A few photos of the state of play before I strip her down and pack her up for painting.
Category Archives: David Andrews Princess Royal
David Andrews Princess Almost Ready For Paint
Well, I got there at last. Her Royal Highness will now go around 6ft curves without derailing or shorting.
I did have to introduce some springing to restrict the movement of the bogie.
There are two spring wires at the rear which fit between the inner and outer bogie frames. They restrict the sideways movement of the rear of the bogie. The bogie pivot point has side control springs which allow more movement at the front of the bogie. This sort of worked but the front of the bogie was so light that it had a tendency to lift of the track so I added a second element of springing which holds down the front of the bogie and all runs nicely. This spring has a loop which is held in place by the pivot screw then bends over the front of the plate that you can see in the image below before curving onto the front of the bogie frame. Although it looks huge in the enlarged image it’s only 0.5mm spring wire.
David Andrews Princess Royal – Increasing the swing of the rear truck
All issues of whether the styrene might wear over time aside, even with added weight on the trailing truck, the chassis still wouldn’t go around a 6ft curve reliably so more drastic measures were needed.
Using a piercing saw I cut out part of the inner frames.
Then I soldered a plate across the ends of the frames at the front by good fortune there were two tabs at the rear with could be soldered to.
I then reduced the width of the inner plate and soldered the frame pieces back together with some end plates to take up the gap left by the saw kerf.
A quick dry fit of the rear truck leaves plenty of space either side of the inner swing so there should be no shorting but I may need to remove some of the spring casting to allow more swing to help it get around the curve – it’s a long chassis.
DA Princess – Shorts, short and more shorts!
Having solved the issue of the wheels touching the upper frame I then discovered that the wheels were touching the inside of the frames when going around a 6ft curve.
So I added some styrene insulation either side of the inner frames.
This cured the short problem but running trials revealed that although it would now go around 6ft curve without shorting it didn’t do so reliably without the trailing truck derailing.
In an attempt to cure this I tried introducing some weight on to the trailing truck. I cut a couple of rectangles of lead and using a V block and a couple of different sized rods I created some weights that fit on top of the ruck over the axle.
I was getting low on lead but just this week we have had a couple of chimneys repointed and re-leaded as well as four wet verges I asked the roofer for the lead that they removed so I now have sufficient to see my days out I think.
David Andrews Princess Royal – Still working on the shorts
It’s been getting on for six weeks since my last update on HRH. I haven’t been idle and the process of eliminating shorts has been a journey of education, frustration and determination to not let it beat me.
Starting with a belt and braces approach I remade the drawbar in Delrin.
Next, having already added insulated washers to the wheels which are insulated at the hub I turned my attention to the driver which are rim insulated. I had previously made inner balance weights from Nickel sheet and although I had stuck them to the wheels with epoxy I was concerned that they be be helping to bridge the insulation gap should they touch the frames. My answer was to remake the balance weights for the insulated side from styrene.
Then I noted that the cross piece pf the rear inner frames was touching the tyres of the rear truck wheels. You can see the plate with the half etched rectangles in the image below.
A look at the instructions mentions the possible need to remove the half etched sections in case of shorts so the plate was removed and the rectangles removed.
Sadly, this didn’t cure the problem so in the end I took of the outer sections leaving just the brace in the middle.
As it turned out that solved one problem but left another which will be the subject of another post
David Andrews Princess Royal – Pressure Turned Washers
Then I connected the loco and tender together and it immediately tripped out the controller and so I started a further round of troubleshooting. First I removed the bogie and after coffee I went back into our cloakroom where I have temporarily set up my test board. This room is west facing so gets sunlight mostly in an afternoon but it’s below ground level as the path outside the window is cut into the embankment and so doesn’t get quite as much natural light unless the sun is really high in the sky and it’s late afternoon.
Now one of the suggestions from Thursday nights meeting besides dig out the multimeter was to try hunting for shorts in the dark as sparks are easier to see. As I went in for further testing I forgot to turn the light on and so the room was a little gloomy. This proved to be a benefit, because as soon as I moved the bogie on it’s own, I noted a spark which I wouldn’t have seen with the light on. I noted that the guard irons were quite close to the rails and may have caused shorts on curves so they were adjusted and then further examination showed that I had fallen foul of the etched washer/hub insulation again. A further check of the trailing tuck revealed the same issue. I had a few spare insulated washers that I had turned when working on the tender but they proved to be too thick even after turning/milling down the axle bushes.
