Archie Atkinson
Active Member
Tim I have a spare set of correct pattern Alan Harris wheels turned to Scale 7 if you are interested
7mm Geordie bruiser (NER A7)
- Thread starter mickoo
- Start date
Tim Humphreys ex Mudhen
Western Thunderer
Yes, I am interested John, do you to pm with a price.
Tim
Tim
Tim Humphreys ex Mudhen
Western Thunderer
Bad typing! Will you pm with a price.
Thanks
Thanks
Tim Humphreys ex Mudhen
Western Thunderer
Its my intention to post this build Mick, there's a Tyne Dock 9f to follow.
tim
tim
micknich2003
Western Thunderer
mickoo
Western Thunderer
Whilst waiting for the etches to come back I've started to draft up some basic GA drawings, starting with my BR small boilered (DIAG 55) one. Just need to add the little details tomorrow and then it'll form the basis for some others. So far I think there are four types of smokebox, three smoke box doors, but that may be four, three boilers (well ten actually but three distinct visual types), three types of front sand box and two types of chimney and dome.
Micks picture also partially solves something that's been niggling me for some time, that of the slide bars, no matter how you measure it and juggle it on the GA, Pipe and Rod or motion drawings the cross head rear appears to come off the slide bars by a small amount, about 2" if the measurements are correct. I'm sure I've seen this trait on a GWR Prairie but for the life of me cannot find the photo to prove it.
In Micks picture it certainly looks like the crosshead at full RDC is off the end of the slide bar.
Micks picture also partially solves something that's been niggling me for some time, that of the slide bars, no matter how you measure it and juggle it on the GA, Pipe and Rod or motion drawings the cross head rear appears to come off the slide bars by a small amount, about 2" if the measurements are correct. I'm sure I've seen this trait on a GWR Prairie but for the life of me cannot find the photo to prove it.
In Micks picture it certainly looks like the crosshead at full RDC is off the end of the slide bar.
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micknich2003
Western Thunderer
Boothferry Park, Hull, April 1955.
Yorkshire Dave
Western Thunderer
It'd be interesting to model 9777 (post #27 above) with twisted front buffers to see the reactions and hear the comments 
....
....then produce the photo
.
........then produce the photo
.
Brian McKenzie
Western Thunderer
Mickoo,
I also came across this new-to-me phenomenon of the crosshead coming off the end of the slidebars (by 5/8 inch). I thought I had cocked up the CAD, but it is shown as such on the makers plans (Sharp, Stewart), and I was also able to verify it by measuring a derelict prototype.
A young engineering apprentice explained this was deliberate, so that as the slide bars wore, the crosshead would not keep hitting a lump of unworn portion - and hence the groove for the same purpose in the forward part of the slidebars.
This six second video clip shows the action:
-Brian McK.
Brian McKenzie
Western Thunderer
Mickoo,
Prior to your editing of the previous message
, I checked to see if indeed there were 'wear' slippers in the crossheads of my Scottish built New Zealand prototype. Not really relevant to our small scale model construction, but yes, there were thin pads of cast iron set into pockets. However, this didn't preclude substantial wear, not only on the inside faces of the slidebars, but also a surprising amount along the sides, where the crosshead made contact.
This plan snippet, showing extent of crosshead travel, might help allay any concerns you have with the A7.
-Brian (making a quick dash to NRM archives Thursday 26 October, if you're about)
(old grey, bearded and bespectacled, ex Port engineer, so probably won't stand out from the crowd
Prior to your editing of the previous message
, I checked to see if indeed there were 'wear' slippers in the crossheads of my Scottish built New Zealand prototype. Not really relevant to our small scale model construction, but yes, there were thin pads of cast iron set into pockets. However, this didn't preclude substantial wear, not only on the inside faces of the slidebars, but also a surprising amount along the sides, where the crosshead made contact.This plan snippet, showing extent of crosshead travel, might help allay any concerns you have with the A7.
-Brian (making a quick dash to NRM archives Thursday 26 October, if you're about)
(old grey, bearded and bespectacled, ex Port engineer, so probably won't stand out from the crowd
mickoo
Western Thunderer
Brian,
Cheers, Yes I edited it as I wasn't sure, last thing I did was to look at several detail shots I had of A4's, 9F's, etc and couldn't really discern a sacrificial slipper so edited my post accordingly, they did all show a machined recess at the front and rear as you have just now shown
The idea was to post up some photos today in the cold light of day, which I'll do this morning at some point.
26th Oct will be no good I'm afraid, Ze Germans are here and we have another two cranes to commission that week so any leave is verboten
MD
Cheers, Yes I edited it as I wasn't sure, last thing I did was to look at several detail shots I had of A4's, 9F's, etc and couldn't really discern a sacrificial slipper so edited my post accordingly, they did all show a machined recess at the front and rear as you have just now shown
The idea was to post up some photos today in the cold light of day, which I'll do this morning at some point.
26th Oct will be no good I'm afraid, Ze Germans are here and we have another two cranes to commission that week so any leave is verboten
MD
mickoo
Western Thunderer
Ok moving over to the A7 in 3D a simple knock up of some of the frame parts to see what 'it' should look like, hopefully in seven days I'll have some metal work that looks similar if not identical, excepting the 3D prints of course, I'm not pulling that trigger until I know the metal work is good enough.
Overall view
Front end close ups, inside front view.
The blue grey bits up here are the proposed castings and the rod is the cylinder drain cock lever, hopefully after supper I'll add the linkages lifted off the art work and we'll see if they all fit.
