David Andrews Princess - Princess Marie Louise 6206

[Rob Pulham]

The last week has been spent preparing the chassis for assembly. I started by adding additional strips to edges of some of the frame spacers to make them more three dimensional their appearance.

 

 

The extras include some nice cast springs and hangers for the driver so the next job was to cut off the etched versions from the frames and open out the horn guide slots.

 

 

The horn guides are Finney and made up without difficulty

 

 

The loco is to have a basic form of inside motion animated by a pair of eccentrics to give an element of movement to the cross heads which are visible through the cut outs on the frames above the bogie. To facilitate this, I made up a motion plate and cylinder front.

 

 

[Chas Levin]

Nice work Rob; I particularly like the idea of adding those additional pieces to the edges of the spacers to give them a more 3D appearance - a neat trick I shall unashamedly store away for future use!

[Rob Pulham]

The last few days have been spent assembling the chassis frames ready for detailing.

I had to trim away sections of some the frame spacers to accommodate the thicker cast spring hangers, the horn guides and the gearbox. Most of this adjustment was done prior to assembling the frames but the cut out for the gear box was done afterwards. The mill came in handy for removing the bulk of the cut out, I just needed to square up the round corners of the slot with a file.

 

 

 

 

 

[Rob Pulham]

After a bit of fiddling about I got the cylinder front and motion plate for the inside motion made and assembled.

The fiddling about was my own fault, I initially made the motion plate too shallow and therefore it would only accept the slide bars at their very ends and I needed to mount it further along. I was also considering adding the valve guides and after spending some time fettling the rather misshapen castings, I realised that they wouldn't actually be seen so decided not to go any further. After considering them I had started to remake the cylinder front plate in order to accept them but in the end used it for the replacement motion plate so it worked out perfect in the end if a little convoluted getting there.

 

One beauty of having a mill is that cutting out the centre section of the motion plate was so much easier than using a piercing saw and files as I have done in the past.

 

 

 

Then I needed some pins for the cross heads, so I went the whole hog and made some castle nuts.

 

 

 

[Chas Levin]

Not seen those before - very happy to have made their aquaintance here!

[Rob Pulham]

The last few days have been one step forward and two steps back...

 

The wheels have been drilled 8BA as the guy that I am building it for prefers the thicker material.

I didn't have any steel 8BA screws so I turned some rod down and threaded it 8BA. Next on auto pilot I made some 8BA crankpin nuts.

 

 

Then of course I did what I should have done first and looked at photos...

 

 

 

So far I have made a pair for the rear.

 

 

I have also made some rear plates for the balance weights but I haven't taken any photos yet.

 

While I was at the lathe, I decided to make a replacement vacuum cylinder. The casting supplied was actually one of the better castings but it was not quite the right shape and undernourished when compared to the drawing.

 

 

 

 

 

A fun time was had turning a new one and dressing it with studs/nuts. Those who are paying attention will note the odd arrangement of studs which I took from the drawing. I had an interesting time working out all the different angles which equated to: four at 45 degrees and the other three at 56.25 degrees from those.

[Chas Levin]

Rob, I am one of those paying attention; I noted the odd arrangement of the studs; I love this level of detail! 

[richard i]

I pay attention but have little I can constructively add as the is far beyond my capabilities.

it looks very impressive.

richard 

[Rob Pulham]

Thanks Richard,

 

I must admit, buying a lathe and taking the time to teach myself how to use it has opened up another word in my modelling.

[Rob Pulham]

Steeping back slightly, I was asked by a fellow GOG member on the forum how I planned to tackle the front crank pin 'nut'. Initially I hadn't a clue how I was going to do it other than probably reversing a crankpin bush. As I was pondering on how to reply to the enquiry I had the germ of an idea.

I had a go at a proof of concept this morning after my lightbulb moment when replying last night.

This is what we are looking for (just in case you needed a reminder)



This was my first attempt, I think that there was a slight bend in my bit of spare 8ba stud as it didn't machine each face evenly and the nut/stud portion was far too big


After a coffee break I reversed the short length of stud and had another go.

 

And yes it should have a cotter/split pin....

[Rob Pulham]

Now that I have a proof of concept on the front crank pins, I returned to the brake linkages.

 

The linkage that connects the cylinder with the brake pull rods is supplied as a pair of etches that are laminated together. - Parts AA/AB in the diagram below.