I was initially going to make some up by using a hole punch to cut holes in some styrene sheet and then snip of /file them into circles. By good fortune a video that I had seen some time ago that was lurking in my memory surfaced on my Youtube feed. After rewatching it I decided to have a go at pressure turning a number of washers all at once.
Now unless you want really big washers the process is a little wasteful because you need enough stock to hold onto to drill the centre hole. I chose to cut some 0.5mm styrene sheet into 20mm x 20mm squares aiming for a finished size of 10mm diameter. You also need some scrap to hold the parts and one of them becomes almost sacrificial.
The first step is to grip the styrene squares between the two pieces of scrap material.
I used a 1″ G clamp and a small engineers clamp to hold them all together to drill a 5mm hole through all the parts. This was to allow clearance on the 3/16 (4.7mm) axles. At this point you transfer the whole set up to the lathe before releasing the clamps.
I created the above set up which consists of a 22mm piece of Delrin in the collet (I had to turn a stub down to fit in a 16mm collet which is the largest ER25 collet that I have). This had a 5mm hole drill partially through it. At the tailstock end is another piece of 22mm Delrin which has had a 60 degree cone turned in the back so that it fits on a live centre then a short section turned down to 10mm to allow the tool to clear the workpiece(s) again it has a 5mm hole through it. Then a length of 3/6 rod was passed into the hole in the mandrel in the collet chuck and the parts fed onto it, before removing the clamps. Lastly the live centre is wound tightly against the parts which squash and grip all the parts for turning and locked.
The next step was to turn down the sacrificial scrap support until all the parts start to be turned. My sacrificial scrap was plastic which has a layer of aluminium either side of it and I found that the most depth of cut I could manage was 0.25mm per pass otherwise the parts started to slip. I started turning with a carbide tipped bit until it would no longer fit, then I changed to high speed steel grooving tool that I had ground for another job some time ago.
One piece of advice given in the video was to make sure that you were using a sharp tool for the final pass to help prevent the tool from rolling the edges of one part over onto the next.
These are the finished parts and they are all really crisp, aside from the one that was nearest the left hand piece of scrap which had a small burr around the edge (visible at the corner of the ruler). This burr was easily scraped off with a scalpel blade.
David Andrews Princess Royal – Tender Shorts Sorted
Since my last post I have been beavering away identifying and curing the shorts on the tender which I am happy to say that I have done.
As with many things in life getting there required at least one side project. During last Thursday’s GOG online modellers meeting the consensus was that I really needed to dig my multimeter out of the depths of the shed. On friday morning I bit the bullet and started to pull out plastic stacking boxes (having first removed the lawn mower, petrols cans, oak kitchen cabinet doors and finally my router table). An hour and a half later I had retrieved one of my two multimeters and put everything back.
Sadly the one that I found was the one with the missing probe, the wire was there but the common probe which had broken off in the dim and distant wasn’t with it. Before embarking on making a new probe I fitted a new battery to test that it still worked which thankfully it did. The metal section of the probe was made from a length of brass rod which sat atop my useful bits box on the workbench and I quickly drilled one end to accept the wire and turned a step onto the other to fit snugly into the yet to be made insulated delrin handle.
I didn’t take photos along the way but this is the finished article alongside the original ‘live’ probe.
Once I had it I reassembled the tender chassis test along the way without find any further shorts.
David Andrews Princess – Tracing the Elusive Short Circuit
The last week and a bit of modelling time has been spent tracking down shorts on the tender and isolating them. This has required me making a number of additional bushes and delrin/acetal washers.
I also had to rethink the way that I had mounted the two U shaped brackets which fit across under the tender. Unthinkingly I had mounted them in the same way as on the MOK Stanier tender using small pieces of brass angle drilled and tapped for 14ba screws. Sadly when assembled these frames touch the brakes which although the shoes are insulated the hangers are not and between the two breached the insulation between tender chassis and body.
I made up some wire supports and then shortened the brackets to clear the outer frames. Below are a couple of shots of the sets that I used to get them soldered vertical to the brackets and then cut them off to the right size. I read recently on one of the forums someone say that you cannot have too many engineers clamps. I agree wholeheartedly although when used as soldering aids they do have a tendency to rust. I do have a cunning plan to get around that, I have a length of brass bar that I have had for about 10 years which will be just enough to make a pair of brass jawed clamps which shouldn’t rust.
I used the Expo pliers that I recommended recently to bend the corners pretty uniformly.
I also had a feeling that the washers which I had used to reduce the side play in the axles, might have been bigger than the insulation gaps in the wheel hubs thus creating a short, hence my making the delrin washers.
