Adams "O2" Calbourne in 5" gauge

[springcrocus]

Calbourne is the sole surviving member of the William Adam's "O2" design of tank engine and is the flagship locomotive of the Isle of Wight Steam Railway.


Photo courtesy of Isle of Wight Steam Railway

Eighteen months ago, I started to build a 1/12 scale / 5" gauge model based on how Calbourne appears at the present time but using the Don Young "Fishbourne" drawings as the main source of reference. I am aware of the discrepancy between the scale and the gauge.

Living on the Isle of Wight, I have reasonably easy access to the locomotive for photos and measurements. I have used laser-cut mainframes, bogie frames and equaliser beams and also cast wheels but the rest has been machined or fabricated from scratch using basic materials. Where the photos differ from the drawings, the photos take precedence.

Although I have been recording progress on another ME site, I thought I might continue the story here in MEM. I may well continue with the other site also but there is much upheaval there at present and the future is uncertain. I hadn't planned to repost all that material here because it would amount to about ninety posts and anyone interested in the back-story can always go and read it  HERE

The majority of the components are now made and the next stage is to start assembling the beast and remaking those parts that need changing. There are many small pins, fasteners etc to be made as well and other things that are noted on the drawing as "fit to place", an old-fashioned way of the designer saying he didn't have a clue about size or fit. I will pick up the story in the next few days if people think it may be of interest.

Regards, Steve

[crueby]

That is one good looking engine!  Looking forward to seeing your build progress.

[Jo]

Sadly when I was on the island the last time the full size one wasn't running  I had to make do with a go on the Hovercraft and then Underground train (Class 483). It wasn't the same, it didn't make up for it

Looking forward to seeing some pics of your build Steve

Jo

[springcrocus]

Sadly when I was on the island the last time the full size one wasn't running  I had to make do with a go on the Hovercraft and then Underground train (Class 483). It wasn't the same, it didn't make up for it

Looking forward to seeing some pics of your build Steve

Jo

Now you've kindly shown me how to. 
Regards, Steve

[cnr6400]

Great looking locomotive Steve! Look forward to the model pages here, as you build. 

[wagnmkr]

A very interesting engine indeed. I will be watching.

[Kim]

I'll be following along too!  Looking forward to seeing your progress! 

Kim

[Admiral_dk]

I'm sure rather many more off us here will follow and Enjoy your build 

Per

[samc88]

Been following this on the MECH forum, its a wonderful build so far

[Keith1500]

Onward Adam…

Look forward to seeing your work progress.

Keith

[Dalboy]

Have been following on MECH will you be posting here with the build from now on. Even though I do not make many comments on posts I get plenty of knowledge from people like yourself through your builds

[springcrocus]

Handbrake

Before leaving the other forum where I was recording this, the last thing I worked on were the brake blocks. This picture shows the brake rigging partially assembled and is the last picture I posted over there. I will continue recording the build from this point.



The two bell-cranks had to be fitted to the brake shaft and, once again, the designer had made a pig's ear of things. The bellcrank for the airbrake on the right side of the loco was fine but the one for the handbrake on the left was drawn completely wrong. This is what he drew...



... and this is what he should have drawn! Both arms need to be outboard of the spacer piece, not either side. I unsoldered the two arms and remade the boss to allow both crank arms to fit on one end and spaced correctly, then silver-soldering the parts together again. The handbrake adjusting bottle has been fitted to the lever arm with a clevis pin and the winding bottle to the lifting arm, with the winding shaft temporarily in place.



The handbrake pedestal has been made from a piece of bronze plate, milled all round to produce a regular block at the maximum dimensions. After setting up on two parallels, one was removed and the other moved to the centre to allow drilling of the four mounting holes.



The sides were milled away next, using a 3/16" diameter end mill.



The upper catchplate was made next from 1/8" x 1/2" brass bar and the three holes drilled. The handbrake pedestal was held vertically and matching holes drilled and tapped, as appropriate. After taking this photo, I milled the counterbore which I had forgotten to do before.



