SUPPORT JIG FOR FINAL MACHINING OF THE STEAM CHEST

Making a jig to support the steam chest by the cylinder bore while I machined the other faces and for drilling holes.

The steam chest supported by the jig and able to be rotated about the bore axis. (Just fits on the mill)

The mounting holes have been faced and the holes are being drilled.

Final machining of the slide valve.

Steam drain ports being drilled and tapped.

Drilling steam port hole from the cavity in the casting base to a cavity around the cylinder lining.

The regulator slide valve is mounted on a shaft which goes completely thru the steam chest and I did not have a drill long enough to drill completely thru from one side. My solution was to drill and ream the hole to size from the bottom side in the photo then turn it over and drill a bigger hole on the top side. (Fortunately the hole on this side is much bigger to accommodate a gland fitting). I then fitted a piece of bright bar in the bottom hole and found its center and opened up the hole with a boring bar.

There was a mistake in the casting and the boss (shown in the previous photo) was too small for the gland fitting. (supplied as a gunmetal casting). The solution was to mill it off completely and have a slight recess as shown.

Cover plate for the side of the steam chest. Holes still to be drilled

Cover for the front of the cylinder liner. The supplied cast iron casting was firstly turned and polished on the lathe before drilling the holes. The spotface made by plunge cutting with an end mill. Although not completely flat because of the shape of the end of the cutter, they will be OK.

Edited By Neil Wyatt on 19/11/2015 13:32:11

TRUNK GUIDE

The trunk guide attaches to the rear side of the steam chest and guides the piston cross-slide, keeping the piston on center with the cylinder liner. Fitted inside the guide at the steam chest end is a shaft packing gland which seals the piston rod to stop steam from escaping.

Below the trunk guide is a mounting plate which supports the control lever shaft for the Stephenson reversing assembly.

The trunk guide casting was cleaned up with an angle grinder and a small hand held belt sander then mounted on a mandrel made from a piece of threaded bar. Cone shaped wedges located the guide on center with the holes in the casting and a lathe dog clamped to the mandrel for turning. The cutting tool caused the casting to slip on the mandrel so I added a drive plate in the middle to turn the casting.

Trunk guide mounted in a chuck on a rotary table for machining the bottom plate and oil drain.

Note: The cross slide is drip-fed with oil from a small reservoir on top and has to be drained or will splash everywhere. In full size engines the oil just runs onto the ground but I will add a small tray to collect it (and save my driveway).

The trunk guide has a spigot on the mounting end which locates on the bore of the cylinder liner but this was too narrow to hold such a long part in a lathe chuck. Instead I clamped a 6” dia steel disc in the chuck (an old pipe flange), took a slight cut on the front to face it and opened the bore up for a tight fit with the trunk guide. Then clamped the guide to it. The tail end also supported on the lathe for extra rigidity. The internal diameter then bored to size.

I had to make a special tool for cutting the internal face of the casting and boring a hole where the piston stuffing box is fitted. CAD was used to layout and draw the special tool which holds a small carbide boring bar. One that I use on the boring head on my mill.

Edited By Paul Lousick on 19/11/2015 08:54:14

Edited By Neil Wyatt on 19/11/2015 13:32:28

SMOKE BOX DOOR – It is mounted on the front of the engine and provides access to the front of the boiler for inspection purposes and for cleaning the inside of the heating tubes. Regular cleaning is necessary to for the efficient heating of the water to make steam.

The outer housing for the smoke box door was supplied as a heavy cast ring, a casting for the door itself and a cast nameplate for the front of the boiler.

The front face of the smoke box door being milled flat, then bolt holes were drilled for attaching the name plate casting.

The door hinge has been faced on the rear side and mounting holes drilled for securing with rivets to the front of the door. It is shown here being drilled for the hinge pivot pins.

The OD of the name plate has been machined and the center boss face cut on the lathe. Hole being drilled for a bolt to hold the door in the closed position on the boiler.

Trial assembly of the door and tapping of the holes for the hinge blocks.

Door support ring on a lathe, turned to size and a radius cut on the outer corner.

Final assembly of the support ring and the door. The bolts holding the heat shield will be replaced with rivets.

BOILER FABRICATION

The pieces of plate which make up the boiler were plasma cut from boiler plate (460 MPa steel) and machined to the finished size on my SX3 mill. All joints for the plates are full penetration welds and have to be made by a certified welding operator and beyond the capabilities of myself. That will be done by someone more qualified. The weld preparation is a combination of bevel welds and “J” shaped welds.

Bevel welds are far easier to machine (or grind) and “J” welds much harder. The advantage of “J” shape weld preparation is that they are more compact and the cut is not as wide.

The holes for the firebox wall stays were cut with a rotary broach, held by a collet in the mill and then chamfered for welding in of the firebox stays.

The rear plate of the boiler is mounted on a rotary table and a full depth chamfer is being milled leaving a 1.5mm flat on the bottom of the hole of the firebox opening. The exact location for the centers of the each side of the hole is not that critical and was done so "by eye" to line up with the circles which I scribed on the mounting plate below.

The boiler rear plate is supported at 20 degrees by a jig and is being milled by a cutter with a round insert which will produce the shape required for the “J” weld preparation on the edge. (Note: My milling machine can only rotate in the sideways direction and need this support for an inclined cut in the other direction.)

