7mm The Derby Line - Rolling Stock Gladiator Crab

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Genghis

Western Thunderer
We are in the process of changing casters for all of our nickel silver castings as we are not happy with the current quality from the old supplier. Not got round to these yet, but as I noted before, the L1 kit is up for a redraw so will do it then. I think that the K1 and L1 share the same parts but will need to check (we certainly pack the same castings in these kits).
Dave
 
dibateg

dibateg

Western Thunderer
Holiday, good weather and more lurg has slowed things down, but I did resolve to make some 1.8mm N/S rod by turning some down. It can deflect a bit in the so I used a live centre to stabilise it. I already had a short length of 1.8 for the the other side.
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There is no location for the slidebars so I drilled them 0.7mm to make a locating lug of sorts. One is inverted to show the hole. Piston glands are Ragstone.
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G

Genghis

Western Thunderer
Good idea for the slidebars. When I built the K1 (same parts) I lined everything up through the gland and applied heat: but if a gamble as I was using the whitemetal castings. IIRC I then removed the whitemetal to get a proper amount of heat into the slidebar-cylinder joint.
Your solution is much better.
 
dibateg

dibateg

Western Thunderer
Before I attached the valve guides to the cylinders, I had to make sure that they would function in name. So I opened out the slots. To make the clevis for the valve I used some thick wall 1mm bore brass tube, filed the sides flat, drilled a hole for the pin and then cut a slot in the end. It was then cut off from the stock and some 1mm N/S soldered in to the bore. Slightly crude but it won't be seen inside the guide.
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The next probem is to try and resolve the motion bracket and slide bar support....
 
RichardG

RichardG

Western Thunderer
dibateg said:
The wooden stirrer is to stop the crosshead rotating whilst it's being drilled. I've yet to work out how to make a retainer to go behind the slidebar....
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Click to expand...

Please, what brand is the machine vice? It looks compact and substantial. I bought a Proxxon one to go with my own pillar drill and it might as well have been made from cheese :(
 
Dave Holt

Dave Holt

Western Thunderer
I don't attempt functional valve crosshead guides in 4 mm scale. Instead, I rely on a full cylinder length valve spindle running in a full length brass tube. This gives a large bearing area and avoids any drooping of the spindle due to the weight of the (cosmetic) valve gear and also resists any valve gear derived vertical forces.
Your arrangement looks impressive by comparison.
Dave.
 
dibateg

dibateg

Western Thunderer
I've been struggling with the position of the cylinders and details of the motion bracket and after two days battling with the cyclinders was on the verge of giving up. I could not find a decent picture of the weighshaft and slidebar support in all the well known L1 works. I know Peter Dunne had difficulty with it too. Finally one turned up in Tony Newman's book on the GC. I knew it was similar to a K1, but it's not quite the same:-
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So I have made up a support from brass... This is a first pass and I need to refine the shape a little. The valve guide looks a little undersize now, I suspect I might revisit that. More going round in circles...
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Dave Holt

Dave Holt

Western Thunderer
Well, that certainly takes away the guesswork. That said, Tony, your initial effort doesn't look too far off the mark. Just add the stiffening rib?
Dave.
 
dibateg

dibateg

Western Thunderer
Whilst I pondered over the drawings I made up the pony truck and bogie, which involved adding end plates to the bogie and the AWS pick up. I used some LNER castings from Ragstone to add some more detail. I discarded the white metal guard irons ( they would have a limited life ) and scratched up some new ones from brass.
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I fretted out a new support bracket.... just have to make the other side.
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dibateg

dibateg

Western Thunderer
A days work gets the valve gear together and the bogie and pony truck mounted. I wanted the loco in gear and the radius rod is held to the expansion link via a 14BA screw. The expansion link is simplified, I could not come up with a way of making it up with a split radius rod. So theoretically the assembly can be repositioned to be in back gear. I managed to loose a set of drivers, no doubt they will turn up when the replacements arrive... There is still a long way to go.
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dibateg

dibateg

Western Thunderer
The weather has been to good to spend much time at the workbench - a backlog of outside jobs goes back 18 months due to last years poor summer. It's taken several morning sessions to assemble the motion and get it running freely. Easing joints, adding washers, filing clearances and setting the return cranks. There was no clearance between the leading crank pin and the crosshead. The slide bar seemed rather wide so I filed a portion of the rear face and that resovled the learance problem. The cross head has nothing at the back to prevent it from flopping outwards. I'm still to work out a solution.
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Ragston to the rescue with the relief valves, I shall have to tot up the parts from Andy as the box for this kit is now full of those little bags ....
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I think this is one of the most difficult kits I've tackled...
 
simond

simond

Western Thunderer
dibateg said:
The cross head has nothing at the back to prevent it from flopping outwards. I'm still to work out a solution.
Click to expand...
Tony,

if your piston rod is running in a tube in the cylinder, does this not provide sufficient restraint to prevent the crosshead falling off the slide bar?

best
Simon
 
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