My first loco conversion to EM wheel standards was a Hornby J94 0-6-0 shunting tank but it must rate as a most exceptional gauge change! My J94 had previously been converted from its purchased condition of OO to S4 wheel standards & had served well, with a DCC chip on board, on both of my S4 layouts, - 'Birch Vale' and 'Bowtons Yard'.

Question: - How many other modellers have converted a P4 model to an EM model, and from digital to analogue, ? Not so many is my bet.

However, the choice of using the S4 J94 (sorry! in earlier submission I had written "J39" here) was the knowledge that it is such an easy conversion. Remove the keeper plate and coupling rods and then drop out the complete wheel set. Rescue the wormwheel from the middle axle for re-use on Gibson replacement wheel and axle kit, having been sure to order the correct axle diameter kit.

I point blank refuse to tell you who ordered the wrong kit, but I'm very happy to add that Colin Seymour- (Alan Gibson No.2) was totally unfazed when a change was requested.

Loctite the wormwheel in position on one axle, check before the Loctite cures, that things are OK, because the wormwheel does not sit on the axle centre line. Happy? OK now add the wheels and quarter them. Drop the new axles in place and return the keeper plate but check that the Hornby pick-ups are adjusted for the new gauge. This next bit is the hardest part. The crank pin holes in the Hornby coupling rods are way too large a diameter for the normal Gibson crank pins. I turned up a set of bushes (well no I didn't, I'd already done 'em for the S4 conversion), but I think Colin can supply some if you are not a lathe nutcase.

That's it; job done. No. 68063 is a beautifully smooth runner on the new EM layout which has now been officially named 'Wheegram Sidings'. Apply the little grey cells to "Wheegram" - "Whee", as in wee meaning small; and "gram", a unit of weight, - and I consider Wheegram an apt name for a layout that has been designed around a desire to construct an exhibition layout that can be carried by a decrepit old modeller without strain.

Oh! before I sign-off. I see that in para. four above I have said simply -"... quarter them". Sorry, I do realise that many modellers are afraid of this wheel quartering necessity but honestly it is not so difficult nor demanding of precision as many seem to think. My method is to use a very fine tipped, permanent ink pen, to place a thin line on the wheel tyre and coned section, immediately above the spoke in-line with the crank pin, or the first spoke clockwise from the crank pin if we have a 'crank between spoke' wheel. Do this for half of the driving wheels but for the other half, draw the line on the tyre above a spoke, (count them!) which is approximately 90 degrees clockwise from the crank pin spoke used before. Loctite one wheel on each axle and allow to cure. Now add the other wheel to each axle but ensure that your penned lines line up with each other for each pair of wheels.

Honestly, that level of precision is quite acceptable. Obviously you should work as accurately as you are able, the lines should be kept as thin as possible and they should be, as best you can manage, on the centre-line of the chosen spokes.But it is just as simple as that.

My next conversion was from a new, RTR J72 but it was a much more model engineering job than the first. I'll tell you about that one in a few days time.