7mm Rob's workbench - Gladiator J6

Dog Star

Western Thunderer
The motion for the J6 differs from other versions of Stephenson’s motion in that it has four valves rather than the more usual two. There are two between the cylinders and two above them.
Interesting and puzzling... so there are four valve spindles? and four slide valves? (assuming that the prototype is a slide valve engine).

I infer that the steam inlet ports and valves are between the cylinders and the steam exhaust ports are above the cylinders - correct?
 

dibateg

Western Thunderer
Rob -
I puzzled over this for ages, I suspect that the lower pair are just guides for what effectively is a radius rod. I don't think they extend in to the cylinder block and that is what that hefty bracket ( which I've left out! ) ahead of the rockers is for - it supports those guides. It's movement via the rocking levers is transferred to the actual radius rods above the slidebars.

Best Regards
Tony
 

Rob Pulham

Western Thunderer
Rob -
I puzzled over this for ages, I suspect that the lower pair are just guides for what effectively is a radius rod. I don't think they extend in to the cylinder block and that is what that hefty bracket ( which I've left out! ) ahead of the rockers is for - it supports those guides. It's movement via the rocking levers is transferred to the actual radius rods above the slidebars.

Best Regards
Tony

Thanks Tony, what you say makes perfect sense having had a further look at the GA and a look at this photo of the same layout on the preserved N2.

Talk about not seeing wood for trees, I hadn't even noticed that great big bracket:oops:. My only excuse is that I was so busy concentrating on and trying to work out how the waggly bits fit.

I have no idea of the photographer so I am unable to credit them and only share it here to illustrate what Tony describes.

Stephensons gear 2.JPG
 

Rob Pulham

Western Thunderer
Interesting and puzzling... so there are four valve spindles? and four slide valves? (assuming that the prototype is a slide valve engine).

I infer that the steam inlet ports and valves are between the cylinders and the steam exhaust ports are above the cylinders - correct?

Sorry Graham, I have no idea, I just model what I see.
I am the first to admit that my knowledge of what everything actually does is embarrassingly lacking.
 

Dog Star

Western Thunderer
Rob (@Rob Pulham), looking at the photo I think that I can see two valve spindles above the frame stretcher and two "spindles" below the frame stretcher, between the slide bars. The upper spindles pass through round cover plates which are of sufficient diameter as to permit removel of piston valve heads.

The LNER Info encyclopedia (locomotives) records that the N2 class was built with piston valves above the cylinders as can be seen in the photo above. Further, LNER Info records that the N1 class was built with slide valves, so I ponder on the possibility that Gresley retained the Ivatt motion arrangement to which he added rocking arms to accomodate a change from slide valve to piston valve.
 
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Rob Pulham

Western Thunderer
Nick Dunhill’s, Rhymney Railway R class post on preparing the eccentric sheaves couldn’t have been timelier.

I am just at that point so the night before last I made up a similar jig from a couple of bits of wood that I had on the bench and having consulted the GA for the length of the sheave I marked up and drilled a hole for the pin (a 0.8mm drill bit). Finally, I filed and soldered up the first sheave. Last night I managed a couple more.







 

Rob Pulham

Western Thunderer
Today has been a brilliant day on quite a few fronts but the main one being that I successfully soldered the crank axle up without any issues.

I followed advice given to me by fellow modeller Nick Dunhill, which was to use Bakers Fluid as the flux to solder to the steel axle, to replace the piece of steel rod provided to line up the cranks and eccentric with a length of similar diameter brass rod which being more flexible allows the cranks and eccentrics to be squashed tighter together and positioned better. And finally, to wrap wet tissue around the eccentric sheaves to stop the soldered end coming adrift with the heat.

It couldn't have gone any smoother, I spent some time making sure they were all lined up correctly and orientated against one of the flat edges of the axle end. I grip the other end in a biggish pin vice applied the Bakers fluids from a bulb type dropper and some short lengths of 180 solder curled slightly around the axle either side of the cranks then gently applied heat with the microflame until the solder flashed. While it was cooling I couldn't resist moving the eccentrics slightly to make sure that they hadn't become solid.

All was well Phew!!!

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Next job is clean them up and then before cutting out the section of axle I think that I am going to drill and pin the cranks. I know that Nick doesn't bother as they aren't under any real load but I think that I will be belt and braces for this my first go.
 

