Brassmasters Rebuilt Royal Scot, 46109

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Fri Dec 04, 2020 9:16 pm

Thanks, Paul.
Not much modelling just now. I've acquired a small but very painful cut near the tip of my left index finger - might have caught it with the piercing saw but can't remember doing it. It's making it too uncomfortable to try to grip parts between finger and thumb as any pressure on the finger tends to open the wound.
That said, I have finished off the exhaust steam pipe to the injector, ahead of the removable section, already shown. I've had to add a substantial and completely un-prototypical support bracket near the lower end to locate the pipe joint relative to the frames.
Adding these extra details, not envisaged by the kit designer, throws up all sorts of clashes with other parts of the loco. On this case, the top level of the pipe to the inside cylinder passes through the rear cross member of the outside cylinders. I strengthened the reduced depth of the cross member with 0.8 mm brass wire - which did the job, but then it clashed with the top of the inside combination lever at its furthest back position, so the strengthening wire had to be nibbled away local to that.
It all clears now, as shown by the assembly.
Scot_108.JPG

On with the bogie once the finger improves.
Dave.

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Will L
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Will L » Sat Dec 05, 2020 12:03 am

Dave Holt wrote:...Adding these extra details, not envisaged by the kit designer, throws up all sorts of clashes with other parts of the loco...

I know the feeling,

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johndarch
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby johndarch » Sat Dec 05, 2020 9:07 am

Me too!

I can sympathise with you re your injury. Last week I attacked my thumb with a cheese grater and a finger with a scalpel. You can't get much grip between finger and thumb when they are both encased in waterproof dressings!

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Tue Dec 08, 2020 1:50 pm

Whilst trying not yo overload the finger tip, I decided to make a representation of the exhaust steam passageways between the three cylinders and the smokebox saddle using plastic card, laminated where necessary to represent the required thickness. Not too sure why I've bothered with this detail as once the footplate is on, it's almost impossible to see, even from underneath! Well, it's there now.
It has allowed the square flange on the pipe to the exhaust steam injector to be included.
Scot_109.JPG

Scot_110.JPG

Some prep work has been done for the front bogie.
The main bogie bottom stretcher and the cast W/M crosshead have been opened up to fit a 2 mm O/D tube which fits over the fixing screw, allowing the latter to be fully tightened (after cutting the tube and screw to length) whilst still allowing the bogie to pivot and slide sideways. The etched extensions to the top edge of the side frames, which I assume are supposed to represent the centre casting, have been removed (one can be seen close to where it used to be attached) so that proper side bearers can to used. The odd shaped part on the left of the photo is the start of this piece on the model.
The external compensating beams have had the half-etched linking piece between the beam and the axlebox removed from what will be the outer face, after bending to shape.
Scot_111.JPG

Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Wed Dec 09, 2020 4:11 pm

The slide bars have been fixed to the cylinder frame, ensuring they are square to the cylinder faces in all planes. A trial fit shows the top bars to sit nicely in the support bracket. The connecting rods and cross-heads run smoothly, without any clashes.
Scot_112.JPG

Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Fri Dec 11, 2020 8:40 pm

A bit of progress has been made with the bogie, in amongst writing and posting Christmas cards. The things that get in the way of modelling!
It's been more of a struggle than it might have been. I couldn't find the side control springs and arranged with Brassmasters to obtain a replacement set. Whilst waiting, I ploughed on with folding the frame etch, enclosing the central cast W/M crosshead in the structure. The instructions stated that the holes for the side control should be opened to 1 mm and 1 mm rod used as the guides.
The problem arose when the new springs arrived and were found to be slightly under 1 mm O/D and about 0.7 mm I/D. In fact, although they would just push on to a 0.7 mm drill bit, they wouldn't go onto nominally 0.7 mm rod because it was 0.02 mm over size.
The solution was to sleeve down the holes in the frames with 1 mm O/D tube and to mount small washers between the inner ends of the springs and the ears on the crosshead. 0.6 mm rod was used as the spring guides. To be honest, although extra unplanned work was required to recover the situation, the side control action is the best I've achieved with a Brassmasters bogie.
The external compensating beams have been made up, as seen below.
Bogie (seen from underneath) and compensating beams.
Scot_113.JPG

Close up showing the side control arrangements.
Scot_114.JPG
Scot_114.JPG (156.47 KiB) Viewed 2672 times

Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Sat Dec 12, 2020 3:05 pm

Other than some fettling and cleaning up, the bogie is now finished and trial fitted.
Bogie ready to fit:
Scot_115.JPG

Scot_116.JPG

And fitted to the chassis. Boy, are those rear wheels close to the brake hangers. I can see some judicious paring away of the front edge of the hangers.
Scot_117.JPG

Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Sat Dec 19, 2020 2:59 pm

Work has progressed on the cylinders. Except for the drain cocks - the castings in the kit are disappointing and nowhere near as good as those in the Black 5 kit, so will have to be replaced - the cylinders are now complete and the piston rods have been added to the cross-heads. A bit more work is required to get a completely smooth action, but this is probably best left till the slide bars are attached to the motion bracket.
An awful lot of work was required before the wrappers could be fitted as the bottom of the laminated slide bars, inside the cylinders, protruded by quite an amount below the bottom of the cylinder formers.
Beginning to look the part, I think.
Scot_118.JPG

Scot_119.JPG

And with the footplate loosely fitted.
Scot_120.JPG

Scot_121.JPG

Scot_122.JPG

Valve gear support frame next.
Dave.

