C2 Project News

Late April 2018

Making the most of a few sunny days!

To fill the gap between the Easter and May Day Bank Holiday working parties, an additional working party was held mid April. Work was again predominantly focussed on the tender, and involved a lot of painting.
Paul and Dave 1 started work on Thursday morning, by sitting down in front of Paul's laptop and creating a spreadsheet of previous measurements of the tender hornguides. As with the locomotive hornguides, it is important that the tender hornguides are aligned, although perhaps not to quite such a high precision as there are no coupling rods to worry about on the tender. Several sets of measurements were taken, using different measurement techniques, all of which give slightly different results. The challenge is to work out what is reality and what is measurement error. After an hour or two, we thought we had a plan for machining the lateral hornguides.
The tender lateral hornguides run between the lateral horns on the tender axleboxes. The tender axleboxes are a fixed distance apart, held in place by the roller bearings on the axles. Now that we have assembled the roller bearings and axleboxes, an opportunity existed to measure the spacing between the tender axlebox lateral horns. It's not straightforward, since the wheels are in the way, but there are holes in the wheels through which the internal stick micrometer could be passed, which made the operation practical.
While Paul finalised the spreadsheet, Dave 1 took the tender hornguides to the degreaser, to remove the protective oil which had been applied at the end of the Easter working party. Paul gave the longitudinal face of each hornguide a skim on the surface grinder, to form flat surfaces which could be used for taking the next set of measurements.

