Some significant progress has been made with my first scratch built 2FS loco - It works!!!
Following on from the last instalment, I had determined that I needed to construct some of the body work in order that I could determine how well or otherwise my dog clutch arrangement would be successful in transferring drive from the motor to the gearbox. A dog clutch is used in engineering when turning between centres so I had some conviction that it would work, but I was a little worried that if the centre line of the motor and that of the gear box were too far adrift that the final drive at the wheels would be erratic.
Because I was mounting the motor in the boiler/smokebox, effectively I had to mount the boiler on the footplate to judge the centre height of the motor shaft compared with the centre height of the gearbox. In order that I could do that I had to make the tanks so that I could fit the boiler on top of them, and to ensure that the wheels and gearbox would not encroach into the cab space I had to make the cab too. In addition, because I needed a way to anchor this top assembly to the footplate, I decided that the best way was to make the sandboxes ahead of the tanks and drill and tap them 12BA so that the tank/boiler cab assembly could be held together. in the end I also needed to make the bunker/cab floor too so that I could screw the chassis into something!!
Below is a photo showing all of these separate assemblies (the gearbox is held on the main chassis block with a peg at one end and a 12BA bolt at the other (from underneath) :
Once I could actually put all of this lot together, I found that I could fit a slightly larger flywheel, so a new one was made with a 0.5mm peg protruding to provide the drive to the gearbox :
This peg acts on a bar which extends across the gearbox drive shaft (another turning in stainless steel, the end of which filed to provide bearing surfaces for the peg on the flywheel - The Dog Clutch :
In order that the motor could be fitted in the boiler, the original wires from the Nigel Lawton motor were cut short, and replacements of enamelled wire soldered in place - the enamelling preventing shorting. The new wires can just be seen in the photo below before they run along the top of the motor through the boiler. Because of these wires, the motor is now an interference fit within the boiler so there is no need to glue or otherwise secure it in place :
With the boiler bright work just plonked on top, this how she looks now :
And to prove that (after much fettling) she works :
To get this far has been a bit of a trial - getting the thing moving without binding has proved much more difficult than my saddle tank did. That in itself is particularly frustrating because the original chassis that I built in traditional 2mm ways of phosphor bronze frames held apart/together with PCB still has the wheels (with coupling rods) in it and rolls happily without issue, it just lacks weight which is why I went down this route of a solid chassis.
The next stage is to start making and adding the details to bring her to life as it were (buffers are already done). Will she be ready for the AGM? Highly unlikely!! Hopefully, I will get her completed for Warley so she can share a turn hauling my 4 wheel coaches up and down St. Ruth's branch line.
Regards,
Ian
- 10
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