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Internally Gas Fired Mamod update
we made both toaster,and holes both worked the same on our engine.as for the jetting that was down to a partially blocked jetand the burner being pushed in to far
Internally Gas Fired Mamod update
as for the lubricator they should be drained after each run so they will need filling each run
Internally Gas Fired Mamod update
Why do you think that older Accucraft locos have an issue with slot burners? I have a Mortimer from 2004 with a slot burner  and it runs fine with no flames in the smoke box. I also have a Ragleth from 2011  with a slot burner (although admittedly it sounds like a 747 taking off) that again doesn't have an issue with flames in the smoke box (I'll try and get some video tomorrow). I also have a Regner Lumber Jack with a holes burner which have a reputation for smoke box burning (I haven't experienced it, although that may be because I've fitted a hinged smoke box door to improve lighting).

Are you sure its not just suppliers cashing in on punters with more money than sense and getting "improvements" to their locos when in fact there's nothing really wrong with them? I ask this after being to a weekend steam event where it was pointed out to me that you can buy second hand 5" gauge sit-on locos for less than second-hand 16mm locos. Somebody somewhere is cashing in on what is popular at the moment and its not going to be too far down the line  before the bubble bursts. I paid less that £500 for a new Ragleth in 2011 and now the list price is £850. You can't tell me that re-introducing the Mortimer design of gas tank into the Ragleth plus a few additional holes in the footplate for a second servo, is worth £350 difference (and yes, this weekend I was able to directly compare my 2011 Ragleth directly with a 2016 one, they were even the same colour).
Internally Gas Fired Mamod update
I'd really need to start a new Topic regarding the Accucraft Gas System woes, so will try to keep it brief to reduce this going 'Off Topic'.

I've recently been talking to customers with the BPW burner conversion, and all report good improvements over the standard fit.

Accucraft products are apparently made in several subcontract factories which helps to explain the different owner experiences. Not all of the burners came fitted with an air control ring/sleeve which does help as the standard 4 primary air holes are too much (Roundhouse only use two). The gas regulator valve thread is too coarse for fine control - the Train Department replacement gas valve is highly recommended. Accucraft use a thin walled superheater pipe which is prone to bending with the heat right beside the burner thus affecting the burning pattern (Roundhouse use a thicker walled superheater pipe). Their gas tanks have their filler valve above the gas outlet, thus compromising any air void above the liquid gas (in my experience the side tank version is worse for liquid gas carryover than the cab version which has a taller filler neck).

Our scratch building member purchased the original Accucraft UK loco, the Excelsior, and his was one with the very noisy burner. Accucraft supplied a replacement burner. Whilst building his scale Lilla model he was looking for a burner to test it. Fitted that original Excelsior burner, which worked perfectly and is still fitted to date. Thus the size of the burner is also important in relation to the size of the centre flue.

Whilst I do have problems sometimes with my Accucrafts (Edrig can burn in the smokebox initially (smokebox door was not supplied with a heatshield on this model), Ragleth suffers badly from liquid gas carryover which can blow it out initially, and my Caradoc is such a smooth runner that the burner can occasionally go out at the low gas settings required), I've never had a gas/burner problem with any of my Roundhouse locos.

Worth pointing out that Mamod have switched to firing with mixed gas only - has there been any associated burner modification/changes?

Chris Cairns
Internally Gas Fired Mamod update
Quote:
the standard 4 primary air holes are too much

Both my Mortimer and Ragleth only have two. Perhaps some subcontractors provided burners with 4 holes and they're the ones that give trouble?

CORRECTION: on proper examination both my locos have 4 air holes, so ignore the paragraph above.

To complicate burner comparisons further, Accucraft ones are upside down which seems sure to give a different flame pattern compared to ones with "normal" orientation. I've just had my Ragleth and Lumberjack running and, although you can see the incandescent part of the flame easily enough, its virtually impossible to work out where the exhaust gases are going without an infra-red camera which I don't possess. No idea if Mamod have used one while designing the Stirling.

Quote:
I'd really need to start a new Topic regarding the Accucraft Gas System woes

I think you should Chris.
Internally Gas Fired Mamod update
ok chris so roundhouse have 2 holes and accucraft have 4 is the surface area  of the holes the same ? in relation to the gas jet.we all know how the jet can change things
Internally Gas Fired Mamod update
mikewakefielduk wrote:
Perhaps some subcontractors provided burners with 4 holes and they're the ones that give trouble?

My Accucraft roster: -

Caradoc (paperwork undated) - 4 primary air holes, fitted with your air control ring.

Edrig (no paperwork) - 4 primary air holes, fitted with air control sleeve by previous owner.

Ragleth Mark I (2013) - 4 primary air holes & factory fitted air control ring.

Decauville 0-4-0 (no paperwork) - 4 primary air holes & factory fitted air control ring.

Superior (no paperwork) - 4 primary air holes & no air control ring/sleeve.

As the factory have been fitting air control rings for some time now, what situation still needs 4 primary air control holes - high altitudes?

