7mm Mickoo's Commercial Workbench

mickoo

Western Thunderer
Not as much progress as hoped, I'm short the cylinder wrappers, fixing the front end and the stretcher flanges.

Today was frame overlays....twice!...don't ask and trailing truck. I'm jumping around the build a bit and not following the instructions or logical steps, primarily as the most important factor to resolve is the minimum radius.

I'd already heard that the trailing truck needs a tweak to go around 6' radius curves so I'd planned something different already, in short if I can get more play at the rear then I won't need so much at the front. Being as the front is tighter and more exposed visually then we need to keep that end as real as possible.

The problem with the trailing truck is it's width, I think it's designed for S7 and maybe even true scale width, the other issue is the wheels, the hubs are too fat and stop the outer wall of the trailing truck being moved inward.

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The springs are not fitted yet but will be shortly, they're not essential at this point.

To cut a long story short I took 0.75 mm off the wheel hubs, they're fine and need to go on a diet anyway, plus the modification cannot be seen. This allows the outer plate work with the springs and axle box on to be moved in by 1.5 mm each side, there was an existing 1.0 mm gap before any modifications. By reducing axle side play to near zero you can reduced the gap to the tyre to around 0.3-4 mm with no shorts. The upshot is that the trailing truck is now 3.0 mm narrower, which allows for an extra +-1.5 mm throw. Is it enough :eek:

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The 6' radius test curve.

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It's close at the rear end and the width reduction has thrown up a new issue, previously it would of been the axle box or spring casting that would of impacted the inside of the frames, the springs still may' but at current guesswork...just. The reduction in width now allows the trailing truck to swing further and it's the outside wheel that is now going to impact the inner frame extensions. Some sort of stop will be required or I might epoxy a sacrificial nickel silver plate here and just let it touch, I'll probably do both.

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At the front it's as expecting, it's not a true test as the bogie isn't there, there are no stops and there's still play in the main axles, even so, and taking all the factors into account, it's too close to relax and move on at warp speed.

I think it's safe to say that the inside cylinder floor will have to come out and the cut outs increased in depth by 1.0 mm; I'll also epoxy a sacrificial rubbing plate in there as well to isolate it electrically, in case of any unforeseen events that might cause a short.

MD
 

LarryG

Western Thunderer
Building beautiful locomotives fully detailed down to the last rivet is one thing; Scaling down track radius for them at even the minimum value (around 6 chains or 9' 2½" in 7mm scale) is something else. Model railway curves are where realism goes out the door. ;)
 

mickoo

Western Thunderer
Building beautiful locomotives fully detailed down to the last rivet is one thing; Scaling down track radius for them at even the minimum value (around 6 chains or 9' 2½" in 7mm scale) is something else. Model railway curves are where realism goes out the door. ;)
Yup :thumbs: and those that shout the loudest about the size of a cab opening being 0.05 mm too small or the footplate being 0.37 mm too long are the quickest to walk by and ignore the blatant fact that the radius is significantly below 1:1.

Best MD
 

Cliff Williams

Western Thunderer
Masterpiece Models used a form of double plunger to act on the rear truck, akin to two long thin buffers back to back.
They also played about with the wheelbase to get clearances better, lots of little tweaks but they still only manage smooth 6ft on a good day with a trailing wind....
 

LarryG

Western Thunderer
I marvel at the ingenuity of the plastic RTR manufactures who are strapped to getting today's scale models around trainset curves and run with no lateral oscillation on the straights.
 
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simond

Western Thunderer
There's an interesting comment on the GoG website comparing a Heljan GW Mogul with a Lenz German loco, noting that the German loco is provided with a self-elongating tender drawbar to provide a better appearance along with the cornering ability of a fork-lift-truck (ok, I paraphrase...)

I think that the bottom line is that sales volumes in the RTR marketplace are dependent on a significant number of people whose locomotive ambitions exceed the space they have to run them, but these ambitions are not assuaged by having a thing of beauty in a glass cage.

I guess for many, if not most of us, the ability to run across a Peco crossover is the passport to use of club tracks & mates' railways.

Way short of the 9'odd that Larry mentioned a few posts ago. And it makes coaches more difficult too.

best
Simon
 

Yorkshire Dave

Western Thunderer
There's an interesting comment on the GoG website comparing a Heljan GW Mogul with a Lenz German loco, noting that the German loco is provided with a self-elongating tender drawbar to provide a better appearance along with the cornering ability of a fork-lift-truck (ok, I paraphrase...)

