WORKING ON A SIMPLEX STEAM LOCOMOTIVE - PART #16

Added: 2026-05-31

[00:00:03]Working on a simplex steam locomotive.

[00:00:06]Part 16. Fitting the smokebox door that came with the new boiler. Making some hinge mounting brackets and a new smokebox dart fixing bar.

[00:00:16]The smokebox door in this image that's painted black was the original one that was fitted to the smokebox of the old boiler. And it didn't have any hinges as such. They were just dummies.

[00:00:27]The smoke box had a stick on rubber gasket all the way around it. And in this clip, I'm removing it. I'm going to use the other smokebox door on the right hand side. This was fitted to the original smoke box that came with the new boiler.

[00:00:43]Luckily, when I bought this engine from the owner, he gave me this book with it, which has proven quite useful just to double check dimensions and see how the locomotive is put together.

[00:00:53]I've compared the smoke box door that I have and it is the same size as the one shown in the book. The first thing I'm going to do is remove the hinges and clean them up with some emey cloth just like I'm doing with the smokebox door.

[00:01:07]Using emey cloth on metal this way is a very important part of the job. It keys the metal ready for the coat of paint.

[00:01:14]If the metal is perfectly flat and shiny, the paint won't adhere to it.

[00:01:19]Here's a pair of hinges looking quite a lot cleaner. I didn't show it on the video because it's really difficult to get the camera into a good position, but I reprofiled the end of both of these hinges using my 1-in belt sander.

[00:01:34]In this clip, I'm refixing the hinges to the smokebox door, but I'm using shorter bolts. These are very small bolts.

[00:01:40]They're actually 10BA. The original 10BA bolts were very long, which is not a problem. You just snap them off. But the problem was that the heads were different sizes on the original ones, whereas the heads on these bolts are all the same size and look a lot better.

[00:01:56]This clip shows the hinge pin in place along with one of the original fittings.

[00:02:00]And I really don't like this. Using the long hinge pin as a guide, I scribed a couple of lines on the smokebox ring.

[00:02:08]And then I made these.

[00:02:11]I didn't bother videoing this process because I did them all in the drilling machine. No lathe work at all. Just a simple drilling operation on two pieces of square bar.

[00:02:21]I drilled two holes for the pin and two underneath for the mounting. I'm threading the hole underneath 5BA to take a 5BA bolt.

[00:02:31]Once the 5BA bolts were screwed in position, I silver soldered them in place. But on both of them, some of the silver solder ran down the threads. I rectified this by using a 5BA die in a die holder to clean off this silver solder from the threads.

[00:02:48]This is definitely a job for the calibrated eye.

[00:02:52]If you don't have enough confidence to drill the holes in the smokebox ring in the correct place, then you could drill the holes in a small piece of metal and use this as a template to transfer the holes to the smokebox ring.

[00:03:05]But I like to live dangerously. I live life on the edge. It's the only excitement that I get these days. So, I drilled and tapped the holes completely by eye. Then, I lined up the fittings using the edge of a ruler. In my opinion, these shaped pieces of square bar look much better than the original fittings.

[00:03:26]And when I put the pin in place, the door is a perfect fit to the smokebox ring. The joint between the smokebox door and the smokebox ring has to be airtight.

[00:03:41]By repeatedly opening the door and snapping it shut, I can see that this is the case. It's a perfect fit all the way around. This is the crossbar that was going to be used in the smoke box that came with the new boiler. But I don't like it. I put it together. Here we see the smokebox dart. You can see how it works. The smokebox dart goes through the slot in the bar. But unfortunately, this bar is not strong enough. It will bend.

[00:04:08]I intend to make a complete new assembly using two pieces of square bar this size.

[00:04:15]That makes for a much stronger construction.

[00:04:19]The construction is very simple. It's just two pieces of square bar with spacers in between. After I've made the unit, I will need to make two brackets so that it sits in place inside the smoke box. With a cutting disc in my small Proxon motor tool, I cut off the excess thread from the hinge supports inside the smokebox ring. After looking through my box of various pieces of steel bar, I could not find a piece the right size. This piece of steel bar is/4 an inch thick, a little bit too thick, I think, and also it's too wide. I'll machine it to the right size after I've cut it. And to do this, I use my metal cutting band saw.

