"Voiding the Warranty" - Mol's experiments in 21mm gauge

[Horsetan]

2 hours ago, Mol_PMB said:

.... I wish IRM/AS would use finer scale wheel profiles ....

I think they have to cater for the surprising number of people who still use Code 100 track.

[Mol_PMB]

Well this weekend's progress on the H vans has been less than expected, partly owing to a day spent working in the garden and some time with friends.

But also a significant realisation that once I reassembled the first wagon, the wheelsets would be trapped, and therefore I needed to finally make a decision about wheel profiles and back-to-backs. That also required some tooling to be made. So I've done all those other activities and haven't yet made any progress on the H van itself.

I have decided to use 21mm gauge, 19.2mm (-0 +0.1) back-to-back, and mostly Alan Gibson EM gauge profile wheels which have a rim width of 2.3mm. This compares with the 2.8mm rim width of the IRM wheels. I had previously found that the IRM wheels in the Bulleid wagons could not be set to even 19.0mm back-to-back without the front faces rubbing on the back of the W-irons. With the thinner EM profile wheels, there's adequate space for a 19.2mm b-t-b and still good clearance to the W irons.

So, for the IRM wagons the process is to take the wheels off the axles, and replace them with EM wheels set to 19.2mm b-t-b. This has required me to make a little press tool adaptor so that I can push the axle quite firmly without pressing on the pinpoint. Also I have made a 19.2mm b-t-b gauge.

The stock of Markits(?) wheelsets I got from John with 28mm axles have an intermediate wheel rim width of about 2.6mm, and they fit OK in John's models with a 19.2mm b-t-b. The flanges are a little thicker than the EM gauge wheels so I'll have to check they're OK once I get some pointwork.

For other wagons such as Parkside kits, I have used the Alan Gibson axles as well as their wheels, and extended the axles by 2mm by cutting in the middle and sleeving with a 2mm ID brass tube.

Gibson wheels on IRM axles in IRM H van chassis:

 

The next step is to do a batch of these and secure them to the correct b-t-b with a dab of superglue, and then paint/weather them as a batch.

 

Whoever said that getting started in 21mm took a lot of extra effort was right! But I like a challenge.