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Post by steamer5 on Dec 30, 2019 2:34:37 GMT
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Post by steamer5 on Dec 30, 2019 6:10:38 GMT
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Post by springcrocus on Dec 30, 2019 9:13:55 GMT
OK, the suspense is killing me.  What's a QD truck? Kerrin, your firebars are a bit too long and thin for a Britannia box.  They look like something designed by B. S. Johnson in Terry Pratchet's Discworld books.  Regards, Steve |
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oldnorton
Statesman
5" gauge LMS enthusiast
Posts: 726
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Post by oldnorton on Dec 30, 2019 9:51:55 GMT
Quickly Detachable ! Suspense over... Pull an 'R' clip out of the central support pin and it all falls off.
I have seen them on a Duchess and (I think) they work because the rear frame extensions come around the outside of the firebox. On a Britannia it is not going to work because the rear frame extensions sit well and truly in the middle of the shaped ashpan.
Norm
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Post by delaplume on Dec 30, 2019 11:44:12 GMT
Hello Norm,
Quote}--"because the rear frame extensions sit well and truly in the middle of the shaped ashpan."......In that scenario could you not assemble the grate from 3 separate units ??
Alan
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Post by delaplume on Dec 30, 2019 11:50:34 GMT
Hello Steve,
In your drawings is an item marked as}--"Grate lifting assembly"...Can you tell us what that's all about please ??....It seems quite small and flimsy compared to the grate itself...Could you show other parts of that same drawing so as to shed some light on the matter ??
Many thanks in anticipation
Alan
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Post by steamer5 on Dec 30, 2019 20:02:45 GMT
Hi Steve,
Yep to narrow for you by a long shot! But it was the idea of the bendy grate to get it in & out that might be useful, maybe not to you either given the width of the fire box is the same as the cab....
Cheers Kerrin
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Post by springcrocus on Dec 30, 2019 23:18:38 GMT
This thread has started to drift away now so I will leave it to others to continue the discussion as they may. Just one last question, which is a more direct version of what I asked at the start.
Has anyone on here ever PERSONALLY burnt through a set of firebars? If so, how long did your original bars last? We all know that Uncle Tom Cobbley from three clubs away did but his were probably made of green cheese, hearsay is irrelevant.
I will decide what to do over the next couple of months and add it to the diary at the appropriate time. Thanks to all who contributed to this thread.
Regards, Steve
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jma1009
Elder Statesman
Posts: 5,922
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Post by jma1009 on Dec 30, 2019 23:44:35 GMT
Hi Steve,
The Merthyr Club acquired a Milner 7.25"g Hunslet with a badly burnt and distorted cast iron grate.
I've never had a grate burn out. Bit of wastage etc of the black iron grates over the years. Not a fan of cast iron grates, or the welded stainless steel grates supplied by some of the trade.
I've driven quite a few 5"g Brits over the years in the UK and don't recall issues with the grate - perhaps the inner frames underneath the ashpan were omitted - as they are not required in miniature.
You must be able to clean the ashpan and the grate thoroughly, and ash must not build up to get underneath near the firebars.
Have you considered a rocking grate in 3 or 4 parts, horizontally split from side to side?
Cheers,
Julian
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Post by delaplume on Dec 31, 2019 3:59:19 GMT
Hello Steve, In your drawings is an item marked as}--"Grate lifting assembly"...Can you tell us what that's all about please ??....It seems quite small and flimsy compared to the grate itself...Could you show other parts of that same drawing so as to shed some light on the matter ?? Many thanks in anticipation Alan Hello Steve, Before you leave the thread I would appreciate an answer to this question if you please...I don't have access to those drawings and I suspect that the grate is designed to tip--- is that the case ?? Many thanks Alan |
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Post by springcrocus on Dec 31, 2019 9:56:20 GMT
Alan, PM sent with full drawing (not relevant here, though).
