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