C2 Project News

Late August 2019

A Bank 'Holiday' is just an opportunity to work harder!

The August C2 working party is normally timed to coincide with the Summer Bank Holiday weekend, and this year was no different. This gives us a nominal three-day working party, but Paul and Dave 1 were available a couple of days earlier, so we turned it into a five-day working party. Plenty of opportunity for making progress.
Thursday was a planning day. Paul and Dave 1 spent time creating a long list of jobs, varying from cleaning things all the way through to complex machining tasks. It means that whoever turns up and offers us their help, we will have a suitable job for them whatever their skill level. The job list has grown to such an extent that Paul moved some of the information off the original whiteboard and onto the second whiteboard which Dave 2 put up for us recently. We now have a separate list of drawings we need to create, as well as an enlarged 'shopping list'. Also on the new whiteboard is Paul's explanation of the C2 Project logo, conveniently below a real Forestry plate from a C2.
By breaking major jobs down into manageable tasks, it is easier to see what needs to be done, as well as quicker to tick the tasks off the list. A good example is the work on the cylinders and motion brackets. Now that we have decided the thickness of the packing plates to be inserted behind these items (some homework Dave 1 carried out since the previous working party), it became apparent that it won't be long before the cylinders can be re-bored. Remove the rear cylinder covers, bolt on the cylinder alignment jigs, take a set of measurements, remove the cylinder alignment jigs, remove the cylinders and re-bore the cylinders. Most of those jobs won't take more than 15 minutes each, so it's definitely time to get the cylinders booked in for re-boring.
While the works' staff were in, Paul and Dave 1 took the opportunity to ask their advice on a number of matters. First we asked Martin when the big horizontal borer might be free. His reply wasn't what we really wanted to hear; the machine is currently out of action. Oh bother! He recommended we talk to Dylan about when the borer might be mended, but also suggested that there may be facilities at Dinas which we could use. We'd rather use the machine which we're familiar with, so we went in search of Dylan, who gave us the hopeful news that fixing the machine is a high priority. All being well, the horizontal borer shouldn't be out of action too long, and we're in the queue for using it to re-bore the C2 cylinders and valves.
Robco was able to assist us with a couple of other queries. According to the original drawings we have, the brake shoes are held in the correct orientation by spring steel strips, to prevent them dragging on the wheels. We need to make replacement springs, but were concerned that applying heat to a strip of metal to obtain the correct shape would reducing its spring properties. Robco suggested that using a strip of stainless steel, cold formed, would probably work. We'll give it a try.

A number of components are likely to require case hardening. Robco advised us that Boston Lodge use external contractors to carry this out when required. He also advised us to use nitriding, as it avoids distortion of finished components. Also, nitriding can be applied locally, by masking off parts which do not require hardening. Very useful advice.

Paul was rostered to drive the 'Chippy Train' on Thursday evening, so work on the C2 was finished half an hour earlier than usual, to give him time to get changed. An evening trip up the Ffestiniog Railway to Blaenau Ffestiniog, to collect fish and chips which are eaten on the way back down the hill, all surrounded by beautiful Snowdonia scenery. It's one of the things which makes the Ffestiniog Railway special.
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Paul at Blaenau Ffestiniog with the rest of the crew of the last chippy train of the year: fireman Alastair and guard David.
First thing on Friday, Dave 1, with Paul's assistance, removed the rear cylinder covers. In their place were attached the cross shaped jigs which Al had made. The jigs (attached to both front and rear of each cylinder) have an accurately bored hole in their centre, through which a stainless steel rod is passed. It is common practice to use piano wire (light but very stiff) to extrapolate the cylinder centreline to the driving cranks, to check alignment, but we decided to use more modern technology. Al has provided us with a laser pointer, which was clamped to the stainless steel rod. After adjustment of the laser, the rod can be rotated to trace a small circle at the measurement point, the centre of which will be exactly on the cylinder centreline. Using a longer rod wouldn't be possible, because the rod will bend down slightly due to gravity acting on it. Light is rather less affected by gravity, and so for our purposes, can be assumed to always be perfectly straight.