Regards, Steve
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oldnorton
Statesman
5" gauge LMS enthusiast
Posts: 726
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Post by oldnorton on Dec 31, 2019 10:02:11 GMT
I've driven quite a few 5"g Brits over the years in the UK and don't recall issues with the grate - perhaps the inner frames underneath the ashpan were omitted - as they are not required in miniature. The frame extensions, that run under/through the ashpan, hold the dragbox so they are kind of important. |
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oldnorton
Statesman
5" gauge LMS enthusiast
Posts: 726
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Post by oldnorton on Dec 31, 2019 10:13:18 GMT
Has anyone on here ever PERSONALLY burnt through a set of firebars? Yes, in my early days I made a hole in a Butch CI fire grate. The ash pan is very close in the centre (axle underneath) and my belief is that ash blocked it because I used a poker on the fire. Bad thing to do! never done it since! I agree with Julian's view that it is ash build up, stopping localised air flow, that will potentially melt the bars. Norm. |
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Post by springcrocus on Dec 31, 2019 10:58:59 GMT
I've driven quite a few 5"g Brits over the years in the UK and don't recall issues with the grate - perhaps the inner frames underneath the ashpan were omitted - as they are not required in miniature. The frame extensions, that run under/through the ashpan, hold the dragbox so they are kind of important. Regards, Steve |
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jma1009
Elder Statesman
Posts: 5,922
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Post by jma1009 on Jan 1, 2020 0:12:57 GMT
A very old late friend of mine of the Cardiff Club was Jack Thomas who built a superb 5"g Perrier Brit that I drove plus quite a few other very fine locos including a Peter Rich 5"g Castle.
Jack was a very practical engineer by trade, and also a very knowledgeable model engineer and experienced miniature loco driver.
I have quite a few pics of Jack and his Grandson driving the 5"g Brit at Heath Park Cardiff, and also vividly remember us struggling with it getting it in and out of his camper van at Heath Park. As a University student I visited Jack at his home in Fairwater, Cardiff, when the Brit was in the back room not steamed then for personal issues, and the GWR Castle was in his workshop being completed.
I would suggest wider inquiries of those who have built the 5"g Perrier Brit as to fire grate arrangements.
I don't remember any issues with Jack Thomas's 5"g Brit - though that example is a long time ago when I last drove it or helped lift it. I recall that one of Jack's big locos was entered in IMLEC one year - it was probably the Brit rather than the Castle.
Cheers,
Julian
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Post by David on Jan 1, 2020 7:54:53 GMT
I have not quite burned through a mild steel grate on the red loco which took 4 or 5 years. I replaced the grate before it got too bad but the firebars were down to maybe 1mm wide in places and that was allowing the fuel we were burning at the time to fall through.
It seems bizarre someone designed a loco where you can't remove the grate. That seems like asking for trouble and just plain difficult to clean and otherwise work around. I've never met a loco like that on our tracks.
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oldnorton
Statesman
5" gauge LMS enthusiast
Posts: 726
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Post by oldnorton on Jan 1, 2020 11:14:50 GMT
It seems bizarre someone designed a loco where you can't remove the grate. I think most of us are in agreement that we would like a grate that can be got out without lifting the boiler, for all the reasons that are obvious. Steve is asking a question in the title of this thread, raising the subjects of "what will happen if they are not removable" and potentially "what ways are there of making them removable"? Just to help clear up any misunderstanding, the Perrier design of Britannia does have a one piece grate with a drop centre. It is 6 5/8" wide at the front widest point and the bolt up assembly is 1/2" deep. If you did try to cut it into three lengths you will have pieces of around 2 3/16" width and the most you can get through the Perrier fire hole is a lump 2" x 1/2". As Steve says, the grate would need to be in four lengths. This is why some builders, like Jim, have designed a grate that can be slid out from the side. The Perrier design was used to make the Winson kits, and these were further modified by Modelworks. I have a Modelworks boiler and set of frames that I am extensively rebuilding. I suspect that Winson introduced the three piece grate and a larger fire hole to get it through because certainly the Modelworks has such a grate and a bigger fire hole that will pass a 2 1/8" x 7/8" grate section. The firebox is perhaps slightly narrower by 1/4" at its widest so its grate is 6 3/8". The Modelworks grate has a centre drop door but by all accounts is difficult to get on with, being too flexible and the grate is a problem to reposition if removed through the fire hole. Because I have that bigger fire hole I have been able to design a much more substantial, welded stainless grate in three lengths. It has centre drop section that will hopefully work most of the time, but when I need to I will be able to use a hook tool to lift out the three sections through the fire hole. Unfortunately, Steve hasn't really got this option and it is one instance of where the Modelworks kit got something right. I myself didn't appreciate the fire hole size differences until this thread made me look at the drawings. Norm |
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Post by delaplume on Jan 1, 2020 22:34:29 GMT
Hello Norm.
