Atlantic's works: Portable layout - Scenic details next

[60800]

I'm still waiting for the title to change to Cock up o' the South...


Another brilliant model Graeme - I have some spare sunshine numbering and lettering somewhere if you want it

[Saint Johnstoun]

Perchance I should arrange for Matthew Hopkins to visit Scunthorpe! (Frodingham)

Do they still burn witches in that parish?

Heresy is a crime still punishable by .....

[60800]

Me, a witch!? I have nothing to do with the SR! (glances at the two SR locos on shed )

[earlswood nob]

Good morning from a rainy day in Surrey (sounds like a Brook Benton song)
It was an early start today as the rain has curtailed my daily walk, and with the railway out between Tonbridge and Maidstone, my trip to the record office has been postponed.
I moved the belts on my drill press so its running full speed. and tried loosley clamping a needle file in the vice and slowly pressing it against the wheel flange, and hey presto, I have a wheel with a 0.5mm smaller flange diameter. A quick dab of wet and dry and I have a new-old Romford wheel for future use. I did try and correct the old wheel that I trimmed before, but no luck, so I guess it was in dodgy condition before I started.
Many thanks to Atlantic and Woodcock for without their experience of the subject, I would probably have left the wheels alone and unused. Now to resist the temptation to trim all my old wheels and think of the money I'd be saving by not having to buy new ones,
(what's obsessive compulsive disorder).
Earlswood Nob

[Atlantic 3279]

The Bulleid-beef project is not abandoned, in fact I've been daft enough to order some Hornby wheelsets and a motor to see what I can do. I've also ordered one or two other items from the chaps at EKM, uses for which will become apparent in due course. The mystery streamliner project remains oin the cards too, as do my other two clandestine resin based projects. Firstly however, by way of tidying up unfinished work on other locos so as to have a "clear run" at new items, and inspired by a new thought that came to mind a day or two ago, I've been revisiting a Bachmann K3 chassis.

The Bachmann K3 has picked up a bit of a reputation for lumpy running at certain speeds, owing either to basic inaccuries or (more likely) just too much slop in the chassis. The middle axle in particular tends to be so loose in its slot in the chassis that it can be twisted around in a pronounced "yawing" movement by no more than a light finger-grip on the wheels. This potentially creates tightness between crankpins and rods during running as the wheelbase effectively varies! Several good modellers have found that with minimal cleaning out of the axle slots in the chassis it becomes possible to fit new wheelsets with 1/8" axles, taking up the unwanted slop and opening up the option of fitting full size wheels at the same time. Of course this means having to either mate the Bachmann rods to wheels with much slimmer crankpins, or replacing the rods with something new. If you are changing to EM gauge anyway, or you insist on full size wheels, the use of 1/8" axles certainly makes sense. Partly because I have a further move "up my sleeve" for this particular chassis, and partly because I always seem to end up trying unconventional methods, I've had a go at something a bit different, and this may suit those who want smooth running without replacement of original wheelsets and valve gear.

If you drop the keeper plate from the K3 and remove the big-end screws to allow the con-rods and return cranks to drop clear of the driving wheels, you can get reasonable access to the coupled wheels and axles although you cannot remove them completely unless you can either slot the keeper plate through the gap beetween the first two axles, or you detach either the coupling rods or the wiring. Neither approach is really necessary when using my method. You'll see that rather than running on broad bearing surfaces in the chassis block, the original 3mm Bachmann axles run on surfaces around only 1mm wide at the very end of each axle slot. My chassis hadn't done much running but had lots of slop in the relationship between (particularly) the middle axle and the bearing areas.

Now it is time for those who insist on "real engineering" and those of a nervous disposition to move on to another topic! If however you choose to look at the picture below, you can see that with the aid of some strips of 3 thou brass shim, formed into U-shapes and bonded to the cleaned bearing surfaces with a tiny smear of epoxy (presssed in place while setting) I've taken most of the slop out of the middle axle. I've also used two half-slices of 5/32 brass tube to add support and guidance to the outer axles, these tube slices being bedded on slips of 3 thou shim and more smears of epoxy, to try keep all axles level, or to at least avoid any "rocking" on the mioddle axle. I actually ran the chassis around the layout with the shims fitted only "dry" around the middle axleboxes and also ran it at full-tilt against a stop block in both directions. The shims stayed in place, but I decided that the epoxy wouldn't be a bad belt 'n' braces move. The chassis now seems to run very smoothly at all speeds, with rods and wheelbase in constant dimensional agreement. Time will tell regarding durability and reliability. I'll reveal the next part of the plan soon.

Hollow Resin Castings from Coreless Moulds
Inspired by something seen on the WP Notcutt website I've had a go at producing a trial version of my A1/1 smokebox casting without actually putting the core-piece into the mould. Continuous steady rotation of the mould as the resin cures does the trick very nicely. This promises to be a very hand means of saving on time, effort, materials and brainache. I've been holding back from the idea of trying to cast a complete boiler in one go because I envisaged the complexities of producing multi-part outer and inner moulds to cast (and release) the shapes of things such as smokebox bases and lower parts of the firebox sides. I'm now tempted to think that I can take a leap forward......

[Atlantic 3279]

I've been tinkering with the K4 again.

Although I've yet to deal with both sides, finalise the arrangementas for the middle crankpin, and pack the body and cylinders upwards with 20thou plastikard to restore original ride-height, I've found it possible to successfully fit Hornby Thompson L1 wheels to the chassis and to make the Bachmann rods fit the Hornby "crankpins" such as they are. I'll say / show how I did it if it turns out to be a success. These wheels are the correct smaller diameter, with the correct lesser number of spokes and the right style of balance weights for a K4. But does it look worthwhile compared to Bachmann's slightly small K3 wheels with too many spokes but "disguised" by my added larger balance weights, in the followng before and after pictures?

