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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: Some model engineering in sunny South Africa
18/12/2022 16:54:54

I took a few more video's at the RSME today... First one was of Mike starting one of our large stationary engines...

14/12/2022 15:59:33

Your weather sounds a little rough! When the temperatures drop to below 20DegC its considered cold and the padded jackets come out!

Thanks for the kind words on the videos. The channel was actually set up for two reasons; first marketing for the RSME with the target demographic mostly ladies with younger children i.e. showing the grounds and the attractions for the family as well as promoting the fact that we ‘display engineering’ to any youngsters that are interested in an engineering career.

The second reason was to post technical videos for the youngsters in our builders group (a social media platform).

The video’s with the youngsters are a lot of fun and specifically posted on the Facebook page to market the youth group and encourage other youngsters to join (and see if they like it).

14/12/2022 06:54:45

A short walk-though of our club museum...

Thread: TIG welded copper boilers
04/12/2022 19:43:59
Posted by Bob Worsley on 04/12/2022 18:33:03:

A copper boiler is a single metal, copper, plus the odd gunmetal bush. But what about the use of hundreds of monel metal stays? These are metal alloys, not a pure metal. Does TIG welding work with alloys?

When welding the actual metal is melted and the two. or more parts being welded form a liquid pool which cools and freezes, so what is the end result of this pool?

With silver solder the base metal does not melt, the solder does and forms a surface coating on the base metal, and this freezes.

These are quite different. Silver solder relies on the surface tenacity between copper and solder for the joint strength. With welding the joint strength is the inside strength of the molten and then frozen pool.

The basic question is, is my professionally built TIG welded boiler ok with monel firebox stays and other parts? Why?

Alloys can be welded with TIG most definitely. The characteristics of the weld pool will be determined by the phase diagrams and other calculations, and this will guide what the welding procedure should look like. Common alloys are easy because the work has been done already, but the new exotic alloys, or uncommon combinations of alloys, would require the welding procedure to be drawn up and weld qualifications done for the specific joints.

Monel and copper weld joins are no problem, because the nickel-copper alloy (Monel) contains the base metal that you joining (copper) and nickel which will weld to almost anything. Joining austenitic stainless to monel with a high nickel rod is no problem. Gunmetal is a little more difficult, but can be welded with the right filler rods provided you stick to the correct amperage (heat input) to prevent the zinc from gassing in the weld pool. You’ll see clearly if this has happened. Depending on the filler rod used and adherence to the welding procedure there should be no problems with these welds. My preference would be to silver solder the alloys that contain low melting point base metals that could fume, or has a very low melting point and could end up on the grain boundarys. Incidentally I’ve TIG welded copper to gunmetal with no issues.

If your ‘professionally welded’ copper TIG boiler was done by someone that understands the fundamentals of physical metallurgy and has welded the boiler by following the welding procedures the boiler will be more than adequate.

Thread: Some model engineering in sunny South Africa
30/11/2022 05:33:11
Posted by Ady1 on 29/11/2022 09:43:20:

A lot more fun than scraping the ice off the car at 9am

One of the benefits of being in Africa, winter and summer are the same just the grass colour changes laugh

29/11/2022 07:20:55

Hi Gentlemen, took the following video (and telemetry) of our long track at the RSME this past Sunday.

Thread: A Model Engineering Gauge Hack
23/11/2022 17:09:44

A video for anyone that wants to make their own pressure gauges...

Thread: Some model engineering in sunny South Africa
21/11/2022 05:45:31

I took a few videos for our Facebook page yesterday. But there's always time for a little fun and games...

Thread: Mini Bender
16/11/2022 12:04:25

Michael, I also enjoy your postings and links. Keep them coming!

Thread: Some model engineering in sunny South Africa
07/11/2022 09:46:03
Posted by Nigel Bennett on 07/11/2022 08:42:14:

Excellent! Are you much bothered by "leaves on the line" at that time of year?

I was intrigued by the track itself - is it just steel bar on edge let into a concrete base?

Hi Nigel, we have a section of oak trees that can completely cover the rails with leaves and acorns during autumn. The track gets blown (and certain sections swept) before a running day starts to make sure the members have a good time and the loco’s don’t get damaged (the youngsters job, but only takes a few minutes). Having said that, even my smallest loco will go over leaves or sticks within reason.

I speak under correction but as far as I know our tracks are 10x20mm square bar with the same welded to the bottom of the tracks for spacing and to key into the cement. Unfortunately theft is a major issue so they need to be fixed properly in the cement. The locally produced square bar comes from the mill with rounded edges which is beneficial.

Unfortunately the video didn’t come out quite like I wanted it. I tried to film the loop for our Facebook page to show the public what the grounds look like but the field of view wasn’t right and my loco was way too small. Next time I’ll take one of my larger loco’s and try get the wide angle shot with the loco in frame.

07/11/2022 05:39:50

Hi Gentlemen. I took the following video (yesterday) at the RSME, and thought you might like to see what we get up to in South Africa.

Thread: Ballaarat copper boiler
04/11/2022 10:53:35
Posted by noel shelley on 04/11/2022 09:58:31:

...

where or how do you draw the line ? Noel.

