Wednesday, 29 February 2012

Draw-bar Recovery (1)

Sentinel 7109's cab is cramped at the best of times. When the regulator assembly is eventually mounted on the rear of the boiler, cramped will be an understatement particularly when trying to get from one side of the cab to the other. Adding to the obstacle course is an odd shaped bulge by the floor below where the regulator will be.
Bulge - can be a battle when crossing!
If you click the image, you'll see that it has suffered many footfalls in time and is badly rusted near the foot plate floor. A stronger replacement cover plate will be made in due course.

So what is it that is so important to be given pride of place where you really don't want it?

It houses the rubber cushioning for the rear coupling's draw-bar.

Draw-bar cushioning
And in more detail:
After a good clean-out
When the cover was first taken off, there was an inch or so depth of general rusty scale and carp-related material which had to be removed. The cause of this was clearly due to water running down the outside of the cab rear on to the top of the buffer beam and in through a convenient slot left for the purpose.
Water ingress slot
Quite why this slot is there is unclear unless the cover plate was originally hooked through the slot from the inside as its top fixing? Even though not used in that way, it's not a very clever idea as water had seeped in over the years causing the rusty scale etc.
Slot from the inside
The slot will be blocked with a weather-proof sealant before finally making and fitting a new cover plate. In the meantime, it's had a good coat of red oxide primer ready for a black top-coat to keep the rust at bay.
Somewhat smarter than before!
Coming soon: making the new cover plate when, this time, I don't forget the camera when rolling its curved shape and bending its flanges!

Tuesday, 28 February 2012

Completely Baffled!

The last article on the superheater showed the pattern made to cast a baffle plate for supporting the centre of the superheater and directing the hot fire-gases through the tubes instead of up the large hole in the centre.

The baffle plate has now been cast in SG420-12 Malleable Iron by East Coast Casting Co Ltd of Thetford and fitted to the superheater assembly by
Grant Goold.
Baffle plate in place
The baffle plate largely blocks the gap through the centre
so the heat passes through the tubing
View from above showing the support rod to the top plate
The superheater and boiler top plate assembly are now ready for fitting into the top of the boiler via the top of the cab (where there is not a cab roof yet!).

Saturday, 18 February 2012

'Ello, 'Ello, LO!

Apologies for pinching this from the SDC Website!
On Saturday 11th Feb 2012, at the AGM of the Sentinel Drivers' Club in Liverpool, Tony Thomas (records officer) proposed and various members of the Goold family seconded me to take over the committee post of Locomotive Officer for both steam and diesel technologies. This I have gladly accepted and hope I can do the post justice.

The post has been held for many years by Martin Hawkins, uncle to Sentinel 7109's boiler inspector Peter Hawkins, a boiler maker in his own right and driver on the West Somerset Railway. So I have quite an act to follow.

To some extent, the task is a blank sheet for me to make of it what I can; the main object being to be the point of contact for anyone with queries about Sentinel locos. Where I don't know an answer, hopefully I can find someone who does!

Tony Thomas has kept records of locomotives still in existence for many years. I hope to make use of his existing information and to keep it up to date using a website, 'blog or such like.

Wish me luck!

Friday, 17 February 2012

Exhausting! (Extra, extra!)

I've been asked in a comment on the 'Exhausting!' article about something that may have surrounded the chimney aperture.

Here's another photo.

(cropped from a Charlie Verrall photo)
Even clicking on the picture to zoom in does not make it clear.

Thus it will be a detail to be ignored unless reinforcement is needed in practice.

Thursday, 16 February 2012


Unlike conventional steam locomotives, which have their boilers laid horizontally, Sentinel 7109 has its boiler the right way up (vertical) so that steam and smoke exhaust straight up and out of the top, in this case through a hole in the cab roof.
Roof top Chimneys
7109's original roof was clearly showing signs of rampant air-conditioning, nice in Summer but neither structurally nor aesthetically pleasing all the year round.
Air-conditioned original cab roof
A new 3mm thick mild steel cab roof was obtained some years ago and has been waiting its turn for attention.
It's substantial, 3mm thick and takes 4 people to lift it
Another day spent being 'jiggen' by a shake-saw cut the hole for the chimneys.
27" squarish chimney aperture
(the newly-restored, pristine S&D PMV is in the background)
The new baffle plate to support the boiler's superheater has now been cast, machined and fitted. A length of ceramic rope is needed to provide a seal between the assembly and main boiler superstructure. When this has arrived, the superheater assembly will be able to be lowered into place and fastened down - hopefully never to be removed again before steaming.

Then the roof can be put in place.