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The X-shaped jigs previously made by Alan locate a stanless steel rod precisely in the centre of each cylinder. We mounted a laser to this rod, allowing us to project the line of the cylinder bore backwards. By rotating the rod the laser point describes a circle and the centre of that is aligned with the cylinder centreline.
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Checking the alignment of the cylinder with the driving crankpin. When the proposed cylinder packing plates are accounted for, the alignment all looks good and consistent with our expectations.
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While the laser setup was installed, we also checked the vertical offset to the motion bracket.
Measuring the distance from the centre of the circle traced by the laser to one of the shoulders on the driving crank, and carrying out a simple calculation accounting for the packing pieces we propose to put behind the cylinders, allows us to check that the connecting rods will be in about the right place. All is looking good. After little more than 2 hours work, we'd ticked off three of the tasks on the job list. Next is to remove the cylinders and re-bore them. Exciting times!

But before we rush into removing the cylinders, we need to do some preparation in the shed. The cylinders are big, heavy and difficult to move, and there is currently not much free floor space. Next job on the list is therefore to have a tidy up in the shed, move items off the floor onto shelves, to create the space we need. Just for the moment we'll leave the cylinders in place on the frames, as it's a convenient place to store them.
Leaving the cylinders in place gave the opportunity to temporarily re-mount the draincock weighshaft brackets and bearings, which bolt to them. This allowed the distance between the bearings (reduced from original because of the re-gauging) to be measured. Dave 1 carried out the measurements while Paul sketched up the interfaces on his laptop. The C2 has a modified draincock operating linkage compared to the original KP-4, with the operating lever now being on the driver's side. With the Polish KP-4 drawings in front of us, it was possible to work out which dimensions had changed due to the Chinese modifications and our subsequent re-gauging. The proposed packings behind the cylinders had also to be accounted for. With everything understood, Paul was able to draw the draincock weighshaft, ready for manufacture.
Another design job relates to the coupling rod knuckle joints. The original design, locked together using taper pins, is very difficult to dismantle. We struggled to do so in the workshop, using the hydraulic press, so it would be nigh on impossible if the need to dismantle a joint due to failure 'in the field' ever arose. A better design is used in the crosshead for the connecting rod 'little end', which has a stepped pin held in place by a cover plate. A similar arrangement is used on the coupling rod knuckle joints of BR Standard steam locomotives, and Boston Lodge has a large taper reamer used for making this type of joint. Inspection of the coupling rods shows that the same arrangement could be used for our knuckle joints, so that's what we propose to do. Erle has started sketching out a joint arrangement, which still needs final detailing, so Paul concentrated on drawing the cover plate.
Thinking ahead, once the motion bracket packing is ready, we will be in a position to bolt the motion brackets to the frames permanently. Due to a quirk of the design, this will also require us to fit some of the brake hanger brackets at the same time, which requires the use of special countersunk head bolts. Dave 1 therefore compiled a list of all the bolts required for assembling the locomotive brakegear. We'll use this to put together a kit of parts, ready for brakegear assembly.
Paul also found time to take another look at the cab window frames. The frame edges slide in runners, but are very rough and corroded. Replacing the edges with T section steel strip will restore the profile. Paul checked the measurements, which will allow the final machining of the T sections which James started a couple of months ago.
As mentioned above, a tidy up of the shed is required, to allow things to be moved about. Sam and Tom spent much of Saturday sorting through the components on the storage shelves, with Paul's assistance identifying what each component is, and deciding what to do with it. Components which we will reuse, such as the chimney and blast pipe, were placed back on the shelves, but arranged in the order we are likely to want to work on them. In an ideal world we would like to keep all components, including those we won't reuse, until their replacements have been made. But pipework takes up an awful lot of space, and we don't have a lot of that commodity in the shed. Giving the matter some thought, Paul and Dave 1 proposed that just the end fittings from the pipework be kept, since the length of pipe in the middle is not particularly exciting. Sam and Tom took turns on the hacksaw (in some swelteringly hot weather) to remove the end fittings, and stored them neatly in boxes. During the reorganisation we rediscovered some parts which we had almost forgotten about, and some of these have been moved up the queue for refurbishment. By the end of the day the storage shelves looked quite empty, but they will soon fill up again when we start moving items off the floor.
