3/4" or 1 1/2" A3

[kenb]

Hi, my name is Ken. I live in Fayetteville Ga. I've been tinkering in my workshop for quite a few years now building small model engines on a smithy 1220xl combination machine. I want to take on the task of building a live steam locomotive. I purchased the Kozo A3 book and have decided that this is the engine for me to cut my teeth on. I'm going to have to build in 1 1/2" scale if I want to run on a local track. As far as I know there are only 7 1/2" gauge tracks close to me. Now I've read right here on these forums that it is an easier task in the larger scale. I really need some help on this from people who have experience in building this engine. My skills aren't that honed yet, but I'm not really bad at what I do and I'm not afraid of making and correcting mistakes, my scrap bin will testify to that, and if building in 3/4 is going to be more practical and an easier learning experience, then I will bite the bullet and build in 3/4. Also, if I build in the larger scale does everything on the plans get doubled? I know that sometimes there are glitches when things are doubled. By the way I have made the decision to purchase a milling machine in the near future as the mill on the combo machine is a pain to use and gets in the way. Right now it's just swung out of the way. The 12X20 lathe does pretty much anything I've asked it to do so far. Please let me know what you fellows think, 3/4" or 1 1/2".
Ken

[kvom]

Ken,

I'm in the same situation, and am building the 1.5" version to run on a local track. I don't think there would be much difference in the "difficulty" factor for most parts. However, the small version uses a lot of brass while you'd want mostly steel in the larger version. I've had a learning curve in machining steel after doing mostly brass and aluminum previously.

Cost will be a factor with the larger machine, although brass is much more expensive now than when Kozo wrote the book. I'm going to have the boiler made rather than attempt to fabricate it myself. I did buy the driver castings from Friend's, and will likely buy the cylinder castings as well.

Most parts are doubled other than anything related to the width of the frame. This is not doubled as it depends on the track gauge, which is not 2x the 3-3/4 scale track.

I'm in Cumming, GA. if you'd like to visit my shop and see what I've done so far, send me a PM. I also have a 12x20 lathe, which is large enough for anything on this engine. I also have a build thread in this forum.

[phutcheson]

Ken,

Welcome aboard ...

After reading your post many times ... the answer is not so hard.
I am building a 3/4". Why ? So that I can run it !

To me that's the key ... you have a local place to run your 1 1/2".
So the answer is 1 1/2. Done.

Well, having said that ... it may not be so easy. Both scales have their good and not so good issues.

The 3/4" although small it is well documented. The 205 pages provide dimensions, illustrations, how tos, tooling requirements what fasteners are needed etc etc. Pretty much all there. Just following the directions, apply good machining practices and ask questions. You will have a great locomotive.

The 1 1/2 ... much bigger, costlier and time consuming. You will have to determine the new dimensions and ensure that the dimensions are correct not only for the part being made but also all the parts that are connected to it (and some that are not). You will need to determine the correct fastener sizes, allow for material size differences etc. In short much more planning. It will be harder to Silver Solder (especially the Boiler) and in general more material removal. Need bigger tooling ... reamers, fixtures, drills etc.
But ... all doable. It will be more challenging and hopefully more fun. When finished, you will have a great locomotive that can be run at your local track! And that is a big factor.


So go for it ... build the 1 1/2" , keep us posted and ask questions.

By the way, take a look at my website (below) and this forum for my progress.


Pat H.