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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: Stainless steel boilers
28/01/2022 10:21:37
Posted by JasonB on 28/01/2022 10:16:54:

Fizzy's thread a few years ago shows you don't need to be coded if you get the welds tested which was quite a cheap process

You also don't have to get the boiler tested by a club, may independant boiler inspectors able to do it and that is the way a lot of traction engine builders choose to go.

Edited By JasonB on 28/01/2022 10:19:36

Jason you too quick! laugh

28/01/2022 09:56:49
Posted by Martin Connelly on 28/01/2022 09:10:57:

The designation of sch40 or sch40s depends on which ANSI standard is being applied. ANSI B36.10 does not use the s after 40 but ANSI B36.19 does. since at 2" there is no dimensional difference it does not matter if you put the s in or not. #

The issues of stress corrosion and stress cracking possibly apply more to a model boiler than to industrial applications. An industrial application may only have a few pressure or heat cycles a year, a model sized boiler may have more in one day than an industrial application. The smaller boiler may also locally heat up and cool down faster and since stainless has lower thermal conductivity than copper and less ductility this cycling could be more damaging.

Martin C

Corrosion cracking should not be confused with low cycle fatigue. Corrosion cracking is an accumulative failure type spurred on by the surface tensile stresses, temperature and initiation element concentrations. I’m afraid I don’t agree that model boilers are more susceptible. If anything they are less so due to the limited use. Low cycle fatigue due to thermal cycling is another matter and will only accelerate corrosion cracking if the design does not cater for it. With respect to ductility, this is again a design issue and any design needs to take this into account.

The oldest stainless boiler in current use at our club is 27years (SS316L, and that’s a class 2 boiler). Stainless is much cheaper than copper, and in my humble opinion easier for the younger generation to fabricate who would likely have had more experience with TIG than brazing.

Mark: SH10 will be fine for a 30Psi boiler!

28/01/2022 06:00:59

Duplex stainless is preferred but if that is unavailable SS316L is fine for our little boilers (class 1 and below, but need to check regional requirements). All 4 of the stainless boilers I’ve designed and built have been very successful. If you use a backing plate then back purging is not necessary so a little planning will pay off. The design for stainless is slightly different to steel and copper; the design needs to take into account the corrosion cracking issues especially with austenitic stainless. I personally wouldn’t use MIG; some of the tests I did showed the normal MIG gas caused the welds to become sensitized (stark difference to TIG). MMA inclusions are a big problem in SS. The Wahya series had a high level FEA pic showing the calculations to deal with material issues. I’ve submitted an article some time back on stainless boiler manufacture and some of the things to look out for, not sure if it is in the pipeline for print. The part on the Ballaarat boiler will have a little more info…

Thread: The future of casting kits
19/01/2022 17:47:17

Sadly I think the argument for sand casting is a little moot if the required skills are not available (at a commercial level). It would be interesting to find the break even in cost between 3D printed patterns for investment casting vs CNC. I have a feeling the more demand there is for a kit the more they would lean towards investment casting.

Incidentally the skills required for investment casting is different to sand casting. With the stiff mould and pouring into a heated shell the riser design is much easier, in fact in my experience the investment foundry-man is unlikely to have ever calculated casting modulus etc. and they generally feed from the cup.

18/01/2022 15:17:35

I’m honestly surprised sand casting kits are still available. At the very least modern casting kits should go the investment casting route. With modern 3D printed patterns produced from very reasonably priced printers there is no reason for an investment foundry to not add a few parts to a tree. Today most engineers would tend towards CNC or investment for components in the size range of model engineering, especially lower quantity items.

Personally I like the challenge of getting the calculations right for the risers and messing around with the chemistry of the melt. I can’t remember the last time I got hard spots or blow holes. Casting has been part of the hobby since the beginning, as an additional skill to be honed. Not sure it makes sense commercially though, especially if the suppliers can’t get the castings right.

Maybe in the future G-codes will be sold instead of plans and little home CNC units used to finish models while watching 3D movies. Can't wait... wink

Thread: The RSME spring live steam meet
17/01/2022 06:53:21

Another RSME short video...

Thread: Backyard Foundry - oil burning furnace - moulding and casting a spider
16/01/2022 16:54:10

Hi Graham, the name plates look great! Surface looks spotless and they polished and painted beautifully. Thanks for the pictures.

