mikemeg

So, doing the maths - Pythagoras equation for right angled triangles - on the lateral deflection of the front bogie wheels, using the distance between the centres of the front driving wheels and the front bogie wheels (50 mm) gave a deflection of 1.03 mm; just within the profile of the pinched mainframes. Then, trying out the unpowered chassis on a 4' 0" curve, the front bogie wheels did touch the mainframes. So, something was wrong with the maths!!

Then a eureka moment (Pythagoras and Archimedes in the same posting!). The point on the locomotive chassis which is truly tangential to a curve is not the centre of the front driving wheels, it is the centre of the middle driving wheels which, on this loco, are 80 mm behind the centres of the front bogie wheels.

Redoing the calculation using 80 mm rather than 50 mm gives a deflection of 1.73 mm. So the pinching in of the front of the mainframes is not enough to allow  4' 0"  curves to be traversed.

So now a little rework of the front end of the mainframes will be done to increase the extent of the pinching in to allow the locomotive to traverse these 4' 0" curves.

Cheers

Mike

On 15/11/2023 at 16:09, billbedford said:

The B4s had a recessed nut on the leading drivers. This nut shows as a polished ring in early photos. I also think the coupling rod boss was thinner than the trailing one. 

Thanks Bill.

Seems that Mr Robinson, the CME of the Great Central, had the same clearance problems with the connecting rod and the front coupling rod journals on these locomotives. It is one of the inherent disadvantages of P4 that these clearances are simply scaled down without any augmentation through a reduced gauge (EM or OO), so require a great deal of care. Saving the odd 5 or 10 thou (0.125 mm or 0.25 mm) here and there, by using slightly thinned metal sections, becomes the order of the day.

I've pretty well sorted the motion clearance issue and am now checking the extent of the lateral movement of the front bogie wheels. The model does provide for a 'pinching in' of the fronts of  the mainframes but only by a small amount. My minimum radius curve is 4' 0" so I will need to establish this, mathematically, before I put it to the test.

The B16/1 models had this issue, even more, due to the distance between the front driving wheels and the front bogie wheels; similarly the D20's. The obvious answer is to create bogie wheel cut outs in the mainframes but such an approach just 'goes against the grain'.

Regards

Mike

LNER B4

With a trial fitting of one of the coupling rods plus a connecting rod and crosshead, then the efficacy of my mathematics, in the posting above, can be checked out. Are the calculations correct or just so much rubbish? Seems that the measurements and suppositions in the above posting are about right. Phew!! 

I must extend my thanks to John Bateson from whom I bought the kit originally and who has since supplied so many new or revised components, as well as a wealth of advice and copious drawings.

So another photo, a little more complete and a little more of that essence of the prototype. They were lovely things, these early 20th century locomotives!

Cheers

Mike

LNER B4

There are some days when, despite many hours of toil, there is precious little to see for all the effort. On other days, a few short processes and the model takes shape; it begins to live!

So having fitted all of the mainframe springs and painted and weathered them - much easier to do without the wheels - then the wheels can be added. Suddenly the model, which has inhabited all sorts of containers and utilised various supports, can stand on its wheels and it begins to resemble a locomotive.

Still quite a bit to do but the essence of a Great Central 4-6-0 is now clearly visible, though for this photo it's a 4-5-0 as the rear axle will contain the drive train so needs to be removable.

Cheers

Mike

LNER B4

At this point and before the coupling rods and connecting rods are fitted, time to do a little simple mathematics. For this I use a digital calliper and vernier gauge, which is accurate to around 0.02 mm.

a) The ruling measurement for clearances is the distance between the two sets of slide bars, which is 26.2 mm.

b) The overall width of a correctly gauged (P4) set of driving wheels is 22.8 mm over the outside bosses.

c) Thus the maximum space available for the outside motion is 26.2 - 22.8 = 3.4 mm or1.7 mm per side at the slide bars. However, this dimension would give zero clearance between the slide bars and the motion.

d) The thickness of the front journals on the two coupling rods is 0.85 mm. These were assembled without the journal overlays which were applied to the middle and rear journals. Thus, the crankpin nuts on the front journals must be fitted flush i.e. the reverse of their normal fitting, to preserve enough clearance between the front coupling rod journal and the rear of the connecting rod.

e) The combined crossheads and connecting rods are assembled such that the connecting rod does not protrude beyond the crosshead and is, in fact, slightly inset. So the positioning of the connecting rod, within the crosshead, does not compromise the 1.7 mm of overall clearance and, in fact, adds a little to it; but how much?

