Caledonian Dock Shunter 498 Class

[bertiedog]

Odd problem with the crankpins, Markit de-luxe type, they did not screw home in the wheels, it seems the blackening is done after the hole is drilled and tapped, and then it clogs the thread, soon cured with a 10BA tap run right through, and each end of the threaded hole de-burred.

The blackening obviously is a good finish through. Now the brass crankpins screw home properly, and are being fitted with the etched centre boss and the large counterweight fitted to this class of loco.

The nut on the Markits crank pin acts as the bearing, so the rods will have to be drilled out to suit the bearing size and then reamed to a good fit, with the holes de-burred front and back and polished.

 

Next is jig fitting to match the chassis to the rods exactly, and then test run as a unit before detailing the brakes etc. The Cylinders are a separate unit, along with the slidebar supports in the way I am assembling the kit.

 

The gearbox needs a cover made to exclude dirt, and then just drops in on the driven axle. A cover helps retain lubricating grease as well. I use silicon with PTFE as standard.

[bertiedog]

On the Markits wheels, ex Romford  type with squared axles, I note that the hole in the centre has been tightened up a bit and the axles have a bit of trouble entering the square hole.

 

This was true on the thousands I fitted over the years, and needs a bit of attention to detail to get the fit right.

The end of the axles are very cleanly machined, and dead sharp, and if the axle is simply forced into place by the wheelnut, it risks cutting into the softer metal of the wheel, and not running as true as it should.

 

The back of the wheel boss should be scrapped clean with a sharp edge to remove the black, and then a scalpel is used to scrape and cut the edge of the hole to a chamfer, only tiny, but very carefully into each corner as well. Try the axle and it should just enter the square hole now, but may need a bit more scraping to get it to enter properly, it can then be pulled home with the wheelnut.

But at this point you must remove the wheel and check there is no swarf in the square hole and that the axle end has actually touched the boss, it will leave a witness mark.

 

Once this is done the wheels should be removable if required, and go back true running.

 

Wheels can be assembled as pairs with the bearings to drop into frames or be assembled from on side or the other of a fixed frame or frame where the bearings are running in slider hornways as in the Caley kit.

 

I have decided to go all sprung as the Hornblocks where supplied by MJT and have 6 plain sprung on the etch. The bearings will be permanent to the frames, so the wheels are assembled into the frames in this case. They can be made to dropout, but it is not required here on the simple 060 chassis.

 

The Caley etchings for the frame require each hornway to be cut out, loosing the exact register of the frames and axles, so the jig will be need to find each exact axle centre line before soldering on each assembled hornway.

Edited April 22, 2017 by bertiedog

[andytrains]

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.

 

56161.jpg

 

Stephen

Bertiedog.

Not Caley Coaches photo. They used it with my consent.

I was going to post it here.

Here are some more of her:-

[bertiedog]

I do feel there is a bit of a clash between the kit designer and MJT who do the hornblocks, as the springs on the chassis profile have to be removed almost entirely to fit the MJT etched brass horn blocks, no glue as suggested, but firmly soldered up and tested with the bearings outside the chassis with high melt soft solder, the lead free solder. This will allow the blocks to be soldered on with low melt 145 degree solder without affecting the hornways. The axle bearing can be dropped out completely at present and I have left the subs of the spring profile to be able to solder the springs back after assembly and testing.

 

With the rear axle sprung the gear box may be a touch wide as it it very cramped around the driven axle, so I may have to slim the gearbox by about a mm. A lot of issues are interrelated and using parts like MJT etchings gave slight problems, but over coming them. and a fully sprung compensated chassis on it's way now.

 

Personally I would have preferred cast brass hornways as per the real thing and a common design in model engineering, even where the prototype was a little different, The MJT type run up and down on the thickness of the brass etch, whilst a proper one would run restrained by the outer edges of the castings, perhaps a little too much simplification in design to suit etched parts.

 

However the parts do work, but with a lot of fitting and fettling of the parts.

 

The rods are now finished to use in the jig to line up the hornways for soldering into place. Hopefully accurate first time after all this extra fiddly work on the parts!

 The compensating beams are thin plate beams, joined by a middle rivet in a larger hole to allow independent movement of front from rear, but will directly operate on the middle axle box. They pivot on a stub added to the frame. All will be inline and level on level track, with an upward movement of about 1mm and down of 1.5mm, dependent on assembly clearances.

Stephen

[bertiedog]

The jig proved more complex, but worked as the bearings all lined up easily to the rods centres. It needed a bit of checking to keep the axles fully at right angles to the frames.

