Member postings for Luker

I may be able to help with this. The problem with the common bronzes is getting the Tin to go into solution especially if you buy it in granulated form. You need to add a reductant, I came up with the following mix:

10% agricultural lime (garden shop)

35% clean quartz (kiddies play sand, but as white as possible)

10% coal dust

45% bone meal (garden shop)

If you want to melt the manganese bronzes (or brass) this works well as a capping, to prevent fumes. It also works for melting (Cu alloy) fines. The easiest bronze to pour is the alumina bronzes, and they’re more forgiving with draw making riser design easier. To improve machinability you need to add Si with the cast iron inoculant FeSi a good source. All depends on what you planning to cast and its applications.

Most of my bronzes are made using discarded copper from motors or copper plumbing piping with the alloys from various sources. The mixes and sources for the various alloys were described in different articles in ME (Backyard foundry techniques and Fantastic materials and where to find them).

I’d rather not write an essay on a forum .

Hope this helps,

Luker.

Nigel-

Thanks for that background; it gives me a little insight into how the hobby is managed in the UK. All that red tape is bound to stifle innovation. Safety and common sense is incredibly difficult to regulate.

Thankfully our club has a spirit of helping the builders get the best loco onto the track, this includes the boiler. On the rare occasion a boiler is deemed not fit there are normally a number of club members offering to help fix the problem, especially if they see the boiler was self-built.

Going back to the roots of this thread, the Wahya boiler is a 4.2l stainless boiler designed using modern materials and modern heat transfer design techniques. The cost of the boiler was 170GBP (just converted the receipts). What is of particular interest is the grate size (which is small) relative to the cylinder swept volume, and yet it’s an incredible steamer on our poor quality coal. I TIG welded the boiler myself and am by no means a professional (I don’t do it for money) or qualified (no papers) welder. My personal view is anyone capable of a fine model has the ability to master welding with little effort. It’s sad that bureaucracy is limiting development in the hobby (in the UK).

Thanks for the link, I've downloaded it and I'll go through it. Standard test samples are welded and tested to destruction for our club inspector as well. This is just good practice.

I'm curious, if you shake a cola can does the professional inspection authorities come running

One of my copper boilers was TIG welded, with the stays adjusted accordingly. The tubes were silver soldered as TIG welding here is a little more difficult and I doubt the results would be satisfactory on copper. That boiler is still going strong with many, many steaming days under her belt.

I am not a fan of any requirements for professional or welder certification for the smaller boilers. If the club boiler inspector is any good he would pick up welding problems just by visual inspection, especially if TIG is used. Whether intended or not, requirements like these just make the hobby exclusive. We actually had a professionally built steel boiler imported by one of our members from the UK. I was asked by our boiler inspector to have a look at the dissimilar welding techniques used on the tubes. Not something I would recommend on a boiler, but I said it would not result in catastrophic failure so the boiler was allowed to steam. Not 6 months later the boiler failed on the fire door ring due to poor root penetration. The member told me later that the only subsequent service from that “professional” supplier was lip service!

Personally, all my boiler designs are run past our boiler inspector. Weld root design, photos, material certificates etc. all become part of the data pack and this should be done even for the smallest boilers. My view is if he finds something he’s not happy with, he’s helping me in the long run. You most certainly don’t have to be a professional to do a good job…

Noel I’m with you on the cost of copper and silver solder, it’s ridiculous! But this is where modern manufacturing techniques, modern design and materials can bring the hobby back to where it was in LBSC’s time, suitable for the young and people with limited resources. I personally think experimentation on boiler design should be more towards materials and manufacturing techniques, with efficiency and steaming benefits a second thought (from my simulations and personal experimentation I think there is little to gain by digressing too much from the published ME ratios, for copper anyway). To put things into perspective not one of my last three locos cost me more to build than the price of a single set of Tich castings and they were all larger gauges.

Personally I’m too pedantic and safety conscience to have my boilers made by anyone else, professional or otherwise.

I’ve been following this thread with great interest. Thanks for the mention Nigel but I don’t consider myself an engineer… still have a ways to go.

My two cents worth… Thermal radiation depends on the assumptions, with most of my simulations based on grey body radiation, the formulation for the emissivity is adjusted using first principles to account for specific conditions like dust, and build up on the thermal pickup surface. I’ve found with the boiler simulations that using straight black or grey body assumptions results in the heat transfer to the water being over-predicted. The view factor is calculated in the FEA, a little computationally intensive but you only need to do it once for a specific model. This is relatively new, a few years back this was a hand calculation typically using a solver in excel (not difficult just takes a while to setup).

There are many experiments for onset on nucleate boiling with some of these results shown in textbooks; worthwhile to have a look at. The non-dimensional analysis used in HE design is based on these early experiments with the calculations and formulations really just curve fitting. Perfect for water/steam which is what most of the experiments were done on.

I agree with Noel, just build it and try not to overthink! For the boilers and locos I design I do the initial calculation and simulations to decrease the build time and to make sure I’ll be happy with track performance, but I make sure it doesn’t keep me out of the workshop for too long! I have built a Martin Evans loco with the boiler doing the job on the track, but the designs were I’ve put a little effort in heat transfer and flow dynamics is orders of magnitude better (I can’t take credit for this, the computer did the work!).

The attached picture is from a slide show I used in a presentation, I wanted to upload the whole slide show but I’ll spare you all the HT FEA jargon.

Thanks for the kind words Phil, much appreciated.

I'm glad someone is going to give gauge hacking a go, please could you let me know how it turns out. I hope you make the pointer as well; it makes the gauge unique and explaining to youngsters on the side of the track that you can make train parts using cellphone chargers is entertaining in itself. I've uploaded a few additional pictures that didn't make it to the article, to an album. I hope they give a little more insight into how I tackled the job.

Thanks for the welcome everyone. Being on the other side of the pen; it's nice to hear the articles are being enjoyed as much as I enjoy writing them. Well spotted Phil, you correct I should be notching back on the track. I didn't because I was concentrating on holding the camera and watching the track (train robberies aren't unheard of in SA, no jokes!).

For interest: with the designed lead and admission I gave her, I have four notch points to mid gear (there is a gap between the forth point and mid gear). The largest cutoff only works well at high speeds with the designed lead, and at low speeds she tends to stutter a little which is expected. When not pulling any passengers she's quite happy to pull away from the second notch.

Hi Everyone,

I’m new to the forum and a beginner in many ways when it comes to model engineering. I’ve uploaded some pictures of my Wahya 5g American type loco currently being serialised in ME. Unfortunately I am unable to share my dynamic simulations and videos of the completed build in paper format but there is no such limit here! Hopefully those of you interested will click onto the following links:

https://youtu.be/8I9-eJiKn1E is a video of the loco running around the RSME track. Thanks to Jadan for the editing.

**LINK**

this was a short video I put together for an engineering conference and shows a little 3D printing of the patterns and some backyard foundry work. There is also a FEA of the shrink fit tire with lateral forces; and dynamic simulation of the valve gear.

I hope this is of interest,

Luker

Edited By JasonB on 20/02/2021 18:39:50