Entry posted by D869
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D604 is now ready for traffic. I'd like to say 'finished' but I suspect that some further attention to the chassis paintwork may still be needed.
There was one body detail issue that needed to be sorted - I was not too happy with the empty rectangular vent openings in the roof. After trying to find prototype photos to figure out how to make them more realistic I noticed that they were only visible as openings in early photos of D600 and D601. Later roof photos of these and roof photos of D602 onwards are quite hard to find and not totally clear, but it was clear that these holes had been plated over on the whole fleet. This would have been easy to fix before painting but not now. Correcting it involved cutting some 5 thou nickel silver to fit snugly inside the holes and then a second slightly larger piece to overlap. Both were then curved to the roof profile and soldered together. Cleaning and painting such tiny bits of metal was a challenge, but after doing this the completed blanking pieces were glued in place. I'm a lot happier with these than I was with the empty rectangular holes.
The main items missing at the AGM were the completed bogies. These are now done and painted and on the loco. Painting was done (after degreasing) using Halfords grey primer and Humbrol enamels. Putting the bogies back onto the loco proved to be enough to dislodge some of the paint from the raised ribs on the bogie sideframes, so I suspect that the future may hold a strip-down and repaint starting with the Precision 2 pack etch primer that I've been too scared to use until now for fear that it will etch the inside of my airbrush.
Fitting the proper bogies also provided some extra clearance below the body so that the ride height could be lowered. This apparently simple task proved to be a long and difficult process…
The body to chassis fixing is probably the part of this build that I am least happy with. I tried to figure out a way to arrange a robust screw fixing but in the end it defeated me and I resorted to making some wedge shaped clips from plastikard to replicate the ones inside Farish bodies. Some large plastikard strips were glued inside the body and the clips attached to these with solvent. The body height is governed by some spacers attached to a plastikard tray that sits on top of the chassis. For the most part the body stays put when I want it to and can be removed when needed, but it is far from perfect.
In my previous post I mentioned that one end of the loco appeared to be sitting slightly higher than the other. I first noticed this problem late on the day of the AGM and it had not gone away. My first step was to carefully measure the roof supports and then file them down by 0.5mm to achieve the lowering that I had intended. The result was that one end got lower but the other end didn't budge. 
After a lot of peering inside the body under bright lights, assembly and disassembly I finally tried putting just the plastikard tray from the chassis inside the upturned body and noticed that it was slightly too wide and jamming between the plastikard inserts behind the cooler intakes. A bit of filing solved this. I reassembled the loco… problem solved? No. 
More peering through the windows revealed that the parts of the chassis cover that were intended to hide the worm gear were fouling the cab detail insert at one end, so I disassembled, cut this back to provide some clearance and reassembled. Problem solved? No. 
Next I noticed that the high end still had a block of plastikard underneath the cab detail insert. I needed this to provide something to grip with pliers while positioning the cab inserts for gluing. Some tricky work with a sharpened screwdriver removed this. Problem solved? No.
Finally I noticed that the bogie at the high end was not free to tilt in the same way as the other end. Forcing it to tilt caused the end of the body to rise even further. More peering into the cab under bright lights revealed that the cab detail insert was sitting on top of the plastic housing for the front worm bearing. Solving this involved removing the cab insert to allow it to be filed down so that it fitted up against the windscreen more snugly and also trimming a little off the rear. Problem finally solved! 
Once the painted bogies were refitted to the loco I added the couplings. Then I noticed that they were not sticking out far enough at one end. Close inspection showed that the body was not quite central in the fore and aft direction so the cab footsteps didn't line up in the same way at both ends either. Fixing this entailed slicing off the body fixing wedges and re-attaching them after moving them along by 0.5mm. After setting overnight I reassembled the loco… and the body was then sitting too high at the other end :angry: . I figured this problem out in one attempt - the ends of the chassis block were now fouling the cab inserts. I tried shaving the back edges of the cab insert, but it seemed unlikely to get me enough clearance so the fix was… disassemble the whole chassis and cut some more metal off the block, clean everything up again and reassemble. It took rather longer to actually do it.
Since I haven't said much about the chassis and I had it in pieces to fix the ride height, I thought I'd take the opportunity to grab a couple of photos.
It started as a Bachfar 47 chassis bought secondhand. Unfortunately it proved to be a less than perfect runner and the previous owner had tried to 'repair' it by filling every available crevice with oil. It had to be completely stripped down to remove the resulting gunge after which it ran rather better but was still not satisfactory. Swapping in a motor borrowed from the Bachfar Western transformed the running, so a new motor was ordered for D604 and things got better.
One bogie pivot has been moved inwards by 3mm using the notches provided on the bachfar chassis block. This needed a new driveshaft to be made from brass.
Some metal has been removed at both ends to allow the body to fit and daylight to shine through from one cab door window to the other.
The battery box detail has been fabricated from plastikard and attaches to the chassis in a similar way to the original Farish class 47 fuel tank moulding.
The bogies have been hard-wired using the 2mm Association flexible wire to a couple of tags that are held by the main chassis block screws. I think that this is a much more reliable pickup solution than a bit of phosphor bronze rubbing against the bottom of the chassis casting and have used it on several of my locos.
A plastic tray has been made to sit on top of the chassis. This holds the body at the correct height, carries the cooling fans and provides a guide to keep the pickup wires in place. It also has extensions at the ends to prevent the shiny brass worms from being visible through the cab windows.
Another photo of the finished article on its own and one with its partner in crime. Now D6309 is modelled in a condition that's about 4 or 5 years later than D604's presumed date, but I can't really resist running them together 
... especially now that D604 sits a bit lower so their heights are a reasonable match.
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