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The major reorganisation of our storage shelves has created more space to store refurbished parts, and the remaining unrepaired components are stored more logically.
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This unpromising piece of scrap was the raw material for the new coupling rod knuckle joint pin retaining covers. Hopefully at the next working party we will be able to show the completed machined components.
Chris and Dave 2 arrived on Saturday, and were given the drawings which Paul had created the previous day. Chris found some steel plate of approximately the right thickness, and cut out blanks to make the coupling rod knuckle joint covers. Dave 2 took a length of steel bar, and went into the machine shop to turn the draincock weighshaft.
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Dave 2 machines the new draincock weighshaft.
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Now that we have finalised the packing needed behind the cylinders and motion brackets, we were able to complete the drawings for the draincock linkage weighshaft and the reverser weighshaft. Dave 2 manufactured the draincock weighshaft and we will order material for the reverser weighshaft in time for next month.
Erle also arrived on Saturday, and used the Bridgeport milling machine to manufacture the lubricator sight glass spacers. The original design clamped the glass directly, which seems unwise, so Erle has designed spacers and rubber gaskets to hold the sight glasses in place. The thickness of the spacers is quite critical, so Paul used the Churchill surface grinder to make the final adjustments. Erle had ordered the gaskets previously, so was able to assemble the sight glass into the fireman's side lubricator the following day. A coat of primer, and they are looking very neat.
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The fireman's side lubricator sight glass showing the new gaskets and spacer assembly.
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The fireman's side lubricator sight glass now fully assembled. Apart from fitting the ratchet mechanism this lubricator is now oil tight.
Andrew continued work on the crashbeams. The crashbeams themselves are now complete, but we had identified that many locomotives on the Ffestiniog and Welsh Highland Railways are fitted with rail sweeps (strips of rubber which sweep small stones, etc., off the rails ahead of the wheels). This seems like a good idea, so Andrew had designed some brackets, to be welded to the underside of the crashbeams, to hold the rail sweeps. Some careful consideration was required to ensure that the rail sweeps remain over the rails on curved track, where the crashbeams are subject to geometric overthrow, and also to ensure that sufficient vertical clearance is available to allow the locomotive to negotiate dipped rail joints, etc. without the brackets striking the rail head. With suitable dimensions identified, Andrew made the brackets and welded them onto the crash beams. The following day he gave the crashbeams a good clean down, and touched up the primer which had been damaged by heat during welding.
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The new crashbeam for the front of the loco, based on the original design but narrowed to suit the change in gauge. The nearest footstep with Mandarin lettering was recovered from the original.
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Andrew welded some additional brackets to the new crash beams - these will carry rubber rail sweeps to remove small items of debris.
Caleb took the blast pipe assembly into the shade of the erecting shop, and gave it a good clean with a wire wheel. This revealed a considerable amount of casting flash. While the flash is of no functional significance, it is unsightly, and seeing as the C2 Project like to 'do things properly', Caleb therefore used an angle grinder to remove the offending flash. The blast pipe looks a lot neater now.
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During the reorganisation of our storage shelves, we came across the blastpipe casting which was still in a filthy state. Caleb did a great job removing the grime and grinding off some of the original casting flash.
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The blastpipe has a removable nozzle, allowing alternative sizes of nozzles to be fitted. However, years of heat and corrosion had seized the fixing bolts and the nozzle itself. Here, Jon and Caleb discuss approaches for dismantling.
Although the extremely hot weather on Saturday was not conducive to doing a lot of hard work, Dave 1 did manage to carry out some measurements of the coupling rod knuckle joint holes. More measurement is still required, and this information will enable us to finalise the dimensions of the proposed knuckle joint design in due course.
