This is a blog where I will show the trials and tribulations of model builds as they happen
Category Archives: David Andrews Princess Royal
The build of a 7mm scale locomotive kit from the David Andrews Range.
It includes the issues that I have encountered and what has been done to overcome them to get the loco that I was asked to build from it.
Still plugging away at the small details but it’s moving forward and that’s what matters.
I got the top feed fitted to the boiler which in the period being modelled is domeless so one less bit to worry about. Then I added the covers for the pipework underneath and two circular covers on top of the boiler. – Since starting to post this I have re-read the instructions and realised that I have fitted the wrong etched covers under the top feed so they will have to come off and be swapped.
I still have the pipes to fit where they come out of the sides but as they disappear into the centre splashers I need to wait until the boiler is mounted to fit those.
Next I have been working on the front end of the footplate where there is a surprising amount going on and photos are invaluable here as the instructions are not that easy to follow.
Initially I fitted all the lamp irons the same way around but noted that the two outer ones are nfact reversed. Fitting the steps to the curve of the footplate was fun. The first one went into place really easy and first time. I tinned them and used the RSU from the back with the footplate on it’s edge and clamped to the workbench to stop it moving away as I held the footstep in position. The second one took three or four attempts to get it in the right place…
This week has been about adding small details to the body work starting at the front, I added the smokebox door dart, and the handrail above it. The LMS design of handrail has the rail ending in a button at each end. I have heard of people making these from microbore tube but I didn’t have any nickel silver tube so I put a short length of 1.4mm nickel rod in the lathe and drilled it out to fit over the handrail at either end and then fitted the rod into a pin chuck to chop of the appropriate length soldering on to the hand rail and filing to finish. From the photo I still have a bit of cleanin up of excess solder to do on the handrail knobs.
One detail that is quite prominent on the smokebox door but absent from the kit is the door latch. It is included in the GA reproduced on the front cover of the Wild Swan volume so I was able to import this into Fusion 360 not only to get the length and spacing of the handrail and knobs but also the outline and dimensions of the latch.
The latch itself was filed up from a strip of scrap etch which I doubled up at the thicker end to file to shape to accommodate the curve of the smokebox door. The brass rod will be the stay which fits into the front ring. It’s 2mm x 1mm bar and I popped it in a 1-2mm ER 25 collet to turn the spigot on the end. The fun bit will be soldering the latch onto the door. But more of that when I have achieved it.
Well things have moved on somewhat since my last post on the subject. I did get the injectors fitted though.
Then I moved onto the sandpipes which are almost the last bits for the chassis (unless I find something that I have missed. I say almost because there are also the bottom halves of the sandbox fillers to fit to the chassis, they are split at footplate level.
I started with the brackets which come as a hockey stick shaped etch. Looking at photos they need to be bent into handed pairs. where they fit around either side of the wheel.
Next in order to make the fittings for where they pass through the brackets and combine with the steam pipes I soldered two different diameter microbore tubes together.
I cut half a dozen lengths at 2.5mm and another eight at 1mm using a pin chuck a ruler and a piercing saw I also created a hex on some thick walled tube to make nuts from. Again cutting lengths off with the piercing saw
From all the photos that I have, there are only six sand pipes fitted so I have two spare brackets. In the photo below you can see the assembly order of the various bits of tube, bracket and nut. I will have to trim all the pipe ends to the same length
I also managed to get the frame section of the sandbox fillers fitted too but I haven’t taken any photos of that so far.
A friend advised that the spurious bracket was a generic item included in quite a few David Andrews Kits to aid in fixing the exhaust injector casting. in the end I elected to do without it and drilled and tapped the main pipe. I will probably do the same to the flat on top of the bracket too because I have fixed one problem and create another – where it needs to sit there is nothing above it to screw it to. I will add a small plate under the main plates that fit under the cab to extend it and allow me to fix to it.
Hopefully it will make sense when I have done it and taken photos. I have also added the missing control rod on top of the universal joint.
This morning saw the injector back in one piece with all the right notes in the right order – for this loco at least.
This was the set up for attaching the copper pipework using my RSU and cheapo self locking tweezers.
I do have one thing to work out and that’s the bracket below. There are etched slots in the rear frame assembly for it but I am not sure at the minute how it attaches to the injector itself to allow it to mount. The other bracket which I have already attached is quite visible in the photo above to no issues with that one.
I also see from the photo that I need to clean up the etching cusp from it too if I plan to use it.
I am almost at the point of reassembly of the exhaust injector, having added bits, chopped other bits off and repositioned the main elbow bend.
This is a small taster of what I have been up to.
First I milled a square section on the end of a piece of brass rod and drilled a 1.6mm hole in the middle and then a 0.6mm hole at each corner before taking it back to the lathe to part it off. This is the basis for a very visible pipe flange.
Then I made up some miniature fixings and soldered them to the copper pipe. The much magnified photos make it look much messier than it is to the naked eye.
