"Billet" Cast Iron Cylinders - Not a casting

[jschoenly]

I have been following the discussion on steel in fabricated cylinders. I'm curious to hear people thoughts on using a billet, continuous cast piece of cast iron for a set of fabricated cylinders. I'm working on the major design/CAD work for a narrow gauge EBT Mikado and after some searching around and checking prices, I'm pretty sold in my mind to just machine them out of blocks. I'm planning on a good number of CNC operations on my retrofitted Boss machine, obviously followed up by some delicate fixturing and machining of ports and bores after my "castings" comes off the CNC. Doesn't seem like too difficult of a task other than time consuming. I figure I can do it that way just as fast as making the pattern and waiting for castings and probably cheaper (time excluded, at least partially).

Anyway, just curious to hear opinions. I would possibly just use the iron for the bores and obviously add valve liners. Looking forward to thoughts.

[Trainman4602]

Fabricating cylinders is not my cup of tea. All of the locomotives that I have built had cast cylinders. I made the patterns and core boxes as well. I just think that a cast cylinder look better it performs better also. I’m not in favor of the drilling method. My current project is a CNJ Mikado. All though there are castings available for the cylinders I’ll make my own pattern for them. I’ll have all the passages cores as per the prototype. I hope to cover the patterns construction in a series of videos inclusive of the machining processes as well.

The cylinder pictured is for the K4 all passages cored.

[gwrdriver]

I'm curious to hear people thoughts on using a billet, continuous cast piece of cast iron for a set of fabricated cylinders.

Jared,
It's relatively easy for me to get on this bandwagon, albeit conditionally. My next locomotive project, and no doubt others if I live long enough, will have between-the-frames cylinders which I will whittle out of a block of grade 40 C.I. That's a relatively easy pick. Outside cylinders are obviously not so simple and I wonder if there is a declining curve of benefit whereby (ALL things considered) the traditional pattern and casting route wouldn't be better. Another thing that is a BIG factor, at least in my experience and to your point, is where do some of us folks like us have iron poured, and what kind of quality will we receive and for what price? Trainman obviously has a workable and reliable source of iron castings so that is one (of several probably) things that influence his choice of path. I'm not so lucky, we no longer have a local foundry, so fabrication is always on my list of where/how do I get this item. So it depends upon many things, not the least of which are your available resources.

[Dick_Morris]

If carved from the solid I can't see how to avoid having a number of parts that will need to be made and fastened together. For example, I don't see how the exhaust passages as on Trainman's cylinder can work without sitcking them on after the passages are carved out. The sticking on presents its own problems with CI. I understand that welding can be a real challange, so that leaves brazing or silver soldering, each with its own challanges.

Carving from the solid also means there is a lot high quality CI that ends up as scrap. You would have to start with at least a half cubic foot of iron at about 225 pounds. I'm guessing you would need to remove at least 150 pounds.

[Trainman4602]

Yes this is true I do have very reliable sources of quality castings. This is the reason for my choice as well as the marketing factor. I usually figure that I can sell someone a cylinder block and that governs my choice as well, and I enjoy making patterns.

[Bruce_Mowbray]

Hi Jared,

I am a proponent of using continuous cast iron for cylinders especially for slide valve locos. It's easy to machine, there are no hard spots or sand inclusions and ports can be engineered in using sleeves for the piston liners. With careful design, even piston valve cylinders could be machined from solid bar. Will there be a lot of chips? Yes. But the cast bar is easy to cut even on a small band saw. Carving away large amounts on the saw will reduce the amount of machining as well as provide chunks of iron to use for other parts like steam chests and cylinder heads. Hogging away the heavy portions on the saw will make easy work for your CNC to finish up the outside profiles. Once this is done and before finishing the delicate work, a good coarse sand or bead blasting, turns the smooth surfaces into a true cast look. Cast iron bar is really not that expensive and if you're only going to make one set of cylinders, it negates the pattern making step which could run the cost up over the desired "build budget".

PS. I see you might be going to Cabin Fever. If you get there a day early, you might stop by Dura-Bar at 180 Roosevelt Ave in York (practically around the corner from the fair grounds) to see what they have in their "drop" rack. Let them know you're a hobbyist and your building a livesteamer.

[shayloco]

To illustrate what Bruce is saying here are some cylinders I made for a Climax. They were much modified Lucky 7 cylinders but they just as well could have been made from billet. The techniques would have been the same.

After boring the cylinders oversize a bronze bushing sleeve was placed in the freezer overnight and the cylinder was heated by a propane torch. The sleeve dropped right in, forming the steam passageways. The bore in the bronze bushing is excellent. I plan on using PTFE (Teflon) piston rings, which have worked well in my Shay.

Standard dimension PTFE piston rings can be bought inexpensively from Grainger. They even come with an o-ring backer that should be replaced with the same size Viton o-ring for steam use.

Ironically, the 1-1/4" arbor used to hold the cylinder for machining the round surface is one of the axles for 4 truck Shay #3156 also under construction.

CNC not required.

Once you decide on the machining method the actual machine work goes quickly.

-Larry

[LivingLegend]

....Hogging away the heavy portions on the saw will make easy work for your CNC to finish up the outside profiles. Once this is done and before finishing the delicate work, a good coarse sand or bead blasting, turns the smooth surfaces into a true cast look.....

Other things you can do to help simulate a casting surface on a steel fabrication or part machined from solid....

Use an air needle scaler to rough up the surface. Make random pock marks with center and prick punches. Then/or use the largest black carborundum grits and blast the the part/fabrication with it.

LL

[kenrinc]

Here's one side of cylinder block for my Kozo A3 in 1.5" scale. Made entirely from Durabar.

I think it depends on the design of the locomotive. A traditional slide valve I would think would be a "piece of cake", as has been shown. I personally feel it's much easier to replicate a modern piston valve using steel plate and pipe. Couldn't imagine making it from a solid. I'd personally have an issue with the amount of waste, but that's just me. Don't forget that a cast block usually has quite a bit of it's central area cored in so it's not totally "solid" so there could a be huge difference in weight.

"From solid" would have been better than using "billet". I really hate that word....

Ken-

[Sandiapaul]

Shayloco,

That is a slick method...I will file it away for the future!

Thanks for sharing!

Paul

[jschoenly]

Bruce,

Didn't think of Dura-Bar or should I say realize they were right there! I'll have to stop by. I'll be there setting up all week. For those of you who may not know me, My father and I are Cabin Fever. I'll be running around like a lunatic for sure, but everyone is welcome to stop me here and there to say hello.

All,

Thanks for the discussion so far. I don't post often, but I was curious to hear people's thoughts. I really enjoy working the the continuous cast iron and I think I have a design down that will not be very difficult to drill/mill the ports and add a valve sleeve. It'll take a few fixtures and a bunch of setups, but these are the kinda puzzles I like to tackle. Working in the medical field, crazy shapes and CNC surfacing don't phase me too much anymore, home or work...

Keep up the good thoughts!

Hi Jared,

I am a proponent of using continuous cast iron for cylinders especially for slide valve locos. It's easy to machine, there are no hard spots or sand inclusions and ports can be engineered in using sleeves for the piston liners. With careful design, even piston valve cylinders could be machined from solid bar. Will there be a lot of chips? Yes. But the cast bar is easy to cut even on a small band saw. Carving away large amounts on the saw will reduce the amount of machining as well as provