My workbench - Experiments in Resin Casting

[45609]

Good afternoon,

Following my reappearence on Rob's workbench thread there have been a couple of requests to see a bit more detail on the DMR K1 I built earlier this year. I had intended to do a more usual account of progress of things as it went along but time always seemed to be against me.

The basic spec was to build a Peppercorn K1 2-6-0 in OO gauge. Initially a Bradwell kit was considered but it quickly became apparent that to build this in OO gauge was going to be more work that building "as intended" in P4. The DMR kit seemed to be the best option and I had been encouraged by some favourable comments after a brief discussion with jwealleans. He pointed me in the direction of Graham Varley's construction review in December 2000's Railway Modeller. A kit was duly ordered from DMR (Mike Russell) which included a Markits wheelset.

Tender construction was the first thing to be tackled with the basic box structure and underframe being very quick to solder up. Adding the details took a bit longer and in particular the footsteps were a bit awkward due to lack of really positive location that holds them square and level. Some deft work with the RSU was required whilst holding the footstep against a straight edge (a piece of thin square wood). Lamp brackets were easy to fit as they fold up and have their tails inserted through an etched slot on the tender rear. Before fitting the cast electric lamps I added a little extra detail. The conduit pipes from 0.3 nickel silver wire.

Other items that I made a note of in my little black book are as follows

Water filler; casting right size and shape but hinge detail does not look LNER to me. A minor critcism.
Beading; etched as one piece, tinned first and attached with an RSU. A fair bit of cleaning up with scrapers and files needed to achieve a rounded section.
Electric lamps; whitemetal castings glued on with epoxy. Lost wax would be better and allow soldering.
Fire iron tunnel; parts narrow and a bit tricky to bend. Also needed a bit a filing to fit properly. Spent too much time on this to then cover in coal!
Water scoop; appears to be a generic w/m casting. Requires packing on tender subframe to set at correct height.

Making some notes such as this is always useful in case I ever have to build another one.

Finally, for now, here are a few pictures of the tender in the raw.

Cheers.....Morgan

[60800]

Very nice indeed

[jwealleans]

Quality stuff, Morgan. For 'blackout' and anyone else who hasn't seen it, go back through this forum and find Morgan's 'Sam Fay' build from a couple of years ago. You won't see a better looking loco anywhere.

[45609]

Thanks JW. I'll provide the links below to save people the bother of searching

The thread starts here....

on-my-workbench-its-a-sam-fay-p7871.html#p7871

...or it you want to go straight to the finished article.....

on-my-workbench-its-a-sam-fay-p17945.html#p17945

[rob]

Thanks for taking the time Morgan.....that Sam Fay deserves regular exposure too!...Perhaps in time you might be consider merging more of you previous threads,I recall a really superb turntable amongst others items....!

[Robpulham]

Hi Morgan, I look forward to seeing more of this.

As one who was lucky enough to see Sam Fay in the flesh (and I have to say this inspired me to get a 7mm scale Gladiator kit which is in the pile)I can only echo what Rob and Jonathan have said - a superb looking loco.
______________________________________________________________________________

[boeing757]

Hi,
Hope no one minds me tacking a query onto this thread about K1s rather than start a new topic. Basically I have bought a poorly lined model and wondered if any of these locos were turned out in unlined black. Full lining is a bit daunting at my skill level.
Thanks for any replies.
B

[52D]

I think you will find that they were all turned out in lined black but often the lining was hidden under filth in later days, why not a paint job and weathering with the lining partially visible. What K1 have you modelled if i have any pics i will send via pm.

[60800]

Morgan's 'Sam Fay' build from a couple of years ago.

That beauty makes mincemeat of every single RTR loco I have (and I have a ltd edition A4 and Bacchy's 04 in my collection)

[boeing757]

52D You have a PM
B

[52D]

Sorted B, will check books at weekend for East Anglians most of mine are NE.

[45609]

Good evening,

Here is the next installment of the K1 build. Unfortunately I didn't take too many pictures of the chassis assembly but I have attached a photo of what I now find an essential tool. The Avonside chassis jig makes assembling a set of loco frame square and straight an absolute breeze. There are a couple of these jigs on the market and although up front costs are about the same as a quality loco kit, wheels, motor and gearbox the assurance of accurate construction, and heartache if it goes wrong, cannot be overstated.

The frames on the jig shown in the picture are for a LMS Black 5 so I'll say no more about that here. The K1 chassis, being a OO gauge build, was built in a semi-rigid manner. In other words the leading and trailing axles are in fixed bearings but the centre axle is sprung. Whilst some will suggest that rigid is fine for OO gauge I find that spring at least one axle improved electrical pickup and running qualities of the finished loco.

Starting with the coupling rods to set the wheelbase on the jig I managed to get the basic frames erected in a couple of evenings which included tack soldering them together to cut out for the centre hornblock. I normally use the Comet/Brassmasters type because they slide in the frmaes and do not restrict the width available for the gearbox. In this case the gearbox is a Highlevel Highflyer 40:1. The photos below show things at a more advanced stage. Cylinders have been put together and the basic running plate/cab assembly is soldered up. No particular problems were encountered up to this stage but I did spend a bit of time carefully forming the running plate curve where it meets the cab so that I could make a nice tight joint with a minimum of solder. Valances, also a potentially tricky soldering job were not as difficult as I had envisaged due to decent half etched guide slots on the underside of the running plate.

More soon, where I'll explain my approach to making removable brake gear.

Cheers....Morgan

[45609]

As promised in the last posting what follows are a few pictures and an explanation of how I fit brake gear to locos to make it easily removable for painting and chassis maintenance. The fact that it is demonstrated on the K1 build is incidental. I try to adopt this for any loco I build.

Instead of using solid wire for the upper brake cross shafts I open up the frame holes and use a piece of fine tube. 1.3mm O/D by 0.7mm bore is about right. Cut them over length and solder in place. These are trimmed back roughly with a piercing saw and then finished to final length with a file. I use a piece of plywood, of the appropriate thickness, with a 1.5mm hole drilled in as a filing gauge. The gauge is placed over the tube end and held against the frame whilst filing back the bit of tube that sticks out. Repeat this for the other 5 tube ends and they will all protrude the same distance from the frame. The length of the protrusion needs to take account of the thickness of the brake hangers and blocks so that they sit about mid way on the wheel tyre width. Next I ream the holes in the brake hangers with a taper broach to make them a close sliding fit on the top holes but a tight fit in the bottom holes when a piece of 0.7mm wire is pushed through. The tight fit in the lower holes will help with lining up and soldering when you need an extra hand. A tight fit on the brake pull rod(s) is also required. The hangers are then assembled to the tube at the top using a piece of long 0.7mm wire and then thread the pull rods and lower hanger holes onto a similar length of wire. I line up the lower cross shaft by eye so it is square to the frames and solder the bottom cross shaft joints to the left and right brake hangers. The first pair of brake hangers is the trickiest bit but after that the whole assembly gets some stiffness when the next pair of hangers is threaded on and the pull rods automatically dictate the spacing. Only at this stage do you need to line up the brake blocks with the wheels. Once all is soldered up the top wires can be pulled out of the tube and the brake assembly can be removed as one piece. When the chassis is running and painted up the brake assembly can be fitted with 3 lengths of 0.7mm wire through the top tubes. A dab of shellac (or black nail varnish if you are of that disposition) mixed with a bit of matt black paint is enough to retain the brakes in place. If they need to be removed some solvent on the upper pivots will loosen the shellac enough to pull/push the wires out.

What is worth mentioning as closing comments is that, what I call, a short stub pin method on the upper holes can be employed. This is sometimes necessary when a continuous tube and cross shaft at the top would foul the gearbox and/or motor you have installed. It is usually best to put in the continuous tube and shaft before fitting the gearbox and then cut out the centre section afterwards. A good strong fillet of solder on the tube always helps so that the cutting out forces don't b****x things up. Here is a final picture (credit to P.Tarver) showing this latter method.

As I have no doubt said in the past planning out the construction pays dividends later on. Thinking about the positioning of frame spacers, springing or compensation beam fulcrums, motor and gearbox combinations before even turning on the soldering iron is a key stage in everything I build. Sometimes satisfying all the requirements can be a challenge but I find that part of the fun.

Cheers....Morgan

[jukebox]

Great advice! I have previously struggled with the brake block/wheel rim proximity equation - this is a very neat soloution.

[Atlantic 3279]

Removable brakes on a kit build. Very neat! I have been known to arrange the top mountings as "cosmetic only", i.e. stubs that don't actually join the tps of the brake arms to the chassis in any way. The actual attacment of the whole set is then by means of tack soldering pull rods to the back of a netched underhung spring or similar discrete location beneath the chassis. Not quite as neat as your plug-in method, but not too hard to detach if necessary.