WORKING ON A SIMPLEX STEAM LOCOMOTIVE - PART #17

Added: 2026-06-01

[00:00:02]Working on a Simplex steam locomotive, part 17.

[00:00:06]Test assembly of the completed superheater and wet header, improving the petticoat pipe by machining a piece of brass bar, making a new union nut for the wet header steam pipe, fitting the sniffing valve in place on the wet header, and making a new blast nozzle.

[00:00:25]The wet header end of the superheater element is mounted to the flange using four temporary 2BA bolts. This is at the other end and I'm tightening the nut that holds the steam union onto the steam inlet pipe.

[00:00:37]I discovered that the union nut was not a good fit on the steam inlet pipe.

[00:00:42]And to make matters worse, when I fit the blast nozzle, I have to move the steam inlet pipe out of the way.

[00:00:49]This blast nozzle is unnecessarily large because it was at one time also a blower.

[00:00:55]Here is the petticoat pipe.

[00:00:58]And its function is to focus the exhaust blast of steam from the blast nozzle that I'm going to replace.

[00:01:05]This one is rubbish though. The flare is insufficient and it's very badly made.

[00:01:11]It's just a piece of copper tubing that's been assaulted with a hammer to make it flare somewhat.

[00:01:16]Even the mounting lugs are not really in the right place, but I'm not bothered about this because I can re-profile them.

[00:01:23]All I'm going to do is chop off the end of this piece of copper pipe where it all goes wrong.

[00:01:28]And then I'm going to make a new petticoat pipe from some of this brass bar.

[00:01:33]This will be much better. The petticoat pipe will be removable, so I won't have to remove the chimney to get spanner access that will eventually secure the wet header to the flange.

[00:01:45]Once I cut off the part that I didn't want, I fitted the rest of it in the lathe chuck.

[00:01:51]What I'm currently doing is cleaning up the end of the copper tube.

[00:01:55]The part of the tube that I cut off using the bandsaw was 7/8 of an inch long.

[00:02:00]So now using this piece of brass, I need to make a special part that fits over the tube that is 1 and 3/8 of an inch long.

[00:02:09]By heavily editing the video, as you can see in no time at all, the blade went through the piece of brass.

[00:02:15]Back over now to the lathe, the piece of brass is in the chuck and I've speeded everything up.

[00:02:22]By using quite a lot of cuts as I've just shown, eventually I could face off in the normal manner.

[00:02:28]Here you can see that the tool is a bit low, so I'll quickly adjust it and take another facing cut.

[00:02:37]That's better. The tool is exactly on center height now.

[00:02:41]The next part of the job is to turn down the piece of brass to be bigger than the copper tube, but not too big.

[00:02:49]I took a series of cuts until the end part of the brass was the right size.

[00:02:53]When I held the copper tube up against it, it showed me how large I needed the part to be.

[00:02:59]This next sequence is not easy to do.

[00:03:03]I've changed the tool from my normal knife tool to a round nose tool, but before I did that, I started to shape the part using the knife tool.

[00:03:11]This is the clever bit.

[00:03:13]I have auto traverse engaged and I have my hand on the cross slide handle. At a certain point, I slowly start winding out the cross slide handle.

[00:03:24]Winding the handle first quite fast and then slowing it down to achieve a bell type shape.

[00:03:30]At this stage, I'm just checking that it's the correct length using the part that I cut off.

[00:03:36]Now it's time for a drilling extravaganza, starting off with a center drill, followed by a succession of different drill bits to enlarge the hole before I bore it to the correct size.

[00:03:47]I'm not going all the way through the piece of brass, just past the part that I turned previously.

[00:03:53]Now I have a much larger drill bit fitted and this is one that goes into the Morse taper of the quill on the tailstock.

[00:04:01]And finally, I'm putting a 1-in drill bit through. You will notice there's a felt tip pen on this drill bit, which is not new, it's been on there for a long time.

[00:04:11]The next part of this video is quite boring, literally. I've fitted a boring tool into the tool post and I'm enlarging the hole down the center of the piece of brass.

[00:04:21]This is somewhere near. Now it's time to take very fine cuts because I do not want this to be oversize. It needs to be a firm push fit on the original piece of copper tubing.

[00:04:32]I do this by taking a fine test cut, then trying the copper tube in place.

[00:04:38]And once the original piece of copper tube is a good fit in the test part, complete the cut all the way down.

[00:04:45]With each of the test cuts, I use the boring tool going towards the chuck and then also back again.

[00:04:52]And that's what I'm doing now all the way down.

[00:04:55]By boring the hole with the boring bar, what I normally do is reverse the direction of it without touching any of the handwheels.

[00:05:03]And then the boring bar takes a very fine cut and hopefully this should fit the copper tubing fine. The final part of the job is to use the boring bar as a facing tool and pull it towards me.

[00:05:15]After cleaning away all of the swarf, the copper tube now fits into the hole perfectly.

[00:05:21]The final part of this sequence is the parting off operation. I don't need the rest of the piece of brass, just the fancy end bit.

[00:05:30]In this sequence, I've locked the saddle in position so it can't go forward or backwards.

[00:05:35]And I've rotated the top slide so it's at an angle to the work.

[00:05:39]And what I'm doing here is just operating the top slide handle to push the boring bar in and out of the work.

[00:05:46]And this more or less follows the same angle that I cut freehand on the outside of the work.

[00:05:52]All I need to do now is clean up the outside with a file.

