The Watkins Blog

Sorry for the loooong pause between posts. In the year since the last post, a lot has happened. Whilst other-parts-of-life (mostly good) have taken priority, there has been some progress on the Shay:

• I have fired up the Shay a number of times to try and fix the various steam leaks.
• I tried running the loco on air.
• I wrapped PTFE tape around the thread of the lubricator to reduce (greasy) steam leaks.
• I replaced the fibre washers around the banjo joints to reduce steam leaks.
• I hacked around with the smokebox to deal with the problems of poor burning.
• I checked the oil level in the lubricator, and forgot to replace the PTFE tape.

When running on steam, the pressure doesn’t want to rise above 20 psi, and the motor just refuses to turn over. Steam continues to leak from all sorts of places – mainly joints but also within the steam motor itself. This video is from 4th May 2024, at Brambleton.

However, running on air is fine and sweet – the motor turns nicely. A friend in my local Model Engineering Society helped me to make a replacement boiler plug with a Shrader car-tyre valve on the end. I use a portable 12-volt car tyre inflator as a compressor. As you can see in this short video (from 10 August 2023), the pressure got up to about 40 PSI.

Thanks again to my friends, especially David and Tony, for your ongoing help. The next step is probably to take the steam motor apart and tighten anything that can be tightened.

It’s been a few months since I did anything with the Shay – life is like that.

I believe that the wheels of this locomotive were originally designed for G-scale. I say this with reasonable confidence because the flanges are too big, and they bump on the sleepers on 16mm Peco track. Here is one of the bogies, seen from underneath.

I tried a few times to get the bogies apart. Unfortunately, the gears are a tight fit on the axles and won’t come off. Also unfortunately, the bogies are soldered together, and I didn’t want to have to rebuild them, So I investigated how I might reduce the flanges whilst the wheels remained in the bogies.

I made a wooden jig to hold the bogie, and attached various bits to a board to support my cordless drill and the jig. There is also another piece of wood that holds the trigger on the drill. Using the driveshaft and gears seemed like a logical thing to do, but when I held the file against the flange to wear it down a bit, I quickly realised that this was putting un-necessary stress on both the universal joint and on the gears. The grub screws also kept coming loose.

So I rotated the bogie-holding jig through 90 degrees and held the axle directly in the cordless drill. This worked much better. It involved removing a boss from the left end of the bogies and tightening the screws that hold the wheel to the axle, but this was much more satisfactory, and in the space of a few minutes I had filed down one wheel sufficiently that it no longer bumped along the track.

Repeat with the other wheel on the same axle.

The jig was adjusted to drive the other axle, and its two wheels were similarly filed down. The exact diameter of the flange is not critical. A bit of filing on the sides of the flange removes any burrs.

Repeat with the other bogie, and the wheels now run properly on the track.

If you have been following my previous posts, you will know that the boiler and gas tank are both sound. A friend from my local model engineering society encouraged me to try lighting the loco to see if it will run.

One loco that I own is lit by applying a flame to the chimney. The flame blows back into the burner flue. Another is lit by opening the smokebox door and poking a lighter in there. The Shay’s smokebox door doesn’t open. However lighting the chimney didn’t have the intended consequences.

I asked online, and another Shay owner tells me that the loco is lit from under the smokebox. There is a small hole. I tried this, and get a nice blue flame around the base of the smokebox. Again not really what we want.

Apparently the fix is to add a sleeve to the burner air intake (like on a Bunsen burner). That involves removing the gas tank, which involves removing the Osmotor, which involves removing the lubricator. To make this easier, I intend to take the opportunity to put a union joint in the gas pipe to make it easier to remove the jet without doing a full strip-down-and-rebuild. Another job for another day.

Justin – 15 July 2022

In my previous post, I described getting the boiler and gas tank tested, and promised to start putting the loco together. This has proved to be quite fiddly.

The first fiddly bit relates to the bolts in the bottom of the lubricator. The bolts are soldered into the bottom of the lubricator, which is rather useful, as it means they fit and I can’t lose them. As you might be able to see in the photograph below (which is taken from underneath), the holes for the nuts are directly in line with a piece of brass – and they are a bit fiddly to install, and there’s barely enough space to get a spanner in there to do them up. For the record, these are M3 nuts.

“Fortunately”, I told myself, “I only need to do these up once”.

With the lubricator installed, I then looked at installing the boiler next to it. This was relatively easy: two bolts on the angle iron at the back into the frame (also M3), and it fits snugly on the smokebox at the front.

Then I realised I had forgotten to bolt in the burner. So I unmounted the boiler, bolted the burner in place, and re-mounted the boiler.

Then I mounted the steam motor, which is fiddly because there is a steam pipe that comes out the back and needs to fit inside the exhaust pipe that runs alongside the boiler. It is also fiddly because the gap in the frames is only just big enough.

At this point, I looked to see how the pipe from the lubricator connects to the steam motor, and realised that the screw that holds the banjo cannot be done up because it faces the boiler. I also realised that the gas tank has to be mounted before the motor, because of how the gas pipe runs to the burner.

All was not lost. I didn’t need to remove the boiler – just the steam motor and the lubricator. Remember those M3 bolts I said I would only ever do up once?

With the lubricator loose, the gas tank installed, and the motor back in its right place (but not bolted down), I took the opportunity to re-shape the pipes so they are neater. I also checked that they don’t get in the way of the cab.

Bolting everything down again was relatively straightforward. I undid the nuts on the lubricator three times in the end. A few weeks ago, I had looked at the nuts and bolts that hold down the steam motor and gas tank, and found that some of the washers and nuts were missing.

This is the second fiddly bit.

• The two at the burner end of the boiler are M2, and they only hold the steam motor in place.
• The two bolts between the steam motor and the gas tank are also M2, and hold both to the frames.
• The two bolts at the front end of the gas tank are tiny. Possibly M1.6, or possibly 10BA.

I purchased a pack of 8BA washers, and substituted 8BA washers for M2.

I also purchased a small pack of ten nuts, washers and bolts in 10BA from Macc Models (via their eBay shop), but I couldn’t get a 10BA bolt through the hole in the frame, though the bolt that was supplied with the kit does fit. This leads me to suspect that these bolts are supposed to be M1.6 (which requires a 1.6mm hole) instead of 10BA (which requires a 1.8mm hole). However I was able to get a 10BA washer and nut on the bolt-that-is-probably-M1.6 … and it seems to do up.

A note on small bolts – if you are purchasing such a thing, only buy one size at a time. None of my packages came with a delivery note, so it would have been very difficult to tell the difference if I had bought multiple sizes from different eBay shops at the same time.

Oh, and open the tiny bag over a lid (the lid of a Chinese Takeaway container for example) to stop the bits rolling away.

Justin – 16 June 2022