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Class 800 Gauge 1 Upgrades

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Here is a new project for 2019, a Class 800 Gauge 1 built by Brendan Kelly, it's in the workshop for cylinder parts, valve gear, coupler rods, and bake system work.





I couldn't resist posting up some photos- it's a beast

You'll have to wait until after Christmas to see more..........


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42 minutes ago, Horsetan said:

Will you be doing anything to lift the firebox height a bit?

Hi Horsetan

I really only took on the cylinder parts, valve gear, coupler rods, and bake system- though the firebox is something I will discuss with the client and we will see if something needs to be done?


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  • 1 year later...

So I eventually got going on this project, after a few contemplation evenings and pencil sketches I set up a drawing and worked out a plan of action. The chassis, cylinders & motion bracket would be tackled first as this will aid in finalising the drawings for the valve motion gear. After stripping down the chassis I decided the cylinders need to be fixed on but, I may need to remove them so a bolt on affair was decided. The motion brackets are soldered to the underside of the body running board! this is not great, I prefer to work on the valve gear on the chassis alone, rather than having the whole loco on the bench and making things unwieldy and difficult, so the plan is to remove them from the body and install then on the chassis. This will make it easier to take the body off in the future as only one rod has to be undone- the oil pump rod, the other way most of the motion gear has to be dissembled and would be a real pain just to access the motor! 

All asunder.


The chassis is a bit bendy, the new motion bracket and its frame will help. Also the counter-sunk screws on the frame spacers are not counter-sunk- so that will be done.


Valve cylinders need end plates and a few other things.


The motion brackets as is.


.5mm brass angle plates were made up to fix the cylinders to chassis with 8BA screws through those frame spacers behind each valve cylinder.


Cylinder chassis plates soldered on and the frame spacer screws counter-sunk.


Holes about to be drilled and counter-sunk in the cylinder bracket, these holes will be used to spot through to the chassis plate for drilling for the captive nut.


Captive nuts soldered on.


Done, plates need a bit of trimming later.


Removing the motion plates, this is the jig set-up- as both hands are required for the soldering iron and pulling at the parts.


Clamp fixed to bracket with wood insulators between so that the clamp doesn't take all the heat, holds the bracket together- as its three pieces soldered to the running board, and something insulated to pull on to save my fingers.


Done, the 100 watt iron was used only touching the motion brackets and loads of flux, once one gets the temperature up they came away relatively easy!


Brackets cleaned up and two brass bars cut to size for holding the brackets to the chassis.


Soldering up.


Test fitting the assembly and marking the chassis in prep for cutting the slots in the frames to house it.


Thats all for now.



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  • 1 year later...

I started on the valve gear for the Gauge 1 800, getting ready to assemble the chassis frames and axles so need the coupler rods first, so into the metal scarp box to see what we have;-

Various bits of mild steel were found that would work, 8mm thick bit at bottom for the drive rods, 4.5mm above for the coupler rods, then 5mm for radius rods, and finally 2.5mm sheet for the other bits.


Cleaning up the 4.5mm bits for the coupler rods.


Blued up for marking up.


And marked up, this is for initial guide to set-up a jig to hold the metal parts on the mill machine.


First operation done- removing the straight bits along the rods by chain drilling and then milling slots with a 6mm endmill.1118150165_800G1-2420210401_123956.jpg.c7561a772cb4e88b4f1d751cb26b1bb1.jpg

Next the curvy bits are done on the rotary table with a 6mm endmill.


Curvy bits complete, just needing the remainder scrap to be cut off.


Here the rods have been mounted on the jig in the vice and recessed face side cut with an 8mm endmill and then the flutes cut with a 3.2mm woodruff mill to 1mm depth.


And the completed coupler rods after the oil boxes have been cut back on the front face and 1.2mm dia holes drilled in top for the oil filler plugs.


The rods still need a rub down with grades of emery paper to remove the machine marks- but that will be done later.