The catchplate was bolted to the pedestal with 10BA bolts and a 4.1mm drill dropped through for alignment, The the top outer edges were milled away.



The assembly has a curved outer face of about a 3/4" radius and the lower section tapers inward towards the top before returning to the original size. I made a carrier from a piece of 1" x 1/2" steel bar, drilled and tapped 8BA, to hold the workpiece. Nowadays, I tend to use these carbide PCB drills for shallow holes up to 3mm because they don't need centre-pops first. The four holes are 1/4" deep.



I'm getting clumsier as I get older and find free-hand tapping of these small holes more difficult than before so used a small home-made tapping fixture to carry the tap.



The assembly was bolted to the carrier, mounted in the 4-jaw chuck and clocked reasonably true. The compound slide was set round to 1.5^o for turning the tapered section.



The diameter was turned in stages until the last hint of witness disappeared, then the tapered section cut in using the compound slide to back-cut.



The next picture shows two views of the finished pedestal, although a fair bit of polishing is still needed to make it pretty.



The handbrake shaft and handle had been made previously, the handle being made by silver-soldering a bent piece of 3/32" diameter mild steel into a 1/4" diameter rod. The shaft was 5/32" diam material with a stop-collar silver-soldered on part-way up.



And this is the complete assembly bolted to the end of the water tank, with the full-size version afterwards.





Regards, Steve S

[vtsteam]

Frustrating, Steve to build something only to find it doesn't fit or make sense on the project. I've been there. But you've done a fine job of revision and it also must be fun to work on the brakes. I don't know, seems like it must be an appealing part of a build, especially connecting it to a hand control. I've never built a locomotive, just seems like it must be cool to get that working. Keep up the good work! 

[Kim]

Very nice work, Steve (Springcrocus)! Fascinating to see how you did this.

No brakes on the 3.5" Pennsy.  Though Kozo does show plans for brakes for the 7.5" version of the engine.

Kim

[springcrocus]

Air reservoir

Calbourne has air brakes and the air reservoir is a prominent tank on the left-hand side of the loco. A piece of brass tube was purchased for this which was cleaned up with emery cloth and faced to length. A pair of bungs were made for the ends from some 1.1/4" diameter brass rod, skimming the o/d and forming the front reccess with a special radius tool. A 7/32" diameter hole was also drilled for the air inlet.



The front was further reccessed with the same tool and the air connection point tapped 1/4" x 40 tpi before the cap was parted off. Two were made, one for each end, and will be silver-soldered into place.



I wanted a decent-sized chamfer on the backs because these will be soldered from the inside and this will keep the solder in place during the heat-up.



These are the parts, ready to solder together. A pair of rings, from 1mm silver solder rod, were made a nice fit to the bore of the tube. One of them is in the tube already. The ends of the bungs were coated with correction fluid to stop the solder wandering away.



Flux was painted on the inside of the tube and around the perimeter of the bung, then the solder ring inserted into the tube a short way. The first bung was pushed into the tube until flush and then set up in the hearth. The bung was a nice, sliding fit and I'm doing one end at a time. All the flux and the solder is inside and heating was done from the outside. I've kept the tube as upright as possible to encourage the solder to flow all round, rather than pooling at the lowest point.



It's not a very good picture but I can see that the solder has melted and flowed into the joint.



The other end was set up in a similar fashion but, this time, I wasn't be able to see the melt and had to rely on watching the colour of the tube to know when I had reached temperature. The workshop lights were doused and I heated until the tube was a little past dull red at the bottom. This was taken after I had put the torch down.



It was impossible to tell if I had full penetration from sight alone so, after giving it a good soak, then cleaning up all round, I hooked it up to my hydraulic test kit. The drawing calls for testing at 100psi but I've pushed it up to 200psi and it held this for fifteen minutes before I let it down.



I think I can safely say that the job's a good'un. Mounting brackets next.