 

 

I decided to see what I could come up with as an 3D compromise. So I butchered the etches and then laminated them together with some additional parts turned/milled from rod.

 

Which gave me these:

 

 

 

Next, I added strips of nickel to the two etches which support the brake linkages behind the brake cylinder.

 

 

I did need to cut one of them to accommodate the motor, but I preferred to cut it after I had made them up. You can see that there is a half-etched cut line to allow for this.

 

Next, I went to fit them and that's where life got interesting again. If I soldered them into the slots in the horizontal plate as intended, I lost access to the screws which hold the rear springs on. I am pretty sure that during the course of fitting the motor and get it running, that I will no doubt need to remove the rear springs at some point.

 

My solution was to make a small plate from scrap etch which could be soldered in between the two frames and then drilled for a 10ba screw. I had to make a little jig from the 10 BA screw and a piece of spare rod and some washers to space the top part of the frames the right width to allow me to solder the plate in at the bottom. I made it slightly trickier for myself by electing to make it precise enough that the frames still located in the slots. Soldering the base plate on took a couple of attempts before I was happy that it sat correctly.

 

 

 

Then it was a fairly simple matter to drill 10BA clearance (1.8mm) and solder a nut on the frame. This allows for the screw to screw in from the top of the chassis on the basis that it's less likely to drop out in motion that way.

 

 

As an aside I was really surprised that the stub on the base of the brake cylinder was a really snug push fit in the hole snapping into place when I pushed it home. I was surprised because I hadn't thought to measure the hole prior to assembly of the frames and measuring it accurately was quite difficult with the tools I have.

 

 

 

In the view from the top of the frames above you can see the screw and the tabs of the frames located in the slots tightening the screw makes them snap into place quite easily.

[Rob Pulham]

This week has mainly been more lathe work. After a suggestion elsewhere I remade the two front crank pin bearings in steel and then because I had worked out a technique to make them much finer, I remade bearings for the other wheels as well. Hopefully my first efforts will come in somewhere for something.

 

 

 

With those done to my satisfaction I turned back to the chassis and the cylinders/motion brackets. More on the latter in another post but first the cylinders.

 

I used the David Andrews Slidebar/cross heads for the inside motion and the LG Miniatures pair that I will use for the outside motion don't come with the cylinder back plate.

 

Timing being perfect, just this week I acquired some assorted thickness Nickel Silver bar ends. They weren't cheap overall, because I bought quite a few. But they worked out as a one off, about half the price I would expect to pay for similar lengths/thicknesses from my regular supplier.

 

 

Then I turned (if you will pardon the pun) to the fronts of the cylinders. The castings with the kit are nicely detailed but sadly both the cover plates and valve guides are oval, presumably as a result of shrinkage in the casting process.

 

 

 

 

 

They still need a few more details adding before I solder them to the cylinders fronts but I am happy with them so far. Jazz of this parish has the tag line in his signature is, "Learning by doing" and I couldn't agree more with the statement. I have learned a great deal this week while twiddling the knobs on my lathe...

[Rob Pulham]

Another productive session yesterday afternoon saw the parts above detailed ready to fit.

 

Although I have the Milling machine and a rotary table for it, I kept my Proxxon mini Pillar drill and dividing head which I use for drilling out the small stuff.

 

This is the set up when I lift it onto the bench.

 

 

This is partway through drilling out the valve guides

 

 

Once drilled, I did my usual trick of wire and microbore tube filed to a hex for the head. I also fitted the rather nice brass cylinder relief valves that came with the kit.

 

 

 

[Chas Levin]

More beautiful work Rob, and I'm thinking more seriously about getting a small lathe. We plan to move in the not too distant future and I shall have a larger workspace, where a lathe might be a realistic possibility...

[Rob Pulham]

2 hours ago, Chas Levin said:

More beautiful work Rob, and I'm thinking more seriously about getting a small lathe. We plan to move in the not too distant future and I shall have a larger workspace, where a lathe might be a realistic possibility...

Hi Chaz,

I am sure that you won't regret it. The only downside is that it can become an absorbing hobby in it's own right...

[Chas Levin]

6 hours ago, Rob Pulham said:

Hi Chaz,

I am sure that you won't regret it. The only downside is that it can become an absorbing hobby in it's own right...

Yes, that did occur to me... no bad thing though, I think?

