Reinventing the Real.

[steam guy willy]

Hi Jason , this is looking really lovely and lots of really nice photos to explain everything,....inspiring work

Willy

[Zephyrin]

this will gave a impressive and elegant engine, with ornamental turning, as old designs require...
another great thread to follow.
and yes, sharp an clear pictures to show the machining !

[Jasonb]

Thanks Chaps

A slice of CI was held in the soft jaws and turned to the diameter of the cylinder top cover, then faced and the spigot cut. I then spotted, drilled 4.8mm with a stub drill and finally took the hole out to the required 5mm diameter with a machine reamer.



Now holding the other way round the boss for the gland was turned leaving a flat area for the nuts, I used a brazed carbide tool with a rounded nose to get the larger fillet at the base of the boss.



With the cover screwed to an arbor which in turn was held in an ER32 block the outer edge was kept clear so the edge finder could be used to locate the cover's ctr then set about drilling some holes. 8 @ 2.5mm for the studs, 2 @ 3mm which were CSK on the underside for the cross head guide rods and 3 @ tapped M1.6 for the gland studs



The gland was quite straight forward turning to fit the cover and reaming for the piston rod.



Then held the other way round to face off, add a decorative spigot and CSK the hole to encourage any oil back into the cylinder rather than running over the engine.



Another small part tackled at this stage was the valve, just a piece of bronze milled to the overall size and then the recess milled into one face with a 2mm dia cutter



The opposite face had slots cut to clear the valve rod and at 90degrees to that one to take the valve nut which was just a offcut of brass left from the eccentric strap.

[Jasonb]

Returning to the cylinder and it's time to reposition the exhaust connection from the of the valve port face to the opposite side of the cylinder which is a bit less cluttered by columns and the now repositioned inlet. A piece of steel was turned to the same diameter as the cylinder end flanges then bored to the average diameter of the cylinder body. I then used an internal grooving tool to hollow it out to a sort of rectangular "U" section.



A 14mm diameter was turned onto the end of a bar and the Soba boring head used to cut a radius to match the outside diameter of the cylinder.



Then holding it in a collet block two grooves were cut that would allow the air/steam to flow from the new passages around the cylinder into a  drille dhole in the boss and then out to the plumbing.



After sawing a couple of pieces off one end was cope cut to suit the 14mm dia exhaust boss and then the other ends fitted by filing until they sat nicely against the back side of the portface.



Two holes were then drilled on either side down to meet the central port. I used CAD to work out the angle of the holes and set the cylinder using an angle gauge.





Finally a bit of needle file work had the two holes formed into a slot - too deep to get all the way with a milling cutter. At the design stage I had made sure that these slots, the new ducts and the slots in the boss were all greater in area than the smallest port the air/steam would have to pass through so as not to restrict flow.



It was then time to boost Ramons shares in JBWeld and stick the new bits to the cylinder casting. I have a few plastic spatulas that I have cut different corner radii on plus some rods with rounded ends and use these to get a basic fillet which saves time filing and sanding hard JBW





Once set but before tidying up the JB Weld I milled the boss back to the required length and drilled and tapped for four M1.6 studs to retain the flanged pipework.

[Jasonb]

As I mentioned when dealing with the valve chest I'm mot keen on Stuarts way of guiding the valve rod end in a hole that is a long way from where you can hold a drill bit so another option was needed. I decided upon a similar guide to that seen on the No1 which is a bracket that makes use of two of the cylinder studs to hold it in place.

I started by thinning down a short length of Tee section brass though two separate bits could be used. Then hauled up the boat anchor that is otherwise known as my long serving Indian made Soba rotary table and bolted a vice to that. Then another smaller vice to hold the tee section so a semi-circular notch could be cut on the overhanging end, two mounting holes drilled and then the rotary table used to cut the two arcs.





After a bit of rough shaping I  silver soldered a length of bronze rod to the end. To ensure that the valve rod ran nice and true through the guide I first set up the cylinder complete with valve chest on the mill and located the valve rod hole with a short length of silver steel (drill rod) held in a collet and locked the slides. You can also see the beginnings of the inlet elbow in this photo, just needs the D section rounding and a flange soldering on.



I then swung the bracket round into position and screwed it on tight. With some packing under the end so it did not sag it could then be drilled out to take the rod.



A bit of final shaping and rounding over the ends of the curved bottom were all that remained to do.

