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Member postings for Luker

Here is a list of all the postings Luker has made in our forums. Click on a thread name to jump to the thread.

Thread: TIG welded copper boilers
30/09/2021 12:11:27
Posted by Circlip on 30/09/2021 11:03:18:

I think the O/P questioned Tig welded COPPER boilers so Hot rolled boiler plate hardly qualifies. Fizzy has given the simple answer as although Ex, at least he was coded and advised that Mickey Mouse welders and welding equipment is a no no. No doubt the O/P will be checking on the qualifications of the supplier? and yes, horror stories abound of some suppliers disasters. A mate ordered a Simplex boiler from a noted supplier in OZ and was surprised to find water coming out as fast as he could put it into it DESPITE the test certificate stating it had been pressure tested to 150psi. Although taking a bit longer and costing a bit more due to overseas postage, the company set up by a young lady in the UK supplied the excellent new one.

Regards Ian

Hi Ian, I think I may have caused some confusion and I apologise. The point I was trying to make was that; as a Mickey Mouse welder with a Mickey Mouse setup I was able to TIG weld a copper boiler that has been running for many years. Whereas a well-known UK based professional boiler manufacturer failed dismally to understand some rudimentary basics in physical metallurgy, and joint design.

I've always thought the idea of model engineering was to develop as many artisan type skills as possible, and the best way to do that is to give everything a bash. Welding, like machining, is one of those skills that can be developed and honed by reading a few books and practice.

I would encourage anyone to give boiler manufacture a bash (this includes TIG welding copper). If the club has members that guide and help the builder, and a boiler inspector that keeps up with modern manufacturing techniques I can see no reason for a ‘poor boiler’ outcome. If on the other hand the boiler inspectors are not knowledgeable enough and are unwilling to up skill; that is an entirely different matter…

30/09/2021 07:43:38
Posted by duncan webster on 29/09/2021 17:46:14
Agreed, if you turn up with a commercially built boiler and a proper welder cert for the bloke who built it there should be no problem, time for some SFED guidance. If it's commercially built then whatever has replaced CE mark will require welder certs, so there should be no issue. It only costs pennies to photocopy the cert. Problem comes with home built.

My understanding is the UK code [The Boiler Test Code. 2018. Volume 1- Boilers 3 bar litres to 1100 bar litres.] does not require the welder to be qualified but samples do need to be submitted to the boiler inspector to check competency, as it should be. The Australian code [AMBSC Code Part 4 Duplex steel boilers] does require a rather stringent welder qualification (AS1796 with a minimum of two years’ experience) but even there an amateur can weld his own boiler under instruction from a qualified person.

30/09/2021 07:20:23

I have very little respect for certifications and markings. Exceptional designers and builders very seldom make good bureaucrats and I have yet to meet a bureaucrat that can do anything other than talk.

We had a CE UK professionally built Romulus boiler that one of our members imported with all the necessary paperwork. I had a look at it and wasn’t impressed with the welds; as a general rule you don’t TIG weld hot rolled boiler plate without the correct prep-work. It lasted a few runs and failed (quite badly) in the firebox. The supplier was of course very distresses, sorry and would fix it free of charge as long as shipping was covered by the buyer, and another two years waiting; the normal BS (bureaucrats speech). I made the comment that if they couldn’t do it with clean plate there was no chance of them fixing a steamed boiler. He eventually decided to have one of our builder’s fix it and it’s been running ever since (think it cost a good bottle of something nice!).

Lucky for us our boiler inspector is a qualified engineer who has designed and built a few boilers and between him and the other members (who have built locos) any new members are guided through the design and construction of their boiler. In the end each boiler has walked a careful path and the data book is kept with the boiler inspector with the welding samples etc.

29/09/2021 16:03:28
Posted by duncan webster on 29/09/2021 15:42:28:

Not wishing to stir up a hornet's nest, but I think anyone contemplating welding their own copper boiler should speak to their club's boiler inspector first. The SFED rules on testing say

An Inspector acting as a competent person who carries out an examination under the Written Scheme of Examination shall have such sound practical and theoretical knowledge and actual experience of the type of system which is to be examined as will enable defects or weaknesses to be detected which is the purpose of the examination to discover and their importance in relation to the integrity and safety of the system to be assessed

which implies that the inspector should know about copper welding and possible defects. Not all will. Don't get me wrong, welded boilers are fine as long as stuck together by someone who knows what he is doing.