Conclusion is that with very careful assembly and attention to these clearances everything will fit and will rotate.

Perhaps worth mentioning that on the prototype the footplate steps, initially fitted between the leading and middle sets of driving wheels, were removed because the connecting rods hit them when the locomotive was at maximum speed. So even the real things were very tight for clearance - too tight!!

I had a similar problem on the two B16/1's which I built - also to P4 gauge - where the clearance between the connecting rod and the back of the front set of footplate steps was very tight < 0.4 mm or .015". However, on these B16/1 models, the clearance issue was made easier by virtue of the connecting rod being located on the front set of driving wheels.

Cheers

Mike

Mick,

You have done an amazing job on this kit. Given its age (drawn and designed over thirty years ago) and given the known omissions,  then the result is a real credit to you.

As the original artwork is no longer available, then no changes could be made to the original etchings, so any errors in these etchings cannot be rectified. The introduction of additional options i.e. the later LNER designed boiler, the plain splasher fronts applied to those locos built by the LNER, etc. could only be made by adding new etches.

Despite its problems, it's  probably still the best offering for producing a model of a B16/1 or the original NER Class S3.

Regards

Mike

LNER B4

So after the brief interruption, to build a new chassis for a J72, it's back to the B4. I have started this phase with the gearbox, which is a High Level Models HiFlier - 60 :1 ratio. While I was in the 'gearbox department' I did take the opportunity to build a new gearbox for one of the A6's, this time using a High Level Models RoadRunner Compact Plus - 60 : 1 ratio. Both motors will have the non-business end of the drive shaft cropped off before the chassis' are fitted

The B4 motor is a Mashima 1428; the A6 motor is a Mashima1424. Both of the Mashima motors are from my own stock of Mashimas which I bought some years ago, before Mashima ceased production.

So the photos below show the two drive trains B4 (HiFier) and A6 (RoadRunner Compact Plus) with an end on view of the HiFlier to show the various gear stages between the motor and the final drive.

Cheers

Mike

12 hours ago, Chas Levin said:

Nice work Mike - and fast, too!

Thanks Chas,

Has to be said that I did use some of the parts from the first build of this chassis, described in the first page of this thread - coupling rods, gearbox, motor and wheels - so that allowed this build to be done more quickly.  The sandpipes have yet to be painted and 'rusted'.

I do often repeat the final photographs, as I have on the previous posting, as I  find the magnification feature on the RMWeb postings does help to get the weathering right. So below is the latest iteration of the weathering process, with everything below the footplate getting a 'diluted' coat of muck and rust. Even so, the loco superstructure is still probably too clean for mid 1950, though a layer of 12" to 1 foot dust does help!!

Regards

Mike

LNER J72 Chassis

The instruction set for this chassis kit does include various arrangement drawings including the profile and positioning of the front and rear sand pipes. So these pipes have been bent up from 0.4 mm wire and fixed into the chassis.

On the last photo I noticed a tiny gap between the rear of the cab side sheet and the cab roof, which has now been filled.

So apart from painting the sand pipes and a little more work on the weathering, that's about it for this build or rebuild.

So for anyone with a spare Bachmann J72 body, with this kit and a few other additions, it can be made into a scale model. 

Cheers

Mike

LNER J72 Chassis

The new chassis has been primed, painted, wheeled and powered up and all seems ok. While I was in a replacing/repairing mood, I decided to remake both sets of front footplate steps, so that has also been done. The original steps are very thick and even though the backs were thinned, there was very little clearance for the coupling rods with P4 gauge wheels. The new steps have a much thinner upstand, so clearance is now no problem.

Still some painting of the new components to be done and a little more weathering of the chassis and wheels but it's just about there. The sandpipes also need to be made and fitted.

So now, 68724 can go to 'The Shunt Ball'!! 

Actually eight days from the off, one day more than the week  I had planned.

Cheers

Mike

LNER J72 Chassis

So the guard irons have been fitted and then everything assembled and fits together without any problems. Care must be taken to ensure that the wheels will pass the brake shoes, otherwise wheeling the chassis will be a problem.  Sand pipes, front and rear can be added after the chassis is painted and wheeled, as there are holes to position and fix those pipes.