Chris Cairns
Internally Gas Fired Mamod update
Chris, I apologise, you're perfectly right and on proper inspection both my locos have 4 air holes. Sorry. I really must start wearing my glasses before I look at things close up.

As to why they need 4, presumably its easier to have a generic design that can be adjust with a control ring to cater for local conditions. Your suggestion of high altitude could be spot on.
Internally Gas Fired Mamod update
I live in Colorado at 5400 Ft. I had to adjust the air collar on all of my new locomotives from Accucraft. The changing air pressure conditions here some times require that it be readjusted from the last running position.

I have found the quickest and easiest way to quite an Accucraft burner is this. Source some 60 mesh brass wire screen. Make a tube of the screen just smaller than the internal diameter of the burner tube. This tube should be a single layer thick and not over lap.  I then insert this tube into the burner with the seam side away from the slots so that the 4 air holes are left un-covered. The burner will burn without howling and the flame will stay on the burner tube. I have been using this method for 10 years now with complete success on my 6 Accucraft engines. I have not had any damage to the screen with it being inside of the burner tube.

Charles M  
Internally Gas Fired Mamod update
Received these photos from Mamod earlier today, showing the Stirling with its new design side tanks, just back from the paint shop.




The particular loco still has the old style large lubricator
Internally Gas Fired Mamod update
Nice to see the rivets have been replaced by hex head bolts. I did this on my oscillating Thomas Telford & would recommend the ones on the side tanks being painted the same colour as the side tanks, to make them visually less intrusive.

Chris Cairns
Internally Gas Fired Mamod update
Mamod wrote:
so roundhouse have 2 holes and accucraft have 4 is the surface area  of the holes the same ?

To answer that I took the burner out of my Ragleth Mark I and compared it with the Roundhouse FG from an unbuilt kit.


NOTE - the Accucraft burner is mounted with the slots lowermost and the slots are also angled to the front rather than vertical

The Roundhouse FG burner has an 8mm diameter internal bore, but is stepped down to approx. 7.6mm diameter just forward of the jet holder. The air holes are 6.15mm diameter. Note that the forward tip of the gas jet does not reach the air holes.

The Accucraft burner also has an 8mm diameter internal bore, and the air holes are 5mm diameter. The tip of the gas jet protrudes approx. 1/3rd of the way into the air holes.

Not sure how you work out the surface area for a curved surface, but assuming they were flat then the Accucraft one is approx. 33% greater than the Roundhouse one. I was advised by an Accucraft service agent to initially cover half of the air holes with the air control ring, and to vary that with the different air temperatures.

Accucraft use a No.5 gas jet. Previously Roundhouse said their gas jet is 0.2mm bore (stamped 20) which is a No.5, but recently they've been saying it is equivalent to a No.6.

The Roundhouse FG Burner was developed with the help of a number of specialist's in the gas field, including time in the Department of Fuel and Energy laboratory at Leeds University.

Roundhouse use a thick walled 1/8" stainless steel superheater pipe which is difficult to bend without a tool and holds its shape when heated up. Accucraft use a 3mm stainless steel superheater pipe with a 1.6mm internal bore, and being thinner walled is easily bent especially when heated up. Here's the bent superheater pipe from my Ragleth, the pipe was actually bent right up against the burner towards its front which had affected the burn pattern. I've re-bent it so that it is straight again underneath the burner.



Chris Cairns
Internally Gas Fired Mamod update
Seems I kicked open a hornet's nest with my concerns re the burner design...!

Reason I mentioned them is from experience. As y'all know I've got a gen one Accucraft Caradoc and its gas system has always been the bane of its running.

Gas tank:
-gen one with the tall neck - caused gas to prime forward
-filler valve - constantly blocking and/or needing replacing ever 8-9months

Burner:
-loud howling
-sometimes wouldn't light or create a fireball
-wouldn't burn as efficiently as say a RH design
-dragon-style firebreathing out the smokebox especially when first lit

With all this problems I had tried:

- a mesh ring round the air intake as suggested [and tried] by Tony Bird
-an air control ring as suggested by CCairns of the parish

To no dice.

Because I had got problems being caused by both ends of the system as it were, I went "nuclear" and replaced the lot with an RH FG system. It turned the trick and the loco had never steamed so beautifully.

It was partially what inspired BPW to develop their "bullet burner" and some might say: had I waited I'd have saved some money. I say: ah but with the burner, the jet constantly blocking and the gas tank being a pain in the ass, for me to do everything in one fowl swoop was long term better.

So, that's my experience with Accy burners. Could be that my gen-one Caradoc was, again slightly different from everyone else's Mortimers and Ragleths [the motion is, as Abbeybach Engineering kindly explained to me]
Internally Gas Fired Mamod update
Doug,

No Hornet's Nest - just adds to the variable experience that Accucraft (& Regner) owners have with lighting up & operating their gas systems.

Be interesting to see/hear how the Stirling performs in the gas department once it is running in the Garden Railways community.

Chris Cairns
Internally Gas Fired Mamod update
Thanks Chris. I have high hopes for the Stirling, it looks sweet and will hopefully run well.
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