We left the NBL 21 as a nearly finished bodyshell, here . The sticking point was the need to produce flush glazing for those large curved cab windows by hand.

Finishing the loco was my first big lockdown project and turned into a bit of a fight.

It wasn't really the glazing - like quite a few frightening jobs that didn't prove as bad as I feared. I had used the Shawplan window etches as a template for the shape, traced onto an old business card. (Before I glued the etches onto the model, obviously).  I did this 3 times, to give me spares in case one window went wrong. These templates were cut out and fixed to clear plasticard, then I cut round . (I'm trying to remember whether they were held to the glazing with Pritt-stick or judiciously placed sticky tape. I think I may have done both). They were then filed until they went into the aperture and fixed in place with Rocket Glue and Glaze, which took care of any slight gaps between glazing and frame . Yes, ideally the fit would be good , but it looks perfectly ok at any normal viewing distance and in photos. The front quarterlight was also filed to fit - the rest of the glazing is SE Finecast

Next for the chassis. I had sourced a Class 29 chassis frame and two Class 29 trailing bogies from Peter's Spares. I bought a Hornby Class 25 in blue as mint second-hand at Warley last year for about £50, and I robbed the 5 pole motor bogie out of that. (Before you suspect me of terminal cruelty to Rats, I then bought a Bachmann 25 with damaged handrails at Peterborough for £75, and the medium term intention is to combine the Hornby body with the Bachmann body to produce a super-douper blue Rat at a modest price. Ah, the days when we had shows, and could pile up more and more future projects that we never got round to doing...)

Hornby Ringfield motor bogies were standard items across the range, so it snapped into one of the Class 29 bogie frames. The other bogie was rewheeled with Hornby disc coach wheels. This means a finer wheel profile with shallower flanges that don't catch and lift on stray bits of ballast on my SMP code 70 bullhead track, and has proved effective in preventing stalling on my Baby Deltic. Since there are traction tyres on the motor bogie the resulting chassis picks up on 6 wheels plus 2 crossed fingers. A spare Hornby weight - surplus from the Pacer I started long ago - was slotted into place. Those, too, were standard items at Margate.

I fitted Kadees - long underset , from memory - to the bogies. The Hornby coupling is cut away, a plate of 40 thou plasticard glued underneath to bridge the gap, and then the draft box glued on top of this with solvent, microstrip packing round the sides if possible, and with a Kadee nylon screw  inserted from below for added retention. I think I may have added a spot of UHU on the top to stop it working loose.

While I was about it, I did the same to my old Hornby 29 which was detailed up years ago it a desperate attempt to find a main line diesel that would run reliably on Ravenser Mk1. This loco needs converting to DCC and my first attempt about 18 months ago  failed ignominously, trashing a decoder. A complete rewire is needed: when it was first detailed I fitted Ultrascale wheels and all-wheel pickup, and something is evidently not right somewhere. This loco needs a damaged radiator grill replacing and I will probably have a go at reworking the cab front windows as well. The substantial difference in appearance this makes will be obvious from the photo below, and I have a second Shawplan etch in stock. While D6119 has a 3 pole motor and will never run quite as smoothly, this would at least get it into some kind of use. The "rationale" would be that the loco was appropriated by RTC for test train use after withdrawal in 1971, replacing the Baby Deltic.... 

A TCS T1 decoder from stock was fitted , programmed much in line with the Baby Deltic and test running began.

There were problems. (Entirely prototypically, I might add..)  It kept stalling. A prod was required to get it moving. I added more weight , because the thing seemed to be slipping. I played about with settings, but still it kept sticking in places. Sometimes it would run fine . Then it would start to stall and spin.

After several days of frustration, tweaks and weight adjustments, the penny suddenly dropped. The wheels on the motor bogie had been eased out to 14.5mm back to back. This adjustment meant that sometimes the final drive gears to one axle would slip out of mesh. Hence the slipping and stalling. Nudge the loco and they meshed again. 

 The back to back was closed up fractionally (it's now about 14.2-14.3mm)  and all was well. Previous CV values were reverted to in the matter of start and mid volts. And now it runs as well as can possibly be expected from a 5 pole ringfield with traction tyres on one side. There are pickups to those wheels, but I doubt if electrical pickup is more than erratic. So we have 6 wheel + 2 pick up, rather than proper 8 wheel collection

The underframe was then weathered, with washes of Railmatch Frame Dirt and Brake Dust, and some AK Light Dust Deposit on the centre tanks. And I wasn't happy. The problem can be seen by comparing the top and bottom photos - the bogies were just too bright orange. A further wash of AK Shaft and Bearing Grease over the lot knocked it back to something acceptable , though I left the sandboxes  as colour  photos show these as something of a tonal highlight. The second photo shows D6103 after the extra weathering wash.

The loco is seen  departing Blacklade with the steam-age engineer's train, my recently completed Toad B leading, and the engineers'  ex GW 4 wheeler (Ratio) just behind . Set 4  (Hachette Mk1 + Hornby Gresley BCK) lurks in the background . I need to weather that BCK at some point. D6103 is evidently working test trains so the engineers at Derby (or should that be Toton?) can work out what the heck is wrong with these things.

This one fought me all the way, but I now have another small short Type 2 that is pretty well bang in period for the Kettle Period. This final write-up has been part finished and outstanding for an indecently long time (D6103 has been in traffic since August) , but we are done. Sorting out the 29  is still outstanding......