Not So Grate!

Most of the Sentinel 7109 articles I've written in this 'blog over the last 8 or so years have been fairly upbeat although I did get frustrated with gland packing not so long ago.

However, not all goes as well as I'd like and I've had a new downer to deal with. I've shown the photo below a number of times to illustrate the how the fire-grate began.

The Fire-Grate as new prior to first steaming in 2016

With an eye on environmental issues, at the beginning of 2019, at Midsomer Norton, we began using a cleaner Welsh coal. All seemed fine for some months and I did the usual half-yearly boiler and fire-box washout in August. However, shortly before the start of the four Santa Specials in December, the centre section of the fire-grate decided to disappear spectacularly as shown below.

Fire-Grate after cleaning at the start of December 2019
(After the first of four Santa Specials)

(This was the reason a diesel shunter was used as banker for the Santa Specials).

Obviously this was not great news and the timing was particularly inconvenient.

I've had to dig deep to figure out how this could have been caused to prevent it happening in the future. I think there are basically two causes, both to do with the coal.

The Welsh coal is clean; it produces very few 'volatiles' (the nice-smelling but smoky stuff) and burns hot. It also tends to disintegrate through agitation and during combustion. In either case, it forms a lot of 'dust' which sits around underneath the coal nuggets. Our nuggets were large, some about the size of three fists.

The dust tends to form into clinker and block the grate in places. Air then has to be concentrated through the remaining unblocked areas and causes hot spots which melt the fire-bars, a bit like a blow-torch. As the year progressed, the coal in our storage bunker became more dust than nuggets and so the amount of grate blockage increased as the year went on and finally precipitated the damage.

Anyway, in summary, that is my interpretation of what happened. All we have to do now is to prevent further damage and replace the fire-bars.

Traditionally, fire-bars have been made from grey cast iron. However, I've had advice that a 20-30% alloy of Chromium and iron is much longer-lasting than plain old grey cast iron.

I've taken this advice and, to be ready for the first 2020 steaming on March 22nd, I rapidly placed an order for a pattern to cast the new fire-bars from Chromium Cast Iron (the pattern has to be specific for the material as the metal would not cool to the right size otherwise). I had to purchase a minimum quantity of 30 fire-bars (which should keep us going for a while!).

The bars arrived just ahead of the delivery date and I am grateful to the staff at Cerdic Foundries Ltd for their help in a time of difficulty.

Quite a car load!

I've not tried a funding appeal before but this is one occasion when I think it is the right thing to do.

Including VAT, the pattern will be £2,400 in round figures - I have bought this.

Including VAT, each of the 30 fire-bars is £120 in round figures.

Please consider donating a fire-bar for Joyce. Donations can be made via PayPal or cheque (preferred as PayPal takes a percentage) by clicking here. I would be more than happy to entertain donors with a cab ride on your next visit.

Go on, you can do it! Thank you in anticipation.

Unexpected Surprise

A very cold Monday 2nd Feb. started with an attempt to repaint the cab roof. The first problem was that the paint was so cold it had the consistency of Tar! Leaving the paint tin in hot water for a while turned its contents back to liquid.

Problem solved so I thought but only to be thwarted by 7109 being chilled to the core overnight in Midsomer Norton's goods shed. As soon as the paint touched the cold metal, it went back to tar and couldn't be spread. I gave up at this point.

Nigel (co-owner) appeared with two sheets of the cold steel to make a pair of superheater steady plates something like in the drawing below (apologies for the low resolution). These are screwed to the boiler top plate around the superheater tubes to eliminate leakage of air into the boiler's superheater space every time there is a 'chuff'. Each 'chuff' is supposed to draw air up through the fire not in via the leaks! I'll come back to this another time.

Superheater steady plate drawing

We had a visit from Mr S., an S&DRHT member whom I'd not met before. I showed him over 7109 in my usual manner. He remarked that he followed the blog and enjoyed seeing the progress. To my great surprise, he delved into his pocket and produced a modern version of the item below to make us a donation. This immediately paid for the just-purchased cold steel mentioned above!

Oldie but Goodie

Many thanks Mr S. May more visitors such as yourself please come and see us at work and be shown 7109's secrets! (If you can't visit in person, there's always this as an alternative!).

Work continued with attempting to persuade the boiler cover to fit. I have to admit that part way through the afternoon, I had to give up due to the cold. When the entire loco is freezing cold, every touch of the cold metal, whether it's feet or hands, loses a little more body heat. I'd run out!

Next Saturday 7th Feb. 2015 is the Sentinel Drivers Club AGM for the group of stalwarts who support all things Sentinel, including 7109.

Many thanks ...

... to all who kindly made donations to the Sentinel 7109 restoration project at the S&DRHT AGM on Saturday 8th October 2011. Much appreciated!

The queen definitely looks younger in this photo!

Appeal for 'JOYCE' & her maker's plates

Amongst the Sentinel 7109 missing items are the 'JOYCE' nameplates and the Sentinel maker's plates specific to works number 7109. These were mounted on the side of the cab as in the photo below. I have no idea where these plates are but the chances are that since the loco survived, so did these plates; but where are they now?

Sentinel 7109 Near-side 'JOYCE' & Maker's Plate

Sentinel Waggon Works had various designs of maker's plates and the design specific to 7109 is shown below. With a lot of work, a new pair could be recreated from the design; however, I don't have those sorts of skills, nor the time with all the other restoration activities in progress.

Locomotive Maker's Plate Design

Another simpler approach is to make a mould from another actual plate such as the one below. The drawback is that the result always comes out slightly on the small side due to shrinkage of the cast metal when it cools. (Normally a pattern is made oversize to suit the shrinkage of the particular metal to be used).

Isebrook's (6515) Makers Plate

Peter Mitchell, owner of Isebrook (6515) at Quainton Road, has kindly offered to make one available should we decide to do it this way. Obviously, we would have to blank out the 6515 and replace it with 7109.

But I'm still wondering where the originals are. I'd be really glad to hear from anyone who can throw some light on their whereabouts. Please post a comment below if you can help.

How do I support the restoration?

The easiest way to support the restoration of Sentinel 7109 is by using Paypal to donate. For this you will need a Paypal account which can be arranged through the Paypal website. All you need to do then is click the Donate button below and the rest is easy.

Another simple way to support the restoration of Sentinel 7109 is to donate to the project by writing a cheque made out to "Sentinel 7109" and either handing it to the Midsomer Norton station shop assistant or sending it by post to:

Sentinel 7109 Restoration project
c/o Midsomer Norton Station
Silver Street
Midsomer Norton
Radstock
Somerset
BA3 2EY

Don't forget to include a phone number, email or contact address so we can thank you.

Offers of engineering skills are of course welcome (please)! Just post a comment below and say how you would like to help.

And finally...

...there's always these (or the modern equivalent)!