Caledonian Dock Shunter 498 Class

[bertiedog]

After a purchase on Ebay, a new locomotive kit, which makes a nice change from restorations or part assembled kits, A Caley Kits 498 Caledonian Railway Dock Shunter 060 with outside cylinders.

 

 

The John F. McIntosh design was used by Martin Evans to produce his live steam 3.5 inch gauge loco "Rob Roy" which was published in the Model Engineer Magazine

 

The kit was bought as new and is still available from Caley Models, but this purchase included the Markit Wheelset, which would have added a further £30+ to the basic kit. As they are not part of the kit or wheels, the crankpins from Markit, deluxe type are required and appear to be the only purchase needed, bar the motor and gearbox, Caley supply overlays to fit to the wheels for more scale appearance and counterweights.

 

It has fully sprung and compensated chassis, with split side rods, and a floating motor which moves with the driven axlebox suspension.

 

The suggested motor is an Anchorage DS10, but a Chinese five pole motor replacement will be used, fitted with flywheel drive, on a new design gearbox mount for the motor. It requires a ratio of about 50:1 overall for really decent slow speed operation.

 

The kit is designed for all insulated wheels, all picking up power from concealed short wire springs, behind each rim. No DCC will be fitted, so the interior is fully available for lead ballast to increase the overall weight. The side tanks can be filled up as well.

 

The first job is the Markit wheels, they did not fit on the square ends of the Markit Axles as easily as they should. If forced on it will raise swath as the steel axle is dragged into the tight fit by the mounting nut on the axle. It need a bit of the edge removed around the cast back of the wheel, to remove any burrs or flash. Also check the square  end of the axles have no burrs etc. The wheels should be a firm fit, not loose, and slid cleanly off each stub axle end as needed during assembly. The flanges will be reduced to minimum size compatible with RP25 00 specs. This is done in the lathe.

 

The rest of the chassis follows, and the suspension method set up. I like a fully adjustable version of the wire support system, with coil springs added to the wires in the original Gordon Varney type of wire suspension. It should fit easily under the short chassis.

 

The kit has its own etches for the chassis, to which are added MJT hornblocks and bearings.

 

Next assembly will be the gearbox to assess the clearances between the frames in an 00 version, (not P4).

P4 spacers are provided in the box. of etched parts.

 

Stephen

Edited April 9, 2017 by bertiedog

[bertiedog]

As the drive is to the rear axle, and the side tanks completely cover the view of any transmission parts, I am fitting a conventional Markits 60:1 gearset in a own design brass milled, enclosed gearbox, with the motor raised at the front and flywheel in the smokebox area. There is no need to add a high level gearbox with extra idle gear etc., the motor unit will pivot on a cross bar to allow the suspension to operate up and down correctly.

 

A set of 60:1 gears ordered  just now, with a set of 8 Markits brand "super deluxe" crankpins to provide spares if required. The nuts are miniature versions of the Romford wheel retaining nut, and can be slimmed down a touch in the lathe and a stainless steel cap washer made to fit to hide the slot. The Crankpins base screws directly into the pre tapped 10BA hole in the Markits wheel face. The etching of the counterweights is fitted with Epoxy glue, after opening up the crankpin hole to suit the particular crankpins used.

 

Caley Models say in the instructions that the etched side rods are steel, not nickel silver, and therefore must be reamed carefully to fit the nuts, as steel etchings retain a razor sharp edge that would wear the nut bearing surface rather rapidly. It may pay to open out the side rod holes enough to add phosphor bronze, or brass, home produced lathe turned sleeves that would eliminate any problem.

 

A Jig will be needed to fit over the frames to provide alinement stubs for soldering the rods to exactly match the chassis, as they are a set of overlays, not solid rods, and have a working centre joint to assemble, and the set must 100% match the frames.

 

The Motor unit will be fitted with replacement sub miniature ball races on the motor shaft to allow for the flywheel in operation. The sintered bearings wear out rapidly with the strain of the flywheel on them.

 

If I can find suitable 1/8 ball races, then the axleboxes will be so fitted as well. Very slim 4mm ballraces are made, but would need sleeves for 1/8th axles made.

 

Stephen

[Daddyman]

Very interesting, thanks. 

 

How are the etches on this kit? I got a tender from Caley Coaches (not Kits) a few months ago and there's a "shadow" on the etched parts - that is, every edge and aperture has a half-mill or so half-etch that follows the line of the aperture. The problem affects the top and right of apertures on one half of paired parts (valances, frames), and left and bottom of the other half of the pair. As can be seen in the photo, the etches can't be flipped as then you'd lose the half-etch locator for the steps. 