Regards, Steve

[flying fox]

Greeting Steve, very nice, what pressure are you thinking of using for air brakes?

[springcrocus]

Greeting Steve, very nice, what pressure are you thinking of using for air brakes?

I've no idea, Brian, but as Don Young's drawing calls for testing at 100psi, I assume that working presssure is half of that. It's all moot, however, if I can't make a working compressor and that appears to be quite a daunting challenge at this size. 

Regards, Steve

[flying fox]

That's the tricky bit Steve, I had some success using Schrader valves from car tyre as valves and a stem driven pump, but the volume of air produced was low, although it seemed to have a fair pressure.  My experimental system suffered from leaks.  I have a crosshead driven pump fitted on a GER loco I have now put aside, but I might finish it sometime.
Regards
Brian B

[springcrocus]

I've been completing various jobs around the loco but none of which warrant an individual write-up and one of those jobs was to reduce the height of the safety valve bushes. When I tried to fit the manifold to the rearmost bush, the outermost connections of the manifold fouled one of them. The boiler was removed from the loco and set up on the mill with a very light clamping arrangement to hold it in place. The copper is still very soft and I didn't want to risk distorting anything. Ten thou cuts with a very sharp tool being the order of the day. I made a pair of threaded brass bungs to block the holes and stop a load of swarf falling into the boiler.



With the manifold screwed into place, I was able to finish the front spectacle plate and get that fixed into position. Also, the tanks have had the filler caps and the front footstep assembled.



At the rear, the buffer stocks and the drawhook plate have been fitted. The roof is just resting in place at present while I work out how best to make a removeable section to allow access for driving the loco.



A pair of pressure relief valves were made from brass stock, starting by making the threaded end first, then screwing into a mandrel and turning the outer form and boring the internals.



The spring adjuster nuts were made by threading a short length of brass rod, then milling four slots down the sides.



An adjusting spanner was made by milling a cruciform shape on the end of a length of steel bar. One of the parted-off adjusters is sitting on the collet.





The brackets for the air reservoir were made and the assembly fitted to the top of the left-hand tank. Also seen in the next picture are the two pressure relief valves fitted to their bushes.



Calbourne has flatted rivets around the running plates, rather than the more common roundhead rivets so these have all been filed down to suit. The smokebox door has also been completed, along with the hinges.



The last picture today is an overview from the left-front quarter. It's starting to look like a loco now.



Regards, Steve

[wagnmkr]

This is coming along very nicely! 

[Kim]

I would say that is great progress!   

Kim

[Admiral_dk]

What a lovely Tender Lokomotive 

Per           

[Prowler901]

Wow, what a beautiful locomotive!  You're doing great work.

Todd

[flying fox]

Looking good Steve, well done.
Regards
Brian B

[springcrocus]

Wagnmkr. Kim, Per, Todd and Brian, thanks for following along. 

The boiler clacks are quite prominent because they have a fancy spacer between the valve and the pipe flange. I made all the parts for these assemblies from phosphor bronze, starting with the two main body parts. These are just straightforward turnings that get silver-soldered together.



Previous experience has shown me that they never line up properly when assembled in place so, this time, I made sure I had a means of tightening them into the clack bushes before soldering. After screwing into a stub mandrel, the two branch pieces were drilled 4.3mm diameter for about 20 thou, followed by drilling through with a 4mm drill. A hexagon shape was formed in the ends by pushing in a cut-off Allen key with the end ground flat and square , then forcing deeper in the bench vice. This was followed by turning the O/D with a radius tool. I was able to remove the parts from the mandrel without damage.



The branch pieces were then screwed tightly into the bushes, complete with a gasket washer, and the top marked with a line. They were also noted as left or right. Having the hexagon for an Allen key really pays off in this situation.



The four bolt holes in the body were drilled next, a four-jaw self-centering chuck proving ideal for holding the work in this operation. Sorry about the poor out-of-focus picture. The auto-focus sometimes chooses the wrong detail to highlight.



