Steve Beattie kit NBL Class 21 build

The sub frame looks a relatively straight forward build, the bogies I can get my head round and seek out the best way forward. I may well glue the whitemetal castings on as heat sweating will be a challenge with the Slater's wheelsets located inside the brass inner carriers.

 

Just like this Toto, the inner carrier frame consists of four parts, two headstocks and two sides which the wheelsets fit into once the axle stub bearings have been soldered and axle extensions added. The last side carrier piece can then be soldered into place after the wheelsets are dressed with Delrins and gear drive and the floating motor frame etch. Hmm then the white metal castings are added at some point... now you see why the frame castings cannot be sweated on without risking damage to the Slaters wheels.

 

Thanks Pete... I knew I could rely on you for a confirmation of product type. I was thinking of using a two pack Araldite epoxy to glue the white metals into position, that will give me a better working time than using Roket Cyano (which is good for small parts) and it eliminates the need for getting it spot on first time with literally only seconds to work with. I would feel a shed load better if these bogies had inner frames such as on the Class 24 build... even if it did add a bit on the price I think the build integrity would be better. What is your opinion about the glue on frames versus having an internal bogie frame unit Pete?

 

Thanks Steve, funnily enough in the solitude of working at a clients property this morning that same thought entered my head, thanks for confirming this is the way to go.

 

This evening I focused on the building the mainframe which is covered in Part 6 of the Class 21 build instructions, the mainframe simply consists of two sides, two centre stretchers, two bogie stretcher which have to be folded, two base flanges and one top unit, effectively what is being made are two parallel I beams with cross bracing. Once the mainframe items are released from their frets and filed clean I soldered the two middle stretchers into the side pieces which when complete will form the web section of mainframe girders.

Next I used my hold and fold to form the bogie stretchers, it was at this point I ran into a glitch, when the bogie stretchers (part 16) are folded the width is just 10mm but the tab slots on the side web holding part 16 correctly is just 4.5mm wide, not a problem. Just remove the inner tabs on part 16 and align the bogie stretcher using the outer tab mated to the outer slot, I checked the position against the top piece for correct alignment.

When satisfied the position is correct I soldered the bogie stretcher to the side web on the one remaining tab, at this point I'm just looking to tack solder this item together.

The next move is to solder the side, middle and bogie stretcher assembly onto the base unit, I started in the centre working outwards ensuring that the side web is seated correctly inside the half etch line. It is at this point the bogie stretcher can be soldered to the side piece proper.

 

Now the two base flange lengths are next to be soldered onto the side web after gently bending to shape, this will then create the I beam girder section. It was at this point I encountered a bit of an issue with the bogie stretchers which were obstructing the fitting of the base pieces, the reason is that part 16 when fitted sits above the top of the side piece

An easy fix this Steve and didn't affect the integrity of the build at all... just needs some lateral thinking. I guess it can be amended on later etches.

 

The answer to this was to cut away the obstructing brass on part 16 to allow the base angle flanges to sit down properly on the side webs.

And the first base angle piece drops in nicely and can be soldered so the whole mainframe unit is exactly as it should be... nice and flat and completely level. I guess the modification I made could be dealt with in different ways had I been aware of what was coming but in the dry assembly this never even occurred to me. Anyway the main thing is everything is as it should be now.

 

Next thing I knew was that my best 45watt Weller iron suddenly went cold... oh dear and the 35watt Wellerwith pointed tip isn't up to the job and the solder station has the wrong tips fitted. Only one thing for it and that is get out the 80 watt big boy, its mean and messy but will get me out of a hole until tomorrow when I'll buy a new 45watt iron.

This picture shows that the mainframe is a pair of shaped girders.

Now the M3 brass cheese head screws and nuts arrived by post today so a little play was in order just to see how the build is going to look at the next stages, I fixed the mainframe to the body skeleton ... nice fit and straight too.

And finally the class 21 bodyshell was slipped over the assembly... all in the name of fun. I'll separate all these component assemblies again tomorrow and focus on making the battery box which fits underneath the mainframe and then I'll refocus on building up the bodyshell again.

 

Now its starting to look like a loco.

 

Just to clarify this area Toto, yes there is an offset in the mainframe beam, now the base angle strip has a half etch line at each end where the offsets are made and the central section which is where the beam becomes deeper has no half etch. So it is very important to start the solder of the base piece at one end and proceed to the other end making sure the web remains located inside the half etch. otherwise you will come adrift when you get to the centre area if the web has not been located properly. Here is a better picture showing the finished item and what I mean.