I agree; as with anything there is a standard distribution, my sample set is very much skewed to one side (if there was any doubt, amateurs win!).

The line should be drawn by the boiler inspectors. It’s their job to determine if the boiler is fit for purpose by testing etc. I think the same onerous criteria for welding qualifications should apply to the boiler inspectors. In other words, they should be highly qualified and/or certified, with practical experience in building boilers. Let’s just peg it to a few tertiary engineering degrees and they must have, at least, completed 5 boilers to qualify! Seems a little ridiculous?

04/11/2022 07:54:20

I think the point I'm trying to make is the requirement for a certified welder for ME boilers scares me. The one professionally made boiler we had at the club (71/4 Romulus, made in the UK) failed dismally and there were a few welding techniques that were simply unsafe. From what I've seen in industry the skills are not nearly as good as the amateur welders that have built their own boilers (at our club). We are very fortunate to have a boiler inspector that understands engineering first principles, and has himself, built more than half a dozen of his own boilers.

04/11/2022 07:44:45
Posted by JasonB on 04/11/2022 07:18:54:

Would be interesting to see if the other side was a better "weld" as access may have been a bit tight from the side where the photo was taken depending on scale of job.

Its a big job, those bent plates are 10mm thick. Other side looks like this...

20220525_082716.jpg

The paint is for specific testing.

04/11/2022 07:28:09
Posted by JasonB on 04/11/2022 07:18:54:

Is that actually weld on the first photo, colour of filler rod looks more like it was TIG brazed?

Yep, AlBr filler rod, MIG. The pre-heat and interpass temperature was completely wrong, not to mention the welder was holding the gun incorrectly. The copper welding they did was worse.

04/11/2022 05:42:09
Posted by Simon Collier on 03/11/2022 22:29:14:

The AMBSC code does not permit TIG welded copper joints except by suitably certified welders.

Yep and unfortunately, unlike the AMBSC stainless code, there is no allowance for supervising an amateur welding his boiler. An interesting inconsistency in the AMBSC codes. It is highly unlikely you will find anybody with the correct certification and recent expieriance as required by the code. My view of certified welders…

This was welded by a qualified, experienced, certified welder and passed inspection. This was for a very large Australian company.

20220620_093020.jpg

This was welded by an amateur with no official experience, certifications or welder qualifications to try show the company what it 'should' look like.

img-20220625-wa0009.jpg

Destructive testing...

img-20220627-wa0005.jpg

Nuff said…

03/11/2022 06:47:30
Posted by duncan webster on 02/11/2022 22:15:40:

So it's copper and zinc with a touch of tin (1%), which makes it brass. Will it de-zincify? Academic anyway for me, doesn't come up on ebay UK search Aus and USA only suppliers

The AMBSC code allows for both bronze brazing and silver brazing; with a wide range of allowable filler metals (other manufacturer’s equivalents are specifically allowed). The only limitation is phosphor bearing alloys or silver bearing alloys with Ag below 15%, which is not allowed. TIG welding of copper boilers is allowed in this code.

Dezincification is an interesting topic. I've found that diffusion or leaching of alloys that are in solution is not very common (and results in a pitting), but if these alloys are on the grain boundaries you may have an issue (cracking). This typically occurs if the transition past the liquidus of the low melting alloy is too slow.

I personally think the silver brazing or TIG welding route would be easier for a beginner.

Thread: Ballaarat construction series
02/11/2022 10:14:44
Posted by noel shelley on 02/11/2022 09:30:01:

Luke you have shattered my dreams! That it steered like it was on rails I was prepared to believe, but that it had the tractive effort of a tracked machine ?

I thought you were a magician, then you mentioned the tank full of lead ! Ah well ! Noel.

Cheating I know wink... One of the benefits of CAD, can put the CG exactly where needed.

02/11/2022 05:35:48

Ron's copper boiler write-up for the Ballaarat is currently running in ME (well written and easy to understand, thanks for broadening the design). Here's a slightly different way of doing the 'brick arch' if you would like to go for something that's not loose in the firebox... I've been testing it the last couple of months and it works well.

Thread: Casting and machining motorcycle risers
30/10/2022 06:41:53

Hi Tim, I never took your comment to imply I should not rely on my castings. I very seldom take issue with any comments on what I do; in fact I appreciate the feedback. I will always point out that anybody can do anything and anything is possible with the correct knowledge. It’s a fine line to walk giving caution versus dissuading people from trying. The idea is to show that something is possible which will give most people the confidence to give it a go; by reading up further. The necessary technical knowhow is probably outside the scope of a forum and more suited to formal articles/books (the benefactors of this site for example).

I have the same facilities and skills as most people, lathe etc. My furnace is not a commercial furnace, but home-made so the tools required to make a furnace are well within the average home machinist arsenal.

Michael; read the abstract, thanks for posting. Shows quite nicely how a commercial ‘professionally’ made item can fail wink. That’s probably been duplicated many times over so there may be a few faulty brake levers out there. It actually speaks to the point made about hardening the alloy, which I decided against to improve the fatigue life of the handles at the expense of strength (but this was designed for).

Bill; Gloves, jacket, jeans, riding boots and the front wheel on the ground is the norm!

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