I made the two spacer pieces and the two flanges next so that I could drill the bolt holes while the 4-jaw chuck was still mounted on the mill. The drawing says to make the spacers 1/4" wide but this looks too chunky to me and I have made mine 3/16" thick. The grooves were cut with a 4mm ball-nosed endmill and the outer radii formed with files, although they could do with a bit more work. The flanges are 3/32" thick, the same as the flange on the body. Then it was the main body, drilling and counter-boring the side hole for the branch piece to be soldered into. A pair of 10BA threaded studs were screwed into adjacent holes and rested on the vice jaw for alignment purposes.



The two parts of each valve were joined together using a ring of 0.5mm silver-solder wire on the stem of the branch. The work was held in an engineers clamp so that heat could be applied from below and avoid directly heating the solder. Correction fluid has been painted onto the threads to protect them from stray solder. Edit: I forgot to mention that the alignment mark on the branch was used to ensure accurate positioning in the body of the valve.



This is the collection of parts needed to make a single clack, with an assembled one to the left. The sealing ball is a silicon nitride one; these are extremely hard and even more spherical than traditional steel or stainless steel ones. The only disadvantage is that they are half the weight of steel balls and have a slight tendency to float off the seat when not under pressure. You can give them a damn good whack to bed them in, though, and you won't damage the ball.



After cleaning up and assembling the various parts, they were fixed to their respective clack bushes using the same gasket washer as before. Nice and tight, and perfectly aligned. The body is a bit too long compared to the prototype but this is one of those situations where things won't scale properly. If the clack valve was scale size on the outside, the inside would be too small to let enough water into the boiler.



Regards, Steve

[Kim]

Very nice looking clack there, Steve.  Does the other one go on the opposite side of the boiler?

Kim

[Keith1500]

Still following your build Steve, enjoying it too.

Yes that’s my technique. I like the fitting to tighten nicely and be in the right position without the need to pack with copper or fibre washers. I like to use liquid Ptfe on the treads. It seals nicely and doesn’t look unsightly.

[Prowler901]

Nice!  Excellent reproduction of the prototype.

Todd

[Kim]

Still following your build Steve, enjoying it too.

Yes that’s my technique. I like the fitting to tighten nicely and be in the right position without the need to pack with copper or fibre washers. I like to use liquid Ptfe on the treads. It seals nicely and doesn’t look unsightly.

OK, I had to re-read Steve's post a second time to catch that.  That's a very clever way to set the orientation of the valve prior to soldering!  I'll have to file that away.

Kim

[Mike R]

Steve,  I'm following along.  I'm keenly interested in your steel cab and tank work, as the cost of brass is prohibitive in this and larger scales.
Carry on please and great work so far.

Mike

[springcrocus]

Thanks to everyone for their various comments. 

Mainspring brackets

Don Young never drew any part of the authentic main wheel springs for this loco, relying on a single coil spring below each axlebox. However, one model engineer, Nigel Bennett, drew out the various components to make the traditional leafspring components for his very nice model of "Ashey" and kindly sent me a set of his drawings so that I could make the same for "Calbourne". I don't think Nigel is a member here but he contributes on both the MECH and ME forums (fora).

I started with the spring brackets, cutting eight pieces from some 25 x 10 black bar and milling all round to get blocks at the maximum dimensions. Then one side for reduced to 17mm for about 20mm length. These drawings are in metric so I decided to work in metric, complete with metric cutters, without converting anything to imperial, just to remind myself that I could!



One change I made is the frame bolting arrangement, opting for three M3 screws instead of five M2.5 screws. The three holes were drilled through 2.5mm diameter, then tapped M3 freehand in the bench vice. The DRO was zeroed on the fixed vice jaw and the middle hole.



Next, the root of the inside shape was cut, plunge-cutting with a 6mm diameter end mill.



Three more operations were done with the same setup to produce end-points for shaping the sides of the vertical component, working plus or minus either side of the centre-line.



