LRM J25 & J21

[Nick Lawson]

Having resolved the suspension issue, I have been able to make better progress on the tender build.

 

 

 

This is a bit of an art form due to a lack of precision in the instructions - for example one has to curve the insides of the coal space around a "suitable sized" drill bit. Oh you tease...

 

Also there is some latitude in where you centre the curve so that one can e.g. bend a piece that is a bit too wide at the front and too short lengthwise or too narrow and too long. Getting this right is not assisted by the footplate having slots across the front for non-existent tabs which make you wonder whether you are missing something. Anyway it wasn't really a big deal to adjust to fit.  ("I can't complain but sometimes I still do" Joe Walsh)

 

Then there was the well-known scratch-building step to create the missing sloping rear of the coal space and cover the securing nut. Luckily I had a piece of scrap which was almost perfect width. Soldering it in place was a pig with my rather short stubby iron and I didn't manage to get a nice continuous seam; but it is secure.

 

 

Fitting the drag beam, buffer beam, valances and cosmetic frames was pretty much as per the loco. Take no notice of the instruction to pack the valance out from the frames that you will be fitting in the next step! (I'm starting to think the writer of the instructions may have been a school teacher who slips odd things in to see whether the class is still awake).

 

Also the instruction for fitting the cosmetic frames just says that they should be slightly further inboard than the tank sides. When you get to this step, in practice it means fix the frames along the edge of the cutout in the footplate, which actually gives a nice definite line to work to; and is much easier than implied.

 

However, putting it all together I was dismayed to find that, with the frames and body screwed together, the horn guides on the frames do not align with the cosmetic frames by about 1mm. I don't think there is any way I could have assembled the various parts differently in order for them to align correctly. Unfastened, there is enough slack to allow the frames to be positioned further forward under the body, so I will have to elongate the screw holes in the frames to allow this and insert a packing piece inside the buffer beam to stop the frames sliding back.

 

(Memo: another time perhaps align the frames, cosmetic frames and footplate all together while still flat; measure up a pair of frame spacers which are not pre-drilled and drill them to suit.)

 

[Jol Wilkinson]

Hi Nick ,

 

this is intriguing. I had to go and have a look at the tender on the LRM D23 I built in case that was the same but I hadn't noticed it. The D23  kit includes the same tender as the J21 and J25. As far as I can tell everything lines up satisfactorily. I don't recall any issues when I built the tender.

 

 

 

 

In fact I quite enjoyed it, as it was easier than the LNWR Webb tenders with their rounded tanks and coal spaces. Getting the wrap around one piece tank surround is challenging. The worst part is filling the flared corners of the tank. However I have done enough of them now to get the hang of it.

 

[Portchullin Tatty]

Hi Nick, is there any chance that you have put the outer valances on back to front?  They do not look to be equal distances to both ends?

[Worsdell forever]

8 minutes ago, Portchullin Tatty said:

Hi Nick, is there any chance that you have put the outer valances on back to front?  They do not look to be equal distances to both ends?

 

Just measured my class C tender and drag beam to front axle is 17mm, buffer beam to rear axle is 16mm.

 

[Nick Lawson]

18 hours ago, Portchullin Tatty said:

outer valances on back to front

Mark,

ok firstly the outer valances are just plain straight strips less than 1.5mm high, easily overlooked. Inboard of these are the prominent cosmetic frames that are out of whack with the actual hidden frames that will carry the wheels. These cosmetic frames are symmetrical end-to-end so it doesn't matter which one goes on which side. Their position is determined by butting them up against the drag beam.

 

They are correctly positioned so the position in which the actual frames have been bolted must be wrong. More on this shortly.

 

But thanks for the suggestion - it was a likely candidate for correction.

[Nick Lawson]

18 hours ago, Worsdell forever said:

measured my class C tender

Paul, yes that agrees with my cosmetic frames.

[Nick Lawson]

22 hours ago, Jol Wilkinson said:

As far as I can tell everything lines up satisfactorily.