Thread: The RSME spring live steam meet
12/01/2022 12:00:06

The young lads at RSME put together the following video for the 2021 RSME spring live steam meet. Full article in 4678. I think the lads did a good job on production and story line! Tri-pod is on order laugh

Thread: Backyard Foundry - oil burning furnace - moulding and casting a spider
10/01/2022 17:13:25

Hi Graham, that's great news! Thanks for the feedback. I'm always glad when someone can take something I've written about and reproduce the results, then I know I'm sharing knowledge and not just boasting wink.

Yep my furnace design, including the burner, is in ME4626. I gave the ratios of what will work based on my calculations, but my actual sizes are also given.

Please let me know how you get along!

PS have you got some pics of the name plates?

Thread: Dummy tri-cock video
06/01/2022 07:39:01

My neighbor said I should make a video of the live steam locos I design and build, but compressing 5000hours into a video is a little daunting. I thought I would give a machining video a bash just for fun... Nothing has been sped up, and most of the techniques are very simple especially for the old hands. Audio has been removed because apparently my lathe sounds like a good tune, according to the record companies; I agree!

If you watch, its 10 min of your life you never going to get back laugh

Thread: Backyard Foundry - oil burning furnace - moulding and casting a spider
03/01/2022 19:23:44
Posted by MikeK on 03/01/2022 19:15:27:
Posted by Luker on 03/01/2022 18:59:44:
The running joke in our house is that anyone who looks over the wall and complains about someone casting metal should rethink their strategy. At least the person casting has a hobby and doesn’t get up to mischief. Seriously though, I live in a city suburb and have asked all my neighbours if the furnace makes a noise and they all said it does not. I have a large box covering the blower (this makes most of the noise) with inverted egg boxes glued to the inside which dampens most of the noise. The furnace itself isn’t too noisy.

Thanks, Luker. Unfortunately, I live in the city proper. Small city lot and exposed to neighbors on all sides, no fences. If I lived in the suburbs I would have much less concern. My next door neighbor has complained about a lot of things, including me parking my car in the *public* street in front on her house. I suspect she would think I *was* up to mischief with a casting furnace. Some people take the hint when being ignored, others unfortunately don't. From the videos I've seen, the burner has a pretty big roar even without the blower. No?

Yep it does... I would guess its similar to a vacuum cleaner.

03/01/2022 19:21:20
Posted by the artfull-codger on 03/01/2022 19:12:59:

Hi Luker I must look at your oil fired burner seeing as how i inherited gallons of oil from my late father in laws central heating tank, next door. luckily I live in a village & we have a large back yard so noise isn't an issue & we're not in a smokeless zone , the good thing about coke furnaces is they're quiet, I use a bouncy castle blower with a home made restricter disk on the inlet, no electronic gizmo to go wrong, in fact when I'm fully glowing the inlets almost closed so the motors doing hardly any work in fact it's using less electric!! btw I've mixed up some of your additive for melting fine turnings, I'll be trying it this week. as I have some nameplates to cast for his loco .


If you're melting brass fines rather pour them into ingots, you might end up with too much super-heat. Gunmetal and the bronzes work a little better when pouring directly into moulds from fines.

Yep please give it a go and let us know how the burner works for you.

03/01/2022 19:15:36
Posted by the artfull-codger on 03/01/2022 18:52:35:

Interesting posts about different fuels,I built my first furnace nearly 50 yrs ago with my late father,[& burnt a few out since!!] the only information for an amateur [like me] was B.Terry Aspins "bible" foundrywork for the amateur, no internet then, with folk casting alloy wearing flip flops & shorts & pouring it into tart tins & getting loads of praise on their apparent skills, as Luker says [& I really enjoyed his articles & also learned a few things from him!!] there's various ways to build a furnace, when I started I built mine to run on coke with a blower, as per B.T.A. 50 yrs on I'm still on coke poss because we always have a couple of tons in for our rayburn cooker but as said above it's getting more difficult to get coke now with demise of the steelworks,I did build a small propane furnace powered by my flamefast torch & it's really good but having inherited a large amount of central heating oil along with the central heating burner I might try that, propane is really expensive, of course you can get re-fillable bottles & it's much more cheaper at the forecourts.


Thanks Graham. There's a few more I've submitted to ME about casting, from methoding to furnace linings, and alternative-simpler alloys from base metal scrap for the model engineering. I hope you guys find them interesting!

03/01/2022 18:59:44
Posted by MikeK on 03/01/2022 18:40:50:

I'm curious...How quiet can these furnaces be made to run? I would love to try casting, but live in the city with close neighbors who may complain.

