David Andrews Princess Royal - 6206 Princess Marie Louise

After taking the photos about and preparing them for upload I realised that I hadn't fitted the guard irons. So that was a quick task this morning. As supplied the slots in the bogie were much wider than the thickness of the etch so I beefed them up with another layer and then shaped them to suit.

 

Thankfully not my problem on this one, it will be going to Warren Haywood for painting.

 

The last bit of the bogie puzzle is a side control unit.

I started with a short length of 1/4" square brass rod. I drilled a 5mm hole through the centre and then milled 2mm off the side of each end to create the main central block.

I don't plan to do anything more with it now until I have assembled the chassis and can confirm if it needs any further adjustment to fit it.






Apologies that the first photo is slightly blurred.

 

Thanks Gents,
I have always liked making things and I realised as I was selling my 4mm stock and moving to 7mm that my pleasure came from the building of stock rather than running it or layout building. So I took the decision to not buy anything ready to run. Or after a couple of failed attempts to build any more layouts. Now I just do what I enjoy, which has allowed me to concentrate on improving my skills in a more limited area.

 

I am currently working on preparing the chassis for assembly. Due to the provision of cast driving wheel springs and hangers I had to cut of the etched versions from each side of the chassis. Here I am half way through the process. I am also cutting out for the horn
guides at the same time



The horn guides and blocks are Finney and consist of an etched backing plate with a fold up guide.
Time spent making sure that they are square and free moving at this stage saves loads of hassle down the line.

Previously I have soldered a 12ba nut on the top of the guide to allow the screw to set the ride height later in the build. I found myself short of 12ba nuts so rather than wait I cut some strips of 0.7mm nickel and drilled them 0.8mm I then soldered them to the top of the guide and then drilled through both sections 1.0mm finally tapping them 12ba. I still have three to finish tapping this morning. The replacement springs will serve to retain the horn blocks once fitted. and I am considering making them removable as the Harris wheels on telescopic axles need more movement to allow them to be removed.

 

Also worth mentioning is the reaming of the horn blocks. I usually start by reaming using 3/16" reamer but due to the slight vagaries of axle diameters this doesn't always allow for the axles to be free running. The late Bob Alderman put me onto a supply of slightly larger reamers .190" which give even the stickiest axle room to move. In this case the axle diameters are .185", .186" and .186" so they have 4/5thou clearance.

 

Since my last post available time has been spent finishing tapping the horn guides, cutting the springs and hangers from the other side frame and then cutting out and modifying frame spacers.

Like most kits many of the provided frame spacers are either flat or L shaped plates. How ever there has been some attempt at replicating the actual frame spacers of the prototype albeit it in a very 2D form.

I have taken these 2D spacers and made then more 3D by adding framing to openings making them look a bit more like they do on the real thing. I still have some to go but this is a flavour of what I am aiming for.


This model is also going to have the rudiments of inside motion. In so much as there is a large hole in the frames where the crossheads of the inside motion are quite visible. Due to the axles being telescopic I cannot fit a proper crank axle so what I plan is to use eccentrics to impart a small amount of motion to the crossheads/pistons giving some visible movement behind the frames.
Before moving ahead to assemble the frames I need to make a motion plate and cylinder front for these.
I started this by cleaning up the David Andrews cross heads and slide bars (I have a set of more detailed Griffin castings for the outside motion).



For anyone who is planning on fitting outside or inside motion time spent fettling the parts to get them smooth running without any hint of hesitation will pay dividends when you come to assemble the various rods etc. to them.

The piston rods on the DA casting were tapered getting noticeably thicker at the crosshead end but reasonably straight. I have come across quite a few castings even from the better kits where piston rods have been like a banana. To remove the taper I put the end of the rods in my Dremel and making sure that it was rotating centrally I gently filed the crosshead end until the rods slid cleanly through the piston glands.

If you do this make sure that you don't have the drill set on too high speed or the weight of the cross head spinning if slightly out of balance may bend the piston rod.

 

It's really a case for slow and steady. It really doesn't need to be rotating fast to get the job done.

The other alternative is to chop the misshapen piston rod off. Then drill out and fit a straight piece of rod in.
This was my fallback position.

 

To be honest piston rods are one of the few things that don't really lend themselves to casting and to my mind designers/suppliers would be far better designing the crosshead with a hole in it that could be opened out to fit a straight piece of rod. I haven't yet found a cast rod that was completely straight and didn't need some attention to straighten it out.

To straighten piston rod I have a sheet of toughened glass covering part of my work bench which I solder on and use to ensure assemblies are flat. It also useful for placing the crosshead hanging over the edge with the rod on the glass sheet. I then use to solid metal block of a square to roll over the piston rod running backwards and forwards until the pressure of the two hard surfaces straightens out the rod - think rolling a sausage of plasticine but using a piece of wood instead of your fingers as a roller. I only use the block on the square as it's always on my bench but an off cut of steel or aluminium would do equally well or possibly a piece of hardwood.

The other issue besides them being bent is that sometimes they have casting lines down them too which need filing off. A smooth running piston is essential if you want the loco to run without issue.

 

I agree, I have done similar in the past myself. I will see how these run when installed before I decide on whether I need to do it on the Princess.