7mm David Andrews Princess - 6206 Princess Marie Louise

[King Crab]

Very methodical Rob. Your care pays dividends!
Lovely work.
Peter

 

[Rob Pulham]

I finished adding the remaining details to the drawing yesterday and it now just needs the sketches tidying up and checking/adjusting to ensure that it fits on the kit footplate.

It has been suggested that I also look at drawing replacements for the parts of the firebox that fit under the footplate too as the cast on boiler bands don't match those above which would look a bit odd. So that will be next after putting the firebox to bed.

 

[OzzyO]

That's looking good but have a look at the R/H side of the fire box and the back washout plug.

Also make sure that you draw the correct firebox for your loco in the right time period (you will have done that, I know).

ATB

OzzyO.

 

[Rob Pulham]

Well spotted, thanks Paul.

 

[Rob Pulham]

Thanks to Paul's eagle eyes, I have now corrected the washout plug issue.

Thanks again Paul, sometimes you look at these things for so long you miss the obvious...

 

[Rob Pulham]

Over on the GOG Forum Ian Allen, asked what I was going to do about the Firebox shoulders and my initial reply was that I planned to see how they printed and then possibly file them down. Ian then kindly posted a really good photo of the offending article so I revisited it yesterday.

 

[mickoo]

This week has mainly been about returning to the elephant in the room, the Firebox. There had been some discussion on here some time ago about issues with the resin casting and I must admit I didn't get 'it' and after a (very!) rudimentary measure up, it didn't seem far out so I left it at that.
Fast forward to last week and Nick Dunhill posted on my thread on the GOG forum and mentioned how far out his had been on all the ones that he built (he built four in total) and how much work it had been to rectify the problems.

You can lead a horse to water

Glad you've seen the 'light' and working toward a better solution, there's only one place for the DA Princess Royal firebox....the bin, many a fine model aesthetically destroyed by people fitting it.

 

[Gavin Eyre]

Rob,

First of all I would like to thank you for taking the trouble to create this posting. I have a David Andrews Princess (Lady Patricia) in my build queue that I'd been looking forward to starting - but now I'm not so sure... The idea of designing and 3-D printing a new firebox is perhaps a step too far for my Fusion 360 skills.

For some of the items that you've been knocking up on your lathe and mill can I recommend that you have a look at Small Parts & Hardware. I've been using their bolts, rivets and nuts in the few models I've finished and they really do look very good. The other thing I've found very useful is a collection of different sizes of hypodermic tubes. These are great for simulated pipe joins and lubricators which I sleeve with hypo tubes (to simulate the unions) before running through thin wires for the oil lines.

Gavin Eyre

 

[Rob Pulham]

Hi Gavin,

I have bought from Small Parts and Hardware in the past but on my last order I got stung for import duties so I haven't ordered since.

To be fair at that time I didn't have a lathe, but now I have, making things myself adds to the pleasure from the build. For me the journey is as important as the end result.

I had a quick look online for hypodermic tubes but was struggling to find any available in smaller quantities so a pointer to a supplier would be appreciated. As you might expect those that I found were all stainless steel and I am wondering what advantages this might have over microbore brass tube as I can solder the latter whereas I assume that you would use adhesive on the stainless tube?

 

[Gavin Eyre]

Hi Gavin,

I have bought from Small Parts and Hardware in the past but on my last order I got stung for import duties so I haven't ordered since.

To be fair at that time I didn't have a lathe, but now I have, making things myself adds to the pleasure from the build. For me the journey is as important as the end result.

I had a quick look online for hypodermic tubes but was struggling to find any available in smaller quantities so a pointer to a supplier would be appreciated. As you might expect those that I found were all stainless steel and I am wondering what advantages this might have over microbore brass tube as I can solder the latter whereas I assume that you would use adhesive on the stainless tube?

Hi Rob,

I think I have an advantage over you on getting things from the States and customs duties as I'm half American and I currently live in France. I've been getting stuff directly from Small Parts without any customs duties but I can also get stuff shipped to a family member and then either onward shipped as a "birthday present" or carried in airline checked baggage. My wife is heading across at the end of January and she'll be bringing some stuff back for me.

For hypo tubing I get this from McMaster (McMaster-Carr) in 12" lengths. I've been able to solder it to brass with Carrs Brown Label flux and Loctite 420 works well in other situations. I particularly like the thin-walled stuff to make shouldered bolts for motion components and small pipe unions. I built the springs for a DJH A3 from 3-D printed leaf springs held to nickel silver hangers using 14BA threaded bolts inside thin walled tube. I've not encountered microbore brass tube - where do you get this?

Gavin

 

[Rob Pulham]

Hi Gavin,
Got you. Easy if you have the means to get hold of them.
I buy microbore tube from various suppliers in this country usually at shows where I can see the size. I have mainly bought from Hobby Holidays in the past but I see that Phil has now stopped attending shows.
The best place for you to get it would Albion Alloys via eBay or model shops such as the link below.
305x0.3mm 0.5mm 0.7mm & 0.9mm Brass Micro Pack Albion Alloys SFT2 | Scale Model Shop

 

[Rob Pulham]

I have been working away at the ashpan sections during odd half hours where it wasn't worth getting into any physical modelling. I am almost there with it now, I just need to thicken up the top at bottom at the rear to make it match the DA castings and add access holes for the screws in the firebox base.

The clamp on the bottom curve is very much a representation as I didn't think anything finer would print successfully and if it did it would probably get knocked off during fitting.

 

[OzzyO]

Rob,
that's all pretty well bob (sorry) on , about the only thing that I can think of that you could do to "improve" them would be to randomly rotate the washout plug heads.
Very nice work.

ATB

OzzyO.

 

[Rob Pulham]

Rob,
that's all pretty well bob (sorry on , about the only thing that I can think of that you could do to "improve" them would be to randomly rotate the washout plug heads.
Very nice work.

ATB

OzzyO.

Hi Paul,

It actually wouldn't be a huge job at this stage to do that. I may have a look if I don't get fed up first...

 

[simond]

Well, you only have to rotate one of them…

 

[Rob Pulham]

Well, you only have to rotate one of them…

On the lower bit, there are a few more on the main firebox....

 

[simond]

Ah, yes…

 

[Rob Pulham]

Your wish....

Unfortunately because I had drawn those on the upper firebox as an array, I was unable to edit them individually and it would have been a big job to replace them in the design so they will remain as is.

Perhaps the last person to washout, was a bit OCD about them all being aligned

 

[Dave Holt]

Thus speaks someone who's never tightened up a taper threaded washout plug?

 

[Dog Star]

Thus speaks someone who's never tightened up a taper threaded washout plug?

Spot on.

The thread in the firebox side wears... the taper thread on the washout plug wears... and likely not at the same rate over all washout holes - with the result that, when tightened, the square head of the plugs adopt a wide range of positions.

regards, Graham