Next up will be the turning of axle jigs from 6.35mm dia aluminium rod, for soldering in the axle bearings in the chassis frames, the coupler rods will be used for this to line it all up.....



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  • 2 months later...

Time to fit the coupling rods and set up the chassis so that final dimensions can be set for the drive rods and crossheads to be made.

First though, as mentioned above the chassis is a bit fat and the wheels lock on the axle bearings when bolted up! So a 1mm shaving was taken off the face of all the bearings.



Bearings faced and then a set of axle jigs was turned up from 1/8'' aluminium rod to set the bearing centres while soldering them into the frames.


Just about ready to solder them in and I noticed the back bearings were sitting a bit low which held the centre wheels about 1.2mm above track level!


So a slight adjustment of the frames bearing holes was done on the mill.


Adjustments done and the bearings jigged up with the coupling rods, which sat beautifully level for soldering.


Next was to set up the centre drive wheel crankpins for the coupling and drive rod thickness at around 15mm- this is longer than what is available! Slaters do extended crankpins which will work for the other wheel setups, but the 800 has huge lumps of metal here and I'm kinda sticking to scale! So some extra long crankpins need to be machined and to do this we need two tools- a chuck tool with an 8BA threaded hole and a tailstock tool to support the end of the crankpin 10BA shank which equates to a bar with a 1.65mm hole in it to be held in the tailstock chuck- on the left is the chuck tool and on the right the tailstock tool machined from 6mm MS bar stock.


Demo of the Slaters crankpin screwed into the chuck tool.


And now the 10BA shank in the tailstock tool.


The 6mm bar stock parts cut to length and ready to be machined, thats a Slaters long crankpin below the bits.



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  • 4 months later...

Motor and gearbox is next;-

A hunk of a motor, a worm and axle gear were provided, the motor has no mounting screw holes so a gearbox with a sleeve motor mounting was designed up.


The gearbox frame parts being cnc'd from .8mm brass sheet.


All cleaned up. The sleeve mount will be soldered to the frame with the aid of tabs n slots, and the fold lines are half cut to aid folding.


Rolling up the sleeve.


A bit of fettling and it fits.


And so does the motor, very snug, the clamp strap will only have to pinch it.



The sleeve clamp strap being rolled up.


The strap flats being folded where the bolt will be fitted.




Axle bushes for the gearbox frame being turned from brass rod.


And reamed to the axle size.


Testing one of the bushes on the axle, the axle gear had to be drilled n reamed also.


Frame folded and soldered.


Soldering the gussets on the clamp strap.


Motor sleeve and strap soldered on.


The strap is soldered to the sleeve.


Assembled up, I waited until the gearbox was in the chassis frames to solder the axle bushes in.



Skimming off the inside face of the axle bushes to fit the gearbox in.


The gearbox fitted in the chassis, now the bushes were adjusted and only tack soldered in- as further adjustments may be required, was required! Measurements are also taken to cut that brass tube, beside the chassis, for axle spacers on both sides of the axle gear.


Cutting the tube, the lathe is great for this, using a slitting saw with the brass tube on a home made clamping table mounted where the tool post should be.



Tubes cut and a flat was milled on the axle for the gear grub screw to lock on.


Assembled again and powered up.


Next is to assemble the wheels and fit the coupling rods, but first we need extra long crankpin bearings. Back to the lathe to turn up 6 bearings from brass rod. The rod was drilled and reamed to fit 10BA screw size and then turned the outer diameter to size , a parting tool is used to do this, once the first bearing is turned to size the topslide dial is noted and marked so that the next 5 bearings are turned to the mark and all come out the same size.


All six with a Slaters bearing in front for size comparison.


Coupling rods installed but cannot set the quartering on the rods because there is so much flex in the chassis! I first need to install the valve gear motion frame and a few 90 deg frame spacers here and there to stiffen things up.


Another shot with the Gauge OO J10 chassis to give some scale to this beast!







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