Julian

What are your thoughts on return cranks of the following nature?

Instead of squeezing them on, having a locking bolt?

Are there any disadvantages to this type of setup apart from the crank moving if it is not tightened properly?

Here are a couple of photos with nuts in place, just wanted to see what M2 would look like. I think I prefer it.

Here are the machining and machined pics of the steam chest with one side done.

Has anyone included a blow-down valve on their Tich?

The original drawings do not include for one and LBSC does not mention it in any of his "words and music".

I am informed that this is a very important addition to the boiler and want to find out if any Tich owners have done the same.

Hi John

Thanks for the advice.

I thought I would show some amazing Tich model engineering photos.

Very nice.

The next step was to drill the holes in the Rear covers. Firstly I found the height of the cylinder bore as per below.

This was then used to locate the guide bar hole at the correct height.

Above you can see I have made a black mark with permanent marker on the interface between the two parts, this will be used as a locating point for future work.

Below you can see a scribed mark which will be used for alignment

A machined washer was then placed onto the cylinder face and aligned so the holes missed the steam passages. A mark was then made on the washer for location purposes.

The washer was then transferred to the rear cover boss and the two marks aligned for drilling.

A quick check of the hole to the left of the red mark on the washer clearly shows that if drilled, it will clash with the boss. A new hole, further around the PCD was then drilled in order to provide for the correct clearance.

Below the rear cover has all holes drilled and tapped. You will notice that the screws on the left side are slightly closer together to allow for the clearance mentioned above.

Here are the front cover holes drilled and tapped.

Here is a GA of the right hand side cylinder. All I need to do now is cut the screws to the correct length.

Here are another two views of the assembly, front and back.

I then made a small jig to cut the screws to the correct length and file the chamfers etc.

These are the results:

Here is a close up of the threaded valve and piston gland bosses and guide bar holes:

I did the glands for the valve spindles and piston rods for both sets of cylinders two weeks ago. Here are the results:

I did not have hex bar so I used normal round rod. I will machine spanner grooves or drill some holes to suit a micrometer wrench later maybe, not sure if i really need it?

I have also been copper smithing and finally made more progress on the boiler.

Above you can see the strap for the butt joint along the length of the barrel. I was going to place this inside but discussions at the club have lead me to believe it will be easier to braze if placed on the outside, so that's what ill do. I have included the two scrap throat plates in the pic as I am baffled. I made the first one and it ended up being too narrow, I thought I had made a measuring error, but when I double checked the measurement on the second one and the same result was obtained I could not believe it… I ended up adding an extra two millimeters to the width between the bend lines and it worked. (I still don't understand this)…

Here the throat plate is clamped to the wrapper and the internal semi-circle traced onto the throat plate.

Here is the throat plate after removal.

Here is the throat plate in place with some of the rivets that will be used.