Monday, 13 February 2012

Sentinel 7109 Cab Roof

On arrival in 2004, the cab roof was (to say the least) leaking! A new panel has been purchased and is due for cutting to shape in Summer 2011.
Leaking roof!
Roof support girder before detachment from the old roof
The cab roof support girders have been refitted and roof edging plates have been derusted to put them back into shape.  Rust had got into confined spaces and forced things apart such that the new roof would not lie as it should. New rain channels have been fitted.
7109 playing in the snow boxing day 2010
The cab roof was hoped to be completed late 2010 but the snow and cold from the start of December put paid to that!

Tuesday, 7 February 2012

How to make an ashpan (3)

Part 2 of this series covered the marking out and cutting of the ashpan base plate. Now the the curved walls needed to be rolled to the right radius and welded in place.

Until now, I'd never seen, let alone used, a sheet metal rolling machine so this was a bit of an adventure.

Sheet metal rolling machine
The rolling machine is not difficult to use; the front two rollers are adjusted to be parallel and to grip the metal being rolled. A third roller at the rear is positioned using the handles at each end. To create a bend, the metal sheet is wound through using the handle on the right and progressively forced upwards by the rear roller. After a few passes with the rear roller being raised each time, the correct curve can be created.

One or two problems can arise; the sheet has to be put in exactly at right angles to the front rollers otherwise a twist is created in the sheet that is hard to correct; it is possible to create an uneven curve or too tight a curve. I found I had to feed the sheet back in to take some of the curve and twist out before re-rolling to the correct curve. Some twist did remain and so one of the walls is slightly angled in - not critical but I like to do better.

There is also a good deal of hammering to get the curve at the ends beyond where the rollers can reach - not pretty but effective!

Apologies for no video of this - it was pretty physical and not conducive to camera work! (Oh OK, I forgot!).

Skipping ahead to after the walls had been rolled and welded in two parts to the base plate.

Base and walls welded together (MIG for inside corner weld)
Right hand inside MIG weld
Left hand inside MIG weld (not quite so tidy!)
MIG welding was good for the inside weld because of the length involved and the need for filler to be used to build up the corner strength.
Left hand outside TIG weld
TIG welding was ideal for the small outside corner weld; two 3mm thick plates corner to corner don't want anything heavy duty and only a small amount of filler! The welds came out pretty tidily but certainly benefited from cleaning up with an angle grinder.

Joint in the two side-wall pieces
The two side-walls had a small gap to be filled between them. I used a MIG welder for this, filled the resulting holes with an oxy-acetylene torch and tidied it up finally with an angle grinder. MIG can be a beast at times!

Then I discovered I'd missed my vocation in life; rather than an ashpan, I seem to have created a simply amazing GONG! I'd left the ashpan leaning against the bookcase in my hall at home (I have a very tolerant wife!). On tapping it with a finger (or later a rubber mallet), I was greeted with a marvellously musical ringing tone. Try this (best on headphones, loud, or on a home cinema system!). (Also on YouTube).

After all the work finding and renovating a whistle, perhaps it won't be needed after all (although perhaps a gong is an unconventional method of locomotive greeting!).

To be continued!

Wednesday, 1 February 2012

How to make an ashpan (2)

In the previous article, I documented some design decisions and was able to purchase the required metal sheeting. This article looks at the marking out and cutting to shape of the base plate.

I first painted the baseplate with white emulsion so that I could see my own markings. Then I had the challenge to draw a circle of 17.75" radius. Pairs of compasses simply don't come that big in my house!

17.75" Radius pair of compasses
A couple of screws 17.75" apart in a piece of dowelling did the trick. Diagonal lines from corner to corner found the centre of the sheet.
17.75" radius circle
(and that's why I painted it white!)
The flap was easiest to mark towards one corner using lines at right angles from the marked diagonal.

And then all that was needed was to cut it out!

I dismissed gas-torch cutting; it is quick and exotic but needs a template making beforehand to guide the torch and leaves rough edges which need a lot of tidying up with a grinder.

The only other method left to me was to use a jigsaw with hack-saw type metal cutting blades. In actual fact, I'm glad I chose this as it is surprisingly accurate (to about 0.5mm, and yes I can do metric when I choose!) and doesn't require other tools to be made beforehand and little cleaning up after the cutting.

Cut that out!
This is when I discovered my hair had gone grey!

Whilst the jigsaw proved accurate, fast is not a word I would use to describe it! (Also on YouTube).

Can you see any progress in 30 seconds?

It took most of a day to complete the cutting (but it was accurate!).

Nearly there,only the flap's cut-out to do
If the above photo looks a bit wobbly, try holding a camera still after a day of being jiggen by a shake-saw!

To be continued!
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