Ballaarat construction series

Thanks for your design of this interesting loco Luker. I know that it ran on 3’6 gauge, but what scale did you use? I can’t find it in the articles. Dividing 42” by 5” gives 1 in 8.4, but what did you do? f

Hi Simon, yep you spot on, I used 8.4. I model in metric so I use a gauge rail multiplier and generally clean up the dimensions as I build. This is a little different to the designers that model inch to the foot. There are a few notable deviations including the wheel and flange which is to the ME standard and the cylinders aren't to scale. The cylinders are different because scale cylinders would have been too small for the boiler etc. I do a few simulations and based on the results of those the boiler is matched to the smokebox and cylinders etc. Then all the linkages are updated for a hard working loco (out track is a little rough!).

Thanks Luker, that makes it clear. It could be a quick build because it only has the essentials, but it is quite a smalll loco at that scale.

The Gooch valve gear and links for the Ballaarat are detailed in the new ME (4677). I thought a small animation of the linkages in motion would be nice...

Thanks Luker

Lovely animation; horrendous valve gear. I enjoyed the article. Double expansion links. What a pain!

Thanks Simon, the Gooch valve gear is interesting to design, but modern simulation techniques make life a little easier. I would not like to design this valve gear with just a drawing board! It is incredibly interesting to see all the linkages working in-between each other. I must say the Ballaarat valve gear hasn’t given me any of the issues I’ve read about, even back notching (within reason) is as good as any of my other locos. In fact it behaves the same as my Walschaerts fitted 3.5g 2-6-2 loco in terms of coal consumption, water consumption etc. (this loco has similar design tractive effort, boiler size etc.).

The expansion link wasn’t that difficult to make, it was easier than the normal type because the laser cut surface was of better quality (thinner section). If I were to machine these from scratch they would be held together and match machined so not much extra work. Some pics…

Took me 9 months from first casting to first steam test ...

Concerning the size of the Ballaarat; there’s a picture earlier in this thread of the loco with two adults standing beside it to give an idea of scale. It will happily pull 2 large adults on our track which has an interesting 1:50 gradient for 60m, under trees that tend to dust the track with slippery juices. My 2-6-2 tends to slip here but the Ballaarat doesn’t. I'm reasonably sure it will haul more but my driving cart only takes two...

Great photo that shows the set up perfectly. The long radius rods would reduce angularity problems so perhaps why you find it works well in practice. Yes, with 4 links, you’d want them laser/water/wire cut.
The boiler scales to a little under 4”. Did you use 4” tube or roll the barrel?

The barrel was rolled... For my boilers I use modern manufacturing techniques and materials more suited for the younger model engineer , but I don't want to give away too much; the boiler part should follow soon...

The new ME is out for the digital readers (ME 4679), which has part 6 of the Ballaarat construction series dealing with my method to machine cylinders. I mentioned that the pistons need to be mechanically free but steam tight, and I gave two different methods of practically checking this. I used the technical term of the piston ‘oozing down’ in one of the tests… the video below shows this ‘new’ measure. I do mention this in the article but I like to remind the young chaps that it's great getting this perfect but practically with steam oil and piston rings you would need a decent rattle fit before you’ll notice any blow-by.

The YouTube video I mentioned in Part 6 for setting up the lathe to turn parallel is embedded below. I put this video together a number of years back for a course I presented.

Apologies in advance for the amateurish video!

hi luker

i am a member of the northern districts model engineering group in perth. myself and three other members are building ballaarats 3x 5 inch and 1x 71/4 inch . an article on this loco was in our local saturday west australain newspaper it does mention a south african who has built a ballaarat

we dont have the facilities to cast wheels with cast iron so we are going to try another way. we are going to get some discs of 125 round bar to the width of the wheel then machine a recess in them. then have some sheet metal laser cut to the shape of the spokes and silver solder them in to the recess

regards tom

HI Tom,

That’s great! Please post pictures as you guys go, even if you don’t follow my design. I’d love to see how other builders tackle the same loco! I’m sure the other forum members following the series would also be interested in different build options.

Making the wheels from a disk and laser cut pieces will work perfectly. These will probably have better wear characteristics than any commercially cast wheels simply because most foundries won’t know how to chill the running surface.

Looking forward to some pictures!

Luker

I found this little local media piece on the Ballaarat the other night. That little loco means a lot to the community which is great!

The young lad building the Ballaarat let me know I was a little vague in my description of making the taper reamer for the drain cocks, so I put together the following…

hi luker

news from the builders in west australia photo of wheels constructed by clive chapman. discs where cut from 1045 steel and recessed .spokes were cut from 4mm steel sheet by a laser cutter. the spokes are a neat fit and held in place with small grub screws . loctite would probably be ok

regards tom hardy

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.

hi luker we need some more measurements for the boiler drawings so our boiler inspector can draw up plans for a copper boiler shell overall and firebox widths

regards tom hardy west australia

Hi Tom, this should do it. You shouldn’t have any issues converting the boiler design for copper. Just check the stress in the crown area if you remove the crown stay for rod stays (Aus boiler code). I’ve found the code is a little light in this area… (see: Modern boiler construction methods for the model engineer)