[Poor Old Bruce]

I've oftren wondered about getting one of these kits as one loco was tried out at Burton-upon-Trent (without success as it was too big and heavy - surprise, surprise!). In my fantasy world it could also have been tried successfully on the Cromford and High Peak to replace the North London tanks. A Fowler Dock Tank was apparently tried there OK but there were none available to transfer at the time. A 498 in Derbyshire would be something different.

[Dave John]

I built one from the kit a long time ago, still runs nicely. I seem to remember that the tightest bit was the clearance between the leading crankpin and the rear of the crosshead. 

[bertiedog]

The Caley kit brass etches seem to be in register, I will get out a measuring microscope and have a closer look at the various plates. At first glance it looks OK. As long as minimal, a couple of thou, then the parts should all be O.K. My only gripe is the thinness of the brass frames, but this applies to most etched kits, they can be reinforced or increased in weight with overlays, but it is not really needed on the design, as it is a small compact chassis and the weight is not an issue with large side tanks for lead ballast weight

 

The big plus point on the kit is that there is no whitemetal used for the parts, all are brass etchings, lost wax brass investment castings, or Nickel silver parts, with steel rods etc

 

Some of the lost wax parts are duplicated in different versions to portray rebuilds, including the stove pipe chimney fitted in later BR years to some of the class. Two types of safety valve are supplied in lost wax cast brass, along with different smokebox door darts.

The tight clearances behind the cylinders and the wheels are just a function of the design, however this is OO and the clearances are eased a bit from P4 or EM gauges, where they are extremely tight on all small outside cylinder locos. It is just a matter of keeping the side play on the front axles to a minimum,  and relying on the short wheelbase to get around tighter curves.

 

A solution would be simple, to move the cylinders further apart than scale, but it would look a bit odd if overdone.

 

The Markits wheels are the usual oversize flange type, not much these days, but it helps reduce them to much nearer scale size, even with 00 track. They must be machined in a lathe, to be gripped by an accurate collet chuck holding the front face edge of the Markit's wheel tyre.

 

The Ebay price of the kit was near retail, but the wheels were thrown in the sale, saving about £40. They are the latest type of Markit/Romford construction, N/S with blackened spokes etc. A lot of the wheel face is covered by a etched plate that provides a crankpin boss and counter weight etching. The spoke count appears to be wrong, due to diameter/spoke clash, but is not noticeable with the brass faced wheels.

 

The working clearances should not be affected by the etchings as the crankpin bears on the usual part, and does not push the connecting rods further out, causing more clearance issues. But this does depend on the exact crankpins used, amount of washers and the nut or retaining collar used to secure the rods in place.

 

The whole kit is about to be photographed for reference in case of lost pats etc. All extra parts have been sourced and ordered in from Scalelink. Some will be scratchbuilt such as the gear box and motor mounting.

 

Although a very detailed lost wax brass casting is provided for the boiler backhead, along with the outline drawings and instructions, (Available on line), there is a dearth of detail on the cab interior, the coal chute, back shelf, or any mention of the brakes or valve gear controls, which can be worked out but it would be nice if a dimensioned drawing was provided to place them accurately .

 

Martin Evan's Rob Roy cannot be referenced as the controls are arranged for practical use of the livesteam loco for passenger hauling.

 

The other issue is the electrical pickup design, which has PC sleeper material soldered into the frame top, and short phosphor bronze springs bearing on the back of the all insulated wheels..... the PC sleepering is simply not strong enough to do this, so blocks of proper Tufnol or Bakelite will be machined to fit with screws, with the pickup strips held in by 14 BA screws and washers, live to the pickup to save wiring them individually, and connected by fine insulted wire to a central point, then to the motor and suppressor circuit board.

 

As the wheels are rim insulted for normal 2 rail operation, there is no need to insulate the piston connecting rods, pistons or the cylinders.

 

There is plenty of space for DCC fittings, at the expense of tractive weight.    

 

Stephen                                       

[bertiedog]

 

The etchings have all been checked under my own  measuring microscope and are perfectly acceptable in register. The match is normal for an etched kit, under 2 thou shift from front to back etching processes. If the kit quoted was all that far out, I am sure the makers would have replaced the offending etched brass sheet.

 

 

The cab interior appears to be two splasher boxes each side of the backhead, with a shelf step on the back wall, with a built in brake column supported on the wall, rather than a separate column. A raised steel or wood clad floor was fitted, most 3.5 inch gauge Rob Roy locos have a planked wooden floor. The reversing lever is on the right splasher and is conventional in design.

