UPDATED on 13 May: A couple of months ago I started to integrate the first spline helix (described in my previous blog entries) into the hidden staging level of the layout. After a couple of weeks, I was ready to continue building the center peninsula from the first 8 foot section that I had finished out to its full length of 18 1/2 feet. It was then that I realized that if I did that, then I wouldn't have any room to build the second spline helix. Thus I stopped what I was doing and started on the second helix.
This is a sketch of the second helix design. The table that it will sit upon is 75" long on the right side as looking at the drawing. It is 48" wide at its widest (each square is 3"). The table on the far left is the adjoining section.
First, I had to adjust the risers on the plywood table that I use to build the spline helix sections and even had to add an extension to one side of the table to accommodate the interface with the hidden staging under the main level on the other end of the layout. This is a picture of the extension. It was necessary to provide the entry/exit route to and from the hidden staging on the other end of the layout.
The learning curve that I went through while building the first spline helix taught me a few new techniques that I will try out during the construction process. The changes are being documented as I make progress on the second helix. Just a couple of tidbits of process changes, include, first - I have built all of the 5 sections of the spline helix and I will be integrating them into the structure rather than building one at a time. Second - I have reduced the number of supporting threaded rods to about half (16 vs 9 pairs) of what I used in the first spline helix. I believe that the stiffness of the spline roadbed coupled with the threaded rod support structure would provide a solid enough platform for N-scale equipment. Also, our local Ace hardware store burned down in February 2013 so I had to find a second source for the screw eyes that I use t hold the threaded rods to the roadbed. I was able to find some on eBay that were slightly bigger both in length and in the eye opening but actually will work better.
Shown below is a vertical picture of the splines aligned using nails in the risers (in case someone was interested). You will also notice that I have placed wax paper on this riser and all of the other ones. The purpose of the wax paper is to prevent the splines from gluing themselves to the risers. When removing the 24 wide section, all that comes up is pieces of the wax paper as opposed to ripping wood from the riser or hardboard from the bottom of the roadbed.
The picture below shows what the bottom looks like. I only scrape/sand the jagged pieces of glue and the wax paper off the bottom of each section. It is surprising how jagged dried glue can be as evidenced by several cuts to my hands which is why I do a little bit of scraping/sanding with the surform tool.
The first picture below is what the top looks like unsanded and the second one below is what it looks like after using the surform tool. It is also a great upper body exercise when using the tool on the hardboard. I use a shop-vac quite a lot when doing this.
Before the spline helix sections can be assembled into a structure, I had to build a table to support it. The following three pictures show the table that was built for this purpose. It is wider on the left side of the picture since it will be where the main level entry/exit will be plus I wanted a little bit of room for a couple of leads or drill tracks for the yard on the main level (yet to be fully designed). The opening in the center is about the same as that for the first helix (48" x 30"). After covering the frame with cabinet grade 3/4" (which in reality is 23/32"), I draw a grid to map the table top to match the drawing as closely as possible. This enables me to align the helix where I want it on the table.
The picture below shows the first level positioned on the table just prior to adding screw eyes to the roadbed and then drilling the holes for the threaded rod. This time I bought longer sections of threaded rod (6 ft) and then cut them to the proper length (approximately 17 1/2"). The longer ones are less expensive (when cut to the proper length by a metal cutting bandsaw) than the 2 footers that have to be cut anyway with the scrap excess pieces thrown away. There is no waste with the longer ones.
Shown below are the spline helix sections 3, 4, & 5. These were all pre-built.
The picture below is a cross section view of the 24 laminated strips of hardboard that are used for the roadbed.
Finally, this is not a picture of a giant horseshoe. It is the pre-built loop that will be placed above the helix to take trains from the main level to the third level that will end up in a "visible staging" yard/city/destination in the center of the peninsula. I had to build this now since after helix # 2 is finished, I will be removing the helix build table from the train room.
Since I just added the second level, I thought that a video would be in order for those that are interested. This video shows my new Walthers N-scale ATSF DL109 running forward and back on the outside track of the double track helix. The video is a little shaky and blurry in places since I could not totally leave the engine running due to the fact that the loop isn't long enough just yet. The spline helix roadbed is 24 strips wide using 1/8 inch masonite/hardboard. It was built on the same 4x8 table with risers at key elevation points that I used in my earlier videos. More pictures and description will be added in the future. Thanks for your interest.