David Andrews Princess Royal Return Crank Shenanigans
Those who are observant, will have noted the jaunty angle that the return crank is sat at, in the top photo of the post with the sand pipes fitted. Having had this pointed out by someone this came back to bite me.
Initially I just thought that in lifting the loco up I had dislodged it causing it to unscrew and come loose. However no matter how much I tried I couldn’t get it to tighten back up in the right place. I tried shortening the bush but realised too late that the crank pin itself must have shifted in the wheel. Then having shortened it I found that when tight it was nipping the conrod and coupling rods so that they wouldn’t move.
Making a replacement bush was the order of the day.
David Andrews Princess Royal – Sand Pipes Fitted at last.
The sand pipes are now fitted without interfering with anything. I did get them fitted a couple of days ago but when I added the front bogie they stopped it from moving. I removed the two front ones and moved them slightly further back which did the trick.
David Andrews Princess Royal – Sand Pipes Round Two!
Well I have the replacement sand pipes assembled ready for fitting let’s hope I have more luck in fitting these. One pipe is soft brass and the other slightly thinner one is copper.
Below are the first ones that I made earlier in the build. I made myself a rod for my own back (if you will pardon the pun) by using hard brass rod for the thicker of the two pipes which when it came to it, was almost impossible to bend where I needed it to go.
David Andrews Princess Royal – Why I needed a sanity project
Well after fitting the brakes, I have spent far too much time in the last week trying to fit the sand pipes. What’s so difficult you might as yourself? Well they fit inside the frames and they also need to fit in such a way as to allow the wheels and brakes to be removable (the wheels won’t come out unless you remove the brakes). the key issue has been getting the pipes to bend in a tight enough bend to allow them to fit without touching the next wheel along.
In the end I have started again by stripping all the pipe work off the brackets and the plan is to reinstate them with finer soft brass and copper wire. I have cut all the parts and I will share picture when I have them reassembled ready to fit.
David Andrews Princess Royal – Brakes Revisited
The Princess is keeping me entertained to the end.
Almost the last thing to fit are the sand pipes but in order to do that I needed to refit the brakes so that I can work out how the sand pipes will fit around them.
Previously after fitting the 3D printed shoes I had fixed the hangers to the frames via soldered pins with the top of the hanger slipping over a square rod (the holes were etched square) for mounting. Having come back to it I wasn’t happy with that arrangement so I removed the pins and substituted some lengths of 12BA stud instead (cut down screws) next I soldered the square end into the hanger brackets. Then I enlarged the holes in the frames so now I can insert the studs through and put nut on the back to hold them.
A bonus to this approach is that not only will it be easier if a little fiddly to get them on and off the studs will rotate in the frames before being fully tightened so that positioning of the shoes against the wheels will be more adjustable.
David Andrews Princess Royal – Replacement Drawbar
These are the drawbar options as supplied. I have a confession to make at this stage. I couldn’t find them and had asked a couple of fellow modellers who have the same kit for dimensions. As it happens one was able to supply part numbers and the other the key dimensions.
Then as is often the way, I opened a box where I keep useful bits (actually looking for a piece of plug pin to see if it would be suitable to make a draw bar from) and there on top of all the bits and pieces was the square of etch containing the two missing drawbars.
While I completely understand why they would be supplied as etches I wanted to see if I could make something more 3 dimensional.
I made a complete hash of my first attempt due to getting the machining operations in the wrong order. I had started by milling and drilling which left the part too weak when I attempted to turn the dog bone section.
This was at the end of the turning operation on the second attempt.
This is the end result greatly enlarged of course. The insulated bushes were made from knitting needles. Sadly the only one I had of the right thickness was green. I did think that I had a suitable grey one but having turned one and subsequently dropped it, it landed with a decidedly metallic click. Further investigation revealed that it was in fact aluminium not plastic so not much cop for insulated bushes…
David Andrews Princess Royal – How I centred the chimney to solder it in place.
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Following on from my An Evening With session last night (which I thoroughly enjoyed and I hope all those that joined me, did too) I can now share with you how I managed to hold the chimney centrally in place when soldering it.
Whilst machining the base of the chimney I had deliberated from the outset how I might best hold the chimney in place after machining and I had considered boring the base out and adding a short length of tube to locate it when it occurred to me that solder doesn’t stick to aluminum so why not use the arbour to centre the chimney.
I parted the end off the arbour and machined the sides so that the chimney sat down properly the other way up.Then using a makeshift arrangement of blocks and strips of wood I fed the modified abour up through the chimney hole in the smokebox.