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johndarch
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby johndarch » Sat Dec 19, 2020 3:13 pm

It certainly is looking the part Dave. Good work.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Tue Dec 22, 2020 8:46 pm

Thanks, John.

A start has been made on the outside valve gear. I need to make up the expansion levers to determine the correct position for the inner supports which I earlier removed from the valve gear support frame. Experience with another of these models showed that the inner frame members, as etched, are too far inboard and clashed with the front boss of the coupling rods near TDC. On the real locos, these inner frames should be roughly above the connecting rod centre lines. Before re-fixing, I want to make sure the expansion levers will fit in the resulting gap between inner and outers of the frame.

So, the radius rods have to be made before the expansion levers as they become trapped within the curved guides. Hence starting the valve gear.
Progress so far:
Scot_123.JPG

Assembly of the LH radius rod was more difficult than it might have been when the short outer lamination (between the die block pin and the reversing slot) pinged off somewhere, never to be seen again, requiring a scratch replacement made from some spare bit of the same etch sheet.
I've modified the valve rod cross-heads by removing the cast rods and replacing with 0.6 mm N/S wire - straighter, smoother and a more scale diameter.

Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Thu Dec 24, 2020 9:14 pm

Not too much modelling right now, mainly due to domestic Christmas preparation duties, but a little progress has been achieved.
The detached inner valve gear support members have been fixed in their new positions, much closer to the outer ones. The openings in the front of the support frame have had to be widened outwards to allow the front of the radius rods to align with the top of the combination levers and a temporary trial fit of the LH parts made, as shown.
Scot_124.JPG

Better check the RH side before going any further.
Merry Christmas and Happy New Year to all. Let's hope 2021 is a much more normal year.
Dave.

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johndarch
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby johndarch » Fri Dec 25, 2020 9:39 am

Looking fantastic Dave. Have a great Christmas.

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Mike Garwood
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Mike Garwood » Fri Dec 25, 2020 8:49 pm

Totally in awe Mr Holt! I really hope to see this running sometime next year on Barrow Road. Beautiful work Dave.

Happy Christmas mate.

Mike

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Sun Dec 27, 2020 9:36 pm

Thanks, Mike. Don't hold your breath!
Hope everybody had as good a Christmas as possible under current restrictions. I certainly did.
Today has been very much a case of a step forward, a step back and another step forward again, so a bit of progress overall.
The mountings for the reverser shaft have been fitted to the valve gear support frame and then used to locate the inner portion of the shaft, which is fixed to the main frames and has the bottom section of the inside gear reversing lever and the central spring balance arrangement mounted to it, although the latter is not yet represented.
The chassis had to be stripped to its bare structure for this work to take place. I always hate taking it all apart as it seems so negative. Anyway, onward.
View, from underneath, of the valve gear frame fitted to the chassis. Originally, the inner frames were designed to be folded down from the inner edges of the frame, so the amount they have been moved inboard can be seen. The inside eccentric rod and drop link/anchor link have been wired up out of the way to avoid possible damage during handling.
Scot_125.JPG

The lower section of the inside gear reversing arm can just be glimpsed through the cut out in the main frame.
Scot_126.JPG

A general view from above.
Scot_127.JPG

Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Fri Jan 01, 2021 10:30 pm

Happy New Year to all.
The front portion of the outside valve gear is now complete and fitted to the cylinders and support frame. The two latter have been joined into a single removable unit.
Scot_128.JPG

And, just to prove I have done both sides:
Scot_129.JPG

Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Sun Jan 03, 2021 8:56 pm

Houston, we have a problem! Well, several problems, actually.
As shown in the photo, now everything is in place, there is interference between the combination lever and the rear cylinder relief valve, preventing the wheels turning to front dead centre. Obviously, something is wrong.
Scot_130.JPG

As it turns out, several things are wrong, with the cumulative effect just mentioned.
First thing to note is the front boss of the radius rod is about in the centre of the valve spindle guide even though the radius rod is set well back from its central position, which suggests something amiss. My first suspicion was that the valve guide casting is too long but, no, it's about the right length. Then I checked the radius rod length - 24 mm - again, correct. However, the radius rod pivot point is about 1 mm nearer the cylinders than it should be at approximately 23 mm to the centre of the valve spindle guide. This all results in the combination lever being 1 mm too far forward.
This error is then exacerbated by the union link being also too long - about 6 mm centre instead of the scale 5.25 mm.
Finally, the cylinder relief valve casting is also too long - about 4 mm from the rear face of the cylinder against a scale length of 3.26 mm.
All these errors add up to cause the problem.
Fortunately, some spare union links from my recent Black 5 loco are exactly the correct length so replacements can be fitted at the cost of having to remove the existing items without doing any collateral damage. The relief valves can be removed and shortened, again at the risk of some other parts becoming un-soldered and moving.
Hopefully, those mods will solve the problem, because altering the valve gear support frame doesn't appear practical.
Oh hum.
Dave.
Last edited by Dave Holt on Mon Jan 04, 2021 10:29 am, edited 1 time in total.