 

No net source shows the coal chute from the back bunker, so I assume a twin door on rails that opened with a lever to allow coal to fall onto the floor for the fireman to shovel into the boiler.

[bertiedog]

Caley's own photo of the BR re-build, with the stove pipe chimney, shows a brake column on the other side of the cab, a full floor mounted one, so not sure who is correct.

 

 

Stephen

 

[bertiedog]

Some of the etched parts are a bit delicate around the hornblocks etc, even when soft soldered, so a lot is going the be silver soldered together to get  neater and tough components. easy flo is no longer made to the low melting point versions so using an equivalent that melts a few degrees higher, still using the active easy flow flux, which washes off quite easily afterwards. The parts are pickled in acid to clean up to clean brass finish.

 

The frames can be silver soldered as well, with the sub assemblies fitted with lead free solder, and final details with 148deg solder, all using Bakers fluid as flux. Body parts will be done in lead free tin, ot 60/40 tin lead solder, with Bakers flux.

 

The sheets are cleaning overnight in mild acetic acid to remove any marks oil or surface stains to the components before removing them from the etched plates.

 

Most of the lost wax brass and nickel parts need to be removed from the sprue's they were cast with.

 

The piston rods and crosshead appear to be in brass, not nickel, so need to be coated, (tinned), with the pure tin solder, and wiped clean to leave a plated finish. The wipe is a damp paper towel, which will remove the excess solder after heating in a gas flame. The guide rods need the same treatment to get the steel appearance.

 

The crosshead support bracket is a solid etching, but not quite thick enough to represent the casting, so will be soldered to another sheet of nickel silver to thicken it up, and then the shape fret sawed out to the part pattern.

 

Small coil springs have been found to add to the suspension wires, and provide smoother suspension ride, fully adjustable with small screw shackles on each spring. It adjusts the ride height if a fully floating suspension is adopted. Suspension can be set to ride on stops and only react downwards, or set to float with up and down motions. This one will be set to fully float, as it ensures better running over points.

Setting on stops or the top of the hornblock works as well, and eases set up, but can make the loco jump a bit over a point frog. The fully floating version is smoother due to the wires acting as compensation.

 

Can't really finalise the chassis totally till the gearwheel arrives, but as it is a separate gearbox most can be put together without problems. The gearbox is made of 1,5mm brass plate, quite thick and heavy, will not give, vibrate or bend in use, and is semi sealed with grease over the gears. All silver soldered into a very solid unit indeed. The ratio is 60:1, which will ensure shunting speeds only.

 

The motor fits the end of the gearbox with 10ba screws, and has the suppressors soldered direct to the motor brush contacts. They are covered with black heatshrink sleeving to protect them. All the wiring is soft flexible multi stranded ex-computer cable wiring, all copper, no aluminium.

[jrg1]

I am impressed with your approach to this build-more model engineering than modelling.  Would it be possible to list the sources you intend using for bought in components-such as the ball-races mentioned?  In the meantime, Good Luck with the build, and I will enjoy reading yor posts.

[bertiedog]

The ballraces are all available via ebay, usually Hong Kong or Chinese suppliers down to 1mm bore various case sizes and types like a stepped case. Most are very inexpensive now, compared to Borden etc., who were costly. The quality is not ultra precise but they work just fine for motor shafts in metric sizes, which most are these days. It seems a lot are made for the Drone industry, as they put a demand on reasonable bearings in the small electric types. There is no one seller of these, the ebay shops in Hong Kong come and go selling batches every so often.

[Daddyman]

If the kit quoted was all that far out, I am sure the makers would have replaced the offending etched brass sheet.

Clearly not - see my photo above. 

[FraserClarke]

I've had my eye on one of these kits for a while, as the main motive power for my in-progress CR dock layout. Haven't got round to buying one yet though!

I'll follow this thread with great interest. Thanks for your already highly detailed descriptions!

[bertiedog]

Slowed progress today as the sheets all needed a very sound clean to remove any tarnish, so after an acid clean they were scrubbed with Vim scouring powder and a soft toothbrush to get to a matt finish that is clean to solder to without further troubles. All the etchings remain in place on the sheets till required for assembly, stored in xylene thinners in a covered tray.

