C2 Project News

August Bank Holiday 2017

Keeping the Machines Busy

The late August C2 Project Working Party took place over the August bank holiday weekend. As is becoming customary now, a few days were added before and after, to make it another very productive event. Many machining tasks were completed and it was rewarding to look around the machine shop and see so many C2 parts being made!
Dave 1 started work on the preceding Thursday, setting up in the Bridgeport mill the billet of steel which Dave 2 had previously prepared for the tender brake hanger brackets. With a tungsten carbide tipped 2" cutter, he started to form the channel section from which would be cut the brackets.

Taking 2.5mm (100 thou) deep cuts across the full width of the cutter, at a decent feed rate and running the machine close to the maximum design speed for the cutter, the rate of material removal was quite impressive. It's not often that the coolant needs to be set to the maximum flow rate! Each cut took about 10 minutes to cover the 600mm (24") length of the billet, so it took over a day to cut the full depth of the slot we needed. By that time the coolant was coming out of the sump at quite a high temperature!
Machining a steel channel, for manufacture of the tender brake hanger brackets.
With the channel section now prepared, Dave 1 marked out centres for the holes which will take the brake hanger pins. These were then drilled on the Asquith. It was then time to use the band saw to slice off sections of the channel, to form individual brackets. The final operations were to mark the corner radii, and to form them by hand using an angle grinder and linisher. Dave 2 assisted in carrying out this final operation.
Dave 1 de-burring the edges of a tender brake hanger bracket.
The six complete tender brake hanger brackets. The two Daves have done a great job of these.
And so at last, after the frustrations at the previous working party, we have the tender brake hanger brackets ready for welding onto the tender chassis.
Whilst the Bridgeport milling machine was set up, Dave 1 milled a somewhat shallower slot in another piece of steel bar to form the base of a jig for assembling brake block carriers. Paul used the Wanderer milling machine to face off a convenient pre-used offcut of steel bar to make another part of the jig. Al welded the two parts together later in the weekend, so the jig is now ready for use.

Last week Paul ordered profile cut plates, along with various bars and strips, for the locomotive brakegear. These had arrived in time for the working party. James and Sam took a piece of strip and carefully rolled it into an arc of defined radius. James then cut it into short lengths. When placed on the jig described above, along with the appropriate profile cut plates, the form of the brake block carriers is immediately apparent. Welding them up will be a job for the next working party.
The assembly jig for the brake block carriers was a good team effort. Paul machined one part, Dave 1 the other, and Alan welded them together!
James poses with the giant 'mangle' used for rolling the plate for the brake block carriers. There's a smaller one in the workshop but this historic tool is the best for heavy work.
A stack of gently curved plates, the correct radius for the brake block carriers. These were rolled from flat bar by Sam and James.
A stack of newly delivered profiles for the loco brake gear. These include parts for the brake hangers, brake block carriers, and pull rods.
A demonstration of the brake block carrier assembly jig, which will be used while welding together the four components of each carrier. Two examples of the original Chinese components are shown behind - these were castings. For various reasons we only have 5 of them and we need 14, so we're making 10 new ones.
Colin set up the Colchester lathe, and finished turning the locomotive brake weighshaft. He had shortened the shaft previously, which involved turning a new bearing journal on the shortened end. However, the journal at the original end was somewhat worn, so he reduced the diameter of of that journal, just enough to eliminate the wear. We will make custom bushes for the bearing housings to account for the reduced journal diameters.

Colin also machined weld preps on the components of the new bearing housing ready for this to be assembled.

Next to make were a set of bosses for the brake hangers. Adding a boss to the hanger increases the surface area of moving parts, and hence reduces the wear rate on them. Each boss had to be drilled out and then parted off. After several hours work, Colin had produced a large collection of bosses ready for welding into the profile cut hangers we now have.
Colin prepared the new loco brake weighshaft bearing housings for welding. Here a weld-prep has been machined on the flange.
The loco brake hangers have bosses at each end to provide a larger bearing surface. Colin machined up 16 of these (8 of each size) and they will be welded to the new brake hanger profiles.
Machining the loco brake hanger brackets. After cleaning up and measuring, we decided to saw off the worn spigots, machine them all back to a common dimension, and we will then drill out and press-fit a new stainless steel spigot.
The locomotive brake hanger brackets are badly worn, and so it has been decided to replace the pins on them with stainless steel ones, such that they run freely in the plastic bushed brake hanger bosses. To this end, Will used the band saw to cut the existing worn pins off the brake hanger brackets. He also flattened the backs of the brackets with the linisher.

Again using the Wanderer milling machine, Paul skimmed the remaining stubs of the pins on the locomotive brake hanger brackets and the tender equalising beam pivots, such that those faces are at a known distance from the rear mounting faces. We now need to drill these components to accept new pins. Al took the locomotive brake hanger brackets home with him to carry this operation out as a homework task.

