be installing the track before getting the modules aligned and mounted.  The track alignments will need to be done in place.  I'm looking forward to getting on to putting down the track, but it's probably good that it's not arrived yet.  This forces me to get the structure of the layout built properly.

Jason Hill

Related Articles:

Jawbone Branch Index Page - List of all my SP Jawbone Branch modeling posts.

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