Front boiler plate on a rotary table and being milled to clean up the profiled plate. A fillet weld preparation on the edge was cut after this one.

Checking the fit with a piece of boiler tube allowing for a 1.5m gap between the pipe and the plate. The 1.5mm gap is required for a full penetration joint when it is welded.

Boiler side plates being machined to final overall size. And drilling holes for the firebox stays.

I aligned the first edge of the plate to be cut and made a clean-up cut then accurately rotated the plate to clean-up the second edge. Then used these 2 edges as datum to machine the remaining edges. The 2 datum edges were then used to mark the positions for the holes using the DRO on the mill. Then double checked all dimensions before cutting the holes. (I have learnt the hard way that it is good practice to measure twice before cutting once. Or having to cut twice if you do it wrong).

Edited By Paul Lousick on 25/11/2015 11:41:08

Detail of the boiler manhole and support ring. The surface of the inner surface of the support ring is flat and not curved as normally found in conventional boiler designs. Although it will protrude slightly into the inside of the boiler, it provides a better surface to seal and makes the manufacture of the manhole much easier.

The steel plates for the inner fire box were profile cut from boiler plate and machined on my SX3 mill in my home workshop. The side plates were sent to a commercial company for bending in a CNC machine which produced the required radius and bend angle. The sides were made as 2 separate pieces because it is too difficult to bend a “U” shape accurately and maintain the required dimensions.

The height of the plate was milled to correct size and the edge machined for a weld preparation.

Cutting holes for boiler firebox side stays with a rotary broach.

Cutting holes for boiler firebox side stays with a rotary broach

Countersinking holes for weld preparation.

The holes for the fire tubes were drilled slightly undersize and will be reamed after welding for a slide fit with the tubes. The tubes will then be swaged with a special tool to expand them and create a steam tight seal. The initial pressure test for the seal will be twice the designed working pressure of the boiler.

Milling a “J” shaped weld prep on the outer edges of the tube plate.

The foundation ring for the bottom of the fire box being machined to the finish size.

The boiler foundation ring has been machined with a “J” shape weld on the inside and the outside. It is too narrow for a standard bevel weld on both sides.

Firebox crown stays were profile cut and only needed a slight clean-up.

The assembly of the firebox. Now ready for welding and inspection before it is finally welded into the boiler.

View of the inside of the fire box showing the temporary support brackets that are tack welded to the plates. The brackets are bolted together, allowing me to dis-assemble the plates if required for additional machining.

Edited By Paul Lousick on 28/11/2015 08:48:38

In the words of that famous cartoon rabbit

This engine build has been a record of the main components of the Ruston and Proctor steam traction engine that I have been building for the past 3 years. I now have to manufacture some of the remaining parts but will add more posts when they are completed.

Thank you to all of the readers who have sent encouragement and positive comments about this post.

I have one more thing to add :

A challenge to other readers to add a bigger model build post.

Paul.

Edited By Paul Lousick on 28/11/2015 09:25:40

Building my Ruston proctor SD traction engine has been massive project and I am nearing the end after 6 years. I have posted updates on the Traction Talk web site, also a lot work. This is a link to the site for anyone interested.

Paul

**LINK**

EDIT. You will need to be a member to see the posts and it can be a long drawn out process to get approved.

Edited By JasonB on 16/02/2019 09:14:10

6" Ruston Proctor SD – Hornplates

The Australian code for model steel boilers shows the hornplates attached to support brackets on the side of the boiler and not to threaded holes in the boiler side stays. Loading bolts in shear is not good design practice and not recommended.   I also added a plate at the bottom of the hornplate which the boiler sits on, eliminating the shear force on the bolts. Having a gap between the hornplates and the firebox with no direct contact will also help to insulate the boiler.

Both hornplates were plasma cut and tacked together to enable all holes to be drilled at the same time using the milling machine’s digital readout to accurately position all holes.

The large hole for the crankshaft bearing rough cut with a series of large holes using a rotor broach in the mill, then finished to size with a boring bar.

The mounting plate for the steering chain shaft was attached to the hornplate with ¼” round head steel rivets. The rear of the hornplates were countersunk and the rivets cold pressed requiring a force of 7 tonnes. The false rivets (just for show) were cut to slightly longer than the plate thickness and hammered flat with a ball peen hammer. They are non-load bearing and only need to be kept in place.

Edited By Paul Lousick on 16/02/2019 22:32:02

Machining Crankshaft

The crankshaft was purchase as a casting. The first operation was to clean up the crank area with a little fettling using a hand linisher and elbow grease.

The crankshaft was mounted on a piece of steel flat bar for drilling centres in the ends of the crankshaft allowing it to be rotated by 180 degrees and keep the same plane thru the centres at both ends.

To drill the holes, the mill head was turned to operate horizontally and an edge finder used to find the centre of the crankshaft. After drilling the first hole the mill table was moved by a distance equal to the throw of the crank to drill the second hole.

Balance weights and jacking screws to prevent shaft bending were attached to the crankshaft while turning the crank journal and the lathe cutter had to be lengthened to clear the crank.

A steel block was wedged between the crank gap to resist any bending by the lathe centres and a steady rest used to stop vibration while turning the crank ends.