Curved diamond crossings for the M&N RR - Part 2
Sunday, January 14, 2007 at 3:36PM In part 1, I described making accurate drawings of the N Scale curved diamond crossing from digital photographs. In this post I’ll describe how I made the diamond crossing track assembly from the drawings. In subsequent posts, I’ll secure the track assembly in place on the layout and wire the thing up for DCC.
Building the diamond crossing at the bench
Here’s the current construction. I have started to lay rails. Most of my latest efforts were more about taking small steps and thinking the project through based on these initial results. I have changed my thinking about the order of laying rails several times along the way. Here’s the step-by-step details so far for construction of the diamond crossing.
Laying out the drawings
Make a couple of printouts of the crossing, both with and without the picture layer showing the photograph of the layout where the diamond will go.
Mark the tie locations on the drawing with the picture using the Fast Tracks 30 degree crossing tie layout as a guide. Including the picture helps to determine tie locations on the track assembly and avoid clashes with any of the existing ties. Cool!
Pin or tape clear low tack adhesive sheet cut to size and over the drawing on an old cutting board.
I used GBC self laminating contact sheet. I got a pack of 10 letter size sheets for $8 at Staples.
Lay out the PCB ties
The PCB ties should be laid on the rails-only drawing and trimmed to length and gapped before putting them on the non-sticky surface. I was eager to get going and just put them straight onto the photo-drawing covered with the sticky sheet without gapping or cutting them to length. I used wood ties to get the spacing right. I really just wanted to get a quick view of whether this overall approach will work.
Each of the ties were laid in with their top end at the correct location I marked the bottom end of each one with a marker. Each PCB tie was then removed from the sticky sheet and trimmed to length with a rail nipper. You can see the tie end at lower right showing the length marking in black magic marker waiting to be trimmed. The ends of the PCB ties could probably be trimmed more neatly next time.
The wood ties were removed from the sticky film and will be installed later after the rails are in place. The wood ties are higher than the PCB ties and will interfere with the contact between the rail base and the PCB ties during soldering.
Here’s a view with the wood ties removed. Notice that none of the frog locations (where the rails will cross each other) have PCB ties. This is to ensure that the base of the frog is accessible and the bases of the frogs can be soldered later to make them stronger once all the rails are in place on the crossing.
The gaps have been marked and the ties have been gapped. As I mentioned, it’s much better to do this and the trimming before putting ties on the sticky sheet. i.e. put them down once, make the assembly, don’t fiddle with the ties once they’re in place, taking them off the adhesive film is a hassle, takes longer, sometimes disturbs other ties and weakens the film’s grip on the tie.
Cut and solder the live rails in place
Use a Fast Tracks Rail Roller to curve rails to conform with each rail on the legs. Check them against the rails-only drawing from 3rd Plan It. Getting the curves right will make fitting each of the rail pieces much easier. The Rail Roller does a nice job of producing much smoother curves than by hand and does it faster. Did I mention that I really like Fast Tracks!
Mark the crossing locations and the end of the curves (there are no easements on this stretch of track) to identify the transitions from curved to straight rail. This makes it easy to see what is straight and what is curved and it also helps to identify which rail is which since they have a unique pattern of black marks.
I cut the relevant pre-bent rail sections at the crossing point to make the first rail on the drawing. I started with the inner rail on the tighter curve. My approach, at present, is to lay one complete rail on each leg then use track gauges to lay in the second rail on each leg. Lastly, I’ll fit in the diamond.
Notice the stock full length PCB ties at the extreme ends of the legs. The sticky film holds them nicely in place and they are great for holding up the end of rails I am fitting. Without them, rails sit at funny angles and stick to the clear film.
Caution! Some brands of lamination film are intended for use in a heat laminator. When you bring the soldering iron in to solder the rails, the tip is only 1/16” away from the film and the heat may distort your plastic film and ruin the project. I haven’t had this happen yet, so for so good. You can see some minor wrinkling on the right hand side of the photo but it does not appear to be moving the ties significantly.
Sighting along the rails is essential during construction. If your eyes are not what they used to be, like mine, the digital camera is an excellent way to see how well things are lined up.
The inner rail on the tighter leg is starting to come together. In working along the inner rail, the frog points need to be formed as the live rails of the other leg connect at the four frogs. You really have to take your time fitting these pieces. It is fiddly work and you need to be in the right frame of mind to do it.
In the photo below, I laid the rail at the bottom and its mate on the other leg first. I then built the guard rail and formed a nice sharp point with the next section of the pre-curved inner rail. It looks nice sitting in place and it is really important to make this piece in order to get the right alignment of the whole curve.
I made the rail at the top of the photo next but this was actually the second rail to get soldered in. The middle piece is just sitting there for now. I still need to make the other guard rail and carefully get everything aligned on the inner rail AND get the flangeways correct before soldering it in place.
My next post will detail completing the construction phase.
To Part 1: Making accurate drawings of the N Scale curved diamond crossing from digital photographs of the layout.
To Part 3: Installing and testing the remaining live rails.
Reader Comments (2)
Hey, I like that railroller, how does it work ?
It has three rollers, the center one can be moved in and out with the thumbscrew at the narrow end. To curve a rail, you slide it into the rollers and progressively move the center roller in while sliding the rail back and forth. With code 55 it takes about three to four passes. Along the way, you check your rail against the curve you are trying to match.It's a great little device, essential for hand laying.
Steve