7mm David Andrews Princess - 6206 Princess Marie Louise

Yorkshire Dave

Yorkshire Dave

Western Thunderer
This is one of these experiences which falls into the 'benefit of hindsight' category - and one for memory should this re-occur.

One solution would have been to re-engineer the rear of the frames by making up another set from scrap etch and solder them on the inside at points X. Then cut away the magenta bounded area of the original frames leaving an inset. This could either be left or filled with plasticard or tissue paper soaked in superglue.

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simond

simond

Western Thunderer
Rob,

I had missed that you were using American pickup. You’ll have guessed from my “diagnosis guide” that I’m far from a fan, though it probably works well on bogie diesel/electric locos or mu’s, and clearly you have made it work for you in previous builds.

I think the Slaters insulated hornblocks with split axles is the way to go if you don’t want to use rim pick-ups, but of course there is some added labour involved!. I’m quite happy with rim pick-ups, using the design I developed from David LO Smith’s drawings, in most cases.

cheers
Simon
 
Rob Pulham

Rob Pulham

Western Thunderer
Hi Gents, I didn't reply yesterday as I am only part way through the saga relaying what I did retrospectively having only taken photos as I went along without writing them up.

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.

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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.

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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.

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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.
 
Yorkshire Dave

Yorkshire Dave

Western Thunderer
Rob Pulham said:
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.
Click to expand...

If the castings can be removed from the truck frames I would thin them slightly from the rear so they at least retain the front detail and sit flat on the the truck frames.
 
Rob Pulham

Rob Pulham

Western Thunderer
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.

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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.


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OzzyO

OzzyO

Western Thunderer
Hello all,

the Princess's always look long even compared to a Duchess, I don't think that there is much in it to which one "is" the longer.
I think the the Princess look long due to the diameter of the boiler.
Nice looking build Rob.

ATB

OzzyO.
 
LarryG

LarryG

Western Thunderer
The Princess's were fav's of mine because they looked like other LMS taper locomotives but were vastly more impressive looking. When you saw one as you approached a station, you knew why.
 
simond

simond

Western Thunderer
Lancastrian said:
Princess - 74' 4 1/4"
Coronation - 73' 9 3/4" (streamlined), 73' 10 1/4" (non-streamlined)
Click to expand...
I do not understand why it should be the case, but the real difference of only 6 inches does not explain why the Princesses appear so very long.

The Duchesses appeared, to me at least, beautifully, even perfectly proportioned, I was never fond of the Princesses.
 
timbowales

timbowales

Western Thunderer
simond said:
I do not understand why it should be the case, but the real difference of only 6 inches does not explain why the Princesses appear so very long.

The Duchesses appeared, to me at least, beautifully, even perfectly proportioned, I was never fond of the Princesses.
Click to expand...
Optical illusion caused by the thinner boiler?
 
mickoo

mickoo

Western Thunderer
The boilers are externally the same between the two classes and smokeboxes the same diameter (but Coronation is shorter)....give or take an odd 2-3/8th".

The Coronation boiler sits higher so has a shorter chimney, the firebox is also larger which shunts the front end forward so the front platform is shorter than the Princess Royals.
 
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Yorkshire Dave

Yorkshire Dave

Western Thunderer
Not only the boiler pitch as @mickoo alludes to, the illusion of the extra length is also completed by the cylinder position, lack of smoke deflectors and the uneven coupled wheelbase (8'+7'3'') on the Princess Royals. (Princess Coronation/Duchess coupled wheelbase is 7'3''+7'3'').
 
mickoo

mickoo

Western Thunderer
Yorkshire Dave said:
Not only the boiler pitch as @mickoo alludes to, the illusion of the extra length is also completed by the cylinder position, lack of smoke deflectors and the uneven coupled wheelbase (8'+7'3'') on the Princess Royals. (Princess Coronation/Duchess coupled wheelbase is 7'3''+7'3'').
Click to expand...
Even when running without deflectors, the Coronations have more bulk, I think the outside cylinder steam pipe covers are a part of that visual aspect and the cylinder position as you say, almost certainly plays into that as well.
 
Rob Pulham

Rob Pulham

Western Thunderer
Late last week I got the Princess back from painting for reassembly.

I started rebuilding with the simpler stuff like the bogie and trailing truck, then the tender chassis, followed by fitting the tender body. All the while being very careful not to damage the paint.
I was just about to fit the tender chassis when I thought it would make sense to fit the buffers first, thus giving me more room to fit the retaining nuts without damaging anything. This was when I found that the buffer heads no longer fitted due to paint build up in the bore of the buffer stocks. I searched all my drill bits and broaches but couldn't find one of the right size to just remove the paint without enlarging the hole.

A few days ago I scrapped a friend's old printer and it turned out that one of the recovered bits of rod, was the perfect size to make a little reaming tool from. I turned the outside to the size of the buffer shank and then using a collet block to index as I rotated it, I plunged an end mill into the end to create some small teeth. Then I popped it back in the lathe and took a small amount off the diameter as a relief. Working away from the chuck, towards the end and just leaving approx. 1mm of 'teeth'. After a slight deburr I tried it and it worked perfectly.

It's not hardened, in fact the steel is quite soft but it only needed to cut through a layer or two of paint.

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I gripped it in a drill chuck as the only pin vice that I had which would take the rod is a bit worn and the rod slipped rather than scrape the paint off.
 
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