Build Diary entries for March 2021
Here are the diary entries for this month. You can use the forward and backward links to see the next or previous months. Most photos taken before 2018 are small size. From 2018 onwards, most photos you see below will have a link to a full size image by clicking on the photo.
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|Bogie Centre Slide Progress|
|The centre slide has moved onto the Juaristi machining station so that the oil lubrication grooves can be formed. The centre slide is upside down on the machine. The 2 holes from the pipe connection boss have been drilled through.Now the machine will form the X shaped oil lubrication grooves. If you look closely at the right hand edge of the flange being machined, you will see that it has an angled edge. This faces onto a "V Strip" plate with a similar angled edge which is firmly bolted to the bogie central stretcher. Thus, the centre slide is restrained from moving vertically (by the angled edge) but is free to move sideways while being restrained by the coil wound side control springs.|
|Pony Truck Radial Arm Model|
|With the manufacture of components for the front bogie proceeding well, our design team are starting to look at the pony truck or trailing truck - the "2" of a 4-6-2 Pacific locomotive. The original 10 Clan locomotives had a leaf sprung suspension system. The Lot 242 Clans were scheduled to receive the coil sprung design which is fitted to 71000 - Duke of Gloucester. This is reported to give a much better ride. The main frame of the truck consists of a fabricated main frame bolted to a cast radial arm. In order to help prospective casting suppliers understand our requirements, we have had this 3D model printed. The right hand side is the pivot and the left hand side is bolted to the fabricated truck frame. The model is sitting on a sheet of A4 paper to give an indication of the size.
The 3D printed models is from FIRMA Engineering Ltd (Structural Analysis & Design engineers); their web site can be found at www.firma-engineering.com.
|Bogie Lubrication Components (1)|
|Ian C has almost finished all of the components we will need for the bogie lubrication (apart from a couple of oil boxes). The component in the lathe is part of a set of 4, 2 of which are fitted each side of the bogie pivot stretcher and will provide the oil feed down to the centre slide. Oil boxes are fitted to the frames just in front of the cylinders and fixed piping is taken down to these connectors. Flexible rubber pipes connect to the connectors through unions and supply the oil down to unions on the centre slide on the bogie. Ian is taking the raw brass castings and now machining them. First job is the boss for the flexible connector which needs a thread on the outside and a taper on the inside. The 2 pieces of metal engaged with the horizontal jaws of the chuck are not part of the casting and are to hold the casting in place.|
|Bogie Lubrication Components (2)|
|The bosses for the flexible connector unions are complete. You can see the internal taper.|
|Bogie Lubrication Components (3)|
|The flange that bolts the adaptor to the bogie pivot stretcher now needs to be cleaned up and the 2 bolt holes drilled.|
|BR1F Tender Frames Modelling|
|James C has been beavering away on modelling the frames for the BR1F tender. This is the front dragbox which transfers the forces from the engine/tender drawbar to the tender. There is a similar dragbox at the rear of the tender. The drawbar goes through the rectangular slot on the front face - which is on the left hand side. The drawbar is secured by a vertical pin that engages in the round hole. Either side of the rectangular hole are circular holes that will contain sprung buffers that will press firmly on rubbing plates on the hind beam of the engine. These were an early modification to the BR standards design due to excessive oscillation being passed on to the train from the engine.|
|BR1F Tender Frames Modelling (2)|
|James has been pressing on with the modelling of the tender frames. The frames are outside of the wheels so that the triangular brake hanger brackets need to be inside of the frames. The 6 spring pivots and brackets can be seen on the outside of the frames. At the front of the tender frame (left) is a rubbing block, very similar to one which we will be fitting to the hind beam of the engine frames.|
|Bogie Pivot Centre Slide|
|We're back in Sheffield again this week so its time to catch up with what has been going on. The bogie pivot centre slide is almost through machining. In the photo, it is sitting upside down. The pivot, which is bolted to the pivot stretcher on the main frames engages with a bush in the hole where the paper work has been pushed into. The centre slide sits on the flat faces which are lubricated by oil in the diagonal grooves. It can move to the left and right under the control of powerful side control springs. As you can see, 2 off 7/8" British Standard Whitworth threads need to be formed which will be used for screws to retain the bush. Unfortunately the tap to create the thread has broken and a new one is required. There's not much call for Whitworth threads these days!|
|Bogie Axlebox Guides|
|8 bogie axle guides with first phase machining complete waiting for inspection. If you look closely, you will note that we have 4 off item 1, 2 off item 2 and 2 off item 3. Item1 are the 4 guides that sit at the outer ends of the bogie frame. The inner ones have to accommodate the bogie spring cradle (or compensation beam) that connects the tops of the axleboxes on each sides of the bogie frame on the outside. The 2 bolts on the tops of the axlebox guides have to have countersunk heads to avoid fouling spring cradle. Once the bogie frame has been assembled and aligned we will final machine the axlebox face of the guide.|
|Phil Yates, on our Engineering Committee, from the Advanced Manufacturing Research Centre (AMRC) has arranged the loan of a laser measuring device. We spent the day measuring the frames; in particular carefully noting the dimensions of the hornguides post machining. Here Phil and Geoff (just visible) are doing a survey) of the cylinder mounting area.|