Sunday dawned misty and cool, which was a much better environment to work in than the previous day. Making the most of the cooler weather, Dave 2 and Tom used an oxy-acetylene torch to heat up the blast pipe, in an effort to remove the nozzle which was corroded in. Tom had previously drilled out the screws used to hold the nozzle in place, and which were now little more that rusted lumps. After a couple of heating and cooling cycles, the blast pipe nozzle came free. The existing nozzle is damaged, and will require replacing, but it's not difficult to make. Of interest is that the Polish KP-4 drawings show a series of different nozzles, each having a different diameter, to soften or sharpen the blast as required. The Chinese one was a smaller size than any of the Polish options! We'll probably make a complete set, as we won't know how well the locomotive steams until we've tried them all.
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Dave 2 and Tom created a setup to extract the blastpipe nozzle, enabling the nozzle to be pulled upward while heat was applied.
With Erle having finished work on the Bridgeport milling machine, Chris was able to set up his job of machining the coupling rod knuckle joint covers. Paul has designed them to be of similar appearance to the crank pin bearing covers which are adjacent, so there are a series of bolt holes, each with a recess around it. Chris centred the small indexing table on the milling machine, then centred each cover plate on it. The digital readout on the Bridgeport milling machine makes repeatable cuts very easy. Between taking each cut the table is rotated 90 degrees, thus giving a series of equally spaced recesses. The bolt hole centres were marked, but not drilled as that is easier to do on a radial arm drill. By the end of Sunday, the milling operations on all four knuckle joint cover plates were complete.
When we re-bore the cylinders we will also re-bore the valves, which are on a parallel axis. From previous measurements, we know we'll have to do a bit of work on the cylinder bores, but we weren't sure exactly what work would be required on the valves. Since re-boring is now imminent, we need this information. To this end, Dave 1 took the temporary valve end blanking covers off, and degreased the valve bores. He and Paul then took a series of measurements, to determine the valve diameters, their roundness, and their parallelism. Results look quite good, with only a skim required to restore the bores to perfectly parallel and round. Paul has obtained a Chinese C2 maintenance manual, and this tells us that the valve bores should be 150 mm diameter when new, and can be bored out to 158 mm before they need to be relined. Our valves are about 153 mm diameter, so have plenty of life left in them yet.
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Measuring the diameter and worn shape of the valve bores using an internal micrometer. Measurements were taken at a total of 24 locations.
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We have a spare set of valve liners, which we will not need at this stage but may be useful in future. Here Dave 1 cleans them up so we could check the dimensions..
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The Chinese Forestry Railways' steam loco overhaul manual provides requirements for the variation in valve bore shape. There are limits on differential diameters, the extent of barrel-shaped wear, conical wear, and surface defects. We will correct these by skimming the valve bores on the horizontal borer. The important dimension for us is the bottom one on this page: the permitted enlargement in bore diameter. The nominal is 150mm; the maximum permitted for a loco after heavy overhaul is 150+7mm, and for intermediate overhaul is 150+8mm.
We also have a complete set of spare valve liners. Dave 1 used a wire wheel to remove the surface corrosion in their bores, and he and Paul carried out some measurements of them too. The bores of the spares appear to be a little under 150 mm, so appear to be brand new. Dave 1 waxed the bores of the spare liners and put them back on the storage shelves, for use many decades in the future.
One of the drawings on the 'do draw' list is the reverser weighshaft. Like the draincock weighshaft, it needs to be shorter than the original design due to our re-gauging of the locomotive. Dave 1 realised that with the motion brackets in place, it is just possible to measure the distance between the reverser weighshaft bearings over the top of the frames. We know that some of the machining of the motion brackets was not well aligned (such as the expansion link bearings), so checking the position of the reverser weighshaft bearings was considered advisable. Paul fired up his laptop again, and sketched the positions of the interfaces which Dave 1 measured, not forgetting to account for the packing plates we'll add behind the motion brackets. Also measured was the position of the weighshaft bearings relative to the valve centrelines, since the lifting link levers have to be aligned with the valves. With all the interfaces defined, it took little more than drawing a couple of lines to represent the main shaft, and the reverser weighshaft design was finalised!