The same cutter was then used to reduce the leg to 12.5mm. These are the eight brackets, starting to take shape.



To do the rest of the machining, I made a fixture with three bolt holes from a piece of 1" x 3/16" flat bar. I drilled the holes 3mm diameter for a good fit on M3 cap screws and fixed each bracket from below. After milling some soft jaws to take the fixture, I had to clock the tilt-and-turn vice in the "tilt" plane to compensate for jaw-lift.



Then the vice was set round to 23 degrees to form the foot of each bracket. The DRO was zeroed on the inside of the ankle and the 6mm cutter was worked round in conventional mode to form the shape.



Once all eight were done, they were remounted and the cutout for the spring support pin plunge-milled with an M5 cutter. That completed all the work in the T&T vice so that was taken off the mill table and replaced with my main vice. The fixture was clamped in the vice, set at 67 degrees, and the holes for the spring pins drilled 3mm diameter. These were then widened and elongated with a 3.5mm dia slot drill.



I modified the fixture plate for the last couple of operations; counterboring the screw holes, shortening the front end and cutting off the corners. This was to allow a 12mm endmill to cut the big radius on the back of the spring brackets. The fixture was clamped to the rotary table after carefully working out where to position it. The spring brackets were then screwed in turn to the underside of the fixture. The extra fences are to prevent the fixture rotating about the single clamping screw.



For the final operation, they were mounted to the fixture one more time and the section where they bolt to the frames milled away.



That completes all the machining on these and, once they've had a bit of a clean-up and an hour in the phosphoric acid, they will be ready to fit to the loco.


Regards, Steve

[crueby]

Nice job on some complex shapes.   

[Kim]

Thanks for the great walkthrough of your operations.  Good use of that jig, too! 

Looking forward to seeing these springs come together.
Kim

[Prowler901]

Those are some complex operations.  Nice job!

Todd

[springcrocus]

Chris, Kim, Todd, many thanks.

Chimney

There is a casting available for this loco but I decided to make mine from various offcuts of brass and bronze. The first of these was the base section which came from a large bronze gear wheel. After facing off, the billet was bored through at 1.1/8" diameter and then opened out to 1.1/4" diameter by 3/4" deep to take the peticoat pipe. The first picture shows it resting on the soft jaws that I machined to hold the work for the second operation.



The o/d was turned to the maximum size of the chimney saddle, then the 13/16" radius flare was formed using a technique  from the very earliest days of turning. A round-nosed brazed carbide-tip turning tool was chosen and a 3/16" diameter hole drilled and reamed through the shank 13/16" from the tip. The toolpost was removed from the lathe and a worktable bolted to the compound slide in it's place, which had a 3/16" diameter silver-steel pivot-pin fitted at the top left corner. The turning tool was fitted onto the pin and a length of steel box-section slid over the back end of the tool. The picture isn't very good but shows most of the relevant detail.



This next picture shows the radius about half-formed and a better view of the tool with it's extension handle. There was no real measurements here, just easing the cut along or down twenty thou at a time and keeping pressure on the handle so that it didn't dig in to the work.



Loads more cuts were made until I reached a point 1/16" thick at the base and 1.13/32" diameter at the chimney neck. Then a spigot was turned to locate the chimney onto. Bear in mind that this radius is only relevant to the widest part of the saddle and further work will be required once the underside of the saddle is machined to fit the smokebox.



Next, the chimney neck was made from a length of 1.1/2" diameter brass bar, drilling and boring through to finish at 1.1/8" diameter. A spigot to match the saddle was machined on the end and the outside cleaned up with emery cloth.



The two parts were silver-soldered together next, a ring of 0.5mm diameter solder resting on the slight lip between the two components. Although this should have been relatively easy to solder, the great mass of the saddle made it much more difficult than expected, with a lot of heat directed into the hole at the top and rather less to the chimney neck to get both parts up to temperature.



