Accucraft to Roundhouse Burner Conversion - Overhaul of an Accucraft Ruby

[Old Man Aaron]

I'd like to see more of those horrible Accucraft burners replaced with something more reliable and quiet. To that end, here's how I did mine. It was easier than I expected. Mind you, this was before Jason at The Train Department started selling their drop-in Accucraft replacement burners. I've not seen them in action but I'd be very surprised if they didn't function as advertised.

Early 2019 - My first loco, a Ruby I'd owned from new for five years by this point, was heavily modified. Frankly, I think we're all aware of the reputation held by Accucraft burners - Replacing it should've been the loco's first mod.

I'd cleared the workbench and was ready to try retrofitting a Roundhouse burner. Whilst it was in bits, the loco would receive yet more modifications:

• Replace the piston rings (weren't yet due for replacement, but they were originals and would soon have been due, if left alone)

• Tighten up some slack in the motion

• Add and improve some detailing

• Rewire the headlight and fit a rear headlight

• Replace the loco's box

• Add a driver

And finally, have a go at at the job of weathering this live steamer. No more "NRM-esque", immaculate locos lugging filthy wagons around, for me..

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13/03/2019
In order for the RH burner to "drop-in", the Accu-Crap burner's brass mounting plug had to be removed from the boiler.

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Bit of a pain to do, but still less trouble than taking the boiler to be re-hydro-tested if I'd have simply de-soldered the plug.

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18/03/19
On test, the burner mounted much in the same way as it would be on a RH boiler, with a spare boiler band. The countersunk screw under the burner "foot" is finger-tightened against the footplate to further support the burner. For now, I'm borrowing the gas tank, valve and pipework from my RH Fowler "Victoria". The original Accucraft gas tank has given me no problems in the past, and like the steam regulator, has a fine-control valve from The Train Department, so I'll be re-using those, and make a new "adapter" gas pipe - one end having an Accuraft M5x0.5mm fitting, the other having a Roundhouse ¼"x 40ME fitting.

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Certainly not the most elegant solution, but this loco finally has an acceptable burner. Slightly quicker to raise steam, silent, lights far more easily and stays lit. Night-and-day difference to the Accu-Crap burner - To the bin with that, and good riddance.

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After stripping the boiler back to bare, the headlight conduit was soft-soldered onto the steel boiler bands. (Pilfered the brass originals for my Mamod TE1A, years back)

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05/04/19
Having wasted too much time on useless commercial paint strippers in the past, I usually strip with lacquer thinners and an old toothbrush or brass-wire equivalent. I like to keep the thinner in a glass jar, (occasionally straining out the paint lumps) and re-use it for some months, until it eventually loses it's potency.

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The blower pipe and smokebox braces (ex-bicycle spokes) were also soft-soldered on, along with dummy mounting flanges cut from brass, with dressmaker's pins as rivet heads.

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The Ruby chimney, not having the usual saddle casting where it attaches to the smokebox, also received a flange. Still looks a bit odd, but now passable for a welded replacement made in a sugar mill's workshop, after the original Baldwin cast iron chimney was shattered in an accident. Well, that's the excuse I'm running with..

This however, means the chimney itself is effectively soldered onto the smokebox - so the screws holding holding the smokebox onto the saddle aren't accessible in the usual way, namely by removing the chimney, and using a Phillips screwdriver through it's mounting hole. Instead, I've soldered M2 studs into the saddle, so the smokebox is now retained similarly to full-scale practice, with nuts. The screw holes in the bottom of the smokebox were slightly enlarged, allowing it to be wiggled onto the studs. Whilst it's now fiddlier to fit nuts on the studs, I no longer have to deal with stripped-out Phillips screws.

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Translating thoughts into words is mentally exhausting. I'll continue this write-up soon..

[GTB]

I'd like to see more of those horrible Accucraft burners replaced with something more reliable and quiet.

Couldn't agree more. Accucraft have improved some of their valve gear lately, but the gas burner design is still pretty ropey.