To complete the coupling rod knuckle joint covers, a mandrel is necessary to enable them to be turned to shape. Dave 1 therefore found a bar of steel, turned it to a suitable length, and drilled it to accept a clamping bolt. He then fitted one of the cover plates, and used one of the bolt hole centres to drill a hole through the plate into the mandrel. A carefully turned pin is a precise fit into the hole, and forms a spigot to drive the cover plate when it's attached to the mandrel (the centre bolt alone wouldn't provide enough force). The cover plates require trimming to approximate size before turning can be carried out, and Dave 2 suggested using the plasma cutter for this. We'll give it a go at the next working party. The remaining bolt holes in the coupling rod knuckle joint covers could then be drilled, and Dave 2 used the big Asquith radial arm drill to carry out this task.
A minor task on the 'to do' list was to fix the side door lock on the C2 shed. The door lock got broken when someone tried to get into the shed without realising we'd locked the door from the inside. It's been a niggle about 7 years now, so is long overdue for attention. Dave 2 took the lock apart, identified what was broken and found a suitable pin to replace it. We still need a screw to replace one that Dave had to drill out, but it's good to get the job ticked off the list.
The engine and tender are linked by a drawbar, with safety chains just in case something breaks. We drilled the holes for the safety chain eyebolts when we fitted the buffer beams, but the eyebolts and associated components have remained on the shelf since then. On Monday Tom was tasked with finding some suitable nuts, including lock nuts, and fitting the eyebolts. The eyebolts fitted under the cab are bolted through the buffer beam, with the ends of the eyebolts visible. Since the eyebolts are over length, Tom trimmed the eyebolts down, to avoid an odd appearance. At the front of the tender, the eyebolts pass through the front headstock inside which are a couple of rubber blocks on each eyebolt. The rubber blocks provide resilience between the engine and tender should the safety chain come into play. Tom applied a little compression to the rubber blocks with the first nut on each eyebolt to keep everything in place, then used the lock nut to lock the first in position without over-straining the rubber.
Erle's work on the lubricators continued apace on Sunday and Monday. He has fitted ten pumps to the driver's side lubricator, including all the necessary gaskets. The fireman's side lubricator is approaching completion, and Erle was ready to fit the rocking shaft when he spotted a major problem; two of the pump drive arms are broken. It's amazing what you don't see when it's right in front of you! Dave 1 suggested using the spare rocking shaft, although it was rather rusty. Erle took a wire wheel to the spare rocking shaft and, much to our relief, found that it was in good condition under the rust. After giving the rocking shaft a very thorough clean, it was fitted into the lubricator. With pumps, filters, sight glass and rocking shaft in place, only the ratchet mechanism needs to be added to make the lubricator oil tight.
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10 pumps have been fitted to the driver's side lubricator along with the slide bar and sliding bearings / gaskets. The photo of the slide bars shows the old driver's side one on the left with two broken ball ends. The center and right hand ones were acquired as spares. The right hand one has now been cleaned up and fitted to replace the broken original.
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Last month we wrote about our decision that we would need a new boiler. We may subcontract this job out, but another option would be to do much of the work ourselves, working with a coded welder. Here are some of the major components for Velinheli's new boiler, currently being built at Boston Lodge.
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And Finally...

During the busy summer season, the railway always seems short of loco crews, and Paul, Sam and Jon were all active on the footplate over the weekend. Rumours of a programme to train other intelligent species to cover footplate duties are apparently untrue.
If you've persevered and read all the way to the end of this report, you'll realise that the working party was a very productive one. As well as making a satisfying amount of swarf, we carried out a lot of planning work, prepared three drawings, and had a good tidy up. Taking the cylinders off and re-boring them will be a big step forward, and we're very close to that.
News Archive 
August 2019 AGM