G3 0-4-4T 'Project' based

jamiepage

Western Thunderer
I found a piece of 60mm OD steel tube in the workshop, so cut it to length and turned a rebate to fit the smokebox. It had been nagging me that the spectacle plate boiler cut out may not entirely align with the boiler wrapper, (mainly because the cab sits on side tank recessed tops and it would have been easy to build in some vertical errors), so the chance to check was irresistible.
The tube sat in ok and only a very small amount of easing will be necessary on the spectacle plate, so relief there.
In fact, it made me think that the tube could form a rigid exoskeleton, solidly affixed to the smokebox, with the boiler proper sliding in from the rear. It may well be easier, and more rigid, than a rolled wrapper. Food for thought.
In the meantime, a quick snap shows the Beyer Peacock look is starting to appear, which is nice.
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Finally, a closeup of some detail on the splasher assemblies. They are held in place with a single CS screw in the lampirons at the front screwed into the buffer beam, and held by the cosmetic bracket at their rear.
The sanding gear linkage, leaf spring etc are all integral with the sub assembly. Filler cap still to come.
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jamiepage

Western Thunderer
It really isn't much, but progress is starting again on this loco after attention was allowed to wander onto other things for a while.

The centre section of footplating is now done. It's hardly worthy of much attention of itself, although it does completes the major platework so is a bit of a milestone.

The 'fit' of the drop down cover is about right when compared with the photos, it did seem to roughly conform to the reverse curves on the mainframes, but generally sit inside them, and lower across the top. Certainly not flush.

I haven't decided where the lubricator will go yet.
If in the cab, as the Project design, then this section will be screwed into the front buffer beam with a CS screw through the lamp iron, as on the outer sections. Fairly permanent, but removable should it prove necessary.
Alternatively, the lubricator might be fitted just behind the buffer beam, in which case this section will just clip into place.

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Anyway, rivetter and tin snips can be put away.
Some good and interesting stuff coming up now to finish the cylinder assembly, erect the valve gear and build a crankaxle. Next stop, running on air.

ps Just noticed the centre lamp socket looks a bit skewed in the photo; not 'in the flesh' though. It's either the camera or my specs, not sure which.
 

jamiepage

Western Thunderer
Next job for the working bits was the piston.
It was sketched out using the principles established by Markus Neeser in G1, using a ring turned from graphite impregnated PTFE, itself supported and 'sprung' by an O ring underneath it.

A piston blank was turned slightly oversized and bored/ tapped for the 1/8 in Stainless rod.

Once rung on and loctited, the rod/ piston was put into a collet and the piston finished to size. A feature of Markus's description is that the piston is iro 0.5mm smaller in diameter than the cylinder bore; it doesn't pretend to seal in any meaningful way, just carry the O ring and get pushed by the steam.

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The ring groove is proportionally deep and in this case, wide as well to carry two O rings.

Two O rings were positioned.
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The groove was approx 0.25mm wider than the nominal O ring thickness (x2) to allow some 'squashing'.

An O ring was then turned up from a rod of graphite impregnated PTFE. Funny stuff to turn, but quite satisfying.

Once cleaned up, it was cut then sprung into place.
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Fortunately it slides nicely, certainly with appreciably less friction than O rings alone, and there is a nice pop when removed from the bore, so with luck should be ok.
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The piston rod will be cut to length and a crosshead loctited and pinned in place.
 

JimG

Western Thunderer
Jamie,

Where do you source the graphite filled PTFE? And, I dare say, in short lengths that don't require an arm and a leg. :)

Jim.
 

jamiepage

Western Thunderer
Jim,
I bought some lengths a few years ago from Noggin End Metals, but a quick look on their website doesn't seem to show them now. It would be worth a query though. I bought mine in 12in lengths., just over 1/2in dia, and just over 3/4in.


A quick google found this
PEEK MOD (10% Carbon, 10% Graphite, 10% PTFE Filled) Black Rod

which MAY be the same thing, I'm not sure. It's black and round anyway.

Markus Neeser mentions that he originally used white 'pure' Teflon which worked perfectly well; the black, graphite impregnated stuff ditto but with less wear and 'better mechanical characteristics'.

He also says it shouldn't need lubrication.
I wonder if the slide valve could be machined up from the same stuff? That really would remove the need for a lubricator. Hmm, worth a thought.

Yours
Jamie
 

JimG

Western Thunderer
Jamie,

Many thanks for the information. I don't have an immediate need but I'm thinking a year or two ahead in making a live steam 1:32 loco and I'm collecting information and bits to that end. I've also been looking at PTFE impregnated packing. Also a discussion on the Model Engineer forum suggested that you could do without packing or rings on small steam cylinders with maybe just one shallow groove to hold oil and water to provide a seal. That would need quite good machining to work.

Jim.
 

adrian

Flying Squad
A quick google found this
PEEK MOD (10% Carbon, 10% Graphite, 10% PTFE Filled) Black Rod

which MAY be the same thing, I'm not sure. It's black and round anyway.
Interesting but :eek::eek::eek: that's an arm and both legs for me - £50 for the smallest shortest length! Might have to search for alternative suppliers as I'm looking for something like this but smaller diameter. If I was using it at these sizes then maybe ok on the price if a little steep but if I'm turning it down I'll end up with more value in waste than the finished component!
 

adrian

Flying Squad
Thanks for trying I appreciate it - although it's still the best part of £33 once postage is added for an 80cm length.

I'll keep looking - it's for one of my long term projects (not that I seem to do anything short term!!) so I'll just keep my eyes open waiting for something to appear. I wasn't even aware that such a material was available and being used in the live steam bubble so I've learnt something today and will file it away. I can see plenty of uses for it so I will just keep my eyes open at the moment.
 

adrian

Flying Squad
Adrian,
If you just want a scrag end, I'll cut you off a bit.
Thank you very much for the offer - it really is appreciated. As I said it is one of my really long term projects, it will get get sorted at some point but at the moment I'm just accumulating information rather than materials. So just knowing that this sort of material is available is enough for me at the moment.

As a little taster my project was inspired by stumbling across this on youtube. A variation on the three cylinder self starting engine being of particular interest especially considering the potential small size of the engine.

 

jamiepage

Western Thunderer
Ah, I wish I could see what that was. Videos are still not showing at all. Is there a keyword or something, I could try on Youtube?
 

Steve Cook

Flying Squad
Apologies for the off-topic continuation Jamie, but I emailed Les Proper this morning and have received back a pdf copy of his drawing and building hints for the single cylinder engine. I did enquire about the book which had all the drawings for the other engines in the video, but at $72.50 inc shipping I'm going to hold fire. Will work out a materials list for the single cylinder though, looks like it could be fun (and fiddly!).

Steve
 
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