David Andrews Princess Royal – Back Head Bling Refitted

Here is it is with most of the bling refitted – just resting in place it will be soldered in from the back later.

David Andrews Princess Royal – Back Head refitted
David Andrews Princess Royal – Back Head refitted

I say “most of”, because the production locos from 6203 onwards had a double regulator handle and I have only just got around to making it.

David Andrews Princess Royal – Regualtor Handle

MOK 8F 8425 – Solving The Enigma Was The Easy Bit!

Having worked out how it all fit turned out to be the easy bit!
Assembling all the elements together with the balance weights was like trying to plait fog. You have to slip the cross pin through eight separate holes in the subassemblies. Much muttering ensued before I got it all together.

MOK 8F 8425 Water Scoop Mechanism
MOK 8F 8425 Water Scoop Mechanism
MOK 8F 8425 Water Scoop Mechanism
MOK 8F 8425 Water Scoop Mechanism

Although they are shown on the isometric drawing there is no provision for or mention in the instructions of the support adjuster rods for the scoop. I made them from some lengths of rod and microbore tube.

MOK 8F 8425 Water Scoop Mechanism

I have made a few of these Stanier Tenders by now and this is certainly the most detailed that I have done to date.

MOK 8F 8425 – My personal Enigma Finally Solved

Today I finally cracked my enigma. One of the reasons that the build stalled back in 2018 was that I couldn’t for the life of me work out how the water scoop mechanism went together.

At this point I need to say a big thanks to fellow Guild member Ian Allen for pointing me in the right direction. As with all things when you know what to look for it is there in the instructions it’s just not that clear.

My problem was the arm that goes alongside the inner chassis.

MOK 8F 8425 Tender Water Scoop Mechanism

I initially had it located in between the clevises at the front. When it needs to fit behind. This meant that when trying to fit the wheels the rod fouled them

MOK 8F 8425 Tender Water Scoop Mechanism

Once I knew this it made things a bit clearer then I discovered that I had the linkage that the water scoop attaches to upside down.

MOK 8F 8425 Tender Water Scoop Mechanism

With that corrected I was able to get it to fit together. It still needs fixing permanently in place but I have the balance weights to fit yet so I will wait until I have done that before making anything else that I might have to undo!

MOK 8F 8425 Tender Water Scoop Mechanism

Cheap and Cheerful Home Made Nut Spinners

For those of you not wishing to spend a packet on BA nut spinners from Markits et,al a chance conversation with a friend brough back a memory of a much missed GOG Member whom I have referred to in the past David Smith (known on various forums as DLOS). He was really a model engineer and he had mention in a posting a few years ago that he had made BA nut spinners from appropriately sized caps screws using the hex head as the socket.

Having a spare couple of hours last night I rummaged through my screw box and found that an M4 and M5 cap head screws were just right for 8 and 10 BA and a couple of grub screws suited 12 and 14BA.

Home made Slim Line Nut spinners 8-10-12-14 BA

Although I used the lathe they could be made by anyone with the ability to drill and tap metric threads. I did turn down the heads of the cap screws but again nothing that couldn’t be achieved by putting it in a drill chuck and applying a file.

A tip worth mentioning: If you use grub screws for any of them, in order to get enough threads to engage the grub screw, you need to drill the hole a bit deeper. This means that the head of the grub screw wont stay at the end. My solution was, once threaded, I screwed the grub screw in as far as it would go and then with a bit of brass rod I measured how far in the head of the grub screw was from the end (1.5mm and 4.5mm respectively in my case).

I then cut a couple of short lengths of brass rod that would slip inside the threads (2mm I think I used) This allows you to tighten the grub screws against the bottom of the hole while the head is level with the end. I was planning on Loctite-ing them but I don’t think that they need it.

The handle parts were made from a length of bent 6.35mm brass bar which equates to a 1/4 inch (I must have bought it as quarter inch but any suitable sized bar would do. Hopefully it’s the last bent piece in my stocks as there is nothing more irritating than trying to tun something that you have to lose half it’s thickness before you get it to run concentric.
It’s not visible in the photo but the bend in the bar meant that the grooves look a bit like Zebra stripes, in that go they go thick then thin as the bar flexed away from the cutting tool as I turned them. You don’t need them for the tool to be functional but I can’t help messing.

David Andrews Princess Royal Back Head Ready for Paint.

David Andrews Princess Royal Back Head

That’s about it unless I think of anything else. I am struggling as to what was fitted the 1930’s and what was fitted later. The Wild Swann supplement has a photo of Princess Elizabeth as built and there is a lot less on the back head than is shown in the GA in part one.