 

All the extras needed have been found or ordered in, like the gearset. The wheels will be re-profiled later in the week in the workshop lathe with a special step chuck that can handle the tyres accurately to re-turn the Markit wheel flange, which I find far too deep for modern track that is well laid. Yet to try out with the still to appear Peco bullhead points, but the finer flange sails through the Peco code 83 US track and points. I suspect the Peco may require a shimmed face to the rail section to tighten up the crossing, which would make older wheels a non runner, but all my stock has the latest wheels or re-profiled flanges.

 

I have left the Hornby Pecketts wheels as standard till the Peco point finally appears, and tests can be made.

[bertiedog]

Made a simple jig for the chassis with rods, (Silver steel) in three grooves set at the wheel base and axle positions, upon which the rods rest placed through the axle boxes at the top position, The shafts have reduced tapered ends to take the coup[ling rods on to them to allow soldering exactly to the correct lengths. The chassis fits in between the side walls that have the grooves in.

 

Caley's own instructions seem to imply that the driven axle remains stationary, whilst the others are sprung and connected by a central compensating arm. This is the Sharman method, and works, but I prefer fully sprung wheels all round, with four plate compensating bars carried on the hornblocks. This ensures all rough track can deflect any wheel, and should not make it twitch, as when one axle is rigid. The rigid axle and the rest flexible works well to pick up power, but can make the loco sensitive to the points frogs, and any drops.

The nuisance is having to set up the ride, but the Varney method works, and allows full adjustment. This little engine is well balanced and should pose no problems.

 

If tensioning the side wires fails to level fore and aft, then extra wire springs can be added to the sagging end to bring it level. The total movement of the axles is limited to about 1.5mm or less, it does not need more, and in P4 it would be far less.

 

Trying to source Frys's Frylux 60/40 solder cream, I cannot see supplies under about £30 for 125ml, and I do not need that much, as it tends to go off if not used. C&L list it in small packs, but are out of stock. I do need the cream to keep the seams tiny and neat on this model. I hate ending up with vast amounts of solder to remove afterwards. With wire solder it is all to easy to melt too much solder into a joint, and  only then discover the excess solder underneath afterwards.

 

Stephen

Edited April 12, 2017 by bertiedog

[bertiedog]

Very quick service by Scalelink, two gearsets and Markits De-luxe crankpins have arrived by return post. Both the sets of brass and steel gears are 60:1, but different worm shaft sizes in case of altering the motor to a different shaft diameter.

 

The Crankpins are double threaded, one side to screw into the wheel boss, and another smaller screw stud, that has a special nut that has a step on the back to act as the bearing for the side rods. The excess thread is filed away on fitting and a cap washer can be soldered on or glued on the the outer face.

 

Previously I have used Hamblings/Romford plain ones, but there is no thread, and I found the Gibson ones to occasionally not be concentric and being steel attracted rust. They might be using stainless steel now, but the brass ones simply do not rust!

 

Now I have the gears the gearbox and motor mount can be made to an exact fit, and a flywheel made for the motor as well, with a support bearing that moves with the motor as the suspension operates. The whole motor floats on the driven axle, with just a torque wire to prevent rotary movement in reaction to the drive forces.

 

Bit of motor testing to do first to find the best option. It certainly will not need a big powerful motor in such a small loco, especially fitted with a 60:1 gear ratio gearset.

 

Stephen.

[bertiedog]

It seems Cup Alloys, the online specialist solder suppliers do the solder paste in small tinlets for about £10, also low melt 148 solder as well.

I tried silver soldering sample surplus etches from the kit, but the new "safe" cadmium free silver solder melts to near brass for comfort, especially on delicate plate work. So reluctantly forced to use soft solder.

 

As Cadmium is available as a metal, I am considering melting a batch of the equivalent of easy flo silver solder, with a tiny amount extra of pure silver as well. I have a gas fired oven that can reach the temp easily, so may experiment. It may need special retort cups to minimise oxidisation, which would raise the melt temperature of the final metal.

[bertiedog]

A change of direction forced by the design of the frames and the hornblocks. They supply only four hornblock bearings, assuming that the driven axle has fixed bearings of a top hat shape. The etchings are two types working and non working for the driven axle, so to add six working it will need a new pair of bearings and a pair of etched hornways.

 

So it is easiest to return to the Sharman method of compensation, with a fixed driven axle, unless I can come up with a way to use the parts in another way.

 

The Hornways are meant to be assembled with epoxy, then solder to the frames, the heat will surely affect the glue, so solder assembly with high melt and low melt, or solder in one go, with things held in the frame jig. The moving hornblocks are retained by a wire through etched holes in the bottom of the slides.

 

The area of the hornway slides has to be cut out of the frames, as Caley have allowed the frames to be built solid if required. It can be fret sawed or filed to size.