Outside front view.
The outer cylinder frame work is an inverted U, the hole in the top should aid fixing either the wrapper or castings, hopefully both.
Front end outside rear.
Currently the cylinder rear cover is an etch but I may change this and add the stuffing gland as one casting, though it is tempting to leave the cover plate in etch and then insert the stuffing glad casting on top.
Rear inside.
Again these are currently etched plates, they're only the same colour as the castings to make them stand out easier. The same thoughts apply to these are the previous outside ones, the jury is out on that at the moment, I'll see what the etched ones look like once fitted to the model.
Rear end.
Probably the most complicated part to fabricate due to the step in the frames and triple plate work require to fix it all together. The rear frame plate work is etch not cast, again coloured to make it easier to see where it all goes. The rear brake shaft is in and hopefully the pull rods can go on shortly. The twin steam brake cylinders are clear to see.
From the rear.
The large flat plate over the rear radial is not prototypical....boo....but is there to limit the side throw of the radial truck and provide a smooth flat surface for the springs to push on; still to add are the two plates on the frame side that act as a guide and bearing surface to allow the radial truck to....well....radial
The large hole in the twin flat plates is where the hand brake linkage passes through and into the cab. There are a couple of rebates along the top of the frame for a couple of other non prototypical plates, one to secure the frames to the body, the other to tie in the rear end and give it a bit of strength.
On the outside of the frames are the footplate brackets and brake hanger brackets to add and all the rivets, they serve no purpose other than to add a bit of bling.
There is no skulduggery here, that would defeat the object of the exercise, each part is simply lifted off the main etch and expanded to 0.35 or 0.45 mm thick to represent the real material. Then it is flipped and poked through the holes to see if it actually fits. So far only one part has a mistake, a o.6 mm hole on the wrong side, on the model I'll fill it with NS wire and file smooth and then drill it on the other side in the correct place.
Enjoy.
Mick D
Overall view
Front end close ups, inside front view.
The blue grey bits up here are the proposed castings and the rod is the cylinder drain cock lever, hopefully after supper I'll add the linkages lifted off the art work and we'll see if they all fit.
Outside front view.
The outer cylinder frame work is an inverted U, the hole in the top should aid fixing either the wrapper or castings, hopefully both.
Front end outside rear.
Currently the cylinder rear cover is an etch but I may change this and add the stuffing gland as one casting, though it is tempting to leave the cover plate in etch and then insert the stuffing glad casting on top.
Rear inside.
Again these are currently etched plates, they're only the same colour as the castings to make them stand out easier. The same thoughts apply to these are the previous outside ones, the jury is out on that at the moment, I'll see what the etched ones look like once fitted to the model.
Rear end.
Probably the most complicated part to fabricate due to the step in the frames and triple plate work require to fix it all together. The rear frame plate work is etch not cast, again coloured to make it easier to see where it all goes. The rear brake shaft is in and hopefully the pull rods can go on shortly. The twin steam brake cylinders are clear to see.
From the rear.
The large flat plate over the rear radial is not prototypical....boo....but is there to limit the side throw of the radial truck and provide a smooth flat surface for the springs to push on; still to add are the two plates on the frame side that act as a guide and bearing surface to allow the radial truck to....well....radial
The large hole in the twin flat plates is where the hand brake linkage passes through and into the cab. There are a couple of rebates along the top of the frame for a couple of other non prototypical plates, one to secure the frames to the body, the other to tie in the rear end and give it a bit of strength.
On the outside of the frames are the footplate brackets and brake hanger brackets to add and all the rivets, they serve no purpose other than to add a bit of bling.
There is no skulduggery here, that would defeat the object of the exercise, each part is simply lifted off the main etch and expanded to 0.35 or 0.45 mm thick to represent the real material. Then it is flipped and poked through the holes to see if it actually fits. So far only one part has a mistake, a o.6 mm hole on the wrong side, on the model I'll fill it with NS wire and file smooth and then drill it on the other side in the correct place.
Enjoy.
Mick D
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mickoo
Western Thunderer
Ok last parts for today, quite enough in Autocad for one session
Outside steam cock linkages, not having a tap to cross reference but it looks pretty close.
Inside and clearly an error, not with the linkage but with the casting, the drain is way too low and if you step back it's fairly obvious that the drain would not be that far off centre and virtually on the flange.
A quick check and re measurement if the GA shows my drain boss is too low by 1.2 mm, it's an easy fix on the master part before sending for 3D printing.
Brake hanger and footplate brackets, simple fold up affairs with webs attached where required.
Rear brake linkages, suffice to say it all works tickity boo
Though I had placed the cylinders too far aft by 0.7 mm last time.
That's all folks
Outside steam cock linkages, not having a tap to cross reference but it looks pretty close.
Inside and clearly an error, not with the linkage but with the casting, the drain is way too low and if you step back it's fairly obvious that the drain would not be that far off centre and virtually on the flange.
A quick check and re measurement if the GA shows my drain boss is too low by 1.2 mm, it's an easy fix on the master part before sending for 3D printing.
Brake hanger and footplate brackets, simple fold up affairs with webs attached where required.
Rear brake linkages, suffice to say it all works tickity boo
Though I had placed the cylinders too far aft by 0.7 mm last time.
That's all folks
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john lewsey
Western Thunderer
There is something rather appealing about these engines
micknich2003
Western Thunderer
oldravendale
Western Thunderer
What a great photo, Mick. Do you have any details of where and when?
Brian
Brian