Jump to content

SSM GNR(I) "S"-class 4-4-0

Rate this topic


Horsetan

Recommended Posts

The piston valves are operated as mike says through a rocking shaft.

From the eccentrics on the driving axle the expansion link is moved back and forth which in turn is suspended from the weight shaft. From the expansion link there is a connecting link which is supported on both sides of the frame spacer and this rocks back and forth. At the cylinder block side of the spacer as seen in the photo the connecting link is connected to the steel casting that the valve spindle link is connected to. This means as mike says that the valve is pushed/ pulled in the opposite direction of the throw of the eccentrics.

I will take a few photos at the weekend and put them up

Link to comment
Share on other sites

Right so, I'm just after completing the shell of the smokebox. Photos to follow as Windows Phone 8 will not work directly with the Forum upload software.

 

The smokebox shell is easy, but mounting it on the footplate reveals some flaws in etch design which "Weshty" might want to have a look at if he gets time to revisit the original artwork that he inherited. These flaws also affect the mounting of the front frame plates, making the job a little harder than it should be.

 

The real killer is forming the smokebox wrapper - you have to go slowly and carefully on this, and it helps to have the use of a rolling mill. The reverse curve where the smokebox sides become vertical must be marked out because if you get it in the wrong place, it will be the very devil to correct. I'll show yis how I did mine.....

Link to comment
Share on other sites

Now, some photos of what was done over the weekend....

 

attachment.php?attachmentid=10921&d=1387800238

 

The smokebox is the subject of our attention, and the kit provides a basic fold-up shell (Part P13) which we saw out of the fret:

 

attachment.php?attachmentid=10923&d=1387800307

 

Stick it in the vice:

 

attachment.php?attachmentid=10924&d=1387800337

 

....and start folding:

 

attachment.php?attachmentid=10925&d=1387800368

 

attachment.php?attachmentid=10926&d=1387800399

 

As can be seen, there are tabs underneath the smokebox sides which are intended to fit into slots in the footplate.

 

The front and rear of the smokebox shell have tiny etch marks; these act as seats for the tops of the smokebox sides:

 

attachment.php?attachmentid=10927&d=1387800429

 

...and this is how they fit:

 

attachment.php?attachmentid=10929&d=1387800666

 

A minimum of solder is now run into the inside corners, and eventually, we get this:

 

attachment.php?attachmentid=10930&d=1387800695

 

...which means we can test-fit it onto the footplate:

 

attachment.php?attachmentid=10932&d=1387800749

Edited by Horsetan
Part number added
Link to comment
Share on other sites

It's not all plain sailing, as we will now discover. First, I took out the post-1938 front frames (Part P16 and P17) from the etch:

 

attachment.php?attachmentid=10922&d=1387800275

 

attachment.php?attachmentid=10948&d=1387806276

 

These have two layers, with the riveted layer being attached last of all.

 

The inner layer has no tabs at all along the base, so trying to hold it in place is going to be the very devil:

 

attachment.php?attachmentid=10949&d=1387806282

 

attachment.php?attachmentid=10951&d=1387806297

 

Note that the left-hand frame has a tiny notch in the top - this is where the lubricator and its bracket will be places.

 

Now, let's have a look at the underside, so yis can see what I mean: if the slots in the footplate are going to be that long, why not have tabs on the base of the front frames to fit into these, and provide a stable location?

 

attachment.php?attachmentid=10952&d=1387806304

 

"Weshty": what d'ye think? Is it worth modifying the etch artwork?

Edited by Horsetan
Link to comment
Share on other sites

Horsetan,

 

These etches were done 30 years ago and the handdrawn artwork has long since disappeared and is certainly not available to me. I would have to recreate the etch design from scatch using the etch transparancies as a template.

 

Straight up this is not something I can give priority to, given I will have my hands full with the ammonia rake.

Link to comment
Share on other sites

.....These etches were done 30 years ago and the handdrawn artwork has long since disappeared and is certainly not available to me. I would have to recreate the etch design from scatch using the etch transparancies as a template.....

 

Ah, that's a shame. Lost in the mists of time. Never mind, it was just a question that occurred to me as I went along.

 

Send me up an etch Des, i'll redraw it for ya :P

 

You'll have to build it, though....

Edited by Horsetan
Additional comment
Link to comment
Share on other sites

Smokebox front overlay soldered on tonight - the bottom of it has an upward curve, which had to be formed using the handle of a needle file to get close to the right curvature.

 

Front frame laminates also assembled but will not be added to the footplate until the smokebox wrapper is on......

 

I think I have made a mistake with the buffer beam. Can anybody spot what it is.....?

Edited by Horsetan
Link to comment
Share on other sites

The next bit of the work was - on the face of it - simple: seating four tiny caps into the half-etched marks shown for them on the footplate. The etch provides five, just in case you lose one of them:

 

attachment.php?attachmentid=11002&d=1388145562

 

I tinned the backs of four of them with the usual 188 solder and Carr's Green Label flux:

 

attachment.php?attachmentid=11003&d=1388145591

 

However, separating each individual cap, filing off any excess tags, and positioning them is the very work of the Devil himself:

 

attachment.php?attachmentid=11004&d=1388145623

 

Eventually you get there:

 

attachment.php?attachmentid=11005&d=1388145654

 

...though if you use too much solder, you end up having to scrape all the excess off (as here).......which may take you longer than it did to position the caps in the first place.

 

With all four caps soldered in their correct positions, I could then add the front mounting 10BA nut. This is simply screwed tight in position using the matching 10BA bolt, brushed all around with flux, and soldered. The reason why it's screwed tight is to prevent solder leaking in towards the bolt and soldering that solid!

 

attachment.php?attachmentid=11006&d=1388145685

 

I test-fitted the smokebox shell, just to see where we were:

 

attachment.php?attachmentid=11007&d=1388145709

 

...and you can also see the curvature at the base of the smokebox front overlay. This is why you solder the front overlay at the top and upper sides, BUT NOT THE BOTTOM! As stated earlier, I used the handle of a needle file to form the curve, but you could also use a 3mm dia. drill bit. A useful point to note when forming the curve is to ensure that, when finished, the base of the overlay should sit perfectly on the footplate. If you can see a gap, your curve is too tight. Conversely, if the smokebox shell won't sit neatly on the footplate, it means your curve is too shallow.

 

This can be a difficult area to get right, and photographs of 171 and her sisters don't always show the curvature clearly.

 

I moved on to solder the preformed firebox and boiler barrel together:

 

attachment.php?attachmentid=11008&d=1388148720

 

....and since all the soldering is on the inside, with luck you should end up with a flush joint on the outside:

 

attachment.php?attachmentid=11009&d=1388148748

Edited by Horsetan
extra photos
Link to comment
Share on other sites

I have no idea what's going on with the images. They are uploaded into the normal albums, all of which are publicly viewable. I posted them up using the standard forum image links and they are visible to me in IE, Firefox and Google Chrome.

 

Not being any sort of IT expert (feck, I only use the thing), is there some sort of coding error that makes the images visible to only a few people?

Link to comment
Share on other sites

I have put another 2 photos in the album showing the slide valve crosshead which I hope will be of use or interest. It is unfortunately rather difficult to get a decent photo of the slide valve crosshead due to the proximity of other bits of valve gear and the trailing bogie axle.

 

It all helps. Thanks.

 

As it happens, I have another 4-4-0 kit with inside motion - the ex-Great Central/LNE D11. This is an old Perseverance kit, and the inside motion frets for it were designed by Peter K Dawson. Some of the smaller links appear broadly similar to the "S", so some duplication might be possible.....

Edited by Horsetan
Update
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

Terms of Use