David Andrews Princess - Princess Marie Louise 6206

[Rob Pulham]

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.

 

 

 

[Chas Levin]

Top job Rob! 😀

[Rob Pulham]

This week has mainly been about working on the back head, 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.

 

 

 

 

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 .

[Rob Pulham]

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.

 

I have also made a start on piping up the steam fountain.

 

 

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

 

 

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.

 

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

 

[Rob Pulham]

I was working away on the back head this afternoon, filling the holes for the water gauges prior to redrilling the right size for the castings spigots when the door bell rang it was the postie with the final production version of the firebox print. I was then distracted so I will pick up the back head again tomorrow.

 

This was printed by Mike Hopkins of Scale-Factor. 

 

These show the firebox print as received with all the supports attached.

 

 

 

 

 

Then with the supports carefully removed. I still need to clean up the base and the cab end but I have tried the boiler on and it fits perfectly. A nice friction fit.

 

 

 

 

 

 

 

[Rob Pulham]

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.

 

 

 

Then I realised that I also needed a smaller version

 

 

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

 

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

 

[Rob Pulham]

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.

 

 

 

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.

 

 

This is a cruel close up but they look pretty god at normal viewing distances.

 

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.

 

 

 

Two turnings and a bit of rod and tube later...

 

 

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. 

 

 

[richard i]

Impressive.

I am looking forward to all the dials being painted white, the hands fitted ( which move prototypically) and the numbers individually added around the dials which show how much steam is in the boiler.

 Richard 

[Chas Levin]

This is seriously fine scale modelling - in both senses!

[Rob Pulham]

In between assembly of the 8f water scoop  gear I also managed to prime and top coat the Back Head.

 

 

 

 

[Rob Pulham]

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

 

 

 

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.

 

 

 

[Rob Pulham]

More detailing of the cab has ensued since my last update. The reverser is a mixture of David Andrews and Ragstone castings. 

 

 

The David Andrews Seats are reasonable castings but I was struggling to work out how best to fit them. They look like the idea is that the two pegs fit into holes but I didn't really want to be drilling holes in the cab side sheets for them. With the pegs removed there is very little to secure them so I made some replacements with a rear strip to solder to the cab side.

 

 

What is unclear is whether they fold up or down. At the minute They just drop down but if they fold up I can make a couple of stays to hold them when folded down.

 

 

 

[mswjr]

I would say that, they fold up like the GWR seats.

[Rob Pulham]

2 hours ago, mswjr said:

I would say that, they fold up like the GWR seats.

Thanks, that was my gut feeling but nice to have it confirmed.

[Rob Pulham]

Recently there has been much work but not a lot to show for it. I returned to the chassis in an attempt to get that running before carrying on with the body and cab. Much of the time has been spent fine tuning the fit of the gearbox so that it doesn't rub and getting the rear axle to pass through the gearbox and be a tight fit but still be removable for painting etc. This is more interesting because of the wheels being fixed to the axle stubs and the gearbox having ball races which want to grab onto the axle.

 

I also had a rather frustrating time trying to make a pin for the outer end of the return crank which attaches the eccentric rod. I had tapped the small end of the return crank 12ba and the plan was to make a small shouldered pin threaded 12BA with a large flat head that I could attach an etched cover to.

 

This gives an idea of the desired pin with the etched covers below

 

 

The observant amongst you will note that the threads look very undernourished on the pin. This was possibly my fifth or sixth attempt and I kept putting it down to my having the pin too thin, too thick etc. as each time the thread came out too small for 12BA. Eventually I examined my 12ba die under some magnification and realised that one of the three cutting edges is out of line with the rest and is what I am sure was causing all the failures.

 

I can't actually recall if I have used the 12BA die at all (I use the 12 BA tap set regularly but generally for fitting bought hardware) and if I have I would have only used it on brass or nickel so I very much doubt that I have deformed it. It has been consigned to the bin and a new one ordered from Chronos. in the meantime I will probably modify a a couple of 12BA set screws to get on with the job but when the new die arrives I will have to make another to prove once and for all that it's not something that I am doing wrong.

 

[Rob Pulham]

I got around the problem last night by modifying a 12BA screw and soldering the etched covers on, making a small bush from tube threaded 12BA and a small spacer. Once I get them assembled, I may not need the spacer but if I don't they will go in the spares box.

 

 

 

I still need to add oil corks to the eccentric rods.

[Stuart Dodd]

On 16/03/2023 at 23:41, Rob Pulham said:

I was working away on the back head this afternoon, filling the holes for the water gauges prior to redrilling the right size for the castings spigots when the door bell rang it was the postie with the final production version of the firebox print. I was then distracted so I will pick up the back head again tomorrow.

 

This was printed by Mike Hopkins of Scale-Factor. 

 

These show the firebox print as received with all the supports attached.

 

 

 

 

 

Then with the supports carefully removed. I still need to clean up the base and the cab end but I have tried the boiler on and it fits perfectly. A nice friction fit.

