7mm David Andrews Princess - 6206 Princess Marie Louise

[Rob Pulham]

Rob,

Mostly I use 10 thou NS for boilers and roll them in my home made Vee type rollers. I have a piece of rubber sheet, could be neoprene, about 2mm thick which protects the rivets. I also have a Metalsmith set which are quite long but of the ‘pinch’ type which tend to bend and give a less than perfect tube.
Ian.

If I were rolling my own I would do the same Ian.

0.45 is more like panel beating than modelling, but we have to use what's provided when building for others.

Thanks for tip about the rubber sheet, I will look out for something similar.

 

[Richard Spoors]

Looking at all the rivets to be pressed out I decided that I would finally get around to doing something that I had been promising myself for years. That’s to make a more comfortable handle for the GW Models rivet press. Those who own the smaller of the two models will understand where I am coming from. The bigger 7mm/Gauge 1 version has a round end to the handle the smaller version just has a rectangular bar which gets mighty uncomfortable when pressing a lot of rivets.

My solution was to drill a 13mm hole in a piece of 20mm acetal rod and tap it onto the rectangular bar.





So simple but so much more comfortable.





It didn’t make pressing the rivets out any quicker but it saved the hand, some grief.

Ordinarily I would have taken the slight curl out of the sheet by setting the rivets using a jeweller’s stone setting tool, a technique picked up from Peter Dunn. However, because I plan to roll this and the curl is in the right orientation, I left it as is.

To roll the smokebox with the rivets embossed I backed it with a piece of card from a biscuit packet (Tesco Finest Chocolate Gingers – other sources of card are available).





Once I filed the etching cusp off the rear former it dropped straight in.

Lovely work!

 

[Max M]

...good excuse to eat more biscuits...

Need an excuse to eat biscuits??????! You live and learn.

 

[Ian@StEnochs]

If I were rolling my own I would do the same Ian.

0.45 is more like panel beating than modelling, but we have to use what's provided when building for others.

Thanks for tip about the rubber sheet, I will look out for something similar.

Cheap car mats can be a good source of rubber sheet but not the ones with rubbing! You could also use a mouse mat which are a wee bit softer and usually have a smooth surface and one with a big more spongy give.

Ian.

 

[Len Cattley]

Or you could use a camping mat. Rob are you going to do the smoke-box detail like Nick did?

Len

 

[adrian]

So, the answer is “wrap it in card”.

We always used a sheet of plasticard when I was scratchbuilding for my Dad.

 

[Rob Pulham]

Or you could use a camping mat. Rob are you going to do the smoke-box detail like Nick did?

Len

Not on this one Len, I may do it on something for myself at some point.

 

[Rob Pulham]

There has been quite a bit of conversation over on the Guild forum about the Smoke box saddle for the David Andrews Princess. It seems that the main saddle casting which is brass is 2mm or so too deep. Oddly there is a second casting which is white metal. I find it most strange that they are made from two different materials

A couple of fellow Guild members whom I have corresponded with on the subject, had the second casting missing from their kits (both bought second hand) and I wonder if was actually there, but like me they missed it because they were looking for a second brass casting. I certainly did until it was pointed out that it was white metal.









Before I go any further, I need to assemble the cab (I have already soldered the inner and outer cab sides together) and I am sure that I will need to remove some material from the middle splashers to get the boiler to seat properly between them.

 

[Dave Holt]

That looks to be a potentially interesting problem, Rob. Is the boiler barrel attached to the firebox or just temporarily plugged on? The firebox appears to be seated down at the rear but a mill' or so up at the front, which would require the smokebox to move down by quite a way. Obviously, the smokebox also needs to the parallel with the footplate from the side, so it looks like the rear of the boiler needs to come down also. That might open up an uneven gap at the barrel/firebox joint, requiring trimming/filling.
Dave.