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45609
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby 45609 » Sun Jan 03, 2021 9:45 pm

Oh dear Dave. Some unfortunate news. Hope you can fix it without too much bother. Thanks for letting us know. I recall an old friend (no longer with us) found a fault with the BM Jubilee valve gear but that might have been due to him attempting to put it in forward gear. You’ve built the same kit. Did you have any problems with the 5XP?

Cheers... Morgan

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johndarch
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby johndarch » Mon Jan 04, 2021 9:34 am

Don't you just love this frustrating at times hobby of ours. Good luck with the mods Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Mon Jan 04, 2021 10:28 am

Morgan,
It's an awful long time since I built the Jubilee chassis but I can't recall any particular problems with the valve gear - and mine is in forward gear, too - although at a fairly short cut-off.
Dave.

Philip Hall
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Philip Hall » Mon Jan 04, 2021 12:12 pm

Dave,

Your perseverance with this and the trials you have faced with the complicated doings of Monsieur Walschaerts have my admiration/slightly frightened me as I jump into my latest project, which I am going to keep quiet about until it’s done. It’s a conversion, supposed to be a quickie, by the way, so I won’t be stepping on your toes! But it’s the perennial problem of clearances, not just crankpins and the like, but as you have highlighted, clashing of rods which turn out to be fractions of a millimetre adrift from what they should be.

Isn’t it wonderful that we enjoy this sort of thing. If I was a beginner I’d be truly frightened/put off!!

Happy New Year...

Philip

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Mon Jan 04, 2021 8:42 pm

Thanks, gents, for the supportive comments. I suppose it is where experience comes in when these sorts of problems occur. And it's useful to have spare bits from previous models just lying around waiting to be needed!
I'm now back to somewhere near to state before I noticed the problems. Thankfully, the parts that had to come off did not put up too much resistance and no collateral damage was inflicted - precision, laser guided removal techniques were applied.
Here are the old, over length union links, somewhat wrecked in getting them off, the over length relief valves and the replacement, ex-Black 5 union links, laminated and ready to fit. The opening of the forked jaws was adjusted to fit the combination lever and drop link during fitting.
Scot_131.JPG

The replacement union links after fitting. To be honest, they're a better job than the originals, as well as being the correct length.
Scot_132.JPG

And with the valve gear unit fitted to the frames. The wheels now freely rotate and the front dead centre position will allow the final length of the relief valves to be determined, but this won't be done till after the valve gear is fully completed with the eccentric rods and return cranks fitted. Just to be sure.
Scot_133.JPG

It's not visible in the photo, but the connecting rod retaining bushes have been shortened to eliminate excess end float at the big ends. The return cranks will be soldered to the outer flanges to allow the valve gear to be screwed on and off, as is my normal practice.
Dave.

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45609
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby 45609 » Mon Jan 04, 2021 10:28 pm

Nicely rescued Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Thu Jan 07, 2021 12:47 am

The remainder of the valve gear has been assembled and fitted. No clashes detected so that's a good outcome. That said, without the driving axle springs in position, the coupling rods do hit the rear cross member of the valve gear support frame near top dead centre, but since it's not required to run without springs, I can live with that.
Scot_134.JPG

Scot_135.JPG

No excuse not to sort out and refit the rear cylinder relief valves now.
Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Sun Jan 10, 2021 9:12 pm

Not much modelling over the weekend, but the cylinder relief valves are back on and clear the combination levers. I've also added a representation of the exhaust passage ways inboard of the front valve chests so that the vacuum relief or snifting valves can be fitted. Strangely, two rather nice N/s castings are provided in the kit but as far as I can see, no mention of fitting them appears in the instructions. Of course, there should be a third one for the inside cylinder. Luckily, I've found a suitable white metal version left over from a previous Brassmasters kit. Not too sure how to fit it as the correct location falls right on the joint between the chassis and the footplate.
Close up of the LH cylinder with white plastic card exhaust passage and cast snifting valve.
Scot_136.JPG

And a more general view of the same side.
Scot_137.JPG

Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Mon Jan 11, 2021 11:28 am

Error corrected. I realised that I had fitted the outside cylinder snifting valves upside down. This has now been corrected - thank goodness I hadn't fixed them very well in the first place!
The inside valve has also now been attached, probably a fraction low as the mounting hole had to fully in the main frame.
All three valves visible in this shot.
Scot_138.JPG

Dave.


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