Fairlie Merddin Emrys

5.3 Cylinders and rods

Work on the cylinders is a bit tedious. It starts with deciphering the instructions [30]-[32].
	The cylinder back casting was a mystery to me. "Solder the gland". I did find separate glands on the casting sprue. But there was a gland on each cylinderback casting already! Although the drawing in the instructions showed the cylinder back from the rear it suggested there were two parts, forming exactly what I had here in one part! I inquired at EDM Models, and again the answer was swift. There had been a design change and later kits contained a complete casting. So I could skip the instruction to solder the the gland.
	[30] I merely had to ream the gland to the size that the piston would fit. I did not drill as I think that is too inaccurate. Reaming gives you more control. Before reaming first see to it that the piston is freed up from any casting marks. File and sand it as round as you possibly can.
	The castings themselves were rather crude on the back side which was to fit in the cylinder etch. In the middle was a round form that was probably intended to fit in the corresponding hole of the cylinder etch. So far so good, but there was another embossing which made no sense. As the instructions were unaware of this new casting I was on my own again.
I decided to file it flat. That was easier said than done. After filing the edges of the casting would still not sit flush in the cylinder etch.	So I chucked it in my drill stand and carefully milled the offending raise in the middle. Although this helped it was still far from a good fit

	Then I chucked a wooden pin in my drill moved the cylinderback on it and secured it with a drop of AC. I have a lathe chisel which I bought for just this kind of situations. Brass is not overly hard and for a simple, not too accurate job the brass can be turned freehand. No, I do not have a lathe. This simple way of working sufficed so far and need of the hobby so far did not justify the heavy investment in a lathe. If you have one if anyway this would be the better option of course, but you can solve this without one.
After reworking the back and narrowing down the centre emboss there was a good fit. Any remaining crevices will be filled when soldering.	While at work anyway I did all four and stored two for the time being.

	[33]-[37] Cleaning, drilling and polishing resulted in two bright and shiny piston rods. There is no need to polish the crosshead itself as it will be painted black later.
	[39]-[40] Making the connecting rods and splaying out the end
[41] After cutting out from the etch the rod is folded and soldered	and the big end's extra layers are folded and soldered.
	To bend the fork I soldered two layers of scrap etch (2 x 0.5 mm) together and filed the leading edge by 45 degrees from both sides towards the middle. This way it acts as a self-centering separator for both legs of the fork.
Like this. I fitted the separator between both ends of the fork, pressed hard and used a pair of pliers to close the fork	Tada, almost perfectly symmetrical.
The connecting rod is then decusped, filed and sanded with 400 and then 800 grain emery paper and finally polished up with steel wool. Sounds like a lot of work, but in fifteen minutes you have a nice and shiny connecting rod.	The instructions do not mention the little notch that can be formed by NOT filing the etch tab away that sits on top of the big end. Fill it with solder and file to size to mimic the the oil cup on top of the big end
	[42] Finally the rear of each fork was countersunk so the bolt will later nicely settle in. Not though that from now on the connecting rods are handed, so for each power bogie you need to make one left and one right connecting rod (with the oil cup on top)
Ain't that a nice set?
	[48] The slide bars are separated form the etch
	and each set is split in two.
	Soldering was easy enough. The resulting slidebars were again sanded with 400 and 800 emery paper and polished with steel wool. See to it that the pin protrudes from the bottom of the bar. "Bottom" is a matter of opinion, so it is the entirely flat side on which the crosshead will slide.
The previous photo dates from 20 January 2016. After that the work pretty much stagnated because I was busy creating my long overdue display cabinet for my collection and finishing my AD60. Once that had been settled spring found its way through the clouds and my professional work needed much attention so work on the Fairlie halted. It wasn't until 23 April, three months later, until I resumed work, I found myself puzzling between the bits and pieces wondering where I'd left off.
	The first thing that struck me when I mounted the slide bars onto the cylinder casting is that the lower slidebar appeared shorter than the upper one. I reread the instructions and finally the intention of it dawned on me. Instruction [58] reads: "At the end with the hole closest to the end leave 2mm of pin showing" If you scroll two photos back you can see that I snipped the pin at the wrong end on three out of four slide bars! Well, some muttering and soldering quickly corrected that. So: make sure that the you keep the pin protruding in the hole that is closest to the edge of the outer end of the slide bar!! It is in the instructions but it didn't ring a bell in my mind.
	From hereon I could continue. The first slidebar was carefully measured with a square to get it right in all dimensions. A quick pass with a hot soldering iron fixed it in place. Check with the square to see if you did it right
	Beforelong the other three slide bars found their final resting place. Check if the crossheads pass freely between the bars.
	This checking is easier said then done. At first the crosshead certainly wouldn't fit over the slide bars. So the slide surfaces of of the crosshead needed to be filed with a needle file until the crosshead fits over the slide bars. Work on it ever so carefully as the crosshead castings have only so much material. Keep the slide surfaces square and file no thinner than absolutely necessary, just enough to ensure free running. The more accurate you work, the less play there will be and the more beautiful the crosshead will slide without jerking or wobbling.
	Then fit the cylinder assembly in the frame and test if the crosshead still runs freely once the slidebars are placed between the notches of the bracket. One crosshead continued to slide properly, the got stuck near the bracket. I measured the distance between the slide bars and found it to be 4.7 mm at the cylinder end and 4.5 mm at the bracket end. I carefully filed a little material away from the notches to make up some space and then the crosshead ran flawlessly.
But why did I get this difference between the cylinder end and the bracket end in the first place? So far the kit has proved to be extremely accurate and any differences in size where my own fault. I suspect I did not pay enough attention to carefully and accurately folding the notches out. Such small pieces have quite a large margin to fold and allow quite a difference in the end result depending on how you work. So when building the next bogie I will pay extra attention to the bracket.

Before starting final assembly of the power bogie a host of small chores need to be done on the running gear, that is the coupling rods, the wheels etc.
	First thing is to make a set of coupling rods. The procedure is very similar to that of the drive rods: fold the thick rods over and solder them. Then fold the thin rod ends over and solder them. The only thing to make sure is that you end up with two handed rods
	The left rod (top) and the right rod (bottom). On the cylinder end (right side of the photo) the outside is not provided with a thin sheet. This to save space as vlearances appear to be very tight in the area of the crosshead, so warns the manual.
The completed drive and coupling rod and their bushes.
	Next the crankpins are insreted. BEFORE you do that however make a countersunk hole in the rear of the wheel in order to let the head of the bolt sit entirely flat on the wheelface.
	Like this. This is the completed leading wheelset