The next stage was to bore the 2.5^o taper in the bore and the 1.25^o taper to the outside, both jobs done with the compound slide set to the relevant angle and with the assembly mounted on the same soft jaws. Finally, a turned section was formed at the top to take the chimney cap. Sorry, no picture of that.

I didn't have a piece of brass big enough to make the cap as a single piece, so used two pieces instead. This is the first piece silver-soldered to the top of the chimney.



The second piece was made and this was soldered on as well, but using a lower melting-point solder. Then the assembly was remounted onto the soft jaws, the o/d of the cap skimmed to size and the upper radius turned with a form tool.



The same form tool was used to create the underside form but, because it was a larger radius, I nibbled away at it freehand (winding both the carriage handle and the cross-slide handle at the same time) using a radius gauge as a reference.



This is the chimney with all the turning finished although I will use a bit of filler to disguise the lower join. It just leaves the machining of the saddle to complete.



Regards, Steve

[uuu]

I do like those soft jaws.  They look a lot more secure than the spigot I used for my chimney.

And I have the advantage over other readers, having seen yours yesterday.  It's rather special.

Wilf

[Kim]

That's a beautiful chimney, Steve! Well done! 

I do like how you pieced it together from several parts.

Kim

[Admiral_dk]

Beautiful curved Chimney 

Nice buildup + good to save / reuse stuff 

Per

[Zephyrin]

turning such large curves on brass or bronze is a great pleasure !
at this point, the metal being already annealed after brazing, it seems that you will make the base part of the chimney by forming it into a saddle on a mandrel as I don't see any metal left for machining ?

[springcrocus]

Wilf, Kim, Per - kind words, thank you.

 Zephyrin, the base will be machined to fit the saddle and you'd think that this would remove too much material. You are, of course, correct (because of the compound curves involved) and the front-to-back dimension will come out undersize. However, I have a trick up my sleeve.... 

 Regards, steve

[springcrocus]

Chimney continued

To machine the underside of the saddle, I modified one of my flycutters to take a tool that I can adjust to 5.1/4" diameter. I have milled a shallow 5/16"-wide slot, with one edge on the centreline, and made a couple of clamps and an adjuster to hold a piece of 5/16" square tool steel. The tool has to be ground as left-hand-cutting, of course.



This was an opportunity to try out my new cross-slide and I created the setup while the slide was still on the bench, using packing to set the centre-height.



Then I swapped the cross-slides over - a matter of two minutes work - and set the flycutter to 2.5/8" radius. Although it doesn't show, I'm holding the flycutter in a collet block and this block in the chuck otherwise I wouldn't be able to get the length of cut required.



As noted in the last post, the compound curves on the upper surface cannot be machined conventionally and this arrangement leaves the front-to-back dimension too short, as can be seen.



So the answer is to fix another piece to the bottom and build it up. First I cut a square from 20swg brass sheet, bored a 1.1/4" hole in it, put a bend in it and then clamped it to the bottom using the petticoat fitting to get it tight.



Then it was rounded off freehand until it sat nicely on the smokebox. It's not a perfect circle because it would foul the rivets.



Once happy with that, I drilled a couple of holes in the baseplate for 8BA fixing screws, spotted them through to the chimney, then set up the angle table to drill and tap the matching holes.



A pair of countersunk brass screws were used to fix the two together, the Hoffman roller being used to keep things in line whilst tightening.



Finally, a load of high-temperature gunk was smeared all round the base and left for two days to cure. Then it was shaped with emery cloth and some light filing to create the finished curves. It is actually a lot smoother than it looks because of how the light reflects but this chimney is going to be painted, anyway, so the primer will hide any tiny blemishes prior to painting. The filler is supposed to withstand over 500^o centigrade, so should be suitable for this.



Regards, Steve

[Kim]

Very nice fabrication work on the chimney, Steve!  It looks great!

That JB weld is great stuff, isn't it?

Kim

[RReid]

What a cunning solution to the problem! Gunks do have their place.