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|
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…
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.
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.
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...
I design the joints so that back purging isn't necessary.
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.
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|
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.
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...
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|
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|
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...
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!
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.
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...
|Thread: Filling the boiler|
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|
For everyone following the Ballaarat construction series here's a nice video showing the frames and linkage in motion.
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!
The valve glands on the steam chest as well as the piston side cylinder cover has some interesting detail...
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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