Textile Mill Diorama

[J.L.]

Good information John. Thanks.

Tug, I welcome your input very much on the timing of the slide valve. In 1946, when O.B. Bolton drew the plans, he too did not consider threading the valve nut either. He employed flats to engage the tangs of the slide valve instead. But as I see it you are committed once those flats are filed.

The suggestion given to you makes so much more sense and, as you say, gives infinite control of the placement of the slide by means of the grub screw.

Wonderful advice!

It's the same setup as for the piston rod. It is not threaded. It slides back and forth for placement in the boss of the crosshead and is secured also with a grub screw at the side. When the rod is in the correct position, a hole is drilled through the boss and the rod from the top for a permanent pin.

Thank you so much Tug. Your timing (no pun) is perfect. I will be working up the slide valve soon.

John

[J.L.]

A cast gunmetal connecting rod came with the cast parts for this engine. This may have been well and good for someone making a display model and not worrying about authentic practices of the time.

But in a diorama setting, where the goal is to represent as closely as possible, the way things looked in that time period, it was immediately dismissed.

I had the rod machined for me with much heavier equipment out of cold rolled steel. I saw the 1 1/4" round rod from which it was turned. It was over two feet long! I guess they wanted to have lots of grip and chew it out of one end of the rod. That's why you see a radius on the edges of the fork and the foot.

My first crack at the finished rod was to make and place the bearing clamping plate at the big end of the part. I couldn't support the foot in my milling vice. It would have been waving around way up in the air. Instead, I used a drill press vice and let the fork dangle down through the hole in the centre of the drill press's table. The jaws then gripped the foot firmly.

[J.L.]

I was under the impression that a split bearing had equal amount of material on both sides of the split. So, a 3/4" block of metal should be able to be made with two pieces 3/8" each. I guess you should not assume such things without checking the drawings.

After milling the two halves of the gunmetal casting (joined) to exactly 3/8", I did look at the drawing.

You will see my error.

I could shave down one 3/8" side, but the block would no longer be 3/4" in thickness. I never thought to check the location of the hole in the block.

[zeeprogrammer]

I think I understand why you might not leave it as is but I'm wondering if there was a reason why the hole wasn't centered.

[john mills]

It would be good to check when the rod and bearing is assembled to the cross head and crank shaft that the the pistons rod and piston will travel in the correct position ,piston travel even clearance at top and bottom of the stoke in the cylinder. if adult meant is required the final thickness of the top block can be made to suit.now is to find out if any errors.Fine tuning can be made.  I don't know how the component assemble and what adjustment is possible.i don't know how important the thickness is for the bottom half ,i don't think it would matter most important have it look right to you can machine more of later .or may have to fit shims.
The engines i have built the thickness for top and bottom varies top often thiner.l

[J.L.]

Not sure either Carl.

Hi John,
Yes, there will probably be a lot of shim work with this engine. The trick will be to set it all up temporarily to test the travel of everything. That means clamping awkward parts in the power train.

But I must say I'm looking forward to finding out how close the diagram distances are to the actual setup. There's always a way of compensating here and there. I think that's what makes getting things running nicely so enjoyable.

[J.L.]

Here is the gunmetal big end bearing halves being fastened together. I chose to not soft solder them.

[J.L.]

I was having trouble getting this casting set in the four-jaw so that it's face was perpendicular to its axis. That's where the tailstock chuck really came in handy as shown in these photos.

I honestly thought I had lost this casting a couple of steps ago, but phoenix may rise out of the ashes yet.

[J.L.]

Success with the parts.

Now for the fit...

[Roger B]

Still following along (trying to keep up)  Splendid work as ever and some interesting solutions to some problems like keeping the valve cover in place and cutting the brass strips     

[J.L.]

Hello Roger,

Thank you for your very kind words. Sharing ideas is the game here. We are very lucky to have a forum of this calibre where we can learn, share and advise.

Hopefully it will be available for a very long time. Many of the fellows are aging and from what I've read, some of the annual shows are dwindling in attendance and participation. Times are changing and I wonder how many of our next generation will experience the thrill of creating model engines and watch them come to life.

On a brighter note, here are two photos of the ends of the connecting rod's fork being drilled and threaded for #2-56 grub screws. It was a bit of a risk working so far up and out of the supporting chuck, but if I don't break a tap, it will have been a success.

Love that threading device to keep the taps running true.

Thanks again Roger,

John

[scc]

I'm enjoying (and learning) with this thread. The engine is taking shape nicely and the building parts are wonderful. The black sliding door especially is spot on. I can almost here the rumble and bang when it shuts!    Well Done   John.............Terry

[scc]

Sorry          White door,   black track

[J.L.]

Thank you Terry.
Building that metal clad fire door was a lot of fun.

I tried to make my own crosshead pin and fit it to the gunmental block that fits in the crosshead frame. It did not go well.

So, I decided to go with materials that are made with precision. The cross pin in photo two is a hardened, polished steel dowel pin.

In photo one, a bronze sleeve has been pressed into an upsized hole.

The grub screws in the end of the fork have been increased in size to #3-48.

Almost ready to put some of this engine together. 

[J.L.]

The Crosshead...