One last photo with the shiny nickel silver before I bury the shine beneath a coat of grey primer and then paint it, prior to fitting the wheels, motor and gearbox and electrical pick ups, which should be done tomorrow.

So pretty well there on this, in the week off from the B4.

Cheers

Mike

8 hours ago, Mad McCann said:

 

 

Mike. I hadn't realised that Chris had arranged the etch so that the stretchers were already set at the correct wheelbase spacing.

The man is an utter genius! 🙂

 

I have a spare Bachmann body and I'm now inclined to build one of these chassis just to get some use from it. Must be seven or eight years since I built a chassis!

 

Nice work.

 

 

Davy 

Davy,

Yes indeed, that is exactly how Chris arranged the etch and for all of the three gauges - 'OO', EM and P4. Chris has also supplied alternative gauged parts for the cylinder fronts and rears and the motion plate, so that none of the detail is lost for EM or OO; just narrowed.

Not only that but the lining up of the brake shaft and actuator, so that the brake linkage matches the actuating linkage is also facilitated. Now you can see why I'm such a fan of High Level's products. They do need some very careful work but they produce a wonderful end result!!

Anyway, the handbrake and steam brake actuators have been assembled - photo 1 below - and fitted onto the brake shaft which has then been fixed within the journals at the rear of the mainframes.

The brake linkage has been separated prior to fitting to the brakes - photo 2 below.

And the brake hangars and shoes, with their fixing bolts have all been assembled and are ready for fitting to the brake hangar shafts - photo 3 below.

So now a few locating holes in the mainframes need filling and dressing off and then just the final assembly, then priming, painting and weathering. The coupling rods from the first build are being re-used and it was those which were used to set up the chassis jig.

Then it is back to the B4, reinvigorated and refreshed!! 

Oh and John (Rowan) on this posting I've managed to space and separate the photos, so thanks again for the tips.

Cheers

Mike

LNER J72 Chassis

With the addition of all of the brake shackle bolts - about ten in all - then the brake linkage is now ready to be separated from the jig. Someone did ask me how I solder things which are so close together without loosening adjacent components which have already been soldered. The simple answer is that the soldering iron I use has a pointed bit i.e. like an elongated sharpened pencil, By that means the solder can be applied to very small areas and can be applied very quickly. That said, when soldering in these shackle bolts, I did clamp those already soldered to prevent the solder from melting and the piece falling out.

I guess the whole process of adding the shackle bolts, including cleaning up the soldered joints,  took around an hour.

As an addendum, all of the straight pieces of nickel silver strip which which surround the etched parts - i.e. the end strips of the jig below - will be recovered, separated and then stored for future use and you'd be surprised how useful this can be.

Cheers

Mike

LNER J72 Chassis

Lastly, comes the assembly of the brake linkage. The single etched sheet of nickel silver, containing all of the etched parts in the kit, is organised such that the etching of the brake linkage components also contains a jig for assembling the brake linkage. This jig, is designed to allow the assembly of the brake linkage in any of the three gauges for which the kit is designed - 'OO', EM or P4, with triplicated parts for all gauge dependant sections of the linkage.

Thus, the main brake linkage stretchers are left in place on the etched sheet and are therefore automatically spaced to fit the wheelbase of the loco. The long piece of brass rod (0.5 mm) is, again, positioned using the jig and allows the correct positioning and orientation of the brake adjuster, after which the brass rod can be withdrawn. A very clever piece of kit design which does make the assembly of this section of the kit very much easier.

However, adding the tiny pieces of 0.5 mm rod, to represent the bolts in the linkage shackles, is still going to try the patience just a tad! 

I'm still just inside my week off from the B4 build, but only just!!

Cheers

Mike

John,

Many thanks for the post, above. I had never noticed the insert option which appears when a photo, already attached, is clicked on prior to submitting (initial post) or saving (subsequent editing) of the posting. My posting, immediately prior to yours above and which occasioned the request, has now been edited using the method you described in your posting. This has achieved the required separation of the two images. 

Many thanks for that.

Regards

Mike

Here's a query which someone might be able to help me with. When I attach two or more photos using the attach option, they appear as a contiguous photo entry with no space between them. Now there is obviously a way of interspersing posted photos with text, both as descriptors of particular photos and as a means of delineating a succession of photos; but how is this done?