It a whole lot easier with solid or thick frames, where the axle holes can be drilled on a milling machine or pillar drill. Etched frames look nice but are a bit flimsy really, and have no weight to them. Once all set up they work, but it's a lot of fiddly adjustment and soldering. next is the springing wires and the brakes and pull rods assembly, plus any other frame detailing.

The slimmed down gearbox is ready as well and fits with working clearances in the 00 frames. It can pivot on the driven axle or float on a sprung mount, which acts as torque bar.

The Markits wheels require the flanges to be reduce to minimum compatible with NMRA size or a tiny bit less. They can be gripped in the lathe in a collet chuck by the front rim of the tyre. the tyre is a bit wider that it could be, but will be left as it is as it aids frog crossing to be wider.

 

Stephen.

[bertiedog]

The Loco will be heading for my new layout Middlechurch Marsh, a light railway setting to be able to get something worthwhile running as a layout to run locos that I already have, mainly small 040 and 060's.

The Chassis is almost finished, but a short break whilst the small layout is sorted a bit.

Stephen.

[bertiedog]

Back to the loco and a purchase on ebay of some MJT hornblocks, and although the ones in the kit were also MJT, these are a different standard altogether, with more folded parts, better details, rivet details, and slightly better axle bearings. The retaining plates bolt on as well, making assembly and fitting easier. They are still sprung by the wire method. They fold up into a much more solid unit than the simpler ones in the Caley kit.

There is also in the pack, a set of Ultrascale 40:1 gears that may prove useful, although the axle size is 3/16th and requires sleeving for the 1/8th axles from Markits. The Ultrascale gears have a nylon worm rather than steel, push fit to 2mm shaft or sleeve. Might run a bit quieter than the Markit brass and steel combination. Both gears seem accurate, although the brass gear had one side face with burrs on it, they would not really matter, but I am surprised gear specialists would supply brass gears without removing all machining burrs.

So a back track on the chassis. but an improvement in the bearings and accuracy of the chassis hornways and blocks.

 

Stephen.

[davknigh]

Stephen,

 

You might want to look into the HighLevel line of gearboxes to get the best out of your 498 class engine. They have a range of gear ratios that will give excellent slow running speeds. http://highlevelkits.co.uk.

 

Usual disclaimer, etc.,.

 

Cheers,

 

David

[bertiedog]

I know the high level boxes very well, but after 50 years of building and designing gearboxes I tend to find in the end a plain worm drive works best, if the gear cutting is OK. The Ultrascale ones are accurate, tested on BS Verdict test wires to support it in a test collet, it shows the teeth to be concentric with the bore to within 1/10 th thou or better. In the past, 1970/80,Romford and others struggled to get them accurate to within 5 thou or worse! The teeth were accurate, but the bore was not, requiring a re-bore and sleeving on  most gears bought commercially.

Some gears like Mike Sharman's were made by hobbing, and accurate, till you realise such a gear cannot have any side play, limiting its versatility.

I like metal gears, but will accept nylon worms as it reduces noise a bit, but I do not find stacked spur gears the way to go, to much accumulated play.

I can cut the gears at home, but the fiddly work is now difficult with arthritic hands. O gauge size is easier.

 

The Ultrascale brass gear was all de burred and the faces papered on a surface plate, as the parting off tool they used had not left a flat cut. Does not affect normal use, but it needs a 1//8th sleeve fitted, and the rim has to be flat and accurate.

 

40:1 seems to suit the Mitsumi motor aside for the chassis.

[bertiedog]

The New Ebay hornways fit fine, the design allows soldering, not recommend on the other simpler type. So the chassis can be finalised now, just a gearbox casing to make to seal the gearbox up.

Maybe the kit parts were older type and the Ebay ones up dated since the kit was put on the Market.

I have bought some Lost wax brake shoes that will fit, and some other detailing parts for the cab etc.

Stephen

[tycho14]

Came across some photos today which show glimpses of the bunker side of the cab of 16153 in 'British Railways Illustrated' Volume 14 June 2005, part of an article entitled LMS Northern Division Dock Tanks. Photo  acknowledgement given as 'J.T. Rutherford / The Transport Treasury'.  Several other good quality photos of 498 Class locos too. 

 

Alan

[bertiedog]

Work on layout is taking up a lot of time, so loco will be weeks if not months away at the moment. There is progress, the chassis now runs fine with all sprung wheels. Very quiet indeed as well, as a bonus.

Stephen