5" Edward Thomas - regulator & steam pipe question

[cgd]

I am looking at building “Edward Thomas” to the design of Ross Harrison serialised in Engineering in Miniature in the early 1980’s.

The boiler drawings show the regulator inserted into the boiler, retained by a flange bolted to a backhead bush, steam pick up is by a vertical pipe into the regulator screwed in through the dome after installation of the regulator. The steam pipe runs through the boiler from the regulator to a flange on the front tubeplate but this is not a straight pipe, rather it is cranked up by ½” at the regulator end and is shown as screwed into the regulator.

Hence to assemble the regulator/steam pipe it will be necessary to manipulate the cranked pipe through the tubeplate bush (the “words and music” already suggest the bush may need judicious filing to admit the pipe), the regulator will then have to be screwed onto the pipe inside the boiler, with no visibility and a fair portion of luck to get a good seal whilst getting the regulator to align to receive the vertical pipe from the dome and seat on the joint face on the backhead bush.

None of this sounds terribly appealing.

I would be very interested to hear from anyone who has built this loco about how they got on with this arrangement both in construction and during running or what alterations they may have made to these parts.

Any other observations welcome too !

Many thanks in advance.

[Nigel Bennett]

I made my Edward Thomas 25 years ago, so memory fades.

I recall making the regulator as a screw-type with a 3/8" BSW thread. Very happy with it.

The front end of the steam pipe was arranged so that it screwed into the regulator body with an O ring seal - possibly two. The smokebox end had a flange on it, which sealed against a modified stepped boss on the smokebox tubeplate; I know it has four screw holes in it and not two as per RH. I'm sure I recall having my regulator assembly as all in line, without the 1/2" joggle; I also seem to recall that the steam pipe at the front had an internal hexagon broached into it (as well as some O rings to seal against the tubeplate boss) so that I could use that to screw it in place.

Get hold of the Sweet Pea drawings and use those dimensions for the valve gear (and port/valve dimensions) rather than the RH ones.

Make the smokebox door dogs at 60 degrees and not 45 and don't use the outer radius given for the saddle tank - it's much too big (unless you want a big tank!) Scale it from the GA.

Sadly I don't have any photos of the construction of the regulator - and I don't fancy taking it apart so see how I made it.

Good luck with it!

Nigel

[cgd]

Nigel

Many thanks indeed for this most helpful information (you also sent me some vey useful information by post years ago, in the pre-internet era, which just goes to show how much prpgress Ive not made with this loco !).

May I ask, does your Edward Thomas use a superheated boiler ?

Regards

Chris

[Nigel Bennett]

Yes, Chris; three return copper tubes from the wet header to the dry. I used block return bends, filed down as close as I dared to reduce its cross-section in the flue as they're not radiant ones. They do keep getting blocked up with ash; if I ever wear them out, I might try stainless steel welded ones, but I dread to think how much that will cost!
Nigel