SP Jawbone Branch (Part 21) - Bolting and Aligning the Modules

April is here!  The concept for my SP Jawbone Branch layout is now five months old.  The first two or so months were spent developing and refining the concept and track plan.  January saw the materials purchased and the cutting start.  The construction began in earnest in February.  March saw more construction and the structure of the first four panels nearly complete, plus the wall mounting brackets fabricated.  To see the complete list of this blog topic, see my SP "Jawbone" Branch Index Page, which has links to each part.

Overview of the four main modules assembled and resting in place.

The layout has finally reached the point where it can be assembled!  During construction, I've been using clamps to pull the modules together.  This took time to align and keep tight.  Clamping the Owenyo (upper level) fouls the lower staging yard at Mojave, so this will not do for the completed layout.  Therefore, last major structural step to figure out is how I will be bolting and aligning the modules to one another.

Drilling Holes

Hardware

1/4-20 bolts with and without nut and washers

For my bolts I selected 1/4-20 bolts, nuts and washers.

First a Jig

I would like to have alignment pins between the panels.  I've picked up some telescoping brass tube and 1/4" brass rod.  To have the best alignment of the bolts and pins I plan to use a jig. 

My new Drilling Jig.

Lacking any hard wood scraps to hand, I pick up a larger piece of MDF 1/2" scrap and drill two holes in it.  Increasing the size of the holes to match the size of the larger tubing.  The tube will be used as a bushing to guide the 1/4" drill bit which will locate the holes in the end plates of the modules.  The holes need to be kept clear of my 2x2 corner blocks, so in someways these holes need to be set in from the edges of the modules a fair distance.

The Jig is clamped in place on the module end.

The alignment of the Jig is critical in the next steps.  Each module joint will be matched to its other half, more-so than a 'standard' which would allow completely interchange abilities between modules.  Ideally aligning the parts with another piece of material, but I simply used my finger to feel the clamped edge and adjust until it feels smooth and aligned.

With the jig in place, I use my drill motor and drill through the bushed guide block.  The outer holes will be sleeved with the tubing for the alignment pins.  The inner pair of holes are for 1/4-20 bolts.

The west end of Owenyo #2 module

The holes look pretty good.  I ream the holes to increase the size of the holes to 9/32" with another drill.  The brass bushing tube is now slipped into the holes.  I used a small amount of Gorilla Glue to bond the tube to the end plate.  This is a lot of extra work if the bolts will be good enough, but it does look very nice.

End plate for future Owenyo #3 module

At this point, I might as well drill the Owenyo #3 end plate, which I have already made several months ago during the early construction phases.

Owenyo modules jointed and bolted in place.

The 1/4" bolts are fitted and in place.  The modules are held with the friction, I may increase the size of the washers, but at this point the bolts are not under much force to clamp and distort the frames of the modules.  

A Word of Warning

Ah... oh well, I did put the Jig on backwards once! - Oops

It would seem on one clamp and drill cycle, I wasn't paying enough attention... and didn't translate the block correctly to the Owenyo #2 module.  Thankfully the only issue with this is the requirement to reverse the jig, clamp and drill again. - Also a couple extra holes are now in that end-plate, oh well.

Do I Need Alignment Pins?

How well aligned are the modules with just the bolts?  Let's have a look...

Pretty good vertical alignment at Owenyo #1-2 Joint

The Owenyo #1-2 joint is very nice in vertical alignment.  

Mojave Staging joint.  The edges are slightly rough.

The 1/4" bolt with a blind section seems to be doing the job of aligning the modules.

A higher angle view of the Owenyo #1-2 joint.

Well, I found out the track centers that I've marked at Owenyo are offset about 15 scale inches.  Looks like I'll need to resurvey the track centers.

1/4" MDF shims installed along wall to straighten modules.

During the process of checking the clamping of the modules, the alignment of Owenyo #1-2 have shown a problem with the wall.  The wall is not straight!  I loosen two of the wall brackets and insert 1/4" MDF shims.  The wall brackets have a flange to catch the module's frame.

Thankfully, the 1/4" shimming was enough to allow the modules and the surveyed center lines to come parallel again.  Now I only need to adjust the track centers 15 scale inches.

With the main construction of the Owenyo modules reaching a stopping point, it is now time to dismantle the upper deck of the stacked layout.

In Closing

Mojave Staging Yard track laying starts next!

Coming up next, the flex track shipment has arrived... Time to start laying the staging yard trackage!

Jason Hill

Related Articles:

SP "Jawbone" Branch Index Page - Links to all my blog posts on my new Jawbone Branch layout.

SP Jawbone Branch (Part 19) - Owenyo #1 Secondary Bracing and Wye - Construction continues.