Cheers

Mike

LNER J72 Chassis

Repeating the build of something which I first built quite a few years ago does provide for some interesting reflections, especially in the almost unconscious acquisition of technique and approach. On this chassis, there are a number of quite intricate parts and assemblies. On the first build, over eight years ago, there were a few times when I thought, dauntingly 'You must be bl---y joking; that's barely possible'. These thoughts were especially prevalent when attempting to assemble the valve motion, the brake linkage and forming and assembling the rear brake cylinder and piping.

This time around those same parts and assemblies were not at all daunting and were put together without any difficulty. It never occurred, this time, that these assemblies would pose any difficulties and indeed, they didn't. I guess that's what age and experience does, though as yet, despite my advancing years, the deteriorating effects of age haven't yet made themselves apparent - touch wood or, perhaps, nickel silver!!

Cheers

Mike

15 hours ago, rowanj said:

I remember you posting these, Mike, and then following your thread, which has inspired me in my own efforts over the susequent years. Many a tip from you has been borrowed/stolen, and we have had a couple of great chats. 

John

Many thanks John.

Equally, your own thread has also long been a 'must read' for me as you build and assemble a wonderful collection of models of the old North Eastern.

Very best regards

Mike

LNER J72 Chassis

Just as an appendix to the previous posting; the very first postings, on this thread, posted on July 10th, 2015 dealt with the building of the High Level Models J72 chassis, first time around. Though the photographs, originally posted to accompany these postings, have long since disappeared, owing to issues when RMWeb updated and then changed their hosting supplier; believe it or not, I still have all of those photographs in my photo files.

Thus I have started the job of replacing some of those lost photos in the very first few postings of this thread. Being a confirmed 'photo hoarder' does have its advantages - eventually!!

The first one done was 68724 with 69003 being the second build of the chassis kit. Both locos were shedded at Hull Alexandra Dock during the late 1940's and 1950's. The photo, below, was taken in 2015. Worth adding that when these two conversions were originally done, I did also do a considerable amount of updating of the loco superstructures, utilising many of Arthur Kimber's castings and small etches.

Also worth mentioning that since these two conversions were done Arthur Kimber (North Eastern Kits) has developed and produced kits for both the short bunker (first twenty locos) version and the long bunker (all remaining locos) version of the J72 both of which I test built.

So, yes, I have four J72's.

Cheers

Mike

Hi John,

Apologies for the delayed reply; been away doing various things. Not least a visit to Malvern in Worcestershire to go around the Morgan factory and thence on to the Cotswolds.

In answer to your question, above, yes; I would love to add one of these water scoops to the tender model.

With the glorious weather of the last few days and taking the opportunity to visit various parts of this country, while I still can, then progress on the B4 has slowed though I'm probably only a week or two from completion.

So many thanks for the offer and yes please.

Regards

Mike

LNER B4

Since my last posting, which was a few weeks ago,  I have completed the tender underframe and am well on with the tender superstructure.

However, I have returned to the loco superstructure to make a modification to the kit. The design of the mainframes follows prototype practice in that they protrude above the running plate around the smokebox. This makes the join between the front footplate section and the smokebox front somewhat fragile but also to fit the loco body to the chassis entails the running plate passing over some embossed rivets in the upper portion of the mainframes, which is gradually 'grinding down' those embossed rivets.

To avoid this and to strengthen the front end of the loco body, I have separated the protruding portions of the mainframes from the lower sections. These can now be soldered to the bottom of the smokebox sides, flush with the running plate, thus allowing the chassis and body to be separated much more easily.

Cheers

Mike

On 26/07/2023 at 09:36, 65179 said:

 

Different buffers front and rear is pretty common on GC types Mike. The tender and loco weren't overhauled together so it isn't that surprising.  There are several sorts of GC buffer as well as the LNER group standard ones too. The GC ones shown in your photo, packed at the rear, and the plain straight shank equivalent are possibly the most common.

 

Regards,

 

Simon

 

 

Simon,

Many thanks for the posting which certainly confirms that this loco, in common with many other ex GC locos, could have carried different buffer types front and rear. Your posting also explains why the buffer beams on the loco front and tender rear are also different.

Progress on this loco and its tender is now restarted and proceeding. I did use the last few weeks to do some maintenance jobs on the loco fleet, wheel cleaning, pick up adjustments, etc.

Regards

Mike