The eccentric strap started life as two pieces of brass that were soft soldered together before milling to the desired thickness and adding a ctr hole.



This hole was used to get the strap running true in the 4-jaw so it could be bored out and then a grooving cutter used to form the groove that the ridge on the eccentric will run in



A quick and dirty top hat bush was made to hold the strap while the outside profile was milled another job for the Rotary table of CNC if you have one. I also cut a recess for the valve rod which helps get a straighter run for the rod thus avoiding the dog leg of the Stuart design



The last job before unsoldering was to drill and tap the two lugs and ctr drill the top to form a small oil pocket.

[Jasonb]

Now that the strap was complete it could be used to gauge the size of the eccentric. After facing and turning to the required OD a small parting tool was used to create the central ridge which stops the strap moving sideways first by plunging and then by moving sideways with shallow cuts.



The size was adjusted until the strap would fit but not bind when tightened together.



I then used the height gauge to scribe the offset centre before punching the intersection and then setting the punch mark to run true in the 4 jaw so the hole for the crankshaft could be bored.



After drilling for a grub screw the eccentric could be mounted onto a stub of bar so that the boss could be turned down to finished size.


A piece of bronze was machined square and then the two holes for the guide rods reamed, piston rod hole drilled and tapped and at right angles a hole for the cross head pin was reamed.



The guide rods are just pieces of 5mm silver steel drilled and tapped M3 at each end afire carefully turning to the same length. They are held yo the cylinder cover by CSK screws from below and studs and nuts through the brace at the top. A quick test before shaping the crosshead and all seemed well with it moving smoothly up and down the guides.



The top bracket was cut from some 5mm flat bar to a shape that pleased my eye, a lot easier than bending up one as per The Stuart design. Here it is having the last two holes drilled for the studs that will hold it to the columns.



To ensure that the top brace was in the correct position slots had to be cut into the tapered part of the columns. To do this I first clamped a straight length of bar to the mill table and clocked it true. Then packed the smaller top end of the column both up and away from the straight edge so that it's axis was true along the mill table. It was then just a case of milling a 5mm slot and drilling and tapping for an M3 stud.



The cross head can be shaped however you like and will in some ways be limited by the available tooling if not your imagination, this is what I went with which was done with a mix of manual and CNC mills. Both this and the eccentric will be bead blasted to give them a nice satin look.

[Kim]

That is a very pleasing shape for your crosshead, Jason!

Kim

[Jasonb]

Thanks Kim

The last major component is the conrod. as I have changed the crosshead design there will be no need to make the "tuning fork" shaped one of the original which had to be shaped that way to clear the extended piston rod. There are a few options for conrod designs but I decided to keep to something fairly simple and came up with a rod that is not too far removed from that found on other Stuart engines like the Beam and Victoria.

Starting with an over long length of 16 x 16 black (hot rolled) bar which was pickled for a while in brick cleaning acid to remove any scale I set it up in the mill vice and brought it down to the maximum size rectangular section needed to get the part out of. I flipped it over a couple of times to take equal amounts of opposite sides and that combined with the black bar meant it remained straight.



After reducing the areas around the big end (right of image) and the small end (left of image) to their overall rectangular size I spotted, drilled and then reamed the two holes. I have left some excess to the left which will allow me to hold it for turning, this gives a more solid setup than turning between ctrs and means the interrupted initial cuts don't seem to knock as much plus you can take heavier cuts to get it down to round. You may be able to make out an angle plate  (mounted at an angle) on the right, this was used as a stop to maintain position in Y as the part was turned in the vice.



With the rod rotated 90deg in the vice I then milled a slot which will form the forked end once the chucking material has been removed. I've clamped the end to another angle plate jost to make sure the overhanging end is as rigid as possible so there is less chance of any cutter chatter.



With the job now held in the 4-jaw chuck and supported at the other end with a revolving ctr it was turned to the largest diameter of the "fishbelly" and then a Sharpie used to mark approx 1/3rd in from each end. You can also see that I have left the rectangle section at the crank pin end a bit longer than the Stuart ones so that I can put in two dummy strap bolts rather than one.



The topslide was then set over a few degrees and one end tapered followed by setting it the opposite way and tapering the other 1/3. I use an insert with a 2mm dia end so that a nice fillet was left in the transition from round to rectangular. All that remained was to blend the three facets with files and then emery to get a smooth looking fishbelly to the rod.



