Member postings for Luker

Hi Dave,

Steel boilers tend to solve nicely in FEA, they don’t have the non-linear material properties typical with copper. Your simulations look good, and it’s good to know that other model engineers are using modern techniques to move the hobby forward!

It’s interesting that you also found the (crown) rod stays in the Aussie code to be marginal. For the Stirling mentioned in the article (my avatar loco) I built the boiler to that code using crown stays and I also found the code to be marginal (in fact there’s a few aspects of that code that can be improved upon). I also had to do a little redesign in this area. The crown stays are stronger and all my later boiler designs use this configuration.

I think the problem with crown stays comes from the old days where the silver solder came loose with subsequent heating, but with welding this is not a problem. I’ve also seem two boilers recently where the cross strut was left out, and the comment was that little plate does nothing. Took a little explaining as to why that little plate is so important for the crown stay!

For the record, I don’t want to create the impression that all boilers need to be verified with FEA. If the design is published, or proven and built to the drawings then no calculations are needed and you have to assume the designer has done his bit. The only reason I have had to use FEA in my designs is because they use materials and manufacturing techniques not commonly used in ME.

Thanks Jon, aren't we all!

The recent articles in ME on my methods of boiler construction using 'modern' techniques and materials hinted to the FEA simulations I do on all my boiler designs to check that they are safe. Here's a short video of two very different boilers I have built, one a Martin Evans copper boiler and the other the Wahya. Both simulations evaluated the stresses for the pressure test and the running conditions of the loco when in service. The failure modes for the pressure tests for the two different materials are similar but for running the design considerations are different. I hope you guys find the videos interesting... Something different in ME...

I really am spoilt with the 3D printer, if I need a pattern I just draw it up and print it overnight. Next day I can normally cast the component. Not like my first loco where all the patterns were from wood. That alone took a few months!

For the fellow foundry-men...

These are astonishingly beautiful! That rose would work really well in a nice jewellery box for my misses...

If they not structural pins work. Just use retaining compound instead of peening the back ends.

Hi Guys, a fun video of our Sir George (club loco). I took the film yesterday during our steam meet...

Zoom or something similar is a really good idea! The young builders at our club often send pictures and videos to each other on private groups for advice and guidance. We have experienced builders on the groups that normally help with pictures or a voice-note. The rule is you need to be upfront if you actually haven't performed the task yourself.

Hi Michael, I used rolled angles to keep the cladding in place, then you don't need to fix it to the cab. The outer angle is fixed to the cladding but just rests on the front cab plate. The inner angles are fixed to the cab and not the cladding. My boiler can expand without any rigid fixing to the back cab. My cladding also doesn't go between the frames and boiler, and the back strap is not functional. Hope this helps...

Thanks Graham. Yep I keep sanding and polishing outside my workshop! Roses in wood sounds interesting, please could you post some pictures. I'm always looking for gift ideas for my better half!

How the other casting came out....

Hi Guys, here's a video I did yesterday of a regular passenger hauler at the RSME. Leon, the master builder, was kind enough to give us a little insight into his loco and what goes into building one of these beautiful SAR's.

I do mix many of my own alloys, or even shift the composition of alloys to what I'm looking for. Mixing base metals can be tricky and unfortunately most of the information isn’t easily available or common knowledge. A good example is the copper alloys. Copper oxide has a melting temperature relatively close to metal copper meaning it goes into solution, instead of the slag, which comes out as porosity in the mould. Graham mentioned ALBr which I have mixed quite extensively the last couple of years as a replacement to the tin bearing alloys (the composition varies depending on the properties I’m looking for). I mix my own free machining version but you can’t just add lead, because this causes hot tears, you need to add silicone. Cast iron properties can be shifted around from a ductile version to a harder wear version for wheels etc. this is easy when mixing from pig-iron.

Thanks Graham. Brass isn't one of my favourite metals to cast and I only need it for the ornamental fittings for my builds (which were quite numerous for the old loco's). I sometime battle with scrap here which is why I’ve had to develop certain replacement alloys and methods of refining fines etc. When I built the American loco I had very little bearing bronzes and ended up making most of the components from cast iron including the eccentrics and straps. It actually worked quite well in the end.

Hi Noel, thanks but technically I'm not a tradesman, just a guy who plays engineering in his back yard . Those were fines so they do get cast at a slightly higher temperature. I have found the loss of Zink is negligible for all the castings I've tested so I don’t worry too much about it. I've set my furnace up in such a way that the exhaust acts as an extractor for the immediate area which clears up very quickly.

I’ll give your ingate maker a bash, thanks for the tip!

Unfortunately buying from the scrap industry is very difficult with all our legislation. Lucky my boxes were made some time back. I do like your idea for a box though…

I have experimented with home-made insulating risers and even hot capping (that can be a little dangerous if you get the calcs wrong), but to be honest I don’t bother. Most of my casting issues can be solved with proper risering or mould orientation. BTW here’re some pictures of the one piece in the video. It’s been machined and gone over with a little emery, just needs to be polished…

Two more RSME videos taken this past Sunday....

Hi John,

I built no 49, which would be similar to Martin Evan’s design (a little more detailed especially on the backplate, and the splashers weren’t closed). The closest greens I found were Dulux Indian Ivy 1 & 2.This was matched from colour chips I found in a book describing Britain’s liveries from 1825-1948. The lining schematic can be found in ‘The Stirling Singles’ by Leech. Sorry I can’t find a way to upload Pdfs? I did do a small write-up for ME on the painting and lining of the Stirling in ‘Zen and the Art of Model Painting and Lining’ if you want to dig that up. If you wan't specific pictures please let me know and I'll upload them for you. A short video of my Stirling…

Hi Tom,

Those wheels look very good! Small grub screws will work perfectly; just don’t push the spider out when pressing the axels home. Some of the guys here build their wheels from laser like you have; then silver solder the lot up. Clive has forgotten the counter balance, it doesn’t add that much weight but is very period specific for these ‘ribbed-disk’ wheels. If you drill one or two blind holes and pour a little lead in there you’ll end up with better balanced wheels than mine.

Thanks for the pic! Please keep them coming.