Spline roadbed Part III …
Well, things have been progressing really well on the spline since my last post. Spline is in place all the way to the first turnout at Kankool now, where I have split the spline. But first, some pictures of the construction sequence so far.
After the two centre strips are in place and glued, the next step was to attach the spacer blocks. These were placed at 100mm intervals.
The glue I am using is a polyurethane product from the SIKA range. I was originally going to use a Liquid Nails type adhesive, but this is not very easy to dispense from the caulking gun and it ‘skins’ pretty quickly once exposed to the air. The SIKA stuff is not cheap at around $15 per 500g bottle, but as I am using only small amounts, I think it will go a long way. It also says, as it cures, it slightly expands into the timber grain to achieve better adhesion. It is also waterproof.
The next step was to work out the position of the bridge. After allowing for the abutments, I worked out where I would terminate the spline either side. Then came the installation of the outside spline strips. These would go up to the start of the bridge only, as I couldn’t see the point in continuing the full spline across the bridge gap, only to remove it later for the bridge. The centre spline however did go across the gap only for alignment purposes for the continuation of the spline on the other side.
The process is quite slow, as I have been allowing at least 3 hours for each glue/clamp process before proceeding, although whilst one section is gluing, I can be gluing more spacer blocks in place for the next section. It all depends on how many clamps you have! I try to glue and clamp as much as I can in one session.
The photo below shows where I was up to on the 18th. Full spline from the storage yards to about two thirds the way along the wall towards Kankool. In the background, note the location of the bridge where the centre spline only is present. This section has now been cut away. Note how nice flowing curves can be achieved with spline roadbed.
During the week, I also erected the next section of benchwork where Kankool will be (well, half of it anyway!). Longer shelf brackets were used here, as this section of the layout will be deeper than where the bridge is. Again, L girders were made from 3×1 and 2×1 DAR pine. Temporary joists were placed to allow for spline construction. These will probably be relocated as I set the elevation of the spline later. Work on the spline continued around the corner and up to where the first turnout will be at Kankool.
Over the last few days, I have been working out how to make the spline through the turnout area. Whilst researching spline construction on the net, I have come across a number of articles which have helped in the process. One of these was very comprehensive, and is here as a PDF. There is a section in the article about how to make spline under turnouts, so I have tried the method which involves splitting the centre spline strips so one continues straight and the other one follows the diverging route through the turnout. Hopefully this is explained better in the pictures below.
As with previous sections of spline, the two centre strips are located on the track centreline and held with nails. I then placed a drawing of the 1 in 8 turnout over the top to work out its location. It was then placed underneath the spline so I could line up the strips. As can be seen, the outside strip has been split away from the other one to follow the diverging route. Then it’s just a matter of starting the spline again within the turnout, all the time holding it in position with nails. Then more spacer blocks and continue on with the spline down both routes. At this point, I’ll only be completing spline up to this turnout, as I want to build the next section of benchwork for the next half of Kankool, so I can get the curve correct and around into the centre peninsular.
Finally, to finish this post, a few shots back at the bridge area. I took the plunge and cut away the section of centre spline through the bridge gap and commenced setting the first section of spline on risers at the correct elevation. Once the first section was cut away at the bridge, I then had to work out how I was going to attach the spline to the storage yard plywood. With the ply being 9mm thick and the foam underlay being 3.5mm, I had to remove 5.5mm from the top of the spline at the storage yard end for about 100mm. I ended up taking the section outside and placing it in a jig to allow a small router to be set at the correct depth. It ended up working out nicely. The spline was then placed back in situ and test fitted. PERFECT!! I then cut some risers from 2×1 DAR and set the height of this section to 42”, same as the storage yards. That means that the grade now begins from the Kankool side of the bridge, as in the prototype. This meant I had to recalculate the overall grade from the bridge to Ardglen in 3rdPlanit, but it hadn’t changed all that much. This section of spline has not been attached to the risers just yet. The first shot shows the spot where the bridge will go, showing completed spline either side. The second shows the spline in its final location on the risers. The third is a close-up of where the spline meets the ply, showing the difference in height to allow for the foam on top of the spline.
Cheers for now.