David Andrews Princess Royal - 6206 Princess Marie Louise

Thanks Steve.

 

After the vacuum cylinder, I started to look at the brakes. The crossbeams came with brass castings for the clevises that fit around the etched pull rods.



However amongst the bags of extras were some really nice Hobbyhorse castings for clevises designed to take round rod rather than the flat etches. I made some adjuster nuts to enhance the rods and fitted them to one end. I will fit the the other end once I know exactly how long the pull rods need to be.





Next job is to drill out the Castings for the brake hangers/shoes.

 

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.






I will have to add a couple of holes to allow the bush to be tightened by a peg spanner but I think that I can make it work now.

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

 

Thanks Pete, I am certainly enjoying solving the questions posed by this particular build.

 

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 more tricky 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

 

Thanks Brian

 

Thanks Andy,

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 coming 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 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, but worked out at about half the price that I would pay from my regular supplier, whose prices I am happy with..



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.
There is a gent, whom I have met a couple of times. Who posts superb builds over on RM Web under the username of Jazz. His 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...

 

Another productive session this 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.

 

Despite the rather neat job that I had made of the bolts on the valve guides, someone kindly post a photo where the front of the vale guide was visible and having seen the bolts, it was clear that mine were way over scale so off they came.


I have to agree that they look much better.

 

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.

 

The extras included with the kit include some very nice LG Miniatures castings for the rear valve guides. The only issue was positively locating them due to the nature of how they have been cast there is a very thin spigot to fit in quite a bit etched hole.



My answer was to turn up a couple of locating bushes.



There are only two I just combined two small photos to show the detail.

This made them easy to locate into place.



There will be a short break now while I prepare for our first demo session for two years.
Anyone planning on attending Newton Aycliffe Model Railway Show on the 26th do drop by and say hello.