I made new burners for my Shay and Ruby to get them to steam properly. I left the Accucraft mounting in place though and just designed around it. Too much like hard work to remove it........

I also had to modify the smokebox saddle on both models to improve the flow of burner exhaust gases. Roundhouse specify much larger exhaust openings through the chimney and smokebox bottom than Accucraft use.

Regards,
Graeme

[TonyW]

Roundhouse specify much larger exhaust openings through the chimney and smokebox bottom than Accucraft use.

And then a lot of people add a chuffer pipe in to the equation.

[tom_tom_go]

Isn't a Roundhouse Exhaust Enhancer their take on a Summerlands Chuffer?

[Old Man Aaron]

Aye, it is. I recently took delivery of a RH Bundaberg, fitted with their exhaust enhancer. I'm looking forward to comparing it's sound and ability to keep oily water down, with the Summerlands unit fitted to my aforementioned "Victoria".

As for opening out the smokebox saddle, I found myself dremel-ing away at it, not one hour after first un-packaging the loco. Chuffer doesn't help, but then I'd not yet fitted one. Even then, the burner needed near constant re-lights and burned only in the smokebox - name any solution barring full replacement, I tried it to no avail. Eventually, I replaced the jet with a smaller one. Turns out the original jet was intended for things like the K-28.
Don't remember the original or replacement sizes, but from then on, the loco was actually useable. It still went out at least once a run, was hard to light and was a little louder than I'd like, but it was finally useable. And in that state it stayed for the next four years.

I rather like their two-cylinder Shay, would make a decent "Mapleton-esque" loco.
Though, after the sheer number of problems with the Ruby (a long list, burner was just the icing on the cake); The inexplicable bind in my near-new Baguley's mechanism (something I've since noticed in other Mk.II models) that I ended up bodging with a flywheel on the motor tailshaft to smooth it out; Then there was the bargain lot of 6-year old AMS/AML(?) track bought from someone moving to 7¼", which of course needed new sleepers.
Let's just say I've sworn off Accucraft entirely.

Having had to replace the Rubies' eccentrics in 2016, (now there's another quality control story!) I'm interested to hear about these motion improvements.

[Mitch stack]

What colour is your bundy?

[LNR]

I rather like their two-cylinder Shay, would make a decent "Mapleton-esque" loco.

I agree, a re-run would be nice!
Grant.

[Old Man Aaron]

If I had the money, energy and patience, and Accy did another run of the Shay, against my judgement I'd still consider one. I'd have to immediately replace the burner and do the roller-bearing eccentric mod, though..

What colour is your bundy?

The Bundy's currently a bog-standard job - Brunswick green with red frames and Millaquin spark arrestor. After "Victoria", it'll receive the same treatment as "Baron", here, along with a name (don't have one yet) and a diamond chimney.


04/06/19
To this day, I still don't know just how Accucraft finishes their locos, but it's the toughest coating the works here have yet encountered; I'll give them that. I figured it was powder-coat or something. But it was still chipped, glossy, and I wanted satin - the plan being to scotch-brite the original gloss finish, de-grease the chassis in enamel thinners, then etch prime and engine enamel.
Returning to the thinners bath a few hours later, I was dismayed to find I now had several more days of work to do, scrubbing the half-lifted remains of the original finish, out of every nook and cranny. Areas such as behind the wheels and eccentrics were left alone and painted over, as for whatever reason, they weren't as badly affected by the thinners..

The rocker arm locking screws were replaced with some spare Roundhouse cheese-heads; As the original grub screws tended to seize, resulting in their sockets being stripped out trying to loosen them. I also added a third lubrication pipe. Now the eccentrics and both axles can be oiled without having to upturn the loco. With a little effort, the "little ends" of the eccentric rods can also be oiled with a fine-tipped nozzle passed under the side tanks. I apologise for the horrific sight I've made of the pipes; A recently-bought set of tube-bending springs should see my copper-mangling consigned to the past..

