My first conversion to EM wheel standards was a Hornby (nee Dapol?) J94, and that must be one of the easiest of conversions to either of the wider gauges.

My second was a Bachmann (nee Mainline?) J72, and that must be one of the most difficult!

There is some guidance in the EMGS Manual and, certainly at one time, though I'm not sure it's still available, the EMGS sold a kit of bits and pieces to help the conversion.I did not follow that route

Now the J72 is one of Bachmann's older models and is still sold with the original design of split-axle chassis, and that is what makes the conversion so difficult. I think the B1, the V2 and the J39 have similar chassis design. Certainly some years ago I decided that the easiest conversion of a J39 to S4 wheel standards was to scrap the Bachmann working parts and scratch-build a new chassis; - split-axle of course.

It's now many years ago since my mentors convinced me that my modelling progression would be via split-axle, split-frame chassis construction.

You can see therefore why I have an interest in these Bachmann products; - LNER

and split-axle!

Unfortunately the Bachmann or Mainline chassis design bares little resemblance to scratch-built chassis and I would describe it as 'individual'. However when I took the J72 apart, I picked up on something that I had not done so when converting the J39; the wheel casting includes the section of the axle which runs in the axlebox (or bearing), while the axle proper simply holds its pair of wheels to gauge and does not run in the axle boxes. (See picture).

As most of you know, I'm a bit of a nut when it comes to using machine tools to help with my modelling and these wheel castings offered a simply way of chucking in the lathe - on the bearing section of the wheel stub-shaft. This means that it is in fact an easy job to thin the wheel and also to skim a little metal off the wheel flange, both very simple and easy lathe tasks, and as the lathe mounting is on the bearing section of the wheel, then all will be concentric!

With no more than a straight pull, the wheel casting will leave the Bachmann insulated axle which is discarded. The stub axle which we use to mount the wheel in the lathe chuck or collet if one is available, is actually open-ended and hides a square protrusion on which the Bachmann split-axle fits. I won't be using these bits of Bachmannism.

Before mounting in the lathe, the Bachmann crank pin boss needs to be sawn away. It is then very easy to centre-drill the wheel casting and then drill out in steps to 3.1mm diameter and taper ream from the inside. I do that by hand power, until a 1/8" rod will just enter and no more than "just", or the wheel will be too sloppy on its 1/8" axle. That Bachmann square protrusion for their axle is machined away in all this action.

Back in the lathe and face 0.020" off the front of the tyre and about 0.010" off the spoke area and axle boss. This is best done with a freshly sharpened tool and with small cuts, say 2 to 3 thou. Otherwise the spokes may get distorted. Now just touch a 45 degree chamfer on the tyre edge.

Again using a sharp tool take 0.002" or so off the flange depth and then with great care use a smooth, round Swiss file to remove any sharp edges on the flange, - remember that word "care"

This gave me a wheel/tyre profile very close to that shown as the wheel standard in the EMGS Manual.

I made my own split axles but those available from EMGS stores are OK if you wish to purchase them.

With the modified wheels mounted and quartered on the split axles the job is then as simple as described for the J94 conversion.

No bearings (axleboxes) to worry about, but don't forget to add the rescued Bachmann wormwheel.