There was enough solder remaining on the smokebox from where the chimney hadn’t sat down flush initially, so some flux and a waft with my microflame had in place in no time with no cleaning up.
David Andrews Princess Royal – Fixing Boiler Ballast
One of the things that I have never been entirely happy with on previous locos is the fitting of additional lead weight to the boiler. Tank engines are a bit simpler because the lead sheet can be fixed in the tanks and enclosed. It’s not so much the fitting of the lead, so much as how to retain it and stop it from shifting over time.
Previously where needed I have used epoxy or 100 degree solder to fix it in place (I have built a number of DJH kits and on those the weight of the cast boiler was more than enough without adding additional weight). This time I thought I would try a different method first I rolled up some sheet lead and then some adjustment to make it fit. I used a hollow punch to cut out a section to fit around the base of the top feed which helped to hold the lump of lead in place next I drilled the bottom of the boiler being careful to site the hole behind the middle splasher so it wouldn’t be seen from the side. Then I tapped the hole as deep as I could 10ba and then screwed in a 1 inch 10 ba screw being soft lead once the screw got beyond the tapped section it continued to cut it’s own thread and now the ballast is held firmly in place.
I would be interested in the methods used by other builders to retain lead ballast in boilers.
David Andrews Princess Royal – Lots of little details
The last week or so has been spent on lots of little jobs that don’t seem to change much visibly on the model. The visible bits are the trimming of the cylinder drain pipes and having to rethink how I planned to mount and retain the motor from moving.
I also milled a hex on the ends of the front crank pins to replicate the fitting on the prototype.
I had initially envisaged that the mtor would sit flat and I did add a nut on to a frame spacer to retain it via a strap around the motor but it wouldn’t fit through the hole in the firebox with it in this position. My final solution was to replace the rear frame spacer with one that is removable. This was needed because the large final drive gear on the ABC gearbox wouldn’t pass between the gap under the existing frame spacer and the top of the rear frame section. A different motor gearbox combination might not have needed this solution.
Now that it’s removable, the motor/gearbox can be lifted out for maintenance etc. and the position of the spacer once fitted, also acts as a stay preventing the gearbox from rotating about the axle. Win, win.
David Andrews Princess Royal – Cinder Guards
The last parts to be made and fitted are the cinder guards that fit on the cab side. Even though they are nickel on this kit, they are very vulnerable and a friend mentioned that he always models them folded back which seems like a good idea. but I was concerned about painting around them. I also had the idea that I would like them to fold in like the real thing and so I decided to experiment with the extra etched frame that David supplies.
I cut off the two pegs that fit into holes etched in the cab side and soldered a length of 0.5mm piano wire on the back of the frame. Then I drilled a length of 2mm x 2mm brass angle at the ends and soldered in some filed down brass dressmakers pins which I cut down to fit through the holes in the cab. I then drilled the other leg of the angle to accept the pain wire and once soldered to the cab it folds back just like the real thing.
Having got the first one fitted I made up the second. Which I took a photo of. Keen eyed readers will note, that there is only one bracket. Sadly, the second made a bit for freedom as I was shortening the peg after a test fit. So unless a miracle happens I will be making up another.
David Andrews Princess Royal – Cylinder Drain Cocks finished and ready to fit
Today saw the last of the tiny components that make up the cylinder drain pipes made and assembled. I also ended up with a nice little bag of extra nuts. I made six for the operating bar and then decided they were a little big (lengthwise) so I made some smaller ones.
Each one is made from 16 individual parts and the valves are a bit of a work of fiction because I couldn’t find any clear photos of what is actually under there but they pass muster when compared to the castings that I have in various kits and at least they fit this particular loco.
The clips that hold the pipes together are still loose and able to slide along the pipes at the minute until I get them fitted and can determine their final position.
David Andrews Princess Royal – Fitting the Cab Roof.
I asked a fellow modeller if he had fitted the cab roof yet, because it too has been yet another challenge to overcome.
The reason for the challenge is that the profile of the roof rib visible in the shot of the roof below is a different profile to that of the rear frame of the cab which supports the cab roof at the back.
When I first fitted it the front of the roof didn’t go anywhere near the front of the cab (it did fit when I first “rolled” it some time ago. To get around the issue I cut a front rib to fit just inside the cab front which brought the front of the roof into the right shape again
This left a gap in the middle of the roof at the rear which I filled with solder (just visible in the photo below as is the additional rib at the front of the cab). Not very elegant but it works.