Saturday, 20 January 2007

08 kit building - Part 3

We were very pleased to be joined by Paul Martin for last night's session, but as he accepted some of our tea, he may well be back in hospital pretty quick. He had his 08 kit with him, and although he read the instructions and looked at the bits, we did not manage to persuade him to start construction - yet.

Dave Stratten and I started by cutting up bits of the axle steel into bits approximately 3.5mm long, using a vice and slitting disk. The gear muffs were drilled and reamed until the axle steel would push into them (1.6mm drill was used eventually).

I fitted the lay shaft with the gear at each end first, using a 1.5mm drill first, then pushing it through with one of the short lengths of axle steel. This method worked quite well. The larger gear was catching on the stretcher tab, so it was filed back a little to clear the gear.

Next would be the worm gear lay shaft. The muff for this one needed shortening as the bearings are further in. Another problem is the fitting of the gearbox over one of the bearings. Excess solder was filed away to allow it to fit, but it was apparent that one of the gears on the already fitted lay shaft needed to be away from the end of the muff to clear the gearbox. The smaller gear had been glued to the end of the muff last week, but the larger gear could be pushed right up to the collar to give clearance. It does mean that the gear train to the wheels is on the opposite side to the model in the instructions, but hopefully that will not cause more problems. To turn that lay shaft round, I had to file the other stretcher tab to clear the larger gear.

You can see the gearbox tab and how it fits next to the gears in the bottom left of the second photo.

Note that the tube that has the worm on it is rusting rapidly, although I am sure I did not get any flux near it.

With the two lay shafts and the gearbox in place, power was applied, and it whirred away smoothly, but slowly. Very satisfying, but I think it needs loosening up a bit. Not sure yet if the gearbox has to be fixed in place, or left to float.

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