5" gauge model of 4472 Flying Scotsman

[drmditch]

Please excuse am ignorant/cheeky question. I did spend some time this morning admiring your post on RMWeb.
The liners as I understand it are for the valve chests.
I think that Doncaster did fit fit liners for the cylinders themselves, did you consider doing likewise?
(Or have I missed something or is it not sensible/required in your scale?)

[greenglade]

Please excuse am ignorant/cheeky question. I did spend some time this morning admiring your post on RMWeb.
The liners as I understand it are for the valve chests.
I think that Doncaster did fit fit liners for the cylinders themselves, did you consider doing likewise?
(Or have I missed something or is it not sensible/required in your scale?)

hi

in general, liners aren't used for the main cylinder bores on models, they can and have been used where there's excessive wear after use or a mistake has been made during machining. Yes, these are for the valve chests just as in full size although the port shapes are slightly different. I can't recall if main bore liners where fitted full size from the off, only the steam chests. They certainly were when the bores wore down below spec. Looking at the specification notes from 1923 there is no mention of liners being fitted to the bores, although there is a note that the metal used for the casting must be as hard as possible allowing for the boring process. So in summary, I think both full size and models follow the same principles unless someone knows better of course..

Cheers

pete

[drmditch]

Thank you very much.
The skills you demonstrate are an inspiration and a challenge!

[greenglade]

Thank you very much.
The skills you demonstrate are an inspiration and a challenge!

Thank you ma'am , that's very kind if you to say so....

Pete

[john coffin]

Those turning skills take me back to my apprenticeship, not sure I was that good though!
Do you have to clean up the steam passage above the cylinder that looks a little rough?

Sure you will make a really good presentation.

Paul

[greenglade]

hi Paul

Yes sir, the liners were fitted a couple of thou undersize, they will have there final reaming once the reamer has arrived, should be here later in the week. I'll also lap them a little to get them smooth like the main bores.

Cheers

Pete

[greenglade]

3 sets of slide bars completed, just need to machine up the bolts and castellated nuts to complete..oh the joy...



Pete

[greenglade]

slide bars now trial connected to cylinders and motion brackets machined to give the correct angle, all currently held together with temporary bolts/nuts, still need to make the proper fasteners...



Pete

[greenglade]

I have now made a start on the inside connecting rod, here is the rod at a very early stage, the critical measurement is the distance between the hole centres, in this case, that equates to 8.5938 inches. I will post a picture of the finished article when complete, perhaps sometime next week.



Pete

[john coffin]

Looking really good Peter

[greenglade]

Looking really good Peter

thanks.. currently it's very much at the roughing out stage, it should look like this picture of the new P2 inside connecting rod when finished although it won't have the rear strengthing rib as this is a later design than that fitted to 4472 during the 30's



Pete

[greenglade]

Getting there, fluting next and then a hell of a lot of hand finishing.. hope my fingers hold out...



Pete

[greenglade]

Hi Guys


The inside connecting rod is now finished baring drilling/tapping the oilway holes and a final file/polish, I need a new set of files for that, mine are a little contaminated.

Rod assembled...



And disassembled...



More soon...

Pete

[john coffin]

Really good Peter, are the nuts and bolts your own, or in bought?

The machining looks special, as for files, I have found that the cheap diamond sets that either Aldi or Lidl sell at odd times during the
week have a special value, since because they are cheap, they are not too aggressive as diamond sometimes can be. Given where
you live, there are a fair few branches of either within less than 10 miles, so worth checking out their weekly offers.

As usual your handiwork is really impressive, we look forward to seeing the complete frame and motion working under pressure.

Paul

[greenglade]

Thanks Paul

Yes the studs and nuts were made by myself, I have a set of diamond files but they would be too course for this stage. I'm well overdue for buying myself a new set the No.2 cut files....all of mine are old and have been abused a few times, plus I have a bad habit of just grabbing what's to hand. Files should be kept seperated for steel of brass/bronze jobs

Cheers

Pete