6" Ruston Proctor Traction Engine - Model Build

Some more photos of the wheel assembly

The spokes are retained in a slotted hole the wheel hub and held in place by countersunk cap screws

The countersunk cap screws can be seen here. The spokes are a slide fit into the hub slots and at assembly will be coated with epoxy glue to fill any gaps and seal them against moisture. A cover plate is bolted onto the outside of the hub thru the holes in the spokes into threaded holes in the hub.

Wheel turned over to drill spokes on the other side

Hub and spoke assembly with temporary bolts which will be replaced by rivets after it has been welded to the wheel rim. Hub cover shown in place

FLYWHEEL

The flywheel is 15" diameter x 2" wide and was supplied as a casting. Again, I had to use a mates lathe as it was too big for my little Southbend.

I used the inside lip on the flywheel to hold it in a 4-jaw chuck. The lip was small and slightly tapered, so cut a center hole and used the tail stock while turning the outside and the side of the boss in case it came loose. Then drilled a hole thru the casting and bored the hole to the correct size.

The crown on the outside edge was formed by cutting a slight taper on each edge, then blending it into a radius. The flywheel then rotated and held by the boss to machine the other side.

PRESSURE RELIEF VALVE

I ordered a gunmetal casting for the pressure relief valve body and a tension spring. The remaining parts were made from materials which I purchased (or scrounged) locally.

Base of the valve body being milled flat

Casting top machined and port holes being marked out.

Holes for the two valve ports being drilled.

Recessed holes for valve inserts bored to size

The valve cover was made from a piece of brass bar and cut to a rough shape. The saw, held in a collet chuck sliced thru the brass like butter.

Turning the valve cover.

The drawings for the pressure relief valve had brass insert with a flat surface on top to seal against the mating part. I made my inserts from stainless steel with a tapered seat.

Using a vice to press the insert into place.

Cover bolted in place for milling a slot for the valve retention lever

Valve insert being turned from brass bar stock.

Three vertical slots being milled in the side of the wing valve on a rotary table.

Machining the sealing face of the wing valve.

Pin for valve spring being machines.

A cut-out in the side is provided for access to a nut inside which is used to adjust the spring tension.

Machining of the valve lever which keeps the valve inserts in position.

Finished valve parts prior to assembly

Pressure relief valve fully assembled.

Note the holes in the side of the retaining nut inside which are used to set the release pressure by adjusting the load on the spring. The nut is retained by a lock wire to stop it coming loose after the pressure is set.

TESTING VALVE SEALS & SETTING RELEASE PRESSURE

The pressure relief valve attached to a testing plate for checking for leaks with the valve inserts and for doing a preliminary release pressure setting. Each valve can be checked individually.

Note: these tests can be done with compressed air but the final setting must be done on the engine with steam.

The test plate has an “O”-ring that seals against the underside of the valve, allowing each side to be tested independently.

The test plate can also be used to blank off the steam chest when the boiler is being tested.

Note: This test must be done by pumping water into the boiler. Air within the boiler must be purged before pressurizing the boiler because air is an expandable medium and if the boiler fails, could explode. Water does not compress (well not much) and if the boiler fails under pressure does not explode.

Very clear post, Danny. Does the cross-arm on the valve have dimples for the cones on the valve bobbins?

Neil

(Continued build log from part 1)

MACHINING THE STEAM CHEST

The steam chest is the largest casting that was supplied by LSM and weighs 22 kg, and is probably the most complex piece to machine. It was also the most difficult measure to make a model in 3D. The drawings of the steam chest had dimensions for the machined surfaces and bolt holes but not for the other features of the casting. Attempting to measure the shape with a rule and straight edge was too difficult because of an accumulation of measuring errors and I was not happy with the outcome. I had just fitted a DRO to my SX3 mill and decided to use this for a more accurate solution. (The SX3 mill is just big enough to machine this size casting).

MACHINING THE FIRST FACE OF THE CASTING

Machining of the front surface of the steam chest casting using a 32mm cutter with replaceable carbide inserts. As this was a raw casting, there were no accurate faces to use as a datum for the milling setup and many double checks were made before settling on this position.

MACHINING THE LEFT HAND SIDE OF THE CASTING

The casting was turned on its side to machine the mounting face for the reverse valve cover and slide valve seat. Holes drilled and tapped for threaded studs which will hold a cover plate.

After cleaning up the casting with an angle grinder and a small hand held belt linisher, the front face was drilled and tapped for the front cover plate. These tapped holes would become a datum for cutting the bore in a later operation.

My solution for holding the casting in the lathe was to use an old car brake disc as a face plate.

The front side of the brake disc was flat and did not need machining, except for a slight ridge on the edge where the brake pads had not worn and I ground these off. Then clamped the disc to the top of the mill table and took a slight cut on the top surface to guarantee that it was parallel to the bottom. A series of mounting holes to match those on the front of the steam chest was next. The steam chest was bolted to the brake disk and held in the lathe chuck for facing the rear side of the casting and for boring the hole for the cylinder liner. The rear side hole was made slightly bigger than the front for ease of pressing in the cylinder liner. The rear end of the cylinder liner is slightly bigger than the front. Both ends will be a press fit into the steam chest.

Machining the bottom of the steam chest which bolts onto the top of the boiler in a BIG MILL. Normally the table is the part that moves, but on this mill it is stationary and the head moves. The steam chest is that little thing under the cutting head and the piece of 10” dia pipe in the middle of the picture is an offcut from the boiler barrel to use as a reference. I have allowed a 1mm gap between the boiler and steam chest for a gasket.

The steam chest, still attached to the brake disc and clamped to the mill table.