[Rob Pulham]

12 hours ago, Chas Levin said:

Yes, that did occur to me... no bad thing though, I think?

Most definitely not, in my view at least. I am thoroughly enjoying  the minor diversions into making additional, or replacing iffy parts.

[Rob Pulham]

As is usually the way in life, when making up the valve guides above I search for a photo that showed them in detail but couldn't make out anything in the gloom from the footplate. Or ones that might have showed enough detail went pixelated when enlarged. 

 

Paul Hannah kindly posted a snip from a photo that did show enough detail over o Western Thunder to make things out and politely suggested that I had the bolts a bit overscale. Having looked at the photo I had to agree so off they came.

 

 

I have to admit that these look so much better.

[Rob Pulham]

As I mentioned in a previous post, in between working on the cylinders, I was also working on the motion bracket.

 

There are two options in the kit depending upon whether you are building one of the first two engines, or the production batch. I am building the production batch so chose the appropriate etches.

 

They are designed as a main fold up with addition folded sections to create both sides of the cast bracket.

 

 

As etched when placed together they don’t fit, because the thickness of the metal pushes the etched slots out of alignment. 

 

 

The simple answer to this is to carefully break of the wo sections at the fold line. File down the edge cusps so that the pieces align properly then solder them on in two pieces.

 

This is the bracket ready to fit after making sure that the slide bars fit in the slots.

 

 

 

[Chas Levin]

That's the proper way to deal with that problem of metal thickness obstrucintg folds, isn't it Rob? I've tried various combinations of filing, squeezing, bending and praying: I now realise my error...

[Rob Pulham]

13 hours ago, Chas Levin said:

That's the proper way to deal with that problem of metal thickness obstrucintg folds, isn't it Rob? I've tried various combinations of filing, squeezing, bending and praying: I now realise my error...

Sometimes you can get away with deepening the fold line but mostly you don't realise that it will be out of line until it's folded. Nickel silver especially, is very unforgiving when trying to 'unfold' etched fold lines. You are very lucky if they don't snap off anyway.

[Chas Levin]

On 18/03/2022 at 10:24, Rob Pulham said:

Sometimes you can get away with deepening the fold line but mostly you don't realise that it will be out of line until it's folded. Nickel silver especially, is very unforgiving when trying to 'unfold' etched fold lines. You are very lucky if they don't snap off anyway.

Agreed, though I have had some success with very, very careful unfolding. As I understand it, metal fatigue is partly through the generation of heat, so sometimes, where I've needed to unfold a fold, I've done it a bit at a time: just a few mm, then put it aside for an hour and do other things, then a few more mm... and it's worked. Though I may just have been lucky of course - I've only had to try it a handful of times...

Edited March 20, 2022 by Chas Levin

[Rob Pulham]

13 hours ago, Chas Levin said:

Agreed, though I have had some success with very, very careful unfolding. As I understand it, metal fatigue is partly through the generation of heat, so sometimes, where I've needed to unfold a fold, I've done it a bit at a time: just a few mm, then put it aside for an hour and do other things, then a few more mm... and it's worked. Though I may just have been lucky of course - I've only had to try it a handful of times...

 

If it's something really critical that you ideally, re use the part 'folded' (for example if the instructions are unclear as to whether fold line goes inside or outside) I have had success with annealing it first. Then slowly and carefully unfolding it, before refolding it the correct way. As you say slowly, and patiently wins the day.

[Rob Pulham]

 

Returning today, to the Princess I tackled the cylinders there was some discussion over on Western Thunder as to the Valve guides and chests being too far away from the edge of the cylinders when compared to a photo that Ian Allen shared.

 

I have filed quite a bit off but being careful not to overdo it. Easier to take more off than to add it back.

Looking at the photo in my last post I am not sure that you can really tell that I have taken any off but I have.

 

 

 

I have also dry fitted the cylinder wrappers again I won't be soldering them in place until I am sure that they don't need adjusting.

 

 

[Rob Pulham]

A little more work last night, had me fitting a couple of pieces of tube to fit between the front and back plates.

Use of the lathe allowed me to cut them very precisely and fitting them has made a very sturdy unit, which without them was quite flimsy.

 

 

I have a vague feeling that I might have swapped the covered over as I picked them up off the bench. The good news is that it seems to have resulted in an even better fit than I had yesterday.