[00:04:58]Time now to try the piece of bar in position to see if it fits. When I place the original crossbar on it, you could see how much bigger it is. The ideal size would have been half an inch wide by 3/16 thick.

[00:05:11]But I have the technology thanks to a man called Dan who sent me this really good phase cutter. Here I'm fitting the cutter into the R8 taper of the milling machine.

[00:05:22]With the bar resting on a suitable piece of packing, it's a very simple job to reduce the width of it.

[00:05:30]In this clip, I'm measuring the position of the hole in the center of the original crossbar. My marking out is generally very messy, but it's only for me, and I know where the lines are. I use the original crossbar as a template, laid it on top of my piece of steel, but the original wasn't in the center of the piece of bar anyway. So, I reme-measured it and drew two lines 2 in in from each end. Back over now to the milling machine, you will notice that I've put the wood packing at the top. In this part of the clip, I'm setting the limiters on the table.

[00:06:03]This feature has proved very useful over the years. By putting limits on each end of the longitudinal travel of the table, it makes milling slots a lot easier.

[00:06:13]I'm using a 3/16 of an inch diameter slot drill for this job.

[00:06:18]By taking a succession of very fine cuts, finally I get through the piece of steel. And now you can see the wood as the slot drill starts to machine the mahogany packing underneath.

[00:06:29]This clip shows me using a small needle file just to clean up the tool marks on the inside of the slot. Here you see the general arrangement. The smokebox doubt is in the right place. And I'm using this to hold the crossbar in place relative to the smokebox ring.

[00:06:46]I'm marking the position of the crossbar on the smokebox ring. And I'm also marking the bar itself at each end. The next part of the job is to make the two supports that will hold the crossbar in the right position.

[00:07:00]There are many different ways of making these supports. I'm doing it like this.

[00:07:04]I've marked out two steel blocks and here they are in the milling machine.

[00:07:08]And here they are again once I milled them to the correct shape.

[00:07:12]This clip gives you quite a good idea of what the end product's going to look like. Using my 1-in belt sander, I shaped one side of each of the blocks to fit the inside radius of the smokebox ring.

[00:07:26]I've also milled the end of the crossbar as well. The next part of the job is the drilling of two holes, one at each side, through the smokebox ring. I will then countersync the holes to take a couple of 4ba counters bolts. So, with very little effort really, I now have a kit of parts. But this is not the only way to do the job. Have a look at the previous smoke box that came with the boiler. This just uses two pieces of bent steel riveted to the smokebox ring, one at each side.

[00:07:58]There are no rules here. Just make the crossbar and clamps however you want to do it. And it's a very good exercise for the calibrated eye because to be honest, I didn't do much measuring at all. It's good what you can do with a small felt tip pen with a bit of practice. Then once again with a small felt tip pen, I made a marks through the holes on each of the milled metal blocks.

[00:08:20]Then I drilled these holes tap in size for 4ba threaded them 4ba using a 4ba tap. After which, as you can see here, I screwed in a couple of steel 4ba bolts.

[00:08:31]I initially left these blocks slightly larger than they needed to be so I had something to handle while I worked on them. But before I rivet the smokebox ring in position, I will probably mill these brackets a little bit thinner.

[00:08:45]Although it doesn't really matter because they are after all inside the smoke box. And they do what they're supposed to do. They hold the crossbar in place to allow me to lock the smokebox door and make it airtight. And also the crossbar is very easy to fit and remove for cleaning the tubes.

[00:09:03]And now it's starting to look like a steam locomotive.

[00:09:07]There's still a long way to go yet though. But that's it for this episode.

[00:09:11]I'd just like to say stay safe and well.

[00:09:13]Thanks for watching and I hope you found it useful.

[00:09:18]Please take the time to visit my mainstream 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. And by using the playlists, you can actually watch the videos back to back.