Two More Seals

Last Saturday I did use the horizintal mill to finish off the other two seals.



It was quicker, though still not fast, and more accurate. A more satisfying job.

Slow Progress

It's not always quick. Today I did a couple of little jobs and I suppose that's the way it's likely to be for a while, at least until we mount the wagon on its wheels, install the draw-gear and finally floor it and plank it.

Axle box dust seals

The new wheel bearings have come back from Bristol Foundry so I could work out the relative positions of the bearing surfaces to the axle box casing and from that the centre-line of the axle itself.



So I measured up the position of the centre of the axle entering the axle box relative to the top edge of the dust seals that I finished last week. I then marked them up ready for drilling out. We'll have to use a tank/pipe cutter as the holes need to be nearly five inches in diameter.

Measuring and marking is a bit scary. Once you cut that's all your chances used up, if it's not right then either adjustments must be possible or it's start again from scratch. I hope I've measured them right. I follow the adage measure twice and cut once, but I've done that before and still got it wrong. The trouble with measuring twice, unless you measure by a different method or route is that you're likely to repeat your errors.

Grease Trays

The bearings are held in place by a cast-iron drawer arrangement that carries grease to lubricate the bearing. Once the bearing is installed grease can be added through the lid on the front of the axle-box.

A couple of the grease trays had at some time in the past come into contact with the bearing journal. That must have been the result of a quite catastrophic failure because the bearing itself is bronze and three-quarters-of-an-inch thick! Ollie wanted the bottom faces of the two damaged trays leveled off to prevent a rapid loss of grease - and hence a possible loss of lubrication with damage to the bearing surfaces.

I leveled them off with "Plastic Metal". I had expected to leave them for a while before fettling them off flat but found that within an hour I could work the filler very easily.



Our next target is to get the frame onto its wheels.

Sunny Day

Meanwhile Marcus politely declines to have his photo taken while cleaning the excrable Thomas face ...



... and Ollie offers assistance to Roger cleaning the wash-out pit.

Axle-Box Dust Seals

Rebuilding is coming on apace and soon we'll install the frame on its wheels. First we must prepare the axle-boxes. The bearing journals are being cast and I spent last Saturday making the dust seals that sit behind the journals, between the bearings and the wheels.



The image shows the pattern that I made first as it fits into the slot in the back of the axle-box, which is upside down in the picture.



I thought we could make the seals out of plywood but Ollie thought that it would delaminate and break across the narrow areas at the sides of the axle. It turns out that the originals probably were made from plywood with an oversize hole for the axle and the actual seal made by having a large leather washer fixed to the plywood and bearing on the axle.



We did a little research and I had a chat with John the engineer about possible alternatives. I suggested something like resin-bonded linen which I remember from my father's engineering days. Old technology, it seems. A search of the engineering catalogue brought us a high temperature, self-lubricating nylon material good for making bearings - at £72 for two small sheets!

I had made a pattern first to check for fitting, that's it in the photos up there.



Now I set about cutting and fitting the (expensive) nylon material.

I'd measured the thickness I needed from one of the axle-boxes and that was my first mistake. The axle-boxes are not identical so the thickness I needed was a nominal half-inch. I'd ordered 12mm thick material, which is just less than half-an-inch so I thought it would fit easily.



I had to file the thickness at the edges so that the seal would slide into the slot in the box, and then I had to thin the end where it goes high up into the box to accommodate the varying thickness of the box itself due to casting imperfections.

In the end it took me several hours to make just two of the seals and we haven't cut the holes in them yet for the axle to pass through. I'll do that when I have the journals set up in the axle-boxes and can accurately mark the centre of the axle. Meanwhile each axle-box is numbered and there's a corresponding number on the seal for that box.