I would encourage all model builders to constantly try new manufacturing methods and techniques to improve the hobby and hone their skills! The boiler inspectors should follow suit, and if needs be, up skill...

29/09/2021 14:54:44
Posted by JasonB on 29/09/2021 14:34:54:
Posted by Luker on 29/09/2021 13:54:11:
Posted by Roger Best on 28/09/2021 21:44:06:

What's the best way to preheat a big copper boiler without oxidising it as a gas torch would ? An oven?

I just use a gas torch,

By that I assume you don't back purge by filling the barrel with gas?

I design the joints so that back purging isn't necessary.

29/09/2021 13:54:11
Posted by Roger Best on 28/09/2021 21:44:06:


What's the best way to preheat a big copper boiler without oxidising it as a gas torch would ? An oven?

I just use a gas torch, so does heavy industry. Shouldn't really be moving a chunk of copper at that temperature; not much mechanical strength for moving. It doesn't seem to be an issue with CuO reducing relatively easy. Interestingly if you watch copper melt in a furnace it melts like ice, where brass or LG tends to leave a shell which needs to be skimmed.

28/09/2021 19:09:08
Posted by Nigel Graham 2 on 27/09/2021 22:33:38:

Fizzy -

I believe the copper has to be a "de-oxidised" grade for welding, could you confirm / explain / correct. please?

Hi Nigel, I've yet to come across a piece of copper I couldn’t weld. Most copper nowadays is suitable for welding, and I have never had any issues (if the copper contains enough oxygen you'll get porosity in the weld so you’ll pick it up very quickly). I’ve even done some minor cosmetic repairs to my copper castings using TIG.

I have a normal DC welder (200Amps) and have never had power input issues with the boilers I’ve welded. Interpass and preheat temperature should be kept to above 400DegC, and as with silver solder you need to insulate the boiler to prevent excessive heat loss. My humble opinion: if you can build a fine model, TIG welding copper is easy…

Thread: Name plate etching for my neighbour
27/09/2021 18:10:36
Posted by Brian H on 27/09/2021 17:50:25:

They look good, would you be willing to share details of how the artwork was produced, how it was applied and what etchant?


Sorry, artwork was done in ms-word, with images from the web superimposed onto each other and the names simple built in word-art overlaid on the group.

27/09/2021 18:01:50
Posted by Brian H on 27/09/2021 17:50:25:

They look good, would you be willing to share details of how the artwork was produced, how it was applied and what etchant?


Hi Brian, of course! I did a full write-up on my method in Model Engineer some time back (not sure of the issue number though). Basically it’s an electro-stripping process with a toner print on a transparency (or any other flat plastic) and transferred on a stove. My article says to use a cell phone charger and CuS but these were rather large and I doubt the power and volts would have been adequate, so I used an old power supply (12v) from a computer. They roughly the size of the current emblems on the bike...

27/09/2021 15:55:49

My neighbour has gone away for a little R&R and left his two Harleys for safe keeping at my place, with the express instruction to give them a go. Won’t argue with that; and as a thank you I quickly made up a pair of backrest name plates for both bikes… Some real customizing!



Thread: Boiler water level
24/09/2021 07:45:11

Hi Bob, I can't help with your specific boiler but with my designs and builds I use the 10% rule as mentioned previously from the top of the inner firebox rapper (works well and you have ample time to recover a boiler). I've found the sweet spot for most of my boilers to be with a steam volume of roughly 10%, and where practical this is my mid-point of the sight glass. I wouldn't be too pedantic now on running at an exact point, as the level does move a little on steam (especially if the sight glass holes are too large) and unless you get a lot of track time in you probably won't notice much difference.

As to the fusible plug: I personally don't install them on my class 0 or class 1 boilers, but then the crown is designed to run dry, and the grate can be easily dropped. This is of course dependent on the local bureaucracy.

The speedy was a successful model, we have one that has run for years…

Thread: Ballaarat construction series
12/09/2021 06:06:22

The little Ballaarat goes to our track often, but last weekend there was a quiet time when I could play around a little. I raked the fire bare and waited for the pressure to dip below 30Psi (roughly, the loco has a commercial ME gauge soon to be replaced!). Added cold anthracite and set off... It kept that low pressure for a while on our long track then slowly started to build pressure and at the end of the run was on working pressure. I was pleasantly surprised by that little boiler and loco!

