Following on from my previous post on the tiebar installation, I have been carrying out testing of the new tiebars and turnouts in situ.
As outlined in a previous post, the wire-in-tube (WIT) hardware were mounted on timber bases directly underneath the spline at each turnout location.
The wire from the turnout back to the lever frame was temporarily connected to the frame using brass screw ferrules from terminal blocks.
During initial testing, I found that length of the vertical drive shaft attached to the brass block had too much flex in it to work the turnout reliably. Due to the thickness of the spline at around 25mm, the resultant drive shaft length was around 30mm. The image below shows the vertical drive shaft and brass block. (Note – image shows the revised drive shaft length)
It was also found that the length of tube attached to the underside of the tiebar was too long. So this was reduced to around 3mm in length.
To reduce the drive shaft length, I realised that a reduction in spline thickness would be necessary at each turnout location.
After carrying out some tests with different drive shaft lengths, I found that a length of around 15 to 17mm operated much more reliably. I decided to reduce the spline thickness to 10mm. This was removed quite easily with my multi tool and saw blade. At one of the other locations, I had to use a router.
Once the spline was cut away at each location, the previously made timber mounts for the WIT hardware were re-attached to the spline by gluing in place.
I am quite happy with the result, so the next stage will be to paint the turnouts and fix in place.
I have made a short video showing the turnout operating from the lever frame.
I have made more progress on the Kankool turnouts. I have now fitted tiebars.
I have always wanted to have tiebars that look as realistic as possible, within the bounds of practicality for HO scale and reliable operation.
Some time ago, Rene kindly sent me one of his 3D printed tiebars. I had planned to look at his design and see if it could be adapted to my new track standards.
I put the whole thing on the back burner for a while, but resurrected it nearly 12 months ago when it was getting to the point that I was going to need something to be able to complete the turnouts.
I put the idea to a mate who is a bit of an expert on 3D design. He thought the idea had merit, so I left it with him to come up with a design.
Over the last few months however, I began to have reservations about the 3D print idea. Because the plastic tiebars would have to be glued to the points, I was worried about the mechanical strength of such a bond. Also, as the 3D printing thing is still relatively new, the materials are untested over time. Will they deteriorate over the next twenty years?
When Andrew and I built the P87 turnouts for Bowen Creek, we used thin pieces of printed circuit board that would allow for a soldered joint to the points. So began the manufacture of a prototype.
My design uses brass strip soldered together in a similar design to Rene’s. It still allows the tiebar to slide underneath the second sleeper back from the toe. It also has a drive tube underneath into which the wire-in-tube turnout activator will fit.
I had to have a method of holding the tiebar underneath the turnout whilst soldering to the points. So, using a piece of old melamine shelving, I marked out and routed a recess for the tiebar to sit in.
The turnout was then located over the tiebar and clamped in position.
Soldering the points to the tiebars requires a great deal of care. It is very easy to solder the points to the stockrails! To reduce the risk of this, and also to reinforce the soldered joint, small pieces of brass strip are soldered to the tiebars then to the points. The point is clamped against the stockrail then the brass strip carefully soldered in place.
Once the first point is soldered in place, the turnout is repositioned so the other point can be fixed in position. Again, the point is clamped to the stockrail, and ensuring the opposite point is the correct distance from the stockrail to allow for wheel clearance, the second point is soldered in place.
The finished tiebar! It is then tested for binding and to ensure both points sit snugly against each stockrail. The turnout can then be removed from the melamine base. The plan is to temporarily clamp the turnout in position on the roadbed and connect the actuator and test the operation using the wire-in-tube. Once it is proven to work effectively, the turnout will be painted and prepared for final installation on the roadbed.
A similar recess for the tiebar was routed out in the cork roadbed at each location.