At some stage, the tender equalising beam pivots had been removed by cutting off the bolts with an oxy-acetylene torch. Due to a lack of care, the torch had unfortunately gouged several lumps out of the flange on the pivot. Paul therefore cleaned these gouges thoroughly, and Dave 1 carried out a weld repair. Paul finished the work off on the Wanderer milling machine, flattening the repaired surface and skimming the bosses flat.
The loco brake hanger brackets after the machining was completed.
One of the loco brake hanger brackets was just too grotty to re-use so we have made a new one! Again this was a team effort between Colin, Paul and Dave 2. The spigot will be replaced with a length of ground stainless steel bar pressed into the hole.
Eight loco brake hanger brackets, ready for boring the central hole. Three are original castings, four are Chinese fabrications, and we have made one new one.
Jo has expressed an interest in advising us with overhaul of our boiler. He has a great deal of experience in such matters, having worked at Boston Lodge for many decades (staff and volunteer), so we are keen to have his technical input. As a start, he managed to crawl into the firebox through the firebox door, to give the firebox tubeplate a closer inspection. This is clearly not a very convenient way of accessing the firebox, and so it was decided to lift the boiler, to give better access via the grate area.

He also designed a tube extracting tool suitable for our boiler, which we made.
Who is skinny enough to fit through the firehole door? Not many people in the C2 Project, but we did find someone! Retired Boston Lodge staff member Jo Clulow inspects the firebox tubeplate, before we lifted the boiler.
We haven't done a lot of practical work on the boiler since receiving the loco, although we did complete a hydraulic test which happily failed to find any leaks. As other parts of the loco progress, it's time to start preparing the boiler for a through internal internal inspection. The first stage is to remove the tubes, and we made this tube extractor to assist with the work.
Sam and Dave 2 found a number of sleepers with which to build up stacks under the smokebox saddle and the firebox foundation ring. But to give reasonable access to the firebox the stack of sleepers under it was unlikely to be very stable, which was not considered to be acceptable. After consulting with Robco, we constructed two steel stands. These were based on a simple frame of hollow-section, suitably strengthened with angle iron braces. Sam and Dave 2 cut the lengths of angle iron and cleaned the interfaces.

Al and Dave 1 took on the task of welding the structures together. With welding taking place on the two stands simultaneously, it only took about an hour for them to be completed.

Back in the C2 Shed, with the newly fabricated steel stands at the ready, Sam, Colin and Dave 2 lifted the boiler with our crane. The sleeper stack was placed under the smokebox saddle and the steel stands under the firebox. The whole arrangement is very stable, and gives the access we will need to work on the boiler.
As we are now preparing to start work on the boiler, we need better access to the firebox and underside. We decided to raise it by a couple of feet. This apparently simple lifting job required the construction of some hefty stands to support the firebox without blocking access from underneath.
Final positioning of the boiler on its new stands and a crib of sleepers at the front end.
We spent some time with packings and shims to get the boiler perfectly stable and firm on the crib of sleepers, bearing equally on all of them.
Dave 2 spent a number of hours with a wire wheel, cleaning the tender suspension rocking washers and knife edges. With corrosion and dirt removed, he was then able to measure the key dimensions of these components. We can now assess what we have, and decide which components we can repair and which will need to be replaced.

Dave 2 also cleaned up some of the tender brake gear components which we intend to re-use.

Robco also kindly lent us his die grinding set, and Dave 2 used this to neaten the edges of some of the flame cut holes on the bottom plates of the tender chassis. He also made plugs for these holes, and ground weld preps onto all relevant edges. We hope to weld these plugs in at the next working party.

As well as providing better access, the new height of the boiler is close to the height it will be eventually, when mounted on the frames. Suddenly it looks bigger than before!
As noted in previous news reports, the locomotive is to be fitted with heavy buffer beams, front and back, to add adhesive weight. The buffer beams will be held on, in part, by fitted bolts. At the front of the loco, these will attach to the substantial remains of the original bufferbeams. However, at the rear the original platework is thinner. Paul carried out some calculations (based on some worst-case vertical accelerations and fatigue loadings) which showed that the fitted bolts would be plenty strong enough, but that the bearing area on the original plates did not have a safety factor as high as we would like. It would probably be fine, but we have decided to add extra platework here, just to be sure. Colin and Dave 2 therefore measured and cut three pieces of 20mm thick plate, which we will weld to the rear of the locomotive frames before attaching the rear buffer beam.
As we work though the overhaul, we are the acquiring tools and equipment needed at each stage. Although Boston Lodge is very well-equipped, it is sometimes useful to have our own tools that we can find easily! Alan was recently offered a small surface plate which will be very useful as we progress to accurate work on loco fittings. The plate was legless, so Alan has made a very neat wheeled table for it to rest on. He and Chantele completed the fabrication, cleaning and painting of this.

The roller bearings for the tender axleboxes are on order, and should be with us soon. Colin and Dave 2 therefore carried out a 'dry run', assembling the front and rear axlebox covers. This demonstrated that the covers all fit without the need for further adjustment, but that they may not clamp the bearings in place as tightly as we might have wished. We will need to carry out some calculations to determine whether this is a problem or not, but it is good to know earlier rather than later, such that we can make up packing rings if necessary. One of the axleboxes will have the speedometer drive fitted, and a homework project for the next few weeks is to design this interface.
The new table for supporting our surface plate, made by Alan and Chantele.
On the subject of homework, Andrew and Paul have been busy with drawings of the tender and brake gear recently. The rate of practical progress has been so good recently that the 'design office' is struggling to keep ahead!
September 2017 
Mid August 2017