Dave 1 found a couple of pieces of steel angle and milled them precisely square, to form jigs for clamping to the tender axlebox lateral horns, for use when measuring their lateral spacing. With one jig clamped against the inner lateral horn of each axlebox of a wheelset, and the stick micrometer passed through the holes in the wheels, a measurement was taken for each wheelset.
Skimming the longitudinal horn faces on Churchill the surface grinder.
At this point Paul and Dave experienced a horrible sinking feeling. The distance between the axlebox inner lateral horns and the inner faces of the lateral hornguides was inconsistent. The axleboxes are about 2 mm closer together than the hornguides will accommodate. How could this be? After checking the accuracy of the measurements of both hornguides and axleboxes, and after checking the measurements against those on the original Polish drawings (all of which showed to be correct), it was still not clear what was wrong. It was only when we carried out a set of calculations based on the Polish drawings that we discovered the problem - the original Polish designed axleboxes and hornguides don't fit together either! They got away with it because the plain bearings had more lateral play than the roller bearings.
To sort out this problem, ideally we would make the tender axles 2 mm longer. We do not intend to do that! It could also be solved by making adjustments to the axlebox covers, but that would require us to disassemble the tender axleboxes (which we've just finished putting together) and to replace the roller bearings. No thank you! After some careful, if fraught, thinking, Paul proposed the simple solution of machining an extra 1 mm off the outer faces of the hornguides (which we've not started machining yet). Lateral loads won't be shared so well with the inner faces, so we may have wear issues in the future, but we have a solution which will get the locomotive into traffic, and which gives us time to come up with a better solution if one is needed. Phew!
Skimming the outer lateral horn faces on the Bridgeport mill.
The change in geometry of the lateral hornguides actually simplifies things a little; only one of the hornguides now needed any material taking off the inner edges. Paul quickly milled that plate, and we could progress onto other tasks. Since the outer horn faces are now the important datums, Paul also milled those faces to provide a smooth surface for the next round of measurements.
Friday was a painting day. With the tender chassis frames grit blasted the previous week, Andrew had primed them and applied the first top coat. Paul gave the frames a quick clean down, and it was then time to apply more paint. Next was a coat of dark blue, not black, which makes it much easier to spot any areas missed. With the complex shape of the tender chassis frames resulting in a very large surface area, Andrew and Dave 2 spent most of the day applying this coat. Fortunately the weather was warm and sunny; ideal painting weather.
The tender frames in blue witness coat. Andrew applies some finishing touches. From this angle the front face is reflecting a yellow tool locker (out of shot) so it's reminiscent of the old British Rail livery.
Although the blue looks pretty, it's not the final colour. We've only found one photo of a C2 painted blue - here it is.
Dave 1 turned his attention to suspension components for the tender. We have placed an order for new CNC machined spring hangers, but we will reuse the existing spring hanger brackets. Dave used an angle grinder and wire wheel to neaten up these components. To repair the badly worn pivot holes, Bob kindly carried out a weld repair for us. As luck would have it, the grit blasters were back on site on Friday, so we took the opportunity to have the spring hanger brackets grit blasted as well.
With the painting of the tender chassis frames proceeding well, Paul went in search of a suitable cutter to open out the pivot holes in the spring hanger brackets to 27 mm, suitable for pushing bushes into. Since almost all of the tools in Boston Lodge works are imperial sizes, we did not hold out much hope for this. But by some miraculous stroke of luck, Paul found a 27 mm end mill. Perfect! He then devised a mounting arrangement on the Bridgeport mill, to ensure that the pivot hole was machined at a constant position relative to the fixing holes in the bracket.
Saturday saw a change in working party attendees. Paul and Andrew spent the day driving trains, but we were instead joined by Chris (between cleaning and coaling duties), James, Alasdair, Erle and Robin. Once the attendance at a working party exceeds four or five people, it becomes necessary for someone to step down from doing physical work, and to assume the role of working party manager (making sure everyone has something interesting to do, keeping everyone supplied with tools and materials, rounding everyone up for tea breaks, etc.). Dave 1 drew the short straw on this occasion. Although we grumble about having to manage people, it's nice that we have so many helpers that we find ourselves in this situation.
David Lloyd George poses in the sun at Tan-y-grisiau, while Paul was driving a passenger train. Most of the working party was blessed with warm summery weather, but it turned wet on Sunday. Meanwhile Andrew was driving Blanche on a freight duty.
James took a look at the setup on the Bridgeport, and with assistance from Paul's notes, worked out how best to carry out the milling operation on the tender spring hanger brackets. A slow and careful start saw the first bracket milled, with the pivot hole exactly where we wanted it. The remaining 7 brackets were then dealt with in the same way. Once finished, James degreased the brackets in readiness for Dave 1 to take them into the paint shop and apply primer.
Robin (Erle's brother) is new to Boston Lodge works, so Dave 1 started by giving him a site induction. While this was happening, Erle used a flap wheel to remove mill scale from the battery box door he had made previously. First task for Robin was to clean (with white spirit) and prime the bolt heads on the tender axleboxes, and to repair any damage to the paint on the axles. He then moved into the paint shop and applied primer to the battery box door. While the paint brushes were out, Erle applied a second coat of black top coat to the tender equalising beam pivots.
After he had finished painting, Norman provided an offcut of plywood for Robin to make a floor for the battery box compartment. To fit behind the tender front headstock, and to fit around the eyebolt backing plate, the front edge of the floor is rather an irregular shape. A further complication is that the ledges which support the floor have welds along them, so the floor needs some shaping to sit down square. Robin found that making a cardboard template first was easiest, and then using it to shape the plywood. There is a little more fettling required, but the battery box floor is not far off now.
Alasdair's task for the day was to find, clean, assess and repair or replace the tender spring knife edges. After finding the original components and laying them out on a bench, it soon became apparent that few, if any, were to drawing, and most were beyond repair. It seemed easier to make a new set. After Alasdair and Dave 1 had searched fruitlessly for some suitable thickness steel to make replacement parts, Bob came to the rescue. He gave us a strip of spare steel which he had lying around which was not only a suitable thickness and width, but was also the exact material grade we wanted too.

