2 Times

Marine compound engine

Building 2-Times

As this would be the foundation for the whole machine it seemed a good idea to start here. Once I had sorted out the dimensions, it was time for a visit to the local shop. Over here in Antwerp there is a firm that can supply cast iron of good quality. But I must admit the size of the raw material was beyond expectation. I had ordered the block with a sawing allowance of 5mm and they had added an extra 10mm !

I did not have to fear because the size just fitted the capacity of the milling machine. I had quite a few hours of pleasure milling it out but I enjoyed it. The leftovers, which the bandsaw nicely cut off, are kept in store for future use.

These are made of bronze and split in halves.

By boring the holes first and using a jig to finish the outside I was able to fit them in with a minimum of adjusting.

It is at the moment only part finished. Much will depend on the later arrangement for the coupling and the reverse mechanism. For the time being only the cranktaps and wings are ok the rest is simply a bar to hold things in place. Machining the wings proved to be just within the capacity of the trusted ML7.

 

These proved to be rather complicated parts. As I had fear they would deform during the process of welding I made them generously wide. Things went well and they came out quite nicely with only a minimum of deformation. Next they were milled to the final width. The mounting against the base and face for the crosshead were milled in one set-up.

These are made of two pieces. The part that slides against the columns is made in bronze and the body is made in steel. The slides are so constructed that the width can be adjusted with bolts. The clampingplates need adjusting with chims to set them properly.

As usual they start as a solid lump of steel. In this case a round bar which needs to be centered in the lathe. For this I use the three jaw with a fixed steady. The work starts with facing the end of the bar and there is the first trouble. The swarf tends to get caught between the workpiece and the rollers of the steady. To prevent this I simply hang a piece of card with a suitable hole in it over the steady. Looks funny but it works nice.

The next step was to mill a datum square at the end of the bar. One side of the bar got an extra piece bolted on to form eventually the caps of the top bearings. Both ends were milled at the same set up, to the same size.

Back to the lathe then and the centre piece of the rods was turned to the right profile. For the rounded parts I used a home-made radius turning fixture. The size and the place of the radiuses were found using a cad drawing. Amazing those computer things, whatever size you want to know it's just a click away.

Then milling the ends of the rods and drilling the holes. Always using the reference faces as a guide.

The finished rods with the bearing bushes. It is pictured on the home made surface plate. Simply a sturdy piece of glass resting on a piece of wood.

 

In the next pictures you can see the making of the bearing for the balance arm of 2-Times.

First locating the centre of the boss, centre drilling, enlarging with a drill, and finally bringing to size with a boring head.

This picture shows the balancing arm assembly for 2-Times.

Thenů Well it could not be delayed any more. Time to start at the cylinders. It took a lot of drawing and sketching but in the end I decided to make the block in two parts. LP and HP separately. So here we go for the HP side.

I don't know how I would do without but as always things started with a lot of bandsawing. And I mean a lot. When I ordered the cast iron block for the cylinders I made a little allowance for the sawing, say 5mm on either side. To do me a favour they added an extra 10mm and rounded off to the next bigger stock size. When I entered the workshop with this masterpiece the machines all scrambled for the door.

My way of dealing with such a large lump is clean one side up with a mill of 12mm and then flycut it. The mill of 12mm removes the excess very quickly not posing to much strain on the machine and the clamping. Thus only leaving about 2-3 tenth of a mm to remove with the fly cutter. Using this face as a reference the rest of the block is finished off nice clean and square.

As there is a lot of material to be removed from the outside I have decided to bore the hole first leaving it about 2mm undersize. This will be finished later together with the removing of an extra 0.5mm from the base of the cylinder. To bore the cylinder I mounted it on the cross slide of the lathe and drilled it trough. Finishing with a subsequent bigger boring bar between centres.

 

Next came the finishing of the outside which also meant rounding off part of the block. For this I used the Vertex rotary table mounted on its side and supported the block with a makeshift bracket. Things went quite straightforward just turning it an extra 5░ round each time.

 

After the drilling of the planned holes things looked like this.

I suppose you wonder what the holes in the side of the cylinder are for. These are for something I would like to try out. They are intended as passages for hot water from the boiler. The idea behind it is that whilst firing up the boiler from cold the water running through these passages would preheat the cylinder block. I hope this will make starting a bit easier with less of condense of steam in the cylinders.