The European (can I use that word!) manufacturers have been using close coupling mechanisms in their HO steam locomotives for years. It is also a feature of their coaches and wagons.
 

simond

Western Thunderer
Hi Dave,

IIRC, the Lionheart mogul also had a similar mech.

I saved up for one, but couldn’t bring myself to splash £2k on a model. Bought one of Warren’s mogul kits, and a Javelin Dukedog, wheels, motors, decoders... And had enough change for a couple of pints...

Best
Simon
 

BR Tony

Member
Bought one of Warren’s mogul kits, and a Javelin Dukedog, wheels, motors, decoders... And had enough change for a couple of pints...


Hi Simon,

Assuming you mean Warren Shephard's 43xx Mogul kit how did you find it? I am looking at options for a BR era 43xx but after Mick's major battle with the County I am slightly wary.

Regards,
Tony
 

mickoo

Western Thunderer
I don't think the 'challenge' of the County is a big secret to be fair, what perhaps isn't taken into consideration is how big the 'challenge' actually is if you're a bit of a detail nutter like me ;)

Anyway, this week has been one of those struggling to get anything done, but things keep getting pushed along bit by bit.

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The front cylinder block is all complete now, for this stage anyway, so it'll be grafted onto the main chassis and secured in place. Next up should be the bogie once the trailing truck springs are fitted, then we'll have a full rolling chassis to work with.
 

BR Tony

Member
Haven’t started it yet, but I’ve built a couple of other of his kits. The County seemed a bit more challenging than I’d have expected...

I’ll do a thread on here if you want. Be a good way of getting feedback!

Best
Simon

Yes please Simon, that would be very interesting.

Thanks, Tony
 

mickoo

Western Thunderer
A better run toward the end of the week.

The bogie is complete and the side control unit fitted and performs as intended, nothing is sprung yet or tightened up so there is the odd short if you twist things around on the 6' curve. I still need to add the trailing truck stop to stop the wheels touching the inner frame extensions but other than that it's all looking good so far with regards to clearances.

The bogie.
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The side control unit is pretty obvious, nothing like the real thing but it's objective is to make the engine negotiate curves easier. I am missing some nuts to fit on the inside studs that hold the compensation beams and springs together; they're in the post and I just had enough to do the external ones.

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I've not treated the axle ends yet but am concerned that after cutting off the outside stub the remaining area is too short, the wheels are pushed on tight and I've not touched the actual shaft that fit's inside the wheel. Normally you're left with a bit of full diameter shaft sticking out to trim back, not so this time. It could be the wheel boss is slightly over thick or the axles have been turned incorrectly, something to look at later.

Progress so far.

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Closer view of the front end.

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The inside cylinder base is doing what it was designed to do, block light and lend visual mass to the front end.

Overall frame views.

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Engine springs (laminates....gnash gnash :mad:) and motion bracket next.
 

mickoo

Western Thunderer
Another little update, I'm constantly amazed how what appear to be the simplest of tasks turn into sessions of frustration and angst; sometimes you just can't fight the modelling gods no matter how much energy and sacrificial goats you expend.

It doesn't look like a lot has gone on, bare bones footplate, firebox base, engine springs and motion brackets, still the collection of etch parts gets smaller and the model gets heavier each passing day.

One thing I did before fixing the firebox base on was to mark out and fit the trailing truck stops, under very tight conditions there was the chance of the wheel rim touching the inner frame extensions. I pondered all sorts of devious solutions but ended up with the two prongs as shown, being nickel silver there is some spring in them so they act as a crude side control for the last 20% of the lateral travel.

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Main frames at close of play today.

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Onward.
 

Focalplane

Western Thunderer
I have been struggling with the valve mechanism today. I need to get the slide bars properly secured but a lot of fettling appears to be necessary tomorrow.

Also, the front brake wire that goes across the frame seems to get in the way of the slide bar bracket. A clearer head tomorrow may help a bit but I am beginning to think that my model might end up being a static exhibit, just like its prototype in The Science Museum.

As always, lots of inspiration to keep me going. Thank you!
 

mickoo

Western Thunderer
I can't really formulate a cognitive reply to the brakes with out some sort of visual image.

None the less I spent the day building the brake gear to see if I encountered any issues, so far I have not. So if it's any help, here's some photos of the brake gear and some close ups of the front end.

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I've yet to add the thin tube collars on the leading brake hanger pivots, these will keep the pivot point the correct distance away from the wheel tread., I've added them to the other pivots, but not the front ones yet. It also needs a good clean up and some nuts adding to the ends of the brake plank stubs.
 
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