Rebuilt Bulleid West Country 3D CAD designed & mft in 3.5 in

[masahiraoka]

Roger and Chris
very sound advice re the boiler cladding and clearance with the spectacle plate thanks.
We're doubly sure to follow this because the boiler we're using on the prototype build is, as i said in an earlier post, a high quality existing boiler that is not exactly to the design we wish for the long term but will use in this case for expediency sake.
we'll get around to designing our desired boiler towards the very end of the project.

This week marks the fifth anniversary of the commencement of the project and i'm pleased we're now able to share the progress with you all

best regards Martyn

[masahiraoka]

Radical Suggestion

• With the ease of 3D CAD design we can now address an aesthetic issue that has always troubled me with the rebuilt West Countries and Merchant Navies i.e. the shape of the cab side below the Vee front window.

• Long before the WC and MNs were rebuilt the cab front window was modified to give much better visibility. The original front window was a sliver of a thing at right angles to the boiler and "buried" in the gap between the sides of the boiler and the cab, and almost certainly impossible to reach from the side window for cleaning purposes, see the photo below of Battle of Britain Fighter Command as-built.



• The revised Vee front window (so called because it was angled at 45 deg to the boiler in a similar fashion to the LNER A4), introduced in 1948, provided much better visibility and the possibility of cleaning the outside of the window by reaching from the side window.

• This design was "cut" into the existing cab side with the result that a boxy section of cab remained below the new Vee front window. To me that has always looked like a crude quick fix.

• Probably the reason it was designed this way is that there was equipment inside the cab below the window that could not be relocated, e.g. the reverser.

• That said on our scale loco we're going to explore a more elegant design of the cab side below the window as sketched below,

• The current, as originally designed, location of the reverser will be checked to see if it does or does not prevent such a fix and even if it does, we'll examine moving it slightly aft to allow such a fix.

[uuu]

I can see the look on some people's faces now. The same look my music teacher had when a pupil played some "improved" Bach.

Wilf

[masahiraoka]

I agree with your music teacher, Bach can’t be improved upon.
but lots of designs can.
for example form an aesthetics point of view I have always thought that the LNER A4s looked much more attractive without the wheel valances, with the sweep of the curve of the bottom of the casing (apparently based on a 1930’s aerofoil) beautifully accentuated with out them. 
pin any case it will be interesting to make the revised cab and see how it looks in the flesh.

[kipford]

Martyn
I understand your point on the cab modification and in the end it is your project. However with the level of detail and accuracy you are employing it seems a shame not to complete the locomotive to standard it was finished in. This would leave a wonderful historical record and dare I say at some point a more fiscally valuable model.
Dave

[chris vine]

I had never noticed that cut-out shape that you don't much like.
Certainly when you look at it in a side elevation drawing it looks like a bit of a bodge. However, from the front, they have done their best with a sloping top and it looks much more "designed".

Chris.

[masahiraoka]

Chris and Dave
that's the beauty of 3D CAD design, we can easily build both the original and the proposed designs to compare the results.

in the meantime in March Andrew began the assembly of the prototype chassis.

The early stage part-built chassis in the photos below was assembled from the 3D printed brackets and stretchers described in earlier posts and water jet cut main frames in 13 hours not including riveting the axlebox keeps to the frames.







this shows the tools necessary to assemble the chassis thus far



In order to keep Andrew busy Phil has sent of a large order for 37 unique parts to the 3D printer - should be delivered by the end of June

[92220]

That's interesting! The horns are on the outsides of the frames, and I thought the 9Fs were the only locos built like that. Were they like that as an un-rebuilt loco? I would think it makes the frame plates a bit close for working on inside motion and cylinder though, in 3.1/2" gauge. Hope you have miniature fingers!!!

........and Thanks for a very interesting thread!

Bob.

[masahiraoka]

Bob
yes the main face of the axle box guides or horns for both the Merchant Navies and West Countries were always on the outside of the frames, see the portion of the original SR dwg no. E30260 of the axle box guides. if you look closely, particularly at the cross sections, you can see that the main face is outside the main frames. 



this 3D CAD screen shot clearly shows this on our scale version

[lankyyorky]

I believe Bulleid was of the opinion that it was a good idea to have the frames on the centreline of the axle bearings, seems BR agreed with him.