All the parts are removeable until I have painted the main casting. 

David Andrews Princess Royal – Cab Hand Wheels and a Lubricator

The back head is well on it’s way now but when I got so far I realised that the only hand wheels I had were the teched nickel silver ones that came with the kit. Nickel of course looks different when you are trying to represent brass so I thought I would have a go at turning some.

I did one to work out how, but the four holes came out all over the place. Once I had a method that worked I made the three that I needed. They actually looked the part when fitted to the back head but what was missing were the handles.

Cab hand wheels
Cab hand wheels

At this size I couldn’t see any sensible way to add them to the ones that I had made so I had a rethink.
I modified the technique and made rings to solder to the face of the etches and then added half round rod for the handle. This is the best of both worlds. the right shape and three dimensional.

Modified cab Handwheels

Out of the castings that I have from the various sources the one that is missing is a sight glass lubricator which sits at the upper left above the brake valve.

Sight Glass Lubricator
Sight Glass Lubricator

David Andrews Princess Royal – Cab Dials.

Still working on the back head, because I am using a mixture of David Andrews and Just Like the Real Thing castings, I have had to move/reduce the size of all the holes except the one for the regulator mounting boss. The JLRT castings are really nice (as are the couple of David Andrews castings that I have) except for the cab dials which are a bit misshapen and the ‘unions’ for where the pipes are proving impossible to drill. The simplest and quickest way was to make some more swarf by turning some more.

Turned Cab Dials
Turned Cab Dials

Then I realised that I also needed a smaller version

Turned Cab Small Dial
Turned Cab Small Dial

It made sense while I had the set up to do some for the Rebuilt Scot at the same time.

Turned Cab Dials

Then I dug out the mountings and attached the dials to them.

Mounted Cab Dials

David Andrews Princess Royal – Production Firebox

While working on the back head this afternoon I was distracted by the Postie delivering the production print of the Firebox.

David Andrews Princess Royal Firebox Print
David Andrews Princess Royal Firebox Print
David Andrews Princess Royal Firebox Print
David Andrews Princess Royal Firebox Print

The above are the print as I received it straight from the packaging. The Printing was done by Mike Hopkins of Scale-Factor.

David Andrews Princess Royal Firebox Print
David Andrews Princess Royal Firebox Print
David Andrews Princess Royal Firebox Print
David Andrews Princess Royal Firebox Print

Again after I had carefully removed the print supports and raft. I still need to clean up the base and the cab end but a test fit on the boiler has it fitting perfectly a light friction fit.

David Andrews Princess Royal – Still working on the Backhead

It was kindly pointed out over on Western Thunder that I had the drivers brake valve upside down and that it was too close to the centre line of the engine/heat shield. I measured it up and compared it to the Wild Swan drawing and sure enough it was 0.9mm too far inboard.

As you can see I had made a small brass bush to reduce the size of the hole but moving it gave me the chance to re-drill at the right size for the brake valve stem.

Here we are nicely aligned.

David Andrews Princess Royal – Backhead

As you can see I have also made a start on piping up the steam fountain.

Driver’s brake valve
Driver’s Brake Valve

The brake valve is piped up the right way up now too.

David Andrews Princess Royal – Backhead Parts

I had to remove a section from the inside edge of the heat shield to allow pipes to pass through it. The pipe at the side is one of the two main pipes coming down from the steam fountain and one thing that stands out on both drawing and photos is that there is a chunky union on the lower section.

Pipe Unions

These are the parts that will make up a representation of those unions.

MOK 8F 8425


I managed to progress the tender for the 8F a little more over the weekend and now the outer frames sport axles boxes and springs.

MOK 8F 8425 Tender underframe – springs and hangers fitted

As can be seen from the inside, I soldered them on (with 100 degree solder). Before fitting them I added a small blob of 100 degree solder to the back of each spring damper. Once I had soldered the spigots from the inside I pressed on each damper with the none pointy end of a pencil and used the RSU again from the inside to quickly melt the solder, firmly attaching the dampers.

As an aside, as I got them out to the box I noted that one of the dampers had broken off and I spent sometime reattaching it using 70 degree solder. I was just about to fit it when I saw that I already had the six that I needed. Dave sharp must have noted the broken one when he packed the kit all those years ago and popped in an extra.

Recycled Allen Key for locking/unlocking the Sieg Mini Mill table locks

I know that there is at least one other reader with a similar Milling machine to mine so I thought that this might be worth sharing.