 

[Rob Pulham]

That looks to be a potentially interesting problem, Rob. Is the boiler barrel attached to the firebox or just temporarily plugged on? The firebox appears to be seated down at the rear but a mill' or so up at the front, which would require the smokebox to move down by quite a way. Obviously, the smokebox also needs to the parallel with the footplate from the side, so it looks like the rear of the boiler needs to come down also. That might open up an uneven gap at the barrel/firebox joint, requiring trimming/filling.
Dave.

Hi Dave,
It won't go down any more at the minute because it's pivoting on the middle splasher.

I made up the cab this afternoon, once I have that in place I will have a fixed point to work forwards from to get an idea how much needs to come off the saddle.

 

[Rob Pulham]

I set myself a couple of goals for the session, the first was to get the smokebox door ring to fit in the smokebox barrel, the second was to assemble the cab.

Staring with the smokebox door ring, I had decided that filing it would be a complete pain and a last resort if I couldn’t work out how to hold it in the lathe to turn it down.

The amount of rim left after turning would be miniscule so no chance of griping it by that and being able to turn it. I didn’t have any material of a large enough diameter to make a mandrel so I decided to try holding it on the outside of the jaws. Because it’s white metal it would be really easy to distort or mark it. I cut a strip of aluminium drinks can to length so that it would wrap around the circumference of the inner ring but not overlap to throw it off centre. Once inserted I carefully opened the jaws until they were just gripping the part.

I started off by attempting to have it hard up against the jaws in an attempt to get it running concentric but the rivets on part of the ring prevent it from sitting flush so I had to move it away from the jaws and then use a pair of thin parallels inserted between the jaw and the face to ease it until I reduced the wobble to an acceptable level. Despite trying to get it perfectly flat on my glass sheet I wasn’t able to without damaging said rivets so I had to accept a little wobble.

I had the lathe running at about 100rpm or less, I set the carriage stop so that I wouldn’t inadvertently chop of the front rim and then moving in 0.050mm at a time I skimmed the rim at the back of the part. The first cut quickly proved that the outside of the part wasn’t completely circular either. I patiently took cuts until the rear rim was completely concentric, all the while checking the fit of the smokebox front after each cut.

In the end I took off a depth of 0.750mm which equates to 1.5mm overall. That would have been a killer with a file while attempting to keep it circular.









Having got that to fit successfully I turned my sight to the cab. I have never had something so simple be such a complete pain in the posterior to get together squarely. Today’s attempt was my third go at it, and it still took both sides being removed and refitted twice before I was satisfied that it fit as I thought it should. The problem is finding some part of it in between all the rivets and window frames inside that you can put a square against, to hold the sides at right angles to solder them.

Next, I spent some time with a spirit level adjusting the horn block screws to get the chassis/footplate to sit level.

Having the cab as a datum I can now see that the Firebox needs a slight trim where it goes over the rear splashers so that it will sit level. Once I have done that I need to sort out where the boiler is currently riding on the centre splashers. The problem here being that there isn’t a great deal of clearance between the wheels and the splashers so I think that I will have to cut into the boiler clothing to get it to seat. Once I have the boiler seated, I can consider what to remove from the saddle(s).









I will start by soldering the cab to the footplate and trimming the firebox…

PS just as I was posting this I moved the loco from the photo area to my workbench and managed to drop the cab on the floor. Now the first job is to solder one of the cab sides back on....

 

[Rob Pulham]

Those that are still with me will have noted that I am at the point of levelling the boiler/smoke box up and that I really need to cut into the boiler clothing as there isn't enough clearance below the splashers before you hit the wheels, to take any off to allow the boiler to sit down.

I have tacked the cab on and got the firebox to sit flush and marked up the boiler barrel ready to cut but this is where I have a question for those who might have had to do this before.

This is the mark that I need to cut to

I am planning on using a diamond disk in the Dremel to make the cuts.

My question is do I make a vertical straight cut parallel to the splasher and then remove some material behind or attempt a curved cut (by leaning the Dremel at an angle as the cut outs for the rear splashers have been etched?

 

[simond]

Are you sure you can’t make enough clearance by filing a chamfer on the inside edge of the splashers?

if you can, (or even if you can only get clearance for the splashers and not the wheels), it’ll be the best visually. And I reckon it’ll be easier to do, too.

if you need to add clearance for the flanges, you can do that “behind” the splashers.