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10/07/19
After masking the moving and mating parts, the boiler and chassis were done with black etch primer, lightly scuffed with scotchbrite, followed by satin black engine enamel. The smoke/fire boxes were hit with potbelly black. We use the same stuff (albeit brushed) on smoke/fire boxes at Woodford.

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Prior to painting the chassis, some styrene scraps were epoxied together, filling the unsightly gap between footplate and boiler.

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A dummy firebox and ashpan were knocked up from brass - A little rough but it'll do. I then had to flip the trailing wheelset frame upside down, and machine a longer pivot pin for it. The paint was removed from treads and flanges with cotton buds dipped in thinners.

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The original ceramic smokebox insulation disintegrated when it was removed, and was replaced with new material.

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The cab finally received a rear "arch", with provision to mount a rear headlight. The grab rail was another long-overdue mod.

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Because I'd added the waist-high rear wall to the cab, it couldn't be removed for refilling the gas tank. So up until now, I was lifting away the cab roof, retaining it with very thin smears of Blu-Tac. This wasn't very reliable, so some rare-earth magnets have been epoxied into the cab. The original screw holes were slightly enlarged, and slotted on one side to help the roof align more easily.

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As for the roof itself, M2x5mm countersunk screws were silver-soldered into the roof's original mounting holes & slots, then cleaned up with the dremel. The screws will function as locators to the holes in the previous photo.

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On top, the screw heads were sanded flush with the dremel. As I lack the equipment needed to simply roll a new roof from steel, with upturned side edges as rain gutters, the home-made steel rain strips I fitted years back were re-used, this time soft-soldered on. A bit of bog deals with the screws' sockets.

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07/08/19
After six years, the running crews now have steps and grabs to access the tank fillers.

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Xmas is coming up, but I prefer hanging primed loco parts on machine tools, to decorations on trees.

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New gas pipe silver-soldered, to adapt the Accy tank to the RH burner. Gotta love that cadmium-bearing solder.

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I didn't photograph the process of re-assembly, painting or weathering; Because as this was my first time weathering a live steamer, it meant a lot of experimentation and such, that would be difficult and tedious to follow in writing. This was also my first time weathering with enamel paints - I usually use Tamiya acrylics for weathering, but we all know that won't fly around heat, oil and water. For this loco, I'd started with Humbrol tinlets, but soon learned all about their now-abysmal quality, and promptly binned them in favor of Tamiya's enamel equivalent.

A Baldwin-style "knob" handle for the sand dome was machined and fitted. My old home-made headlight generator was replaced with a proper whitemetal Stones job from Roundhouse. A scanned copy of an original Stones service manual was invaluable in adding the missing conduits and pipework to the generator. The worksplates were fitted with JB Weld, and the nameplates with black silicone. A rear headlight was turned from aluminium, and both were fitted with 3V grain-of-wheat bulbs and glass lenses, sold as replacements for wrist-watches.

28/11/19
Washes, drybrushing, powders and some miniature spray-gunning seemed to produce the result I wanted - a hard-worked loco, but owned by one of those rare mills that actually takes some pride in their fleet. The effect is a bit less subtle than the camera made it look; could've picked a better time and place for lighting, too.
With no permanent line on which to test, some lengths of flex track were plonked on the lawn. "Baron" performed extremely well, if a little tight, due to the new o-rings. When I get the chance, I'll have to take the loco down to the club track at Zillmere for a proper test.

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A proper roll-on/off carrier was made to fit a new box. Mini bungee straps hold the loco in place, with clean soft rags to protect the paintwork. I think this is the way to go, for me, as the oil stays around the bottom of the cylinders and away from the weathered finish. It also means far less handling of the loco, reducing the chance of damage, and frequency of touch-ups.

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The box is a steel "ammo" style toolbox. The lettering isn't perfect, but this box made good practice fodder for signwriting more critical things, for example, that pub in the background.

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The lighting was also re-wired, with a charge socket, fuse, and center-off switch. The plugs will allow me to remove the cab if and when needed in future.