Quote}----"I myself didn't appreciate the fire hole size differences until this thread made me look at the drawings.".......
Yes, me too...Although I had drawn-up a very basic concept for the whole of this rear-end arrangement on No.111 I deliberately left it until last before committing to one particular design in order "shop-around" and see what others had come up with...
Steve has very kindly sent me via a PM the full view of those drawings he posted recently and they have given me some food for thought..
Thank goodness for kind-hearted folk on this Forum !!
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Post by springcrocus on Jan 2, 2020 7:36:53 GMT
As Norm has stated, the grate in this Britannia is particularly problematic because of the wide firebox spanning the frames. Narrow firebox / ashpan assemblies don't suffer from this. Making the grate in four pieces may be possible but, with two drop-down sections in the middle, it would probably be quite flimsy. Widening the firehole is not an option now the boiler is built but is one that I will add to my website as a recommended modification for future builders. This will allow others a wider range of options in their grate design. There is one further avenue that I am having a close look at, prompted by a comment from Andy Higham, and that is seeing how easy it would be to remove the complete pony frame assembly. At present, six 2BA bolts hold each arm of the pony frame to the mainframes, one of which is captive behind the rear driving wheel. Lose this bolt on each side and it appears to becomes possible to drop the entire frame, truck, ashpan and grate away with minimal work. If so, there lies the solution. Make it as designed and modify the connection between mainframes and pony frame. Adding a support plate to the top of the rear stretcher could support the boiler whilst dismantled. Interesting times ahead.  Regards, Steve |
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Post by Cro on Jan 2, 2020 9:32:33 GMT
As Norm has stated, the grate in this Britannia is particularly problematic because of the wide firebox spanning the frames. Narrow firebox / ashpan assemblies don't suffer from this. Making the grate in four pieces may be possible but, with two drop-down sections in the middle, it would probably be quite flimsy. Widening the firehole is not an option now the boiler is built but is one that I will add to my website as a recommended modification for future builders. This will allow others a wider range of options in their grate design. There is one further avenue that I am having a close look at, prompted by a comment from Andy Higham, and that is seeing how easy it would be to remove the complete pony frame assembly. At present, six 2BA bolts hold each arm of the pony frame to the mainframes, one of which is captive behind the rear driving wheel. Lose this bolt on each side and it appears to becomes possible to drop the entire frame, truck, ashpan and grate away with minimal work. If so, there lies the solution. Make it as designed and modify the connection between mainframes and pony frame. Adding a support plate to the top of the rear stretcher could support the boiler whilst dismantled. Interesting times ahead. Regards, Steve Does the cab support and the whole rear of the loco not fit to this though? So surely removing this area would mean taking off all the fitting/pipework and cab and by then you might as well just lift the boiler? 3 sections, 2 either side and one down the middle - easy! Adam |
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What's a QD truck?
They look like something designed by B. S. Johnson in Terry Pratchet's Discworld books. 
