Well, I have been very quiet over the last few months, but some work has progressed. As I noted in October, we had a quite extensive list of snagging to address, not least the crankshaft re-manufacture…. well, while quiet on line, I have made some progress in the background, so I figured an update is in order:
Inspect/fix/remake the Crank
We have sent the crank pattern off for casting (which apparently done) and I am awaiting it’s return imminently.
Meanwhile John Maltby was good enough to line-bore the main bearings in engine using his fine Kearns S-type Horizontal Borer (thank you John).
I will write more on this as we progress!
Plugging the leaks in the Cylinder Relief Valves
One unpleasant feature that emerged last year, was that when warming the engine up (either when starting from cold, or after a period of being stationary) the engineer was subjected to a (very) hot shower, as the water/steam escaping from the relief valves failed to remain inside their cowlings. So I have made some PTFE “compression rings” to try to seal this leak as shown in the attached picture.
Make some Gauge Cocks (to damp the pressure surges in the gauges)
This was a nice job, that went to plan (although of course we won’t know till we are back in the water in April if they do the job.) The primary purpose of these cocks is to almost close off the connection to the gauge, so that the rapid oscillations of pressure as measured from the engine are damped down so as to stop the needles on the gauges swinging wildly about, and instead to show the “average” pressure in each of the cylinders and on the exhaust.
I went for simple taper plug cocks. The process was to firstly make a set of tapered cock “pins” out of brass and then (without resetting the top-slide taper) make a matching tapered “D”-bit to bore the bodies to match.
The D-bit is made from Silver-steel (aka drill-rod) so that it can be hardened and tempered after the taper is turned, and then exactly half of the thickness is ground away, to produce a tool that can cut matching tapered holes in the bodies of the cocks. You can see the D-bit in the picture next to the high-pressure gauge…
The bodies were made from some spare 1″ hexagon brass which I had in the stores. I silver soldered unions onto each body, and then drilled a (small) hole through the tapered pins – taking care to loosen them from the bore, and de-bur the holes in the pin, before you turn them (otherwise the burrs damage the tapered bores. There are small (6BA) nuts and lock-nuts to allow you to adjust the pins to get a good seal.
Make a new ball-cock valve for hot-well.
The idea is that as the plant is condensing the total amount of water in the boiler and hot-well should be basically constant – (with the water being pumped from the hot-well into the boiler and the steam condensed from the engine exhaust being returned to the hot-well). So if you maintain a constant level in the hot-well, then by implication you should also have a constant water level in the boiler (less any leaks, and whistle blowing). This should remove the need for constant “fiddling” with the pump bypass to maintain water levels in the boiler.
The original installation used a commercial float valve (as you would find in a header tank), but, not surprisingly this failed to hold back the 250psi feed-water pressure, so a new valve was needed.
Others had suggested that a suitable plug-cock valve could be made to do the job, but eventually I decided to make one with a piston valve in it, with o-ring seals. Either of these approaches would mean that the pressure on the valve would not significantly hamper the valve’s operation. The picture shows the current state, and I have included a CAD drawing I made when “designing” this valve to make it’s construction clearer. It might yet require that the float is mounted on a pendulum to allow it to fit in the hot-well.
In practice, this required a slight redesign, to increase the leverage of the ball, to reduce stiction, and a guard to direct the vented water downwards, as it was hitting the cover of the hotwell and then running out and down the outside of the tank.
Make a whistle that whistles!
The whistle on Befur had been profoundly unsatisfactory ;-( , producing no more than an occasional squawk/squeal. My intention was to produce a 3-chime replacement, but I know I had had a lot of problems producing a working one for the Loco, and eventually opted for 3 “organ-pipe” ones for that, but I did not want to do that again, so a simpler single note whistle seemed in order. The length of the “Bell” determines the note, and the diameter of the Bell determines the volume – so this is quite BIG!
So searching the scrap bin produced an old (and unserviceable) safety valve and some brass tube. The steam is injected into the whistle via an annulus formed between the lower body of the whistle and a centre piece known as the “languid”. This gap is only 5-thousands of an inch wide (thickness of a hair), and is shown arrowed in the picture on the left.
The very small size of the gap means that the construction of the languid needs to be solidly located, so it is actually has an extension on the base that is closely fitted into a counterbore in the upper part of the body, with a number of drilled ports to allow the steam through. It also transpires that the the languid needs to sit at just the right height wrt the outer part of the annulus, so it is mounted on a screwed rod, that allows this position to be adjusted from the foot of the body – 10 or 15 thou seems to make the difference between an ear-splitting sound, and nothing at all. Also the vertical gap (aka “mouth”) between the languid plate and the “bell” also seems quite sensitive, and (I think) dependant on the supply pressure, so this is also adjustable via the threaded cap to the whistle.
Finally the Bell needs to sit concentrically over the annulus, so I constructed a small “spider” (a pair of adjustable cross-bars that fit inside the bell to ensure it remains in place.
IF all this works, then I might try inserting a set of plates to divide the bell into 4 compartments, with “stoppers” making each compartment a different length, thus producing the desired “american-loco”-style sound…. but first we need to hear it on steam… at the moment it certainly demands ear-defenders when testing at 150psi on air!
Well, this version did not work well either! So version 3 was made in March 2020, and this does work – the gap (arrowed above) was widened to about 10-thou and this does operate, although it tends to squeal as opposed to hoot – but a result… It would be good I think to install a steam trap in the line, to remove the initial slug of water on blowing….
Attend a VHF course, to get my license 🙂
….I did it!!! Thank you to Glenridding Yacht Club for great organising of the RYA course. After a day of solid cramming, to be able to make a creditable Mayday call (not sure how many people on Ullswater would be around to hear it) I am now a certified VHF radio operator and can use our excellent vintage Sailor VHF transceiver … stressed but happy.