BOXHILL by Martin Evans

[vulcanbomber]

I'd start with about 320 grit!

[jma1009]

I have been busy in the workshop the last 2 or 3 evenings trying to make some progress on the regulator assembly.

Here are a few pics. The first is a trial assembly of the 'Stroudley' type regulator, and the second is the finished regulator handle fitted to the regulator rod.





In the first pic, the links between the rotating valve and operating arm hidden inside the boiler are only temporary and will be replaced, as will the temporary screws and bolt. You can see the 'tear drop' shape to the top port. The links act as stops for the regulator because at each extremity (open or shut) one of the links collides with the regulator rod.

The regulator handle can be seen before filing the square hole in it.

The second pic shows the regulator handle fitted. It is exactly the correct angle, and a nice push fit on the square filed on the rod with no slop.

I am quite pleased with how it has all turned out and how smoothly it works and how easy it all fits together. My regulator body is a silver soldered fabrication made a few years ago when making the boiler and is not to the drawings, and everything will just fit under the inner dome. I did take a 1/16" off the valve face of the body yesterday evening to achieve this - so need to go back and get the rotating valve to mate perfectly with the valve face.

Cheers,
Julian

[jma1009]

This is a silly picture - snapped by a daughter Emma today wondering what on earth I was doing!

Its a vacuum and tongue test on the regulator assembly to check the regulator valve faces I had bedded in was ok.

New links and some of the proper screws made today, and bedding in the valve faces. The proper screw for the valve spring is fitted as seen in the pic. The spring is 1/4" dia and non magnetic stainless.



Cheers,
Julian

[Jim]

Thank heavens for that Julian, now I can relax knowing I'm not the only person who blows and sucks things to see if they are working properly.

Jim

[jma1009]

Here is the completed 'Stroudley' regulator. The fixings for the links are phos bronze and entirely functional and practical if not particularly aesthetic, but they are hidden inside the boiler. New bronze links fitted.

All tested and works fine.

It was too hot in the workshop to do much today. 24 degrees celcius on the thermometer.#

I also fitted the 'stop' on the regulator rod against the backhead fitting, so another job completed.

Cheers,
Julian

[jma1009]

Part 1 today...

The blowdown valves were completed this week plus the socket head cap screw as a 'key'. I had made the phos bronze bodies and stainless spindles and the captive 'caps' ages ago, but hadnt silver soldered on the bosses or made the pipes. Anyway all quite straightforward, and many thanks again to those who helped with advice for dilling the HT socket head cap screw



Cheers,
Julian

[jma1009]

Part 2...

Disaster!

I screwed in the Don Young type blower internal pipe into the backhead bush with the fitting on the smokebox end of the pipe. I am quite sure I had done a trial run of this much earlier. Anyway the whole lot completely seized up on the copper threads on the phos bronze bush and fitting and bush smokebox end part way through.

Everything is pretty much inline, but my tolerances on the copper thickwall pipe must be a bit too tight this time.

Anyway a triangular file pocked in the end made no purchase and snapped. That was punched out through the hollow tube.

So I thought if I loctite a bit of steel into the smokebox end I could unscrew it from it from the backhead end where it had seized up.

The first pic shows this in place (I seem to have spent most of this week making tommy bars).

Second pic shows what happened with only 1/8" left to go (after 3/16" withdrawal)

Usually the problem with this LBSC type blower tube is the threads being too sloppy and not being tight. In my case I have gone to the other extreme with Stepney.





Cheers,
Julian

[springcrocus]

If you could get some rapid cooling onto your fitting, it might contract enough to allow you to finish unscrewing the part. Maybe consider using a gas-lighter refill canister to provide a source of extremely cold gas flow directed at the part. Wear gloves!!

Steve

[runner42]

Hi Julian,

I would stand the boiler on end and apply WD40 to the blower tube so that it runs down to the threads in the backhead fitting, let it soak for a time and then apply the tommy bar again. I am not sure what happened in picture 2 did it snap off the blower tube?

Brian

[Roger]

I got the impression that the problem was now solved...

[Jim]

My impression too but if not Julian is a very experienced modeller who will know what to do next.