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The Baldwin, as I now prefer to call it, still needs a few bits of "loco clutter" befitting a canefields machine - and a driver, now here waiting for paint.
Barring a proper test run when I have the chance, "Baron" should be about done. A "couple of weeks" burner replacement, that snowballed into a nearly bare-frames rebuild over thirteen months.

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My Fowler "Victoria" is next for weathering, and now that I've some clue as to what I'm doing, I can document that job, with a view to encouraging others to have a go at weathering.


*ADDENDUM* - 24/08/2020

The test run at Zillmere revealed an issue that went unnoticed in the previous brief test run:
The burner frequently self-extinguished. The problem was that in having a standard Roundhouse jet fitted, too much butane was being supplied to the burner. This resulted in more combustion gases than could be exhausted from the smokebox, resulting in back-pressure against the burner, which soon extinguished it. The solution was to supply less butane, by fitting a smaller jet.
A No.3 size from Chuffed2Bits was fitted and has solved the issue.
For context, the bore of a Roundhouse jet is 0.24mm. The Chuffed2Bits No.3 jet is 0.18mm.

[LNR]

Great overhaul job Aaron and well documented. You should be pretty pleased with the loco, nice subtle weathering job looks ready for work.
Grant.

[bambuko]

...I can document that job, with a view to encouraging others...

That's the spirit
Threads like this are welcome and hopefully encourage others indeed.

BTW - I am surprised that you have used "styrene scraps" - I hope you are not going to melt them

Your subtle weathering is so much better than glossy toy like appearance from the factory - well done

[GTB]

Having had to replace the Rubies' eccentrics in 2016, (now there's another quality control story!) I'm interested to hear about these motion improvements.

I wouldn't hold my breath waiting for any substantial change in the Ruby valve gear. That said, the Ruby kit I used to build Haydn's tram has modified valve events compared to earlier batches. Bill Allen in the US published an article on improving Ruby valve events by opening up the ports, not that long before my kit was manufactured. I was going to modify mine, but when I measured the ports they were already enlarged. Whether it was done deliberately by the factory to improve running, or someone just picked up the wrong size drill is anyone's guess.........

The modified valve events have improved running to the extent that the loco runs smoothly and at the same speeds in both directions, but it still uses more water than it should. The replacement burner I made works reliably and can now keep up with the steam demand, but it still uses more gas than it should.

The Argyll NA class models have full Stepho valve gear which works properly, but Gordon Watson was looking over their shoulder until they got it right. We can only hope some of that info sank in.

I've not seen an example of the new Accucraft UK generic models with slide valves, so no idea how well they run and what the water and gas usage is like.

My Shay is the current three cylinder version, but it still has the Accucraft piston valves and reversing valve arrangement. It runs OK in both directions like my Ruby, so may have the same timing, but I never figured out how to dismantle the cylinder assembly to check the ports. It runs OK after a lot of work, but it is still heavy on water and gas.

If you get the impression I dislike Accucraft's piston valve design as much as I dislike their burners, you'd be right........

Regards,
Graeme

[Old Man Aaron]

Thanks for the kind words. Right pleased with it, and very much looking forward to the day my little mill fleet is finished to the same standard, standing on shed for some photos.

I'm interested to see what happens with the styrene. Opting to use it was partially because I didn't have the energy to make one from brass, and partially just testing the limits of styrene. Worst case, if it goes droopy, I'll just knock up a brass equivalent.

Oh, it's not that I'm interested in buying any more parts from Accucraft. Just curious. I've already learned that any further motion work on this loco, is better done by an amateur with a seventy year old lathe. Forgot about the steam port mod, thought about doing it, but there's no mill here, wouldn't try it on my drill press. Could do it on the lathe, but too much hassle to set up properly.

Setting aside where the exhaust condensate winds up, I do think those piston valves, not having o-rings, are a small part of the reason those particular locos are so oily - moreso as the bores wear. Gland nuts, in limited experience running my Fowler, seem to help keep the oil better contained..

[tom_tom_go]

A great read, thanks for taking the time to document.

Humbrol moved their enamel paint production back to the UK from China in 2012. All new paint tinlets I have purchased are back to the original quality.