The running joke in our house is that anyone who looks over the wall and complains about someone casting metal should rethink their strategy. At least the person casting has a hobby and doesn’t get up to mischief. Seriously though, I live in a city suburb and have asked all my neighbours if the furnace makes a noise and they all said it does not. I have a large box covering the blower (this makes most of the noise) with inverted egg boxes glued to the inside which dampens most of the noise. The furnace itself isn’t too noisy.

03/01/2022 18:08:29

Hi Pat,

Many ways to make a furnace… My furnace uses a simple atomization tube, and gravity to feed the fuel with a simple gate valve to control the flow. If the furnace is designed properly the tube should never get red hot and should only run a little over the vaporizing temperature of the fuel (the supply air keeps it cool). Most of the combustion should occur at the bottom of the furnace. When I started I used normal MS tubing and this lasted around 5 heats, with each heat roughly 5 hours (I tend to plan my castings to get a batch done). When I changed the tube to stainless it lasted until I broke out the furnace for a reline recently (three trains later) and the lining glassed.

Generally I run waste oil for anything with a melting point below cast iron; the tank has a simple strainer from a French press coffee maker. For cast iron I mix 50/50 with diesel although I have melted cast iron with straight waste oil. You do need a little extra heat if you making the cast iron from scratch using pig iron.

Nice to see the different ideas!


Thread: Springbok completed
01/01/2022 11:43:06


Thread: Pioneer designed by ND Willoughby
12/12/2021 18:15:48
Posted by JasonB on 06/12/2021 07:59:27:

Looks like there may be some photos in No 1852, vol 75 pg 439

I found this article in our library this afternoon. Lovely 6 pager on one of the Pioneers built by a Mr Goves which won an award at the ME exhibition in 1936. Thanks for the reference, much appreciated!

Thread: Backyard Foundry - oil burning furnace - moulding and casting a spider
08/12/2021 16:50:10
Posted by SillyOldDuffer on 08/12/2021 15:56:54:
Posted by clogs on 08/12/2021 14:47:58:

is gas, ie propane hotter than D fuel or not ...

Diesel burns at between 1000 to 1400°C, so cooler than gases. As Bronze melts at 950°C, it can be seen Diesel won't work unless the burner is carefully adjusted to maximise flame temperature. Harder to do than with gases because liquid diesel has to be mixed efficiently with air before ignition, typically as an atomised spray or by vaporising it. Oil burners are more complicated to make and control.

Dave you need to be careful interpreting information from the internet. Flame temperatures vary depending for what application the specific tests were done. Adiabatic flame temperatures of diesel can exceed 2300DegC if you run slightly lean. These tests were specific to diesel burners used in large industrial smelting furnaces. Diesel will most certainly melt bronze, in fact it melts pig iron, cast iron and I have even melted BMS in my furnace.

My burner is incredibly simple, with no nozzle and the diesel is fed by gravity. i.e. no compressed air. The fuel air mixture is easy to get right with a simple gate valve. I have melted using propane, waste oil, diesel and a few other fuels. You would be hard pressed to melt cast iron in a gas furnace without freezing the valve (depending on the ambient temp).

We need to be careful not to steer people in the wrong direction based on internet searches, especially when it comes to foundry work which is inherently very practical. The heat and mass transfer also requires an in depth understanding of the governing equations and not only the flame temperatures...

08/12/2021 15:23:00
Posted by clogs on 08/12/2021 14:47:58:

following with interest......

is gas, ie propane hotter than D fuel or not.....certainly cleaner to use.....

I want to cast bronze items.....getting close to serious about this.....

we do have a place near but they only work during the tourist season.....they manufacture small castings to go with/ display their custom glass works of art........

Hi Clogs, there's more than flame temperature to consider in the mass transfer equations. Specific heat etc. Big melting temperature difference between cast iron and bronze. Bonze will melt no issue with propane, can be done in a ceramic fiber lined dustbin with a blow torch if you want to. Very difficult to get poor bronze castings if you do the basics right...

Oil fired furnaces shouldn't be dirty, mine runs clean. Certainly no smoke...

08/12/2021 13:10:03

Thanks Dave... videos aren't really my thing, was actually for a FEA conference I presented at.

There's quite a step in heating requirements for cast iron compared to zink and the brasses, but with diesel added you shouldn't have any issues. Please keep us updated!

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