For many milling operations, the accuracy of the work is improved if you lock the table in one or both axis. The problem with doing that is access, particularly on the Y axis. Locking the table is done by means of a cap screw which when tightened nips the gibs and prevents the table from moving in that axis while you work. These are located in the mid point of each axis. The Y axis one being under the table at the right hand side and directly in line with the hand wheel. There isn’t a lot of room in the there and for me at least at best I get my knuckles covered in grease at worst I leave skin behind… I do have a set of long T handled Allen Keys but the T bit is too long and it has to be put in at an angle to clear the hand wheel.

While watching a video where someone else was struggling to tighten the mill table down it occurred to me that I needed to make something with a straight shank that was thick enough to grip and turn

I initially planned to use brass or acetal but while rummaging in my tub of Allen keys looking for one that I could cut down I found and old cheapo centre punch with a knurled grip. It was so cheapo that at best only the tip must have been hardened because the tip was totally mashed up and cutting the end off, facing it and drilling it out on the lathe was no effort at all. Once drilled I ground a slight chamfer on one end of the stub of Allen key and bashed it into the punch handle.

Recycled Allen Key

Now I have the perfect tool. It fit’s under the mill table and allows me to lock/unlock the mill table with minimal effort. I had thought of cross drilling it to add a small cross bar but I don’t think I need it.

David Andrews Princess Royal – The Beginnings of the Back Head

This week has mainly been about working on the backhead, one of my favourite parts of a build.

I started by making a driver’s heatshield. The size and shape was worked out from an oblique photo and referencing it to other items located in the cab.

David Andrews Princess Royal – Back Head Heat Shield
David Andrews Princess Royal – Back Head Heat Shield

Once I had the basic shape I took a short length of nickel rod and filed it to half round to create the edging strip. I did have it fixed in place but then when I fitted the Drivers brake valve in place and started to consider the other pipework I realized that there would need to be some relief above the fire door rails to allow pipes to pass behind the shield.

The other castings that you can see in the photos are some of the few David Andrews parts that I have. The ready made holes in the back plate itself are causing a few issues as most are over sized and the ones on the fire hole door needed their placement adjusting to get the levers that open and close it to sit correctly with the two mounting brackets adjacent to the bottom rail. 

The shelf on the other hand fitted perfectly .

Shop Made Scriber for fine holes

While fitting the inside motion subassembly to the Princess I had need of a slender scriber.

I do have an engineers scriber

Engineers Scriber

But it was too big to get in where I needed it. I also have a couple of needle pointed steel inserts that came with an aluminium handle which wasn’t as resilient as the inserts.

Scriber Point

I could have just held it in a pin vice and got the job done but where’s the fun in that. So I decided to turn up a handle for it from a length of 5mm nickel rod.

Shop Made Scriber

Once I had done the job on the Princes. I thought that if I wanted to be able to use it going forward, it could really do with a cap to keep it and me from harm. So I made a cap for it. I didn’t think to take a photo of the scriber before I altered it to take the cap but imagine a taper on the end and no thread or relief.

Shop Made Scriber with Protective Cap

The cap screws on and covers the point, making it completely harmless until needed.

David Andrews Princess Royal – Bolster Oil Pots With Nuts!

Well, it’s a good job I had decided to add the bottom nut as, when I was walking back into the workshop after taking the last photo I dropped the blessed oil pot and it disappeared into the ether. As it turned out if you will pardon the pun the bottom stem wasn’t long enough to accommodate the nut and go through the hole in the bolster so I made too more.

David Andrew Princess Royal – Bolster Oil Pots -With Nuts

David Andrews Princess Royal – Bolster Oil Pots

I am still working away on the details, a gent on the GOG forum pointed out that I had the front boiler slightly band too far from the smokebox so having checked photos and seen what he meant I moved it as far as I could. It’s now sat on the very rear edge of the smokebox/boiler joint rather than straddling them as I had it initially.

David Andrews Princess Royal – Relocated Boiler Bands

Next I turned what are probably the smallest part I have done to date. A challenge but satisfying.

David Andrew Princess Royal – Bolster Oil Pots

This is the working drawing – Fusion in it’s wisdom seems to get a few of the sizes slightly under or over when creating drawings despite having defined dimensions in the sketches. So they are rounded to the full size i.e. 1.75mm for the overall diameter.

David Andrew Princess Royal – Bolster Oil Pots

Finally with my obligatory 5 pence coin.

David Andrew Princess Royal – Bolster Oil Pots