Dave

[92220]

Hi Martyn.

Thanks for that info. As they say....You live and learn!!

Bob.

[masahiraoka]

Dave
you're absolutely right - the outcome of this design is that the centreline of the axle bearings is in line with the centre of the frames
from a design strategy i.e. alignment of forces it makes perfect sense.
i'd never looked closely enough to see this

ciao Martyn

[lankyyorky]

Thanks Martyn, I think Bulleid was a very far sighted and underrated engineer, or perhaps ahead of his time, I'm also following this thread with great interest, modern manufacturing methods are the way to go if you want prototype fidelity and I say this as someone in their (early!) seventies and an admirer of Stirling singles.

Regards
Dave

[masahiraoka]

Further Work on the Stretchers

• Here are some more of the stretchers built up from profile cut parts with tab and slot and/or bent design.

• The first shows the Stretcher at the Reversing Shaft (SR dwg no. W5765) and our CAD design










• This next photo shows again the issues with bending with tight radius corners and exacting requirements with regard to location of the bends



• That said Andrew has done a neat job on the finished stretcher





• And this one the Frame Stretcher Behind the Buffer Beam (SR dwg no. W5714)

[Roger]

May 30, 2020 0:22:04 GMT masahiraoka said:

Further Work on the Stretchers

• Here are some more of the stretchers built up from profile cut parts with tab and slot and/or bent design.

• The first shows the Stretcher at the Reversing Shaft (SR dwg no. W5765) and our CAD design










• This next photo shows again the issues with bending with tight radius corners and exacting requirements with regard to location of the bends



• That said Andrew has done a neat job on the finished stretcher





• And this one the Frame Stretcher Behind the Buffer Beam (SR dwg no. W5714)

These are looking good. Are you making formers for this sort of job? This last one is an ideal candidate since the former can have a boss that locates with the large cutout to guarantee everything is lined up. It also guarantees the inside dimension is correct.
Do measure the sheet thickness first though, because sheet is almost always made at or near the bottom tolerance limit so the manufacturer can save a few pennies. I never trust the purchased size of sheet, it can be significantly thinner, and that would effect the size of your former.

[steamer5]

Hi Martyn,
They look really good!
One question, have you considered bending the plate hot? Read red heat. I guy on another forum, funnily enuff by the name of Andrew, showed how he bent up the spectacle plate for his traction engine. He had a former plate, clamped the part to it & heated to red heat, just the areas to be bent, then used a wooden mallet to bend it, his was full 3 sides so formed the corners as well. Came out well, just another way to skin the cat!

Cheers Kerrin

[Roger]

May 30, 2020 8:40:05 GMT steamer5 said:

Hi Martyn,
They look really good!
One question, have you considered bending the plate hot? Read red heat. I guy on another forum, funnily enuff by the name of Andrew, showed how he bent up the spectacle plate for his traction engine. He had a former plate, clamped the part to it & heated to red heat, just the areas to be bent, then used a wooden mallet to bend it, his was full 3 sides so formed the corners as well. Came out well, just another way to skin the cat!

Cheers Kerrin

Hi Kerrin,
This certainly works, but at the price to dealing with the Black Oxide Curse. Another alternative is to anneal it while covered in flux half way through so you avoid that.

[steamer5]

Hi Roger,
I just had a look at the thread on forming the plate, the only mention on clean up is using a wire brush, I guess for a one off & not to complicated shape would be ok, were as Martyns stretcher would require quite a bit more work to clean up given the shape.

Cheers Kerrin

[uuu]

Now we know all about blasters, a little bit of oxide isn't going to be a problem is it?

Wilf

[Roger]

May 30, 2020 18:34:02 GMT steamer5 said:

Hi Roger,
I just had a look at the thread on forming the plate, the only mention on clean up is using a wire brush, I guess for a one off & not to complicated shape would be ok, were as Martyns stretcher would require quite a bit more work to clean up given the shape.

Cheers Kerrin

Hi Kerrin,
Maybe he's just leaving the oxide on there. Every time I get something Steel red hot it takes a lot more to get it back to bare metal than a wire brush.