Little Wonder

[Trevor Thompson]

I have been spending lots of time on K1 recently which explains the lack of activity on this (and 4420). However I have made the frame stretchers for the inner ends of the bogies:

Trevor

[Trevor Thompson]

It has rained here in West Wales for the last few days so I pulled this project onto the bench again.

I have cut out the frames for the boiler cradle, made the stretchers for the cradle and assembled it. I have also put the pivot stretcher onto each bogie, and made the connecting bolts. So here are a few views of the progress:

I suppose that I will have to start on the cylinders if it continues to rain:

Trevor

[Old Man Aaron]

The only thing equal in this thing's size, is the sheer amount of effort you're putting into it.

[Trevor Thompson]

The only thing equal in this thing's size, is the sheer amount of effort you're putting into it.

Lets hope the end result is worth the effort!

Trevor

[Trevor Thompson]

I have been squeezing in time to work on the cylinders (which I hadn't intended to start straight away) - carried away again!

So 4 sections of the block of brass have been parted off in the lathe and turned to size, width, length and height. I have marked the centre of the bores, and bored and reamed them all. Here are two of them:

I am carrying out each operation on all 4, rather than finishing one and then starting on the next. There is better efficiency in having the machine set up to carry out the operation and having the right tools for doing it to hand, and therefor doing it 4 times.

You might remember from my drawings that the valve face is an extension on the inner face of the cylinder which passes through the frames into the valve chamber. So the first operation was to mill 4.5 mm off that inside face to make the valve face protrude:

The end result required the sharp edges removing and the opening in the combined valve chamber/frame needed slight filing to get a good sliding fit. This is the first valve face and the hole it fits into:

The bolt heads holding the frame to the valve chest prevent the cylinder fitting right down to the frame at the moment - and I intend to mill out a pocket in the inside face of the cylinder to swallow the bolt head. I am going to do all the milling first - and then concentrate on drilling afterwards. So here are the 4 cylinders sitting as far into place as they will go at the moment:

I think it will be milling the bottom of the cylinders to make the flange for the bolts which will hold it to the frame next.

Trevor

[SimonWood]

This is really starting to take shape. The boiler cradle frames look superb.

[Trevor Thompson]

I keep going back to it!

All of the cylinders are now shaped and fitted to the frames. You can see the cutaway around the valve face and the hole in the frame through which it fits on the nearest cylinder:

All of the cutouts for the bolt heads are made, and the cylinder is secured to the frame by 4 bolts. From above the bolts fit from the inside:

From the bottom they fit from the outside. I had to make cutouts in the bottom of the cylinders to make room for the nut spinner to reach the bolt head:

And of course all 4 cylinders are now fitted to the frames.

On to the cylinder end covers, piston and rod next, and then drill all of the holes.

Trevor

[Trevor Thompson]

Four front cylinder covers, and 4 rear covers:

The basic shape turned, then milled and drilled in the rotating table. That ensures that the milled faces are perpendicular and centralised. It also makes it easy to ensure that the mounting holes are all 60 degrees apart (and on the same radius).

And now to work on the cylinders one at a time. The first piston is made and in the foreground of this photo:

As an aside I am finding that having a digital readout has made my work much more accurate. For example I was able to turn the piston blank to a diameter of 11.95mm and find it was a smooth fit in the bore first time. I then turned the groove for the O ring to 9.15mm diameter and 2.0mm width (for an O ring 12mm diameter and 1.5mm cord diameter), just using the readout - no trial and error. The piston with its O ring just fits first time with a nice smooth movement.

Really satisfying!

Trevor

[FWLR]

I bet it is satisfying Trevor. Your'e doing an awesome job.
Digital really does make things easier doesn't it.

[Trevor Thompson]

I bet it is satisfying Trevor. Your'e doing an awesome job.
Digital really does make things easier doesn't it.

Awesome until I made a mistake!

Drilling lots of 1.4mm holes I broke a drill, leaving 6mm of it in the hole.

So in the photo the hole in the end of the cylinder - the one that is uppermost has the drill end in it. I couldn't get it out with tweezers or messing with dressmaking pins. So I drilled a hole from the side ( you can see it) to break into the place near the tip of the drill and immersed it into the acid pickling tank. It took 10 days for enough of the steel to corrode away and enable me to tap the hole most of the way to the bottom. There is probably a bit left in it - and a hole in the cylinder side to fill, but the cylinder is recovered and usable.

I have finished drilling all of the holes:

The fresh looking holes in the top photo are for cylinder drain cocks, and are linked to the ends of the cylinders with 0.9mm holes. In both photos you can see where I have tapped and plugged the ends of the steam ways. There is a plug to make for the exhaust steam way you can see on the face facing the photo in the second photo.

Trevor

[Trevor Thompson]

The first cylinder is test assembled, and holding the air line on each valve port makes the piston shoot from one end to the other (as it should):

I have turned up ptfe rod into seals for the piston rod. 4.5mm OD, reamed 3mm ID, and 2.5mm long. An idea I got from Tony Bird a couple of weeks ago. Worth trying - If it doesn't work for me I can easily go back to ptfe tape wrapped around the shaft.

I am not sure how to tackle the cylinder drain cocks. The automatic ones seem temperamental. The trick seems to minimise the distance the ball has to travel to seal the drain hole - but I'm struggling to get consistent results. They work on Linda but not on K1 (at the moment). Back to that at a later date.

Just 3 more cylinders to finish. I'll be careful with the drill in future.

Trevor

[FWLR]

Easily done, breaking a bit in something. I have done it when I worked in the toolroom for the company I worked for many times. It is one of those things, no matter how much coolant I had running on it.

Still you have managed to get resolve the problem, well done. It works a treat now that's the important thing and it's onwards and upwards now.

[Trevor Thompson]

All four cylinders are now finished, steam passages, pistons, piston rods, drain cocks, and end caps all made and fitted:

The cylinder drain cocks are not actually finished, but the body of each drain cock is made and they are assembled onto the cylinders, with the passages into the cylinders made.

I am now making wheels:

Trevor

[Old Man Aaron]

Marvellous, just marvellous.

[FWLR]

Looking good. Nice bit of recovery there with that broken bit.