 

 

 

 

 

 

 

This is a very nice print, I have a David Andrews Princess Royal to build , do you have the contact details please for Scale-Factor. I am following your build, absolutely excellent!!

 

[Rob Pulham]

Hi Stuart,

 

Mike's contact details are mike@scale-factor.co.uk 

[Rob Pulham]

Still beavering away at the chassis. I had it running with just the inside motion for test today. Actually I had it running last night but then I realised that I had one of the insulated wheels on the wrong side so had to strip the rods off to swap it around.

 

https://youtu.be/xv6bngf4Bfw

 

As an aside I have reversed the front crankpin bushes to look more like the prototype and to give additional clearance for the motion. I was wondering about how to tighten the reversed bushes and remembered the late David Smith talking about making peg spanners as he called them. I chose a similar route but instead of pegs I used the same approach as the 4mm scale Romford screwdriver (I still have one in my modelling toolbox).

 

For those who haven’t a clue what I am talking about this is a Romford screwdriver

 

Original Romford Screwdriver

 

This is the leading crankpin bush that I am talking about

 

 

Front crank pin nut

 

This is the custom big boy’s ‘Romford’ Screwdriver that I made to tighten them. The business end is 3/16 silver steel and the end was shaped with a 3mm end mill with the rod held in a square collet block so that I could keep flipping it over to take the same amount off each side.

 

8BA Romford Screwdriver

 

Continuing my current ‘Dremel’ tool theme I used a ball burr in the mill to make the grip. 

 

Previously I have used the ball burr in a similar manner to an end mill by cutting into the top of the work piece. This time I did it differently and side milled it. This gave a much better finish and was easier to do. I milled the grooves before turning the taper.

 

 

[Rob Pulham]

me much of the way.

 

Some of the issues have been of my making, mostly due to my clumsiness in dropping bits on the floor which subsequently disappeared into the black hole in the workshop floor.

 

As I was working my way through the motion and I got to the motion bracket, I discovered that he support rod for the reversing mechanism wouldn't go through the chassis due to it hitting the middle wheel set.

 

 

Initially, I wondered if the cast wheels were slightly oversized but they aren't and a bit of further investigation got me to the support brackets which are too long when compared to the GA drawings in the Wild Swan book. I wonder if other people who have built the DA kit have experienced the same issue?

 

[Rob Pulham]

It seems that I am not the only one to have had the same issue. So while I need to do something about it, at least I know that it's not as a result of something that I might have done wrong earlier in the build. 

[Rob Pulham]

A wider discussion on the subject over on Western Thunder has highlighted that there is more wrong with the motion than just the reversing rod supports.

 

So far I have modified the Radius Rod, moving the pivot hole nearer to the slot by 1mm. I have also modified a spare set of Combination Rods as those supplied are too long too.

 

Nick Dunhill had a replacement set of motion etched when he built his three. He has very kindly offered me some of his spares which I will collect at Barnsley. Progress on the chassis will be put on hold until I have the alternate etches.

[Rob Pulham]

A major personal issue has kept me away from the bench for a few weeks apart from a few intermittent sessions. I will reveal the issue when I know if/how it's going to be resolved.

 

During those sessions I have managed to move the reversing support rod so that it now passes through the hole in the frames. Once I have finally set the ride height, I may need to make further adjustment.

 

 

Nick Dunhill kindly supplied me with a few replacement parts at Barnsley show and I have managed to refit a slightly shorter combination lever.

 

[Rob Pulham]

Well I managed to get my head into gear and work out a way to get past my issue of not being able to retain the cylinders in the chassis without the body in place.

 

From a piece of 3mm diameter nickel rod I turned a short length down to 2.2mm and threaded it 8BA. I cut it off using a piercing saw then reversed it and face it off until I had just the merest hint of a head as the thread ends.

 

 

I drilled a couple of holes in the top plate between the cylinders and tapped them 8ba there was already a slot in the frame spacer to accommodate one of the screws but I had to drill a corresponding hole to allow the second screw to pass through the spacer.

 

 

There isn't a huge amount of screw thread in the holes so I soldered the screws in to reinforce them.

 

 

[Rob Pulham]

The day before leaving for Stafford I had a bit of a disaster with the motion on the Princess in so much as one of the combination lever's snapped off while it was running on the rolling road. Initially I thought that it was due to there not being enough material left after opening out the holes for the locating pins but once I got back from Stafford and was able to remove the top end (the simple task of unscrewing a couple of 14ba screws) I found that the rod had actually snapped part way down the fluted section. I think that I have just been unlucky in that it was over cooked etch wise and that there was very little material left. there is so little that I cannot get my camera to focus on it to show what I mean.

 

Thankfully I had a couple of spares courtesy of Nick Dunhill so I have prepped a replacement. Not taking any chances on this one I have soldered a small strip of 10thou (0.25mm) onto the back of the rod to add a little extra strength. This has been done in fits and starts because like many other Chris and I picked something up at Safford that has taken a bit of shaking off. We have started to feel better one day only to feel crap again the next. Fingers crossed it's behind us now.

 

 

 

 

 

I just have to refit it to the loco now.