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LNWR Coal Engine - stage 2 chassis



I like to build the running plate along with the chassis to help check for clearance. It might not be so obvious from this shot but it shows how the guard irons hold the front buffer beam in place. There is not much else to hold it. The instructions say leave 1/2 mm over on the valance at the front to fit into the slots in the buffer beam. But there are not such slots! My objective was to try to build something straight from the box. The valances are over scale. At the moment they are holding the running plate flat so I will live with them for the time being. I think they would have benefited from being curved about 1/2mm further back from where I bent them which would look more prototypical but this is nit-picking


At this stage I'd fitted the spacers to the chassis and the front stretchers for the brake hangers. The shot shows how the brakes would foul if I had not cut the guard irons down.




The LRM kit gives EM spacers but not 18.83 ones. I wanted to use the extra width rather have to resort to lots of washers so replaced these with Comet P4 spacers. The chassis has half-etched guides for the spacers fore and aft so it took a bit of fettling to get these to fit and all square.


I made up a motor mount centre spacer from some scrap nickel silver and also fitted the pivot for the compensation beam. Next I reset the jig with the coupling rods again:




Once locked into position, the jig rods are removed and reversed. At one end they are turned down to 1.5mm to fit the couple rods. The other end they are 1/8 inch for the axle boxes. The camera has distorted this but the jig is square :




The High Level horn guides had previously been bent up and the bearings fettled so that they just about fall out under there own weight. They are colour coded so I don't mix them up:




The chassis is offered up to the jig with the jig rods through the fixed axle. At this stage I had already fitted the centre set:




Here's the same from the other side. I used an old spring from the Perseverance system to hold the horn guides in place and tight up against the frames prior to soldering:




The latest P4 dodge is to use Romford/Markits wheels to check a chassis using P4 axles. My Romford wheels are so old that they have not been drilled for crank pins! I also don't have a screwdriver to tighten them so I could not set the quartering but the chassis did run freely.




Reverting to the London Road Model's jigs for setting hornguides as one last check, this shows how the rods fit the axle spacing ok. It also shows how far out the rods and frames are out. The hornguides should be centred in the cutouts but they are hard up one edge. I did fettle a little off the the front cutouts just to ensure they do not bind which they don't:




Next I have to fit the remaining pieces for the brake hangers and then paint the chassis prior to fitting the wheels. This will take some time as I have a backlog of painting and also the Alan Gibson H spoke P4 wheels are not drilled for crankpins so I have that to do too (not the first time)!

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I've just dug out my LRM Coal Engine kit to look at the chassis etch. The wide spacers are marked EM/P4 .It was the second loco kit LRM's proprietor designed in the mid 80's IIRC so I expect he felt that was okay at the time. 


I checked, as best I could, the axle and coupling rod hole spacing's. The front rods are .25mm short and the rears .2mm short on my example. As they were from hand drawn artwork at 2:1 it is perhaps not surprising there is a discrepancy, although it is disappointing. With CAD, it is possible to design to much tighter tolerances. I use .01mm as the registration of the two sides of the tool is probably less than that,


As I also build locos with horn guides/bearings, any mis-match is taken care of during assembly.



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Thanks Jol; it's not just me then.  Surprised that no OO builders have picked this up. 

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