Refitting a radio controlled Glasgow paddle steamer. Part two. Removing the water gauge and cleaning out the boiler. If you’ve already seen part one, you will realize that there is a problem with the water gauge. No water is showing in the gauge, even though the boiler’s full to overflowing. To fix this, I need to remove the water gauge entirely to clean it out. The water gauge bottom fitting usually gets blocked where it fits into the boiler itself. In this clip, I’m trying to loosen the gauge glass using a pair of pliers and you need the most delicate of touches to do this.
Time for a health and safety warning. You also need to wear eye protection in case the glass shatters. I didn’t shatter the glass as you can see, it’s still intact. I had to heat up the top and bottom parts of the fitting using a small blow lamp, and only then did the glass become loose enough to withdraw through the top fitting. Water gauges are very problematic, and the bottom fitting is very easily blocked with lime scale. When you try and remove the bottom fitting, this is usually what happens.
The fitting shears off. Now, why has it sheared off? It sheared off very easily. This is possibly due to the brass de-zincifying. This is a known phenomenon when brass is used for fittings in model boilers. This water gauge fitting is now scrap. I could fix it. It’s better and quicker to buy a replacement. Do you remember in the last episode I showed the very strange arrangement with a perspex disk in the bolt, which was soft soldered to this plug? I cut off the bolt using my bandsaw and then in my Boxford Lathe, I re-profiled the plug.
Now I need to remove what’s left of the water gauge bottom fitting from the boiler, so I’m drilling it out. The drill that I’m using is smaller than the tapping size for the hole. I need to extract what’s left of the water gauge’s threaded part. You can buy special tools to do this before everybody writes in to tell me about them. I do know about them, but I don’t have any of the right size. Here’s a top tip. Why not try this? It’s simple and very crude, just like a girlfriend that I used to have.
You take a bolt that’s larger than the hole, and you grind it square on the end. Then you hammer the bolt into the hole like this. This is not as brutal as it looks and sounds. The hammer blows are quite gentle, and it’s a very small hammer. The idea is to hammer the square part into the round part of what’s left of the water gauge thread and then by simply using an Allen key and the Allen head bolt, it’s usually an easy job to withdraw the broken piece of water gauge from the boiler bush. But not so in this case.
In the end, I had to do drill the bush out like this, making very sure that the drill goes into the hole perfectly in line with the boiler bush. After applying some lubricating oil to a taper tap, I then re-thread the hole. This is more of an art than a science. You really have to feel when the tap engages with the original threads. For jobs like this, stud extractors are very useful. They’re available in various sizes. They’re usually tapered and have a left-hand thread. This method works fine if you’re very careful.
Cheddar model steam engines and boilers were made with 32 threads per inch threads in them. In this clip I’m verifying the integrity of my thread cutting operation by fitting a quarter of an inch by 32 threads per inch blanking plug in the hole. As the lime scale around the fitting was so incredibly thick, I thought it was a good idea to take some acid from my acid bath and using a funnel, pour it into the boiler. Health and safety warning. Acid is very dangerous stuff.
Even though this is only really kettle descaler, it’s still formic acid, and you don’t want to get to any of that in your eyes. It’s bad enough getting it on your hands, but in your eyes would be seriously bad. Always wear suitable eye protection. While the kettle descaler is starting to dissolve the lime scale in the boiler, I think it’s time to look at the engine. This is a Cheddar Models pintail twin-cylinder oscillating steam engine. This particular variant is designed for paddle boats. I’ll show you why very shortly.
The first thing I need to do is remove it from the bracket to have a close look at it. The first part to go is the exhaust pipe, and in this clip I’m removing the engine from the mounting bracket. I’ve owned a few of these pintail engines and they really are very good. They’re made from brass, which is not the best material for wearing, but it doesn’t seem to bother these engines. They just run forever. As I mentioned, this is the paddle boat variant of the pintail, and you can see why if you look closely at this clip.
As I’m oiling around the engine, you will see that the oil holes on the two outer bearings here and here have the holes for the oil in the side. Normally these holes are in the tops of the bearings. As expected, the engine runs very well. I’m fitting the piece of silicone rubber pipe to the exhaust port. With an oscillated cylinder engine though, there’s no such thing as an exhaust port because you can go in or out of either of them, and the engine will go in forward or reverse respectively. That’s what the reversing valve does on the top.
I’ll stop talking for a while and just leave the engine running so you can listen to it and watch it … This is a ceramic burner that fits into the boiler. Here’s a quick tip. When you resilver solder pipes for gas burners, always place the freshly silver soldered pipe into the acid bath. The acid will dissolve all of the scale on the inside of the pipe and therefore the gas jet will not get blocked by it. I’ve refitted the ceramic burner to the boiler, and now I’m lighting the burner.
What a surprise. It’s making a howling noise. This is very common with center flue boilers that use ceramic burners, but usually as the gas chills, the howling subsides because the pressure drops. Although you can modify the sound of the howling by moving the position of the gas jet in the Venturi pipe. That’s the one with the two holes in it. In this clip, I’m slacking off the pinch bolt. This allows me to move the position of the gas jet either in or out, and you find a sensitive spot where it becomes a lot quieter and more efficient.
What you can’t see in this clip is I have my nose over the chimney. When combustion is efficient, there isn’t much smell from the chimney. Once again, another health and safety warning. Eye protection must be worn. Be very careful. Watch this. As boiling point is reached, the whole thing boils over. Not a big problem, but without eye protection with my nose over the chimney, that could have been bad. All I need to do now is leave the hot kettle descaler in the boiler and as a final health and safety warning, don’t forget to always remove the gas adapter from the gas canister once you’ve finished playing with your steam plant. That’s it for this one. Thanks for watching, and I hope you found it useful.