Before, i.e. "disguised" K3 wheels

After, i.e. L1 wheels

[Manxman1831]

Does it really need packing under the body? Looks alright as it is.

[Tom F]

Looking good Graeme! I'm waiting to see a King K1 from an Hornby L1 and B1 mix...

I'll get my coat.... as well as getting that smokebox door sent to you!

[earlswood nob]

Good morning all
It looks good, and is surprising the differnce the wheel change makes.
Now you need a V4 to compliment the K4, as they both worked the West Highland.
Earlswood nob

[60800]

She really looks the part now Graeme (even more so than she did before)

I'm still on the market for 61994 as preserved, and I'd put my cash down for a V4 as well

[earlswood nob]

G'day all
I'm not saying it's beyond Atlantic's capabalities, but while the V4 is about the same length as the K4, there are a lot of differences.
The V4 has a tapered boiler
The V4 has a short coupled wheelbase, 6'6+6'4
The V4 has the footplate curve in a different place
The V4 has an unusual version of the banjo dome
The V4 cab is shorter
The V4 has larger wheels

One good point is that they have the same tender.

Now to get back to the paintshop, I've just ***ked up the masking of my Bulleid Leader, so it's strip the paint and start again.

Earlswood nob

[Bill Bedford]

She really looks the part now Graeme (even more so than she did before)

I'm still on the market for 61994 as preserved, and I'd put my cash down for a V4 as well

ABS do a whitemetal kit……….

[60800]

I'd be no good with whitemetal. Brass, maybe.

[Tom F]

I'd be no good with whitemetal. Brass, maybe.

You don't know until you try....

[Atlantic 3279]

I too am not sure how you can tell that you are no good if you haven't tried. None of us started out as dab-hands at every modelling task, as far as I am aware.

Finishing off the tale of the K4......
Here sits Loch Long with finalised fit of rods and motion plus packing to re-trim the body / buffer height.

Technicalities as follows:

Axleways are shimmed-up as per the picture and description higher up this page.

Wheelsets are Hornby L1 tank, with brass bearings and original spur gear removed, Bachmann K3 gear fitted to middle axle. The axle was keyed/splined in the necessary area by scraping the the teeth on the age of a file firmly along the axle, raising rough edges in process.

Crankpin fit for leading and trailing coupled wheels has been achieved by inserting slices of K & S 3/32" O/D brass tube into the holes in the rods and screwing some spare hornby crankpin screws (ex A3/A4) into the L1 wheels. The screws centre these "washers" nicely, trapping them against the wheel face and the hex heads are bigger than the washers, so the washers are not soldered into the rods. I noted while rummaging for suitable screws that the threaded holes actually appear to be 10BA so would accept Romford crankpins if necessary.

Driving crankpins - the awkward ones! The Hornby middle pin is both slimmer and shorter than the Bachmann one, but not slim enough to simply slip some handy tube over the pin to make it fit the Bachmann rods. I found that the chassis would in fact run smoothly even with all of the slop left in the fit of the middle pin and hole, but for my pedantic eye there was just a little bit too much flexing up and down of the coupling rods about the middle knuckle as the loco ran on flat straight track. I got rid of the slop in coupling rods by curling a narrow strips of 3 thou brass shim into rings, springing one snugly into each middle hole in the coupling rods, soldering in place, and cleaning up taking care to keep the holes smooth and central. It was quite a tedious job, requiring the reduced hole to be progressively "twiddled" out to get a perfect fit on the pin with just that necessary hint of slack. I had the chassis running dreadfully again at one stage because the holes were too tight and uneven. It would be much easier to leave it alone.....
It is easy enough to bush the big end of the con-rod (if you must) to prevent slop / knock by spring in a 2mm wide curl of 3 though brass which need not be secured in place.

That just leaves the return crank. The middle Hornby crankpin isn't long enough for it to screw-on without nipping up the other rods in the process, and the "teeth" on the inside of the Bachmann crank don't fit the flats that Hornby provide on the end of the pin to assure orientation of the crank. I tried a couple of methods, but the best seemed to be to bore out the hole in the crank until a stub of my 3/32" brass tube was a tight fit in the hole. I locked the tube in place with cyano, the outer end of the tube flush with the outer crank face, the inner end cut off about 0.7mm proud of the inner crank face. A 1.2mm screw with a nylon thread insert* (should it really be another BA size I wonder?) will then screw through the tube and into the threaded pin, tigghtening the tube firmly onto the end of the crankpin without having the crank trapping the rod in the process. Crank orientation can be set as desired, the outer pin end seemingly biting sufficiently into the brass tube keep it locked in place under screw tension.
* At last, there are advantages in having access to parts for spectacle repairs!

Ride height I found I needed 25 thou packing under the cylinder stretcher to raise the front end of the body to achieve correct buffer and running plate height plus sufficient flange clearance over the pony wheels. The rear seemed to need only 10thou on the flat part of the chassis under the front of the cab.

I've compared the final look below with that of two burly-bigger-brother K3s, both of which sport full size coupled wheels rather than Bachmann's under-nourished K3 wheels, but only because they run on the mechanically cruder V3 mechanism, complete with its thick wheelrims and (by modern standards) fairly poorly represented valve gear. Both of these K3s have appeared on here previously and (for those who don't already know) are from a mixed bag of components, 2447 having a scratchbuilt plastic body.

So was the change of K4 wheels from the Bachmann "midi" size worth all of the trouble? I still can't decide.