Late June 2025

Before the late June working party, the C2 took part in the ‘200 Wheels on the Cob’ cavalcade as part of the Railway 200 – Ffestiniog Railway Platinum Jubilee Weekend. This consisted of the entire Ffestiniog Railway & Welsh Highland Railway fleet, making their way across the Cob embankment to Porthmadog Harbour Station. The loocomotives crossed the cob in the order they entered service on in the preservation era. Since the C2 has not yet entered service, we were the last vehicle in the cavalcade, hauled by the new newest addition to the fleet - The NG15 locomotive. For more news about this exciting event, please follow the link below to the Ffestinog and Welsh Highland Railways' news page on the event. For added entertainment, see if you can play 'Where's Wally' with the C2 on the festrail news page!

Work continues to be focused on the crossheads. The objectives of the late June working party were to complete the little end bearing pins and to fit the slippers into the crossheads.

Dave 1 spent three days working on the Wanderer milling machine, machining the external surfaces of the slippers.

First, Dave milled each of the four brass blocks to a precise width, removing about 12mm of material in the process. Next, he considered machining the material to a defined thickness. However, the material is only a few millimetres thicker than the nominal maximum slipper thickness and we are aware that some of the slippers will be required to be a little thicker than nominal. Therefore we decided to leave the thickness to be finished after all other machining operations.

Each slipper has an 8mm "lip" on each end, which fits over the crosshead faces to prevent the slipper moving longitudinally. To create these lips, Dave machined away 8mm of material from the back of each slipper, leaving just the lip at each end. The dimension between the lips needs to be quite accurate to ensure a good fit into the crosshead.

None of the above operations were terribly difficult, but it all took quite a long time due to the amount of material being removed. And with brass being rather expensive, we wanted to collect all the swarf for trading in. After three days of milling, Dave had collected quite an impressive heap of swarf.

Checking the slippers against the crossheads showed that most fitted well, but one was a little tight. Dave therefore returned it to the milling machine and took 6 thou off the width. The two bottom slippers also required a chamfer on their edges between the lips, to accommodate the small radius in the bottom of the "slot" in the crossheads. Dave used a flapwheel to create this chamfer. All four slippers now fit into the crossheads.

Andrew continued work on the little end bearing pins. He had previously machined the tapers to fit perfectly into the crossheads, but now the parallel section for the little end bearing itself needed to be machined, the pins needed to be cut to length, and several other features needed to be machined into them.

Due to the shallow taper angle, the start and end of the parallel section had to be positioned precisely. Any error will either cause a ridge within the bearing surface (which will cause excess wear on the bearing) or a dirt trap next to the bearing (which will likely also result in wear on the bearing). Andrew therefore fitted the pins into the crossheads and painted a little engineer's blue onto the interface. When the pin was removed, the edge of the crosshead left a fine line where we wanted the edges of the parallel section.

To maintain the high degree of accuracy Andrew had achieved when machining the tapers, he held the first pin in a four-jaw chuck and used a centre in the tailstock of the Colchester lathe. He then used a dial test indicator to centre the pin. It was then a case of turning the parallel section of the pin, using the start and finish lines created by the crosshead as a guide.

Before removing the pin from the four jaw chuck, the excess material at the small end was turned down until it was small enough in diameter that it could be cut off using a hacksaw. After the end was faced off the pin was removed from the Colchester lathe and moved to the three-jaw chuck on the Elliott lathe. Holding the newly machined parallel section of the pin, the outer end was cut down and machined to shape. A 17.5mm diameter hole, 20mm deep, was also machined in this end.

The whole process then had to be repeated for the second little end bearing pin.

To ensure that the little end bearing pin doesn't rotate in the crosshead (which would wear badly), and that all motion occurs within the little end bearing itself, the pins are keyed into the crossheads. Andrew managed to find a 12mm end mill (most tools at Boston Lodge are imperial rather than metric) which permitted the keyway to be cut.

Each little end bearing pin was mounted on a Vee-block on the Chinese milling machine, and clamped down with machine clamps. The centre of the Vee-block had already been centred under the milling head, and was set up perpendicular to the milling table using a dial-test indicator. This meant that the keyway could be milled on the axis of the pin. Once set up, Andrew had little difficulty in machining the keyways in the two pins.

The holes in the outer end of the little end bearing pins are to permit a bolt to be inserted. When tightened against a bridging plate, the pin can be jacked out. So we needed to cut a M20 thread in the holes. Since the pins are made of a hard type of steel, this proved to be rather hard work. The last thing we wanted to do was break a tap in the hole, so Andrew took great care to apply sufficient force to cut the thread, but not an excessive force. The margin between the two felt very small!

With the machining of the little end bearing ins complete, Andrew prepared a drawing of them as made. This included details of the surface hardening required for the parallel section of each pin. The pins were then packaged up along with a copy of the drawing, ready to be sent off to be hardened.

Dave 2 was able to put in a couple of brief appearances during the working party. We had bought some 16mm diameter steel bar to make studs for the crossheads. Dave cut a number of lengths of this bar, ready to make the studs.

Jack offered his services to us for a couple of hours one afternoon, and continued the manufacture of the studs. Using a M16x2.5 die, he cut the threads on the short ends of the studs. Andrew continued the work, trying to cut the thread on the long ends of the studs. However, he found it very difficult to align the die correctly.

Given the difficulties we have experienced when cutting threads of M16 or greater, we may yet outsource the manufacture of the larger crosshead studs to a company with CNC facilities. We need to give the matter more consideration. Either way, we're learning the limit of thread size which is possible to cut by hand.

Dave 2 put in another appearance a few days later and applied primer to the unprimed faces of the connecting rods, completing the task started at the previous working party. He also tidied the shed for us, which, while not a glamorous task, is extremely helpful.

So, as at the previous working party, we made good progress and achieved the objectives of the working party. Completion of the crossheads is inching ever closer!

Andrew was called into service a couple of times during this extended working party. Once to drive "The Quarryman" service from Blaenau Ffestiniog with the Quarry Hunslet locomotive Linda. And once to drive "The Gelert Explorer" from Caernarfon to Beddgelert using the latest addition to the fleet - the NG15!