First job to make new knife edges was to use a bench grinder to round off one end of the steel strip. To get a nice straight edge, Alasdair finished off the radius with the linisher. Next it was on to the band saw to cut the component off, and the process was repeated for the next one. We need twelve of these knife edges, one for each end of the six tender springs.
Tender spring hanger knife edges in production.
By close of play on Saturday, James had finished milling the spring hanger brackets and Alasdair had finished cutting the knife edges, so on Sunday morning James started to set up the Bridgeport mill to cut a slot in the top edge of each knife edge. With twelve to do, it made sense to machine them in batches rather than one at a time. Erle assisted James with devising a suitable claming arrangement to hold several components simultaneously. James also found it useful to have assistance when zeroing the mill, since the machine is so big that it is not always possible to see the work piece when operating the feeds manually.
Once James had slotted the first batch of knife edges, Erle took them and marked out the chamfers on the top corners. Using a bench grinder and the linisher, the outside shape of the knife edges was formed. We hope to finish this operation on the remaining components at the next working party, and to radius the bottom of the slot in each to complete them.
In addition to all the holes drilled and reamed in the tender hornguides over Easter, more holes are required to fix the axlebox keep plates. Dave 1 marked out each plate and punched the hole centres. Using the Asquith drill, he then started to drill two holes in each plate for the axlebox keep plate bolts. A broken drill slowed the operation down a little, but Chris managed to extract the offending drill tip. Dave 2 then took over and completed the operation.
A further hole is required in each hornguide, to fit a grease nipple. This is a modification we are making to the original design, to try and combat the severe wear seen on the tender hornguides of our locomotive when we bought it. Dave 2 and Erle set up a mini production line, with Dave 2 drilling the holes and Erle tapping them. Once complete, Erle took the hornguides back to the shed an applied oil to protect them from corrosion until next working party.
Tender horn plate, with the additional holes drilled.
The holes for the grease nipples were then tapped, and the nipples trial fitted.
Sunday was another painting day. Paul, Andrew and Dave 2 applied the next coat of black paint to the tender chassis frames, over the blue. For some unexplained reason, the black didn't seem to cover the blue so well. Although we had had good painting weather, the blue didn't seem to have cured quite as well as we expected, so perhaps this was the reason for the difficulties with the black. Andrew is quite a perfectionist when it comes to painting, and was most unhappy with the finish obtained. However, on looking again the following morning, he admitted it wasn't as bad as he thought. A rub down with fine sandpaper on the external faces and another coat of black should sort it out.
We are beginning to think of the assembly of the tender chassis now, so Chris and Dave 1 started collecting together the fixings that we will need. We will buy a complete set in due course, so that we can restock the works stores, but it is useful to know what is immediately available and what we will have to order beforehand.
Over the past few months, the bench in the C2 Shed has become something of a dumping ground for components being worked on, tools which have been used, etc. Dave 1 and Chris therefore decided to have a tidying up session. While being careful not to create any dust while the tender chassis frames were being painted in the shed, finished components were stored in boxes ready for assembly, replaced components were placed outside on the old locomotive cab, tools were put away in their rightful homes, and spare parts were collected together for future use. After an hour's work, the bench was almost clear and in a usable state again.
Whilst tidying the bench, Dave 1 found a couple of brake linkages and the new tender spring rocking washers which Erle had made. They were in primer, so Dave 1 whisked them into the paint shop and applied a coat of black top coat. Chris joined him there and applied the first top coat to the battery box door. We were also pleased to find that the brake links that we ahd made at the last working party had been painted by Carol.
Whilst most people had to head home on Sunday, Andrew and Dave 1 stayed an extra day to carry out more painting. Andrew rubbed down the locomotive front buffer beam and tender rear buffer beam, while Dave cleaned the rear bufferbeam on the locomotive. Andrew then applied red paint to the areas he was working on, while Dave applied another coat of black to the whole of the locomotive rear buffer beam, along with the bolts behind the bufferbeams at front and back of the locomotive. To finish off, Dave applied black to the bolts on the tender axleboxes and to any patches on the tender axles which Robin had primed, while Andrew painted the front buffer beam hooks red.
In summary, it was a working party of ups and downs; some things not going quite to plan but good progress being made overall. Painting things always makes a big difference, transforming them from rusty bits of metal into shiny components ready for use. We're building up a good collection of nearly finished tender suspension components too, so it shouldn't be too long before we can get the tender on its wheels.
As always, a big thank you to our volunteer helpers who carry out so much of the work for us. And thanks also go to the works staff, who not only put up with us getting under their feet during the week, but who also often go out of their way to help us with particular challenges. It really is greatly appreciated.
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