Page 11 - January February 2017

At a late stage in my track laying, I needed a wye turnout, at the top of the Big Hill, just before the entrance to the spiral tunnel. My track is Micro Engineering code 55. Two points were required, one left and one right to precisely fit existing curves, and be compatible. There was only one alternative. I had a thought of taking two lengths of code 55 and combining them to form a wye shape with exact radii:-
Take two pieces of track, long enough to form our wye-shaped point, about 20cm (8"). Place side by side, and cut the two inside rails with a Xuron cutter. See Diagram `A'. The inner ends will form the frog. The outers will become the stock rails.
Now draw, on paper, an exact pattern of the point, the radius and c u r v e of the stock rails as accuratelyaspossible.Foreaseofremoval, spotglue(useEvostick)thepatterntoaflatbaseofmediumbalsa. Alsodraw a straight line from the frog centre to the centre of track at the toe. See Diagram 'B'.
Take one section of track and carefully pin to the drawing using Lill pins. Mark and then cut the track ties at the centre line. Remove track and then repeat procedure with the opposite side. Ties will hopefully butt each other when reassembled. They can be twisted in situ to straighten them. When you are satisfied with the set-up, remove from the base, noting the retaining pin holes. (Use a marker pen if necessary.)
Prepare the underside of the rails to receive four printed circuit board (PCB) ties, to be soldered. They all cross from one stock rail to the other as in Diagram B. Rail positions should be tinned, also the PCBs.
#1 Tie bonds the frog to both wing rails
#2 Tie bonds the 2 switchrails to each of the stock rails
#3 and #4 Ties are soldered to each stock rail, and provide a guide for the point slide bar and therefore extend to one side, and form a location for the switch stand.
The ends of the wing rails are isolated from the switch rails already so a soldered joint is not needed. They should be curved and held to gauge simply by sliding a small section of wood between ties and use epoxy. (Note —Epoxy does not adhere to the Delrin plastic used on the track). The ends of ties must be trimmed as they come together near the frog.
On assembly the ends of the frog rails are placed side by side and possibly brought a little closer by filing the rail flat bottoms.
So far gauge has looked after itself, because it is set by the flexi track moulding, but the triangular frog must be smooth and in gauge when soldered in position. Check this with the NMRA track gauges between the extreme point and each stock rail. After soldering place, adjustment by filing can be done. See Diagram 'C'. For stock rail seating (to receive the switch rails) they should be held firmly and filed on the inside edge to allow the switch rails to bed. The latter also need to filed with a longish taper to a thin blade. For switch rails, I use code 40 strip (.020" thick). It does not have a flat bottom and is flexible. It is soldered to #2 PCB tie with a small piece of copper wire in place to raise the rail to code 55 height. These two rails are held and movedbythe
slide bar at the blade ends, and connected to a nickel silver wire pivot as in Diagram 'D' —Careful soldering! These blades must be filed to a thin section so that they blend with the filed seating on the stock rails. With preparation complete on the undersides, the track should be glued to the balsa base, using the original pin holes but without the pattern. Evostick contact glue is suitable. Thin polythene strips may be used to expedite the correct gluing position. Withdraw the polythene when all is correctly lined up! Don't forget also the 4 PCB ties. Apply even pressure over the complete point to make the final bond.
Wing rails should now be made from code 55. Each rail must be curved to match its partner stock rail. File a nick in the rail base at the point of the bend into the wing, parallel to the triangular frog. The gap here is 0.64mm (.025") for both wings. The wing rails should be held in place, in gauge, and soldered to the PCB tie and the frog. Solder the PCB to the stock rails.
The ends of the wing rails may be held to a thin ply tie, slipped in from one side (remove plastic sleeper moulding and use epoxy to adhere the rail ends).
The slide bar should be made from thin paxolin or PCB with the copper stripped off and fitted between #3 and #4 PCB ties. The slide bar is shown in Diagram `E'.
The slide bar can be operated by several different methods and this can be left to the builder to decide according to their preferred method. I use .010"model aircraft control wire and pull in both directions via bell cranks.
To provide the correct electrical circuit, cuts should be made as shown in Diagram 'B' using a cutting disc in a minitool. The final operation is to tackle all those half ties! Use a slow setting epoxy and mix in some talc to form a paste. Carefully fill the gaps. Place a strip of thin polythene between the switch rails, press pieces of 1/16" (1.7mm) balsa between each sleeper. The polythene acts as a mould and when the epoxy is cured, can be peeled off.
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Rex has also provided the following list of tools and materials used, in addition to any specifically mentionedinhisarticle:- Motor Tool with cutting discs
Soldering Iron 15-25W, Resin cored solder.
Small needle files, emery paper, wet and dry paper Junior Hacksaw
Small drills and miniature hand chuck Screwdrivers, pliers, Lill pins
Two part epoxy resin
Contact cement
Light bench vice
Rex also offers his support to anyone tackling this task and can help with the supply of various odds and ends that m a y b e needed. Please feel free to contact Rex if you are interested in building your own pointwork.
Building a Wye Point Rex Nichamin
ROUNDHOUSE
February 2017 11