Building a Kozo

[James Powell]

2 1/2" exists on IIRC, 3 tracks here in Canada. Toronto Live Steamers, Manitoba Live Steamers & Aldergrove MES. I have seen 2/3 in use with 2 1/2", dad had a 2-8-4 that ran at TLS for several years, and a 2-8-2 at AMES.

The boiler for Thing is steel shell, with copper tubes expanded in. So the price is way down on a 4 1/2" piece of copper & the silver solder required for that way. I have another boiler for it which is copper silver soldered, but has never had a fire in it. (it features 1/4" OD copper firetubes...which I think will work on a vertical boiler)

James

[redneckalbertan]

2 1/2" exists on IIRC, 3 tracks here in Canada. Toronto Live Steamers, Manitoba Live Steamers & Aldergrove MES.

Iron Horse Park in Airdrie makes 4.

[RET]

Hi,

As a bit of history, LBSC's early designs were 2 1/2" gauge and were all capable of pulling at least one person. At that time in England, 3 1/2" gauge was called "millionaires gauge." Curly Lawrence (LBSC) was one of the pioneers in this hobby over a hundred years ago. He used LBSC as his "Nom de Plume" because they were the initials for the London, Brighton and South Coast Railway that he worked on before writing for Model Engineer.

Richard Trounce.

[LVRR2095]

2 - 1/2" gauge used to be the most popular size for live steaming. It is small enough to display on a shelf in a living room. Yet large enough to pull you and, depending on the model,....several other people.

I would like to see it become popular again.

Keith

[Pontiacguy1]

The heyday for 2 1/2" gauge came in the 1920's, 30's and 40's. After WW2, most builders were choosing the larger 3/4" scale running on 3 1/2" gauge, which was then overtaken in popularity by even larger scales and gauges. Great thing about most of the smaller gauges and the way they were designed, they could be built on a small lathe with a milling attachment, a drill press, and some type of torch setup for doing silver soldering. Most people didn't have a milling machine or tons of tools, so things were designed to be made on smaller, lighter equipment. The very definition of making the leastest do the mostest.

I still fool with 2 1/2" gauge, when I can. Haven't worked on any of it in a year or so, but I still like it and have some locomotives that I plan on finishing out. If you are in this part of the world and working in anything other than 7 1/2" gauge, you are going to be a lone-wolf, and that's OK by me. I need to get back to work on my freelance 4-4-0 in 2 1/2" gauge. I'm using L.E. pacific castings for the drivers and lead truck, and everything else will be fabricated.

[xo18thfa]

Back on the subject of building a scaled up Kozo, the thought is daunting to me. Kozo's designs are for 3.5" gauge. There is more to a design then just doubling it. First off, double 3.5" gauge you get 7.0", start adding a 1/2" width to everything. Hundreds of width dimensions get changed. Four of his 6 designs are metric. There is a lot more to making those conversions then simply dividing by 25.4. Raw materials in inch dimension don't divide out nicely. Plenty of chances to compound error. I believe Kozo advises against doubling the K27 series currently in LS&OR

Just seems risky to me.

An option for a 3 truck, 3 cylinder Shay is go with Ken Schroeder's castings and design. Well proven design. Runs great. Boilers are available.

vr Bob

[kvom]

Here's my experience with doubling the A3.

1) Any part dimension that's inside the frame or is a longitudinal dimension can be doubled.

2) Any lateral part that extends across the frame needed to be split. Use the dimension between the frame's outer surfaces and double the portion(s) that extend outside the frame.

3) Use common sense in substituting fasteners.

With hindsight plus the fact that I now can use Solidworks, I'd probably model any Kozo design that I wanted to double to run on 7.5" gauge. I'm sure I'd avoid a number of problems.

[redneckalbertan]

A machinist at the club up here made both a Heisler and Shay from Kozo for 7 1/2" gauge. He said it wasn't hard.

Looking at the A3 book from Kozo there is a section in the back about building one for 7 1/2" track, I don't know if the other books have a similar section. If a person was worried about confusion on dimensions I would suggest that they photo copy the drawings, do the conversions, and then write them right there on the drawings. If one can model it in a computer program all the better.

[kvom]

The 1.5" scale section in the A3 book has a couple of problems. First, the dimensions of the footboard didn't follow rule#2 from my prior post and puts the running board supports in the wrong place. Second, the boiler drawing places the steam dome 2" too far forward. I suspect that the Heisler and Shay in 2X would need some careful analysis prior to jumping in making parts,

As for the K27, the doubling rules would be somewhat different since the wheels are inside the frame.

[kenrinc]

Raw materials in inch dimension don't divide out nicely.

In a Kozo build, raw material dimensions don't matter in metric or inch dimensions. There are very few instances where you will not have to prepare stock to a specific standard dimension. It will almost always have to be prepared to some non standard dimension before layout.

Kirk's right on. There is also an issue of more than doubled physical mass. The silver soldered "assemblies" that Kozo is so fond of can quite literally have so much mass in 1.5" that you can't get them hot enough to solder together. I reengineered quite a few assemblies to simplify them so that I could either solder them or avoid soldering all together. The steam "tee" was one of many. I would drill lighting holes to remove mass so the part wouldn't suck up so much heat. The dress up parts that make it look like a locomotive you should probably take advantage of the mass and make them as heavy as possible. Durabar works well here. The stack was a real bugger to silver older. The steam and sand domes I machined out of Durabar. I think when I weighed these parts they came out to about 21 lbs! On a 10" lathe it was quite the feat!! My cab was 1/8" plate and weight well over 10lbs.

Ken-

[Bill Shields]

you can get anything hot enough to silver solder if you have a large enough torch.

I reality, if you do not have the experience / confidence to upscale a model like this, then perhaps you should not be doing it. Some people's creative strengths do not lie in this area.

[Greg_Lewis]

you can get anything hot enough to silver solder if you have a large enough torch.

...

And don't forget furnace brazing for large parts. You can stack up some firebrick for a makeshift furnace and get a weed burner from Horrible Fright Tools for the heat source. Pre-placed bits of silver solder and bringing the part up to temperature slowly are the keys to success.