Fabricating is another option, and it avoids the mess made by cast-iron. I found Stewart Hart's PottyMill engine suitably challenging a beginner project. Not too difficult, but hard enough to be a good teacher. Stewart is a forum member.

There's a Build Thread here.

A few versions of the plans on the internet. I think I used this one, which is squeezed on to three A3 sheets in glorious technicolour with 3D views. You might prefer Stewart's original plans because they're drawn more conventionally on several sheets: his approach is proper engineering and less cluttered. Unfortunately I can't find a link to them.

Dave

I will second Jasons comments on Stuarts, their casting are good and will replace any that are a problem. Noel.

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The most important thing is to build something you like.

Having built a Trojan and several Stuart 10s and an S50, all using a lathe only, I think the Trojan is possibly the easiest, although there is very little in it. I built mine from scraps of plate and bar stock, and just bought the Reeves cylinder castings, and it makes a neat engine although it is quite small. The drawings are well detailed.

The 10V is perhaps slightly easier than the 10H, but the latter makes a nicer working model as the motion is more visible. The S50 arguably looks best of all when finished, but is not as simple as it appears. There is no crankshaft to worry about, but several operations may be tricky for a novice. Also the main bearing design is poor and as a result it cannot be expected to develop much power.

I would not bother with small oscillating engines. A slide valve engine has more parts, but is no harder to make and is a lot more interesting and realistic.

You should also take into consideration your equipment – metric plans with imperial equipment, and vice-versa, are not a trivial issue for a beginner.

Redsetter mentioned the Reeves Trojan. As it happens I just last week bought the plans for this whilst reconditioning the one I made as my first model (30+ years ago, on a treadle lathe). I'd forgotten that it calls for small Whitworth threads (3/32", 1/8" ), which were difficult enough to obtain back then. I substituted various BA threads instead, but you do need to have some idea of what the best size substitute is for each fastening.I've recommended the Trojan a few times in the past, but having been reminded of the Whitworth threads I'm not sure I would do so again. I know taps. dies and even fastenings are available in small BSW sizes, but when would you ever use them again after making the Trojan ?

In summary – buy the plans on their own first, and study them to be sure you have the equipment (both machine and hand tools), and sufficient skills, before you lash out lots of money on the very expensive castings.

Edited By Bob Unitt 1 on 06/03/2022 12:44:26