[00:05:56]And here I'm cleaning the inside edge using a piece of 100 grit emery cloth.

[00:06:01]The emery cloth is folded over and my fingers are actually nowhere near the rotating parts.

[00:06:07]Here's the finished component. I think it looks a bit better than the original.

[00:06:12]I chamfered the inside edge of the copper tube to make it match.

[00:06:17]I haven't decided how to attach this part to the copper tube, but I've got one or two good ideas.

[00:06:23]A sniffing valve is really a check valve, also known as a one-way ball valve. This is the front of the sniffing valve with a hole in it. And behind this hole in the front of the valve is a stainless steel ball, which normally covers the hole. Any steam pressure applied to the ball inside the sniffing valve will press it against the hole in the front of it, which in turn seals the hole and stops the steam escaping. As I said, it's just like a boiler check valve.

[00:06:49]The sniffing valve in this case is going to fit in the side of the smoke box.

[00:06:54]That's why the thread on it is at that angle. Often, they're fitted at the top of the smoke box.

[00:06:59]I need to make a specially shaped piece of copper pipe, this is 3/16 of an inch diameter copper pipe, to fit between the outlet on the wet header and the sniffing valve.

[00:07:09]Very much like this in fact after I've silver soldered everything in place. The question is, why do we need a sniffing valve on a miniature steam locomotive? I will use this Simplex as an example.

[00:07:20]It's a twin cylinder locomotive with slide valves on top of the cylinders.

[00:07:24]When you open the regulator, steam is allowed from the wet header, which then travels down the superheater, back down the superheater flue. In this case, not into the fire, but quite close to it. So the steam that enters the cylinders is very hot indeed. Which is all very well when the regulator's open, but what if it's closed?

[00:07:43]You can then get a vacuum in the superheater and then it will overheat, but not if you have a sniffing valve which lets air into the superheater to cool it down slightly and also allow the engine to coast more freely.

[00:07:56]I've tried to explain that in as few words as possible and I do hope that you understand the importance now of a sniffing valve.

[00:08:03]Time now to withdraw the superheater element.

[00:08:07]Now it's time to get on with the job.

[00:08:09]This is a piece of brass hexagon in the chuck in the lathe. I've center drilled it and here I'm drilling it tapping size for a 1/2 in by 32 threads per inch thread.

[00:08:19]Please note that I'm not tapping this all the way through. I will be drilling it all the way through, but that drill will be much smaller.

[00:08:26]I've already shown making the flat steam union in a previous video, but unfortunately that was destroyed when I unsoldered it from the superheater element. And why am I making a new union nut anyway? Well, the old one was a rattle fit on the thread.

[00:08:41]To ease the passage of the 1/2 in by 32 threads per inch tap, I've applied some oil and it's not squeaking at all.

[00:08:47]But mainly it's to make it much easier for me to manually rotate the chuck.

[00:08:52]That stage one complete. Here we have the thread. Time to drill the hole for the steam union all the way through.

[00:08:58]This twist drill is two imperial sizes larger than 5/16. The superheater element pipe is 5/16 of an inch in diameter, so I'm drilling it bigger than that to allow for the steam union that I'm going to make.

[00:09:10]Really, I should have bored this hole before I threaded it. Then it would have had a really flat bottom. I suppose from an engineering point of view, that would have been better, but it's okay with the drilled hole as long as it has a shoulder to firmly hold the steam union to the steam pipe.

[00:09:26]I silver soldered the new steam union to the pipe, not forgetting to put the union nut on first, and here it is in position. Much better than previously, the old union nut just spun round and round and didn't clamp anything. Whereas this one tightens up nicely as the thread isn't stripped.

[00:09:42]You will notice that as usual, I'm using my back or spanner for this job. You will also notice that it's not rounding the ends of the nut.

[00:09:51]It's time now to make a really important part.

[00:09:55]And this part is known as the blast nozzle.

[00:09:59]I could have made this entire part by turning it in the lathe from a piece of brass hexagon. Here are the three component parts that make up the blast nozzle.

[00:10:07]The hexagon part that I'm holding in the middle is the old union nut from the steam pipe. The wide bottom part is from the original blast pipe, and this smaller part I made from scratch from a piece of brass.

[00:10:19]Then I silver soldered all three of the parts together. I know it looks a bit messy, but then again, it's not going to be very visible inside the smoke box, but that is not the point.

[00:10:28]This clip shows the nozzle, and can you see the fact that it is tapered? I use the center drill for this. As I turn the part round, I don't know if you can see it, but I center drilled the inside of the piece, too. This gives me a converging and a diverging cone, and that's how it's shown on the drawing.

[00:10:46]A blast pipe is not as simple as it looks.

[00:10:49]An incorrectly made blast pipe will seriously affect the steaming capabilities of the locomotive.

[00:10:55]This clip shows the part after I cleaned it up in the lathe, and I'm screwing it into position.

[00:11:00]Everything that I'm fitting in the smoke box area, including the blower that I haven't fitted yet, will be bent to such a shape that leaves the flues clear for the flue brush. And that also includes the pipe that comes from the blower's hollow stay.

[00:11:14]But that's it for now. I'd just like to say stay healthy. Thanks for watching, and I hope you found it useful.

[00:11:22]Please take the time to visit my Main Steam Models website and click on the section of the website that says video playlists. And by doing that, you can find other videos that you may like to watch.

[00:11:33]And by using the playlists, you can actually watch the videos back to back.