I am working my way along the chassis adding the remaining details as I go. Two quite prominent features are the injectors. The kit included a nice brass casting for the live steam injector. This just needed some of the ‘pipes’ extending so that I can attach it more securely.
The exhaust injector was another matter as I couldn’t find a casting for it so I had to buy one in. I had a look on Ragstone and LG Miniatures and the LG one seemed nearest to what I needed. Living out in the sticks as I do I was most impressed that I ordered it on Monday morning and it arrived yesterday lunchtime.
This is what you get from Laurie and the image below is what I need it to look like.
To completely misquote Eric Morecambe, ‘Most of the right bits, but not necessarily in the right order’.
Sadly this means a bit of butchery is in order to get pipes facing the right way and one pipe joint that needs removing. The hardest thing about doing things like this is actually holding things to work on them. Luckily there are plenty of holes and spigots on the casting so a bit of work on a few offcuts of brass later and we have a few handles soldered on temporarily.
The small hex nut fitting is a part on one end that wasn’t present in any of the castings, so I filed a hex on the end of a bit of rod and turned the spigots on it.
Still beavering away making slow but steady progress. Next up were the front bogie top bearers (or that’s how they are referred to in the instructions) and the fitting of the bogie itself. The former were easy, tin with 100 degree solder and use the RSU to heat from inside the frames.
The bogie fitting was a little more challenging. My fitting of the representation of inside motion had scuppered using the method that the kit provided. At Guildex I had a chat with Nick about how he had done his and he confirmed what I had thought would have to be the solution. Which is do it like the prototype (simplified of course) and fit a plate to the bottom of the frames. This proved challenging because of my seeming inability to drill a hole in the middle of a rectangular plate… It took three attempts before I got the hole in the ruddy middle. Actually, I am being a bit hard on myself. The first one was in the middle it’s just the plate was too small…
With the part finally ready to be fitted I turned my attention to the mounting screw and the ‘nut’. The kit comes with a nice turned elongated top had type bush which is threaded 6ba in place of a conventional nut.
I had already made the side control springing block to accept this threaded bush so I wanted to use it. However now that the fixing point was much lower in the frames.
What I couldn’t work out was whether the bus was threaded all the way to the bottom of the hole or not because I didn’t have a long enough 6BA screw to check. So rather than trying to shorten the existing bush I thought it easier to turn up a new shorter version. I also turned the first 0.45mm to just fit tin the hole in the mounting plate which is slightly larger than the screw.
Despite my messing about for quite some time with a stack of washers trying to work out how long the shortened bush needed to be, it ended up slightly short.
Thankfully I had the foresight to leave it attached to the rest of the stock so once I worked out how much longer it needed to be, it was and easy job to turn another 2.5mm down to the same diameter. A short length of spring allows the bogie to float up and down by about 1mm.
Having got this far there doesn’t seem to be much in the way of swing before it hits the inside of the cylinders but this may change when on track and the side control does its job. Time will tell whether I need to cut back the cylinder wrappers.
A few more micro fixings later saw. a major milestone both mentally and build wise.
These are the pins which hold the eccentric rod to the bottom of the expansion link. Initially I made the two fully threaded versions but then realised that it would be better if they were only partially threaded (14BA).
I had already fitted the return cranks and after this it was a short step to getting the full motion running.
Well with a proper two forward one back amount of progress I think that I am now back to where I was pre Stafford.
When fitting the replacement combination lever I really struggled with the pieces of brass wire which I had previously cut and peined over to hold the various rods in place. After the 4th or 5th pinged off into space I got fed up and chucked up a length of 1.9mm nickel rod in the lathe and turned down some small pins. These combined with some etched washers that I found on a spare etch now retain the rods in place.
It was just prior to refitting that I thought that I had best remove the other combination lever and beef it up as I didn’t want lightening to strike in the same pace twice.
After soldering another strip of nickel to the back and filing to shape I happened to place the two combination levers together on the bench where I realised that the replacement was longer that the one that snapped. As luck would have it I was able to solder a small piece of scrap etch into the bottom end of the fluted section and then drill through to the correct length. The last job was to cut of the over long bit and file the round on the bottom.
These are the four stages of the operation but the good news is that it’s all now reassembled and I am subject to test running back to where I was and ready to fit the return cranks.
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.
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.
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.
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.
The last couple of weeks have been steadily working towards getting the outside motion working as smoothly as the inside motion. It has fought 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?
First run of the chassis with the inside motion fitted. Actually it’s the second run I had it running initially last night but realised that I had one of the insulated wheels on the wrong side so I had to strip the rod off and swap it over.
Still working my way through getting the chassis running and I now have the inside motion running forwards at least.
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
This is the leading crankpin bush that I am talking about
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.
If I wish to use this method of securing the coupling rods to the front wheels again in the future I will probably need to make another one with a smaller diameter to fit reversed Slaters bushes. The crankpins on this build are 8BA so bigger than most builders make them (the wheels were already tapped 8BA for the crankpins when I received them with the kit). 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.
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.
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.
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.