Having the extra SX2.7 mill in the workshop I tend to leave the ARC rotary table and chuck on that so it's a quick setup to mount anything that needs rounding over on one of the many arbours that I have built up over the years and round the ends on the mill. here I have a sacrificial washer between arbour and work so the cutter can have it's end just below the work and the M8 nut at the top is unlikely to be much use for anything now but I've got a big pile of them. Rounding was done with full depth cuts, 1mm stepover for the first few and then reduced to 0.5mm once the nut started to get cut too.



The forked end was rounded in a similar way after sawing off the chucking piece and then just a bit of file work to blend the outside of the fork into the round rod and get the fork to look "U" shaped.

[Roger B]

Looking good and very instructive   

[Jasonb]

having just seen the latest collaberation with Graham C come to life I best get on and finish this one to make room for another project, the dancing can be seen on FB Not sure if the link will work https://www.facebook.com/100013321802733/videos/742278877114088/

I'm a bit of a fan of aluminium pistons in engines both IC and steam as they do reduce the reciprocating weight so starting with some 1" 6082 bar the end was faced, spot drilled, drilled tapping size right through and then counter drilled 5mm (piston rod size) for about 1/3rd the piston thickness before being tapped M5 with a spiral flute tap.



After sawing off a length the sawn surface was faced and a counterbore turned so that a lock nut can be used on the piston rod but not hit the cylinder end cover.



The piston was then screwed onto the previously prepared stainless steel piston rod and locked with a thinned down nut never to be taken apart again. Then holding by the rod in a collet and with tailstock support the OD was taken down to 25mm using the cylinder to once again gauge the fit followed by cutting a groove for an O ring



Well that covers all the parts I took specific photos of but there are a few others which luckily seem to have all migrated to this corner of the group photo.



The Eccentric rod is just 1.5 x 5mm section reduced down from the next available stock size, drilled at both ends (one CSK) and then rounded over.

A couple of pins for the crosshead, valve rod/eccentric rod, etc are just basic turning. A couple of flanged pipe fittings, I decided just to do short stubs and not fully plumb in the engine.

There is also the cylinder cladding which was some veneer that I cut up into planks with a scaple and stuck onto some thin linen which makes them easy to handle as one so they can be cut to a card template. The brass bands hold the cladding in place.

[Jasonb]

The keen eyed will have spotted that I went with an off white paint colour for this engine, Ford "Ivory" was what caught my eye in Halfords. Non ferrous metal was primed with Upol Acid8, the Flywheel and cylinder with Upol High5. Bothe were then given a coat of Halfords white primer as were the remaining steel parts to get a uniform base for the topcoat.

A few shots of the parts laid out prior to final assembly, the engine having been test run before hand as I like to sort out any issues if there are any without the risk of damaging the paint if you have to start pulling things apart a few times. All visible fixings are small hex metric, mostly studs and nuts which you can see in one container and those that don't show are socket head.









Well lets see what they look like all put together.















So that about wraps up the build. I'm happy with how it turned out and it has fulfilled my initial desire to show that an attractive and individual model can be built based on an existing design for about half what it would cost if you bought the full kit and you also get a lot more workshop time for your outlay.

<a href="https://www.youtube.com/watch?v=KIDrN83xxq0" target="_blank">http://www.youtube.com/watch?v=KIDrN83xxq0</a>

I don't know how many of you are like me and enjoy looking at "naked" models (not that sort). Be it plastic AFVs, miniature figures or model engines I like to see them before they are painted a sit lets you see some of what has gone on in the construction as well as materials and methods used so here is a video of the early test run, just tacked together with a few screws, minor bits missing, no gaskets, packing or piston rings. It was also before I added the balance weight to the flywheel.

<a href="https://www.youtube.com/watch?v=7doDFAH32F4" target="_blank">http://www.youtube.com/watch?v=7doDFAH32F4</a>

[crueby]

Beautiful!!

[bruedney]

Amazing yet again Jason.

Where do you keep all your models as you must have quite the collection by now?

What's next?

Bruce

[Kim]

That's a very elegant-looking engine, Jason! 

Kim

[Bearcar1]

Smooth as a baby's bottom!! Choose the colors carefully and the entire presentaion will just POP!! Well done Jason..... I love that cross slide treatment..... just WOW!!!


BC1
JIM