Mounting face of the steam chest being machined. We did not have a suitable cutter and first tried a HSS fly cutter but kept bluntening the tip on the cast iron. Then used a standard lathe tool with a carbide tip which worked well. Just had to run the mill in the reverse direction to suit the handing of the lathe tool.

Edited By Paul Lousick on 18/11/2015 09:56:14

Edited By Neil Wyatt on 19/11/2015 13:31:24

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

Hi Neil,

Who is Danny ?

With my last addition to my build post, I got a message that I had exceeded the allowable size, started a second thread.

What is the file size limit ?

Paul.

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

Hello Paul,

You exceeded the size for individual messages, overall thread length is unlimited (I think).

I have sewn the two threads back together.

Thanks for persevering

Neil

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.

MODEL BOILER DESIGN and MANUFACTURE

Boiler design for the original traction engine

The boiler on the original full size traction engine was 20” OD x 85” (508 OD x 2160mm) overall length.

Boiler wall thickness: ½”

Distance between tube plates: 36”

Fire tubes: 4 x 3” dia and 19 x 1.5” dia.

Boiler for 6” scale model boiler

The drawing for the model boiler specified a 10” OD x ¼” thick steel plate but 10” OD (254mm) is not a standard pipe size and the Australian Miniature Boiler Safety Code specifies that I use ASTM A 106 grade with a wall thickness of not less than 6mm.

I chose to use 10” NB schedule 40 pipe which is the standard commercial size and is 273.1mm OD x 9.27mm wall thickness. Flat boiler plates are 10mm thick.

Because the barrel diameter is bigger than that shown on the model drawings, everything else had to be made wider. The crankshaft has to be made slightly longer and because the hornplates are further apart, the rear axle is also longer.

3D Models of 6” Scale Boiler created with Solidworks

Sectional View of Boiler

The boiler barrel was supported by a piece of pipe and held at both ends to take the load off the table of my SX3 mill while I machined holes for steam & water ports and for the manhole opening.

There was just enough space under the milling head for this operation and the sliding table is too small to carry such a big load.

Each hole was roughly cut to shape with a rotary broach cutter.

Holes in boiler being bored to their finished size.

Boiler barrel mounted on a specially made trolley which is used for the assembly of the boiler.

The barrel is at the height of the finished engine and can be rotated on the trolley for different assembly operations. It is shown in this view after being trimmed for the firebox plates. The cuts were made with a 1mm blade in an angle grinder.

Weld preparations cut by hand with a carbide rotary burr in the chuck of wood router.

I found the router in the bargain bin of my local hardware store, less its accessories for $15. It has an 800 watt, variable speed motor that spins up to 22,000 rpm and easily cuts thru steel plate.

Edited By Paul Lousick on 23/11/2015 08:44:22

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

The front tube plate was supplied at the correct diameter to fit the inside of the boiler barrel and did not need machining. It is being drilled here for the fire tube holes and for an inspection hole at the top and 2 x holes for boiler stays beneath. A smaller inspection hole will be drilled at the bottom after it has been welded into the barrel, it is too close to the edge of the plate and may distort from the welding heat if it is drilled here.

The plate was positioned on the center of my rotary table for cutting a “J” shape weld preparation on the edge because there is not enough space between the tube hole and the edge of the plate for a bevel weld.

The milling head was rotated by 20 degrees to produce the shape and cut with a round head cutter to make a radiused cut at the bottom.

The plate is 16mm thick boiler plate and a bit tougher than mild steel to cut. This put a big load on my mill and especially the rotary table. The small tables only use a small screw and the teeth cut into the worm gear are less than 2mm deep. The repeated impact of the cutter on this plate broke some of the teeth. F #%%%$####*&&&##

The support ring for the manhole opening had to be machined to suit the outside radius of the boiler. The inside surface that is used to seal against the manhole cover is normally curved to match the shape of the boiler barrel but this one is flat on the inside making it easier to seat against the cover . I laid it out on the computer to determine the necessary radius and fabricated a support jig for mounting it on my rotary table. (This was after I broke off some of the teeth so selected an area which still was intact.)

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

View of the temporary assembly of the outer boiler fabrication and the fire box using the holes for the side stays as locators. The temporary round bars are the same diameter as the side stays.

View of the assembled boiler on the support trolley.

Boiler assembly rotated to the correct orientation with manhole reinforcing ring, steam ports and fire door ring in position.

Boiler rear view (rear plate removed)

Boiler front view (front tube plate removed)

Note: Two extra holes for tubes will be cut after the fire box is welded. The holes are too close to the edge and may distort at welding.

Details of the assembly jigs which were made for holding the water and steam ports in position while they are being welding in place.

Sockets for the ports and fusible plug were made from round bar. These will be welded into the boiler shell. The BSP threads were not fully cut and will be finished after welding, in case there is ant distortion at welding.

The Boiler Manhole Bridge was fabricated from a piece of round bar and two profiled plates for the wings. The wings were welded to the bar and cleaned up on my mill. The fillet radius was cut with bull nose cutter. A clearance hole for the manhole clamping bolt is being drilled.

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

WELDING OF BOILER

The majority of the welding of the outer shell of the boiler and the fire box was carried out with a TIG welder. A stick welder was use on a couple of places where there was limited access for the TIG. The welding process took much longer than expected but the finished welds were excellent.

Good grief, that's pretty darn neat welding. Must be one hell of a TIG welder to cope with thick steel plate? What size electrode and were the welds done in one pass?

Andrew

Welding done by a top class welder who normally works on high pressure piping with years of practice. Used 2mm rods and multiple passes to build up the weld using a $6000 welding machine. Most of the welds were done from one side only and required a big joint preparation to achieve full penetration. Took about 15 hours to complete the job and consumed an E-size bottle of Argon gas. And boiler not finished yet.

Edited By Paul Lousick on 01/02/2016 12:09:26