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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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  • 1 month later...

Some cylinder work;-

Gave the assembly a clean up of solder and then sandblasted.


The steam valve cylinders need front & rear parts, turned up from 15mm dia brass bar.




Cutting with a slitting saw the 1mm slot in the clevis part for the ends of the steam valve rods. A .8mm cross hole in the clevis part was drilled before the slot was cut.


Clevis part cut from the 2.5mm sq. brass bar, then a 1.6mm hole is drilled in the back for soldering to the 1.6x36mm rod.



Test fitting the rods into the cylinder face, the rod guides still need to be added.



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  • 5 months later...

Motion brackets, valve gear and brake gear cutting;-



When cutting the parts from .45mm nickel silver sheet, in error I set the cutting passes for wood and not for metal, within a minutes the last 2mm endmill tool I had in stock was dulled. After resetting the cutting passes for metal things progressed poorly, as this was the only tool I had- things had to be left running! Overheating caused the sheet to come unstuck from the machine bed and this caused distortion, intermittent cutting, and a massive burr on the cut edges. Nerve racking time, but the tool and the sheet of parts survived, just a bigger clean up required.


Chisels, knives and the mini drill being used to get the parts out.



A lot of fettling to do........the joy of modelling!!


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  • 1 month later...


Eventually I got all the parts out of the sheet.


First up was the steam valve crosshead frames, the parts were folded up 90deg and a soldering jig was turned up from aluminium stock.


The jig slots into the valve bore, the crossead parts are clipped on both sides and butted up against the brass valve part.




Both done.


These are the hangers to hold the end of the slide bars on the main crosshead- one is ready for soldering.


Hangers soldered up and test fitted to the chassis, the slide bar end will be held in the hanger which is not folded yet! I first need to assemble the crossheads and conrods to check alignment of all these parts.


The parts for the main crossheads - including 4mm dia NS bar for turning up conrod sleeves and two 2.8mm wood nails to make the conrods.


Parts folded up, sleeves turned and nails cut- the extensions on the slide head is a alignment jig to hold the conrods while been soldered into the crosshead.


The holes in the main cylinders need to be opened up to 2.8mm dia, so the slide bars had to be de-soldered from the cylinders to allow for this.


Crossheads clamped and soldered.



Jig bits removed and parts cleaned up.


Testing fit, all is OK, but have to make a decision on the slide bars now. These were made from a bit of NS track! Now that I have them removed I think proper slide bars should be made- back to the drawings.......


Edited by murrayec
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  • 6 months later...

Brakes up Next;-


Brake shoes for the loco & tender being drilled and cut from Tufnol sheet. The shoes are 3mm thick.


The back of the shoes were then cut with a .5mm slitting saw for mounting on the hangers fixed with brass pins.


Some soldering work was needed on the tender chassis, those two brass mounting plates were soldered to the top of the chassis frames to give a bit more rigidity.


The tender chassis being drilled for the brake hangers.


All the brake parts for the loco & tender are ready. Missing from the photo are the loco brake pull rods!


Soldering the hangers and cross bars.


Parts jigged up for final soldering together, the full assembly can be removed for painting.






Loco chassis about to go through the same process.


All soldered.



The brakes are complete.

Drive and valve rod machining is next........


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  • 8 months later...

After a brake from major modelling works for the last 6 months, due to family situation and house building works, I'm now back at it!

This is the machining of the drive rods, it's similar to the coupling rods but with a taper twist!



Two lumps of 6mm thick MS were cut out on the band saw.


The rough shape of the rods were marked up to aid machining, I was a bit short on the length of the metal which made clamping a bit of a nightmare, but it worked out OK in the end.


Setting up the blanks for drilling the holes, which are drilled through into the plate under. The holes in the plate are then tapped 8BA for bolts to locate the blanks on the plate. The small end of the rod is drilled to a tight fit on the 8BA bolt and the big end is drilled out 3mm but held by a 8BA bolt, this allows the blank to swing from side to side at the big end allowing for the taper to be machined.


The upper edge milling complete, done while the blank is clamped forward (towards the camera) creating the upper taper. The clamping is about to be released to push the big end back the other way, clamped again, and the lower taper will be machined.


Both tapers done.


Next the parts are clamped down to the rotary table to machine the rod ends.


Big end done.


Small end done.


After cutting off the excess metal at the big end with the band saw the oil boxes were machined on the clamping plate.



Rod profile shape complete.


Next is the setup to thin the rod shanks, this was done on the clamping plate vertically in the vice, an 8mm end mill was used to side cut 2mm off the shanks, leaving 4mm radius curves out to the rod end bosses, the big end is 6mm thick and the small end is 4mm thick.




Now the flutes are machined using a 2.4mm x 9mm dia woodruff mill cutter, this is done as per the taper cutting above so that the flute follows the taper on the rod edges. The flute is cut 1mm deep and tapers out flush with the rod end bosses.


Rods complete and been fitted to the chassis, some cleaning up of machine marks is needed at a later stage.



Some of the cylinder parts previously made are now fitted.


Body on.

Now that these rods are complete the crosshead slide bars can be fitted and sized, also the slide bars end brackets can be finalised n soldered on to the motion plate, then the rest of the valve gear...............


Edited by murrayec
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On 31/10/2023 at 6:25 PM, murrayec said:



Body on.

Now that these rods are complete the crosshead slide bars can be fitted and sized, also the slide bars end brackets can be finalised n soldered on to the motion plate, then the rest of the valve gear...............


Either the camera lens is going mad, or there's something weird about the top line of the smokebox....

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