Jim

[runner42]

Roger I am sure you are right and it wasn't a cry for help. Julian has far too much experience for that problem to cause no more than a hiccup, but the words did indicate that an 1/8" further withdrawal was required so another try was needed.

Brian 

[jma1009]

Apologies for being unclear.

The steel was turned down and loctited in the smokebox end of the blower tube. The loctite didnt fail, but the turned down steel sheared off from the rest of the steel. Hopefully this can be seen in the above 2nd pic. So the smokebox end of the blower pipe has a 1" length of 120 thou diameter steel now loctited in it.

It is where the blower pipe screws into the boiler bush at the backhead that it is seized up.

Edit- The loctited steel did unscrew 3/16" of the blower tube from the backhead bush before it sheared. As Brian noted, 1/8" still to go. Hoever very few options left now unless I get dratic. Hence 'disaster'!

Cheers,
Julian

[runner42]

Hi Julian,

looking at picture 1 I assumed that the steel bar had an internal thread which went over the threaded tube. Lesson don't assume!

Brian

[springcrocus]

I assumed that we are looking at the smokebox end of the pipe in photo 2 and that the steel bit was stuck up the pipe. I was trying to suggest that one puts the gas-lighter refill nozzle up the other end of the tube (firebox end) and sprays away. This would cause rapid cooling of the pipe but the gas would spray back over one's hands, hence gloves. Once it is nice and cold, it may have shrunk enough to grip the other end and carry on unscrewing.

Steve

[Cro]

Bummer... Not sure how you were gripping it to screw it in in the first instance but as can be seen on your regulator tube you have cut a slot I assume for a tommy bar style fixture or a screw driver? Now you have that steel block in the end of your pipe why not cut a slot across the pipe and steel block and unwind with a screw driver?

Chances are you could lose up to maybe an 1/8" off this end of the blower pipe, how crucial would that be? Assuming the steel block can be removed without further damage....Good luck!

[jma1009]

Job done - many thanks to Roger for an email and in the end I used a combination of Roger's advice and Adam's advice for which many thanks.

First job was to drill out as much as I dared of the tube stuck in the backhead threaded bush without damaging said bush. The phos bronze backhead bush is tapped 1/4" x 40 tpi so No.1 tapping drill (though I always use 7/32") and I drilled the stuck copper pipe No.5 with the aid of a sleeved guide threaded into the bush and a lot of luck.

Second job was to use a dental burr in the dremel to do a screwdriver slot in the other end.

With a bit of more luck the pipe unseized itself and unscrewed

Here is the mangled remains of the backhead end. Something has gone seriously wrong!



Now I just have to work out what went wrong and avoid it happening a second time!

Cheers,
Julian

[Jim]

Well done Julian and a big sigh of relief all round.

Jim

[jma1009]

Here is something a bit unusual of late namely a bit of progress with Stepney.

Havent touched the loco for 2 1/2 months till today.

Anyway I needed to make a new blower ring for George's Butch so thought I might as well make the fiddly bits for Stepney as well



These are the screw in jets threaded 6BA, and drilled for a No.75 jet (21 thou). There are 8 made plus a few spares. They are to the well known Laurie Lawrence design of blower ring which is a considerable improvement on anything else and very effective.

I am a firm fan of this type of blower ring, though making the jets are a bit tricky. As the lathe was set up for injector cones, it was the ideal time to get these bits done.

The HSS taper reamer is care of a set obtained via ebay from China via a tip from Roger, and as a recent purchase should give the jets an extra 'oomph', the taper reamer being inserted from the bottom end.

So that was this afternoon's work during torrential downpours of rain. Typical Welsh Bank Holiday Weekend weather!

Cheers,
Julian

[jma1009]

On the far bottom right of the above pic is a very small dental burr. This is what I use as a centre drill for very small drills in most applications, though for very small work I have some special clock/watchmakers stuff. The smallest slocombe centre is far too big for a No.75 drill.

If you get the centering OK then everything else is OK. I did this batch drilling from the base of the jets to top, whereas I think the last batch I did was the other way round. I test the blower ring on my boiler test rig to make sure the jets of water go the right way. The blower ring needs drilling the threaded jet holes at an angle - of which more anon when I do the blower rings.

Cheers,
Julian