For the Wahya and Ballaarat I did some simulations and design work on the boiler and front ends; comparing these locos to the other locos I've built it looks like it’s paid off...

photo 14 steve taking a closer look at the author?s little ballaarat (photo patrick ackerman).jpg

12/09/2021 05:57:07

Posted by tom hardy on 12/09/2021 00:34:09:

if you are looking for another project 3 steam whims were made in yarloop wa around 1900 a modeller in the netherlands loek proper built one in 1918 and there are 2 videos on you tube he got his information from the pickering brook heritage web site when googling steam whim model i have started to do a whim

Hi Tom, my next project is well on its way. Design complete, boiler, frames and all castings done. But these Whims look great! I won't tackle multiple projects at once but these will be added to my possible projects list!


08/09/2021 13:28:01

Hi Tom, the DFX files for laser cutting are rather extensive and contain all the process specific tolerance and machining allowance built into the files. There is enough information for an unscrupulous commercial entity to use them to make kits at ridiculous prices to the detriment of the designer (and builders). I therefor will not give out the DFX files, but there is more than enough information in the series to draw them up yourself, or even better just let the laser cutting guys do it for you.

18/08/2021 06:50:09
Posted by Chris Perkins 3 on 17/08/2021 20:03:27:

Very Nice Luker !

I notice on the Drawings on the digital format of M E their are a few dimensions missing around the horns on the frames . Am I too keen or will these become apparent later in the series !?! Before I cut metal I prefer to model it in Inventor .

Enjoying what I have seen so far !


Hi Chris, yep you right I missed a few there. All the articles are written to complete a section of the build so I generally won't go back and say drill holes in a completed frame. If you find any dimensions missing please let me know and I'll add the drawings to the forum and update mine. Most of the missing dimensions will be because the item was laser cut using a DFX or 3D printed for the patterns.

Please post some pics of your progress! Can even add it to the series as a post script...

frame horns.jpg

Thread: Filling the boiler
17/08/2021 16:30:47
Posted by duncan webster on 17/08/2021 13:04:57:
Posted by Nigel Graham 2 on 16/08/2021 23:03:24:

Through the injector?

I'd have thought the overflow valve would prevent that? It opens to outwards flow, not inwards.


the water gets in between the end of the combining cone and the delivery cone downstream of the check valve. Photo from Manual of Steam Loco Construction.

For locos that require lower feed rates the delivery cone hole can become small. For my Stirling single I made 10oz injectors with the delivery cone hole just under 0.5mm. Filling up the boiler through that might take a while...

I generally fill from the blowdowns, it cleans the valve seat as a bonus...

Thread: Ballaarat construction series
17/08/2021 16:09:47

For everyone following the Ballaarat construction series here's a nice video showing the frames and linkage in motion.

08/08/2021 17:26:37
Posted by geoff walker 1 on 08/08/2021 14:35:27:

Luker, that's a fine little engine you've made and in such a short space of time. Enjoyed the video doesn't she run well.

If I was 30 odd years younger I'd be tempted to have a go, but not now, not enough time and too many other things to do.

In the 20 or so years I have been visiting Australia I have been to the coastal town of Busselton on many occasions. First spotted the full size Ballaarat in 2018 not longer after it took pride of place in the visitor centre. A handsome engine beautifully restored. At the time I commented that it would be suitable for modelling and low and behold here we are. I like others will enjoy you're build series.

Are you an Aussie Luker? All the best


Thanks Geoff, she is a lot of fun on the track. One of the benefits of virtually checking everything before building it. No I'm not from Aus but I have done work there. Some of the local vernacular was used in the series to make it more interesting. I hope you and the readers find the series of interest. It’s always tricky writing a construction series; I try to keep it interesting enough so that non-builders won’t get bored.

I was invited to the 150 Year anniversary this year in Busselton, but unfortunately I could not attend. Maybe one day I'll get to see the old girl!

07/08/2021 07:34:25

The valve glands on the steam chest as well as the piston side cylinder cover has some interesting detail...



07/08/2021 07:30:07

One casting that might be difficult to find is the smokebox door, but this could easily be built up or machined from a disk. The cutout at the bottom is something unique.


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