 

As the frames are narrow with 00, the gearbox must be as slim as the gear boss size allows, plus small brass bearings. The gear can have no side play between the worm and the gears the teeth are correctly set with a curved face. As the axle will be rigid it does not need any side play as such, just working clearances.

[bertiedog]

Might have worked out a way round the fixed axle, with new bearings that float in an oval hole instead of the missing hornblock and slides. Trial assembly this afternoon, after mounting the working hornblocks in the frames, and securing them in place.

Not too sure about the folded sheet brass frame spacers, soldered in, rather than the screw in variety, which allows firm mounting for insulation for pickups etc.

[bertiedog]

The parts laid out before cleaning for checking over with the instructions, and notice, not a drop of whitemetal, all brass and nickel parts.

 

The only parts that did not fit as well as before are the Markit crankpins, it is not them, but the tapped hole in the wheel, which appeared half tapped. Enough to need to run a tap though the holes and de burr the edge rim to get the crank pins in properly snugged down. They can be finally assembled with Loctite retainer liquid, but left un-fitted for the moment.

 

 

Got a new set of screwdrivers from Poundland to make the two pronged type to handle the Romford nuts. Also a nice miniature folding Stanley type knife, perfect for cutting the etches out, comes with three tiny blades.

 

Stephen

Edited April 13, 2017 by bertiedog

[bertiedog]

x double entry , removed

Edited April 13, 2017 by bertiedog

[bertiedog]

Whilst waiting for the solder paste supplies by post, started on construction with pre-tinned edges on the body work, adding tiny clippings of solder as needed when a fillet is required for strength. The Caley kit seems accurate on bending up parts, the main issue is the tanks, which are supplied flat and need the radiused top folded over a form or rod to get a nice finish to the bend.

 

The cab went together nicely, detailing bars and strips to be added with lower melt solder to protect initial joints from coming apart.

 

Motor chosen is a Chinese 5 pole, double ended, which will fit a single stage gear box at 60:1. The box is 1.5mm brass, a bit thicker than etched kit boxes. It has phosphor bronze bearings fitted by soldering into the frame wings, with a piece of silver steel to align them. It fits between the frames wit a few mm to spare, so will need packing with washers to hold centrally as required by the curved gear teeth. I will turn up a pair of PTFE plastic washers to do the job. The motor and gears are un-sprung, but need restraint against drive torque by a wire from the motor to the chassis. The gears are very smooth, just need running in and an adjustment to minimise back play. The flywheel is brass, turned in the lathe. A back bearing ballrace will be added, which on reflection negates the need for the torque wire.

 

More soon, with pictures of the build.

[jrg1]

For forming radiuses on sheet, I use a set of folding bars with one edge having a filed curve.  I find this helps to accurately locate the curve, as the sheet is clamped in the bars.  It also makes forming curves on the edge of the sheet easy.

[bertiedog]

I have bending bars in the workshop, vital to use rather than fingers, and the fit a 9 inch jaw Record vice as a base.

The motor mount is done, it angles the motor up allowing a larger flywheel hidden in the tanks. I don't really like double geared tower gearboxes they level to motor, but restrict the flywheels a bit. Also a bit more backlash and play can be noisy, unless the gears are plastic.

The flywheel is next and will have the centre lightened with holes to get the best momentum from the heavy rim.

 

Stephen

[bertiedog]

The CuP alloys solder paste arrived, excellent stuff, I do not know if it is repackaged Fry's , but seems better, maybe as it is fresh, as the solder paste dries out in time and needs a flux added steadily to keep it fluid. Does not leave any nasty residual flux unless over heated.

Use very sparingly along a join, both sides and then run a chisel point bit done the joint, adding tiny amounts of solder if a fillet is needed for strength. My own iron is temperature controlled, but run a bit hotter to give a reserve of heat as the joint proceeds.

 

Unlike castings N/S sheet and Brass Sheet do not take away to much heat, but the parts can warp, and some seams are best started at the middle and work outwards to minimise the distortion from heat.

 

The second extra solder for the fillet is the normal 60/40 type, but 145^odeg can also be added as it runs easily along the joint. I try to confine the solder to just the joint, you can mask it with masking fluid, but I find that very time consuming, unless the work is like a gearbox with complex joints, and you do not want solder in the bearings or bearing holes.

 

Most of the chassis is up and running now, but still thinking of best gearbox assembly, and the body is now underway as well, with a trail fit. I will try to leave the cab top openable or held by magnets, or hinge, to get at the interior to detail and fit the driver and fireman figures.