Hi John

Mass, A Tich will weigh more in the UK than in South Africa…

So 20 pounds is roughly 9 kg and i'm guessing that the tanks and boiler would probably hold about two litres of water, giving another 2 kg.

So 11 kg as an estimate?

So on to the cylinder mounting…

I first had to open out the holes in the frames to the correct size. This was not done originally as I was unsure how I was going to mount the cylinders.

The frames were placed onto parallels on the mill bed and the holes opened out.

A long drill was then used to poke between the frames and make a small countersink on the cylinder mounting face.

The cylinder was mounted on the frame with the left crank at back dead center and the connecting rod directly in line with the piston rod. LBSC describes this procedure fairly well so it turned out O.K.

I used a hand held power drill at a slow speed to create the countersinks on the cylinder mounting face (not shown).

The countersinks were drilled out and tapped M3. Following this, both cylinders were mounted onto the frames.

I am happy with the result!

I have also just moved house so here is my new work space. I still need to move things around and organise all my tools, but I could not wait to get started again on TICH.

This last weekend a turned the LHS piston and the fit is great. If I blow into the steam chest and actuate the valve, the piston moves accordingly which is very cool.

I will post some photos of the piston and piston rods etc. (You can see the RHS piston blank in the pic above).

I have made a start on the gear link frame fabrication. The jig works a charm.

Here are the pics thus far.

I still need to cut and file the small square block for the attachment to the guide bar. This will then be held in place by two steel bars and two pieces of threaded rod as can be seen in my previous post of the 3D model.

Here are the pictures of the gear link frame clamped to the frame.

According to LBSC's words and music, the distance indicated as 25.35 mm above should be 24.6 mm and according to my slight redesign, 24.7 mm.

It is clear that the as-built dimension is 0.65 mm longer than drawn and hence the deviation of the guide bar mounting block from the guide bar.

The method of fabrication I have used does not allow for any surplus material to be removed from the mounting surfaces or any of the other faces. I think I am going to re-look at this component again and produce a more refined methodology for the fabrication and machining of the frame.

Any constructive wisdom would be useful…

I will also be using 4 mm plate for the sides and the small block. An allowance of 0.5 mm on each face will be made for machining. All the sizes have been adjusted accordingly.

The brazed frames will then be machined in the mill to final sizes and hopefully turn out better than their predecessor…

I have used the brazed gear link frame as a test piece for machining. Here is the machined piece.

There was some chattering when doing the outer trunnion. I will have to insert a distance piece for support when I do the final motion frames.

I have set aside the gear link frames for now, to work on something new to keep the interest flowing.

I have started on the combination levers.

The levers are going to be machined from one piece, together and then split into separate levers and the final profiles then filed.

I first marked off the relevant sizes and hole positions with a scriber in the collet chuck.

The 2 and 3mm holes were then drilled and reamed.

A slit was then cut using a slitting saw.

The saw was used at the lowest speed on the mill (80 rpm), with a cutting fluid of paraffin and oil, judiciously applied. The embryo lever was fed onto the saw in the direction of the rotation (climb milling) carefully.

The slit was cut to 6 mm deep on the first cut and then to the final depth of 11 mm on the second cut.

Cutting the slot took about 2 hours but the result is perfect.

Here is a photo after the first cut

The bulk of the lower portion of the embryo lever was then milled away to the final thickness and the radius milled using a ball end mill.

Here are some pics after the milling procedures.

Now I need to cut the individual levers out, draw file the milling marks away and finally file the profile of the combination lever. I will be making filing buttons for the ends out of hardened silver steel.

(All of the milling procedures were performed with the material in the same position in the vice. So I had to place the material in the vice ensuring that there was clearance for all of the operations.)

Edited By Ryan Norton on 13/11/2016 10:39:52

Edited By Ryan Norton on 13/11/2016 10:42:32