It wasn't a chance I was going to miss - favourite loco on home railway! Grandad and Dad would have been very jealous, but it's certainly given me added impetus to get the miniature version working again.
The completed adapter. The brass insert is threaded 5/16 x 32tpi ME to match the same fitting used to attach the boiler to the CSME test kit. A M8 hex head screw is used to provide a bypass vent. I intend to use this adapter in future with a long tube nozzle screwed onto the brass fitting to access all the awkward areas that need ash and clinker removing after a running session.
The boiler needs to be placed vertical so the stay nuts that require sealing are horizontal. The cut outs and holes are to accommodate the backhead fittings and mounting studs and allow as much surface contact area as possible.
Vacuum cleaner connected up to allow the Loctite 648 to be wicked into the tiny gaps on the two leaking firebox stays. After applying some around the stay nuts the vacuum cleaner was started and with a little bit of leak plugging on the nozzle itself I left it running until the motor cut out. The boiler has now been left overnight for the Loctite to cure.
EDIT: I forgot to mention; my thanks to David (Midland) for the use of his bottle of Loctite.
That's it now on the boiler until the 2x hydraulic test, with any luck it will pass this time but I'm taking nothing for granted. In the meantime I will be concentrating on the wheelsets, with the first job being a check of the driving wheel quartering. If that looks in order I will be pinning the axles and wheels using taper pins before putting a chamfer and radius tip on the flanges. This will need the wheelsets to be set up between centres on the lathe.
Happy Christmas to all!
Last Edit: Dec 24, 2019 8:32:40 GMT by dhamblin: Thanks added
Once I'd cleaned all the grime off I was pleasantly surprised to find each driving wheel had been pinned to the axle to preserve the quartering. Each pin head has been filed to match the wheel casting profile, so they weren't easy to spot, fortunately there was a second empty hole on one of the leading driving wheels that gave it away.
All the driving wheelsets have now been removed and cleaned. Both eccentrics (axle pump and lubricator) don't appear to be truly square to the axles, the axle pump one also not being properly in line with the pump bore, so much so that the wheelset moves laterally by up to 5mm at a certain point on each revolution. Pressing the eccentric further along the axle should cure this.
Leading bogie has been dismantled to free both wheelsets, which will be the first ones to be re-profiled. The intention is to hold one end in the independent four jaw chuck, secure both axleboxes to that end using cable ties, then support the other end using a fixed steady. A centre can then be drilled in the free end, the whole thing reversed and repeated, thus allowing the wheels to be turned between centres to get the flanges re-profiled.
Now we come to today: second attempt at the 2x hydraulic "shell" test, seen here during the 160psi holding phase. I am happy to report that it passed and boiler W009806 is now officially recognised. I will engrave the number on the backhead over the coming days. Once the wheelsets are completed it will be on with making the new backhead fittings and preparations for the 1.5x hydraulic test, which will add the superheaters to the mix as well.
Best start getting the shopping list ready for Ally Pally
The wheelsets have been the main focus since the boiler passed the shell test. My plan was to try and improve the wheel profiles to better match the SMEE profiles (see first page of this thread), by machining them with the wheelset rotated between centres. An initial attempt at adding centres to the bogie and pony truck axles was unsuccessful as I learnt the hard way how difficult it is to centre something like a whole wheelset in a 4-jaw chuck and expect the free end to be centred too! So, buy a hyraulic press, machine a press tool out of some EN3B, sort out some suitable press plates from 20mm thick steel and the wheels come off. Please excuse the finish on the tool, it wasn't the nicest material to machine.
Getting the DRO sorted on the lathe before lockdown started was a massive boost and the first part of the enforced work from home focused on using it to machine the replacement axles from 5/8" silver steel. Here the axles press tool is being used with a third 20mm thick steel plate to reassemble the first bogie wheelset.
All three tender wheelsets were dismantled and centres drilled in the axle ends using the collet chuck. Unfortunately this showed that they must have originally been machined in a slightly out 3-jaw self-centring chuck as the run out was up to 6-thou. Today I have just completed the third replacement axle.
Lost all of April as I slit my finger open trying to get a new milling cutter out of a tight hole in its wooden packing block, so on to May. Run out on the driving wheelsets was even worse - the leading driver here was out by 0.01"! To try and get the treads in roughly the right place for sorting out the square tip flanges I resorted to manually adjusting the shallow axle centres using an automatic centre punch and carefully applied pressure to move it to a point where the run out was about 0.003" or better. This was successful and, with the wheelet between centres and the 4-jaw chuck used to grip one wheel for turning, it was possible to manually file the flange profile using a smooth cut file and radius gauges for the flange tip. The 20 degree chamfer angle being done by eye as "best endeavours". As there is also a small amount of axial wobble the 2 degree cone angle has been omitted from the driving wheelsets.
Flanges modified on all three driving wheelsets. Only need to adjust the axle pump eccentric position (centre driver, seen here on the left) and repaint then these will be ready for chassis reassembly.
First bogie wheel having the 2 degree cone angle added to the tread. Initially machining is done using a right-handed 95° turning tool, with the DRO used to set the flange root as the datum point, then hand crank the lathe to slowly take the bulk of the material off (using the compound slide set over to 2 degrees). The tool pictured is then set to lightly kiss the newly machined tread and taken across to blend into the dead zone of the flange root from the original LBSC parallel tread profile.
With all the wheelsets done and working days extended due to additional COVID-19 planning tasks coming in I needed something simple to fill the time in. I had hoped to simply touch up the paintwork but given the lack of primer it would only come of quickly again, so have made a start on taking it all back to bare metal. Here the pony truck has been stripped.
Bogie stripped of paint. Everything is getting labelled up due to the long gaps between getting worked on I need to make sure orientation of components is not lost.
Over the next week I'll be re-machining the tender wheelset profiles then on to stripping the tender itself of paint. My aim is to get everything ready for a single session of applying primer before moving on to painting the chassis so it can be reassembled. Then it will be on to new backhead fittings and prepping the boiler for 1.5x hydraulic test.
I've mentioned previously that I work in rolling stock engineering with London Underground, well the job I am currently on was one of the ones that has been kept going as part of essential maintenance. An interesting quirk of working from home is the tendency to work longer hours as you're 'logged in' to the company IT system, which means it is very easy to lose evening workshop time mid-week compared with trying to stick to rigid office hours. We've been told that the earliest date for returning to our office in Southwark is October, but more likely January 2021 or possibly later. Interesting times...