Jol,

 

(This thread now expands to be a tale of three locos! )

 

This is where version numbers would be really useful! To recap, the kits I'm currently building are an old LRM (Romford, Essex), J21; and a more recent LRM (Watford) J25. I also have one of your D23s unstarted, so I have had a look at that as well.

 

Ok, my issue appears to be the position in which the actual frames have been bolted to the tender footplate. The actual frames are taken from the older J21 kit, but their dimensions, particularly the position of the slots for the spacers, are the same as the newer J25 tender frames. 

 

For completeness, while I built the loco frames using wider spacers, this tender uses standard LRM EM gauge spacers - ones which have pre-drilled holes for a fastening screw.

 

Examining the D23 tender etches, it is obvious that while this is nominally the same tender it uses re-engineered etches.

 

Lining  my J21 tender frames up against the D23 tender frames I can see that these have the same dimensions, particularly that the position of the slots for the spacers are the same. The re-engineered frames have a third spacer slot added, but that isn't relevant here.

 

Looking now at the underside of the footplate; the J21 and J25 footplates are the same, both having holes on the centreline to correspond with the holes in the frame spacers. The instructions for assembling the tender body just say: "solder a nut over each of the two etched holes in the footplate after ensuring that the etched hole provide a clearance fit for the bolts - open them out with a broach or round file if necessary. Temporarily bolt the tender chassis to the body to check the fit.

 

In fact the etched holes are larger than the screws so the latter slop around nicely.  I concentrated on getting the frames pointing straight down the middle while soldering the nuts. At this point in the construction the drag beam has not been fastened, so there is nothing to butt the frames against while doing this. I may well assemble the J25 tender differently, but looking at the position of the nuts wrt the etched holes, I don't think I could have positioned the frames against the body much differently without opening out the etched hole towards one end.

 

Coming back to the D23 tender, the body etch has also been re-engineered from the earlier ones. In particular, the size and position of the etched holes in the footplate have been changed. On my J21 tender the centre of the rear fixing hole is about 11.5mm from the rear edge of the footplate. On the D23 etch the same hole is about 12.5mm from the rear edge. This would cause the frames to be bolted to the footplate 1mm further forward et voila! everything will align. The holes are also smaller to reduce the slop while soldering the nuts in position.

 

It seems then that my problem was diagnosed and fixed at some point in the past and then forgotten about; and is just one of those gotchas that lie in wait for people daft enough to build old kits 😀

Edited June 8 by Nick Lawson
Additional detail

[Asterix2012]

@Jol Wilkinson has the J21 etch been updated from the version Nick has do you know?

[Jol Wilkinson]

5 hours ago, Asterix2012 said:

@Jol Wilkinson has the J21 etch been updated from the version Nick has do you know?

 I don't know.

 

Although I help John at shows, have done a number of LRM kit designs, mainly LNWR, and post information on various sites for John Redrup, I am not otherwise involved in the production and sales side of LRM (I live one hundred miles away). Hence I don't know what alterations have been made to those other etch designs John has (over sixty locos plus carriages, horseboxes, etc). Although I designed the D23, it uses the "existing" tender from the LRM range.

 

The best thing would be to ask him direct through;

 

londonroadmodels@btinternet.com.

 

He is away at Scalefour Crewe this weekend so I would wait until Tuesday before doing so, to give him time to recover.

[Nick Lawson]

I have now opened up the securing holes and have slid the tender frames along to align properly with the body work.

 

The next things to sort out are the tender flares. I was tipped off a while back that these are oversized, so I'm contemplating what I can do. The Isinglass diagram says the width of the tender body is 7'2" and over the coal rails 7'10", so a 4" (1.3mm) flare outwards either side; with a vertical height of 7" (2.3mm).

 

The supplied flat components are 4mm high, so "a bit" too tall. (I haven't done the geometry yet!). For comparison, I dug out a pre-rolled equivalent from an unbuilt ArthurK kit, see pic below, which looks substantially smaller.

 

 

It would be impossible to reduce the height without also making them too short, unless perhaps I file diagonally. I'm not going to make any sudden moves on this stage!