Rob Pulham

Western Thunderer
In between adding bits to the GCR Tank, After drilling and pinning the cranks which was thankfully uneventful. I cut out the axle in between the crank webs and refitted the connecting rods. I had to file a little of the sides of one one the connecting rods but very quickly all was rotating smoothly. So much so that I made a short video. Sadly my camera didn't focus too well on my hands but you get the idea.

 

Rob Pulham

Western Thunderer
Modelling time has been in a bit short supply so far this week but I have managed a few bits and pieces. The key one being, on the back of a delivery of a second set of globe lubricator castings for the J6, I got them fitted. I had to order some more because I have misplaced the first lot but I am sure that they will turn up in due course...

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Still a bit of cleaning up to do under there.

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Rob Pulham

Western Thunderer
One of the few remaining details to add to the body are the injectors which sit under the footplate tucked away behind the cab steps. From all the photos that I have of J6's seeing what they actually look like is a real problem.

Not really wanting to model a model by copying either Heather or Tony builds, I remembered that I had taken a few photos of the Injectors on the side of the preserved J52 while it lived at Shildon.

While I have a couple of good side views they don't show the pipes and how they fit.

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Then by pure chance I was looking through some photos that I took in the dark hall at York and found that I had indeed taken photos of each end

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By cross referencing these with the end that's visible on some better lit J6 photos I was able to confirm to my satisfaction that these are the same type of injector fitted to the J6 Now all I need to do is work out how to scale them to size - Despite taking quite a few shots at both locations none of them are side on allowing scaling from a known dimension.
 

Heather Kay

Western Thunderer
Those injectors look practically identical to the castings JLTRT produced for their GWR locos. I wonder if they are the same, probably from an outside manufacturer.

I think I have some spare castings in my collection, which you’d be more than welcome to if they will help.
 

oldravendale

Western Thunderer
Rob.

I've done a blow up and density reduction of the relevant area on Tim Mills' J52 photo. Here it is. I reckon that's close enough for Government work (as has been said in these hallowed threads previously.....)

img431 TM 68846 (Preserved) Hornsey 34B 1957 - Copyright final.jpg

Brian
 

Rob Pulham

Western Thunderer
Those injectors look practically identical to the castings JLTRT produced for their GWR locos. I wonder if they are the same, probably from an outside manufacturer.

I think I have some spare castings in my collection, which you’d be more than welcome to if they will help.

They would be much appreciated Heather, I will PM my address.
 

Dave Holt

Western Thunderer
Rob.
I don't like to be a party pooper, but I think you'll find the GWR injectors (also adopted from BR standards), whilst slightly similar is not the same as the one shown in your photos. The orientation of the overflow and steam feed are different. However, by chopping up the castings and re-assembling in different orientations, you might be able to make an acceptable representation. Good luck. In 4 mm I'd get away with an assembly of various diameters of tube, wire and washers, but I don't think that would look good enough in 7 mm.
3D printing to the rescue?
Dave.
 

oldravendale

Western Thunderer
I agree that GWR injectors are common on preserved locos. However, although the detail shown on that photo of the J52 is far less than perfect it has a lot of characteristics which similar. Now, whether the injectors on a J6 are the same I don't know and whilst I could check the number series for a J6 I can't yet check all the photos I have as they are not recorded by loco number.

Sorry I can't help any further.

Brian
 

Heather Kay

Western Thunderer
2D0D2448-8C57-44E8-A907-E8FCD62F00F2.jpeg

These will be on their way to Rob tomorrow, with luck. I’m sure he’ll be able to work his magic on either of them to make an excellent rendition. :thumbs:
 

Rob Pulham

Western Thunderer
Thanks gents,
It would have been quite a surprise to get a 'perfect fit' casting but hopefully I can modify those to get a decent representation. If all else fails there is always rod and tube to fall back on.

At least I know what I am looking at.
 

Dave Holt

Western Thunderer
Rob.
Looking closely at the rather indistinct photo posted by Brian, I think one can just make out enough detail to say that the RH injector is the same type as your colour photos, but opposite hand. That confirms that the preserved loco still has the original type of injector(s?). Not something that's true for quite a few preserved locos.
Dave.
 

Rob Pulham

Western Thunderer
Hi Dave,

I have some photos of the injector on the other side (only general views) and that too looks original.

At least now I know what they look like so I can attempt to butcher Heather's Heather's castings into a passable representation.
 
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