A while ago, I restored some of the photos from my original RMWeb blog on the subject of converting a Dapol Class 22 loco to P4 - 

Unfortunately I still haven't got round to restoring the rest of the photos....sorry about that.

 

However, I have recently converted another of these models to P4, this time for my friend John (Re6/6), for use on his Forest of Dean P4 layout 'Parkend Marsh Sidings'.

 

This is a green model, with full yellow ends. Only two locos carried this livery combination and John's - D6331 - did actually make an appearance in the Forest after the end of steam (in fact the Class 22s replaced Class 14s on Forest services until they were themselves replaced by Class 25s in the early 1970s).

 

The Dapol model uses split axle pick up, with the two separate halves of the axles being joined by a fairly robust nylon gear assembly in the middle. The axles run in brass bearings, which in turn fit into the plastic bogie side frames, with phosphor bronze pick ups bearing down on the brass bearings.

 

The original conversion described in the blog above, used Ultrascale 3'7" S.R. tender wheels as a basis, because no one did the actual wheels (this is still the case, as far as I know). The tender wheels have one less spoke than the prototype Class 22, but I won't mention that again, if you don't either...

 

John has two Dapol models for the layouts and had one set of the Ultrascale tender wheels on order from several months ago. Those were destined for the second Class 22. For the first loco, I obtained a set of Alan Gibson equivalent tender wheels and set about starting the conversion process in exactly the same way as described in my original blog.

 

To cut a long story short, using Gibson wheels didn't work, for the following reasons:

 

- the plastic used in the Gibson wheel centres is softer than the nylon used by Ultrascale, so that when I attempted to solder the connecting piece of 0.4 brass rod to the slot cut in the axle end, the wheel centre immediately went soft and started deforming

 

- something similar happened when I attempted to solder the 0.4mm brass rod to the slot cut in the wheel rim

 

I tried soldering the brass rod to the axle end without the wheel in place and then sliding the wheel along and soldering the rod to the wheel rim, but I had the same problems with the plastic centres, even with the soldering iron temperature reduced.

 

I eventually got the loco to run, but it ran like a demented, waddling duck and was clearly not fit for traffic.

 

At around this time, John's Ultrascale order for the second Class 22 arrived, so he got them over to me in short order and I started again.

 

The job was made harder, because I had had to epoxy the Alan Gibson axles into the nylon gear holes, so the dried epoxy had to be removed and the centres of the gears gently reamed out.

 

This time I thought I would do the job using the Ultrascales a bit differently.

 

Rather than cut the Ultrascale axles and use a shorting piece of 0.4mm brass rod again, I decided to go for keeping the axles intact and using wiper pick ups on the plastic bogie side frames, which would then be hidden once the outer bogie side and keeper plate assembly had been re-affixed.

 

Unfortunately I can't find any photos from the abortive Alan Gibson wheel stage, as described above, so you'll have to take my word for it for now and possibly just forget all about that embarrassing failure...

 

This is the Dapol side frame with a thin piece of copper clad sheet superglued in place:

 

To get the power from the copper clad to the internal pick ups, a small hole needs to be drilled (0.7mm) in the plastic bogie side frames and a short piece of wire soldered to the copper clad and the Dapol phosphor bronze pick up inside:

 

I used 0.33mm n/s wire for the actual pick ups:

 

The Dapol OO wheels were dis-assembled in the usual way. It's still necessary to ream the centre of the gear unit out a little, to enable the Ultrascale 2mm axle to be a tight push fit.

 

I also turned the outside of the gear assembly a little in the electric drill, to put a slight taper on either side of the gear assembly, which would help the Dapol brass bearings slide over them in traffic:

 

Having then assembled the wheels into the bogies, I wondered why the loco wouldn't work, due to a persistent short circuit...

 

 

After a refreshing cup of herbal tea, I realised that I hadn't shortened the p/b pickups so as not to touch the brass axle bearings any longer....

 

This was then done and it then looked like this:

 

This is what each bogie looked like, once the pick ups were in place:

 

The wheels were, as stated previously, from Ultrascale:

 

This time, I didn't cut the axle into two halves, but used the whole axle. As per the last time, a small 1mm wide piece of 2mm internal diameter brass tubing was cut for each axle end to form a washer and put onto each axle, together with the Dapol brass bearings, as per the following photos:

 

 

 

 

Each wheel and axle assembly was then put into the bogies:

 

With the view of the completed job looking like this:

 

 

The pick ups were pretty much invisible, once the bogie outer side frame and keeper plate assembles were put back in place.

 

All that remained was to add the headcodes:

 

 

...add a working screw coupling with a steel end link for our magnetic coupling poles and add the buffer beam pipework:

 

I had previously glued the lower body panels permanently in place, as I did on my blue Class 22 a few years ago.

 

I haven't yet added a crew, so this will have to be done once I've got a ModelU driver and secondman painted in due course. What I did do to facilitate this, though, was to unglue the cab interior moulding from the rest of the body, scrape the old glue off and re-position it back inside the body. Friction holds it in place just fine and the lack of glue will make it much easier to remove later on.

 

I will weather the loco shortly.

 

I have now weathered the loco: