Hello and sorry for the lack of posting.

Age keeps interrupting my modelling progress due to minor illness that keeps me out of the workshop far more frequently than I’m happy about. It also seems to be causing me to have reduced concentration span, which, unless I realise that my concentration has diminished, leads to error, or at least less precision.

Mid-January I decided to have a shunting session on ‘Bowton’s Yard. Partly to give some running tests on the two new PMVs – still in their bright shiny-new plastic finish – and partly too to give the J10 a decent working session.

Annoyingly the J10 proved to have an irritating tight spot that only showed up at creep speed. It ran Ok, but at speeds at or below walking pace there was a minute jerk at each revolution. I could have got away with ignoring this because at more sensible speeds there was no showing of what must be a minor error in quartering or some such. However I was annoyed that I had not spotted it during construction so I started trying to locate what was wrong.

The quartering was as near spot-on as we can get it by eye and that, in my experience is as good as is needed. With the motor removed but the body in place (remember it’s CSB & therefore needs the correct weight distribution) the Whitnall shake test (see an earlier post) was repeated with no sign of stickiness.

After several hours over repeated workshop sessions I eventually blamed a slight wobble on one of the driven axle wheels. These are plastic wheels and as Mike Sharman say’s, they can have wobble tweaked away. This one couldn’t, or at least I couldn’t! Then, with bench running of the inverted chassis, I also detected a wobble in the final gear wheel. Neither of these wobbles made sense. I’m certain HighLevel would not sell me an eccentric gear wheel and any plastic, moulded wheel should tweak. What on earth is happening?

I removed the driven axle from the gearbox, mounted one end of it in a collet in my Boley lathe and fitted a ‘clock’ to run on the other end. There was a near 0.010” throw on that end. Some of that eccentricity would be transferred to the wheel’s crank pin so the crank pin rotation was not truly circular but mildly elliptical; hence the minute tight spot and the wobble in both wheel and gear wheel.

Perhaps I should remind you that the chassis is a split-axle one. In this case, as it’s the gearbox axle and I always want the gearbox to remain electrically isolated, the axle has two splits. Over the years I have made many of this type of split axle but never before have I experienced this problem.

The system I use is two stub axles each with male appendage of smaller diameter. These male sections are aralditted into the centre section of axle which of course is female. To ensure the three parts line up concentrically it is necessary to have a curing jig that holds all parts firmly in correct location. With a single split axle a lathe is all that is needed, one axle part being held in a suitable collet, the other in the tailstock chuck. This does not work for a two-split axle because the centre section has no support and will gradually sink into the araldite during the curing period.

Branchlines retail a simple curing jig which is two slabs of clear plastic firmly bolted together and with 3 x 1/8”diameter holes and also 3 x 2mm diam.holes drilled on the joint. Drop one or more aralditted axles in one half of the oiled jig and firmly clamp the other half on top. Every axle is held firmly in line.

I’ve also used a 1/8” hole centre drilled down a 1” length of 1/2” mild steel, well oiled the hole and pushed the assembled and aralditted axle into that. Both methods have never before failed me.

The offending axle had used the Branchlines jig. On close inspection there were exceedingly small residues of araldite on the mating surfaces of the jig and that must be the reason for the poor precision of that axle.

Moral? Clean your tools!

Oh yes those SR PMVs I’ve been promising pictures of; here they are:-

Both of ‘em on Bowton’s Yard; the bright green one is the Keyser, the other is from Parkside. The camera makes one look larger than the other – cameras lie!

This is the Parkside version posed on its ‘tod’.

I don’t think that I covered the roofs when I told you about these vans before Christmas, but I have said that I like to get access to the inside of vans, coaches etc, and to any loads inside wagons. You never need such access unless you don’t build it in! Then, something will come loose and that’s a guarantee. This is the Parkside with its lid off. Phosphor-bronze leaf springs at the ends of the roof apply pressure to the van end sheets and retain the roof under normal conditions.

Dave