 

[Rob Pulham]

Are you sure you can’t make enough clearance by filing a chamfer on the inside edge of the splashers?

if you can, (or even if you can only get clearance for the splashers and not the wheels), it’ll be the best visually. And I reckon it’ll be easier to do, too.

if you need to add clearance for the flanges, you can do that “behind” the splashers.

Thanks Simon,

I agree, it would be much easier and apparently John Dale managed to get enough clearance without touching the wheels on his build. So am going to give that a go before taking any more drastic measures.

 

[mickoo]

Rob,

Before you cut anything it might pay you to check the drawings in the LMS profiles book.

The problem is almost certainly not the boiler, it's the resin firebox, to be blunt, it's garbage.

The boiler base is virtually flat, perhaps lower at the rear end by 1 mm or so (I've not measured the drawing for an accurate measurement) as the cone is not concentric on the center line. That will push the rear end up which has been artificially forced lower due to the resin casting being two short, worse yet the fall to the cab is wildly out, from the crown to the cab front the fall (it's a 1:32.356 fall) is only 3" and some small bit inches to be precise; I think you'll find the fall on the resin casing is much greater.

You need to jack the rear end up by the cab to the right height, then set the rise to the crown and fill the gap underneath and I'll bet the boiler will fit just fine.

I also believe the sides taper in too much at the cab end as well, Nick had a lot of trouble hacking and sorting the firebox out on his two, it would have been quicker to make new ones.

 

[Rob Pulham]

Well, having taken Mick advice and look at the drawings, I am not sure whether the firebox casting has been remastered since Nick built his. But checking against the Wild Swan drawings the boiler height at the cab and the shoulder where firebox starts to curve in over the splashers is pretty much spot on to the drawings.

I also checked the taper towards the cab it's actually slightly on the wide side at the cab end rather than too narrow too.

Which I am rather glad about because I doubt that I could have hacked the casting about like Nick did and get the a similar result.

I have also just checked Nick's build thread and he had to cut back the splashers too having altered his firebox so onwards and upwards it will be a steady process of take a bit off and check, rinse and repeat...

Edited to add that Nick kit's must have been older than this one because he had a white metal smokebox saddle whereas it's brass in the kit that I am building.

 

[Dave Holt]

Hi Rob.
I was just about to post the relevant dimensions from the WS drawings but I see this isn't now really needed. However, here are my thoughts to compare with your own conclusions. Height of boiler CL above top of footplate - 21.437 mm; height to top of firebox at front - 45.247 mm; height to top of firebox at cab - 44.077 mm. The width at footplate level isn't easy to determine other than by actual setting out due to the curve starting below footplate level. Rough widths are: front - 49.36 mm, rear - 45.28 mm. For early, non-combustion chamber boilers, the width at the front is somewhat bigger at 51.55 mm, other dimensions the same as the later boilers, as stated above.
I did note that for the combustion chamber boilers, not only are the inner corners of the splashers chamfered, but there are also significant cut-outs/recesses in the boiler clothing for at least the middle and trailing splashers. Recesses being deeper for the rear, so it looks like you will need to make cuts in the barrel after all.
Dave.

 

[Rob Pulham]

Thanks Dave,

This is where my lack of knowledge of the prototype is telling. I take it that the non combustion boiler is what I know as 'Domeless'?

If so that's what mine is. It's to be modelled as around 1936 after it had got the coal pusher tender but still had the Domeless boiler.

Hopefully that means that I don't have to cut the boiler clothing after all.

 

[Dave Holt]

Rob.
It appears that 6206 was fitted with boiler 9104 up till June 1937. 9104 was a dome-less boiler with a combustion chamber firebox, so I'm afraid that cut-outs in the boiler will most likely be required. If you try to stick with the dimensions I quoted previously, that will suit 6206 in 1936.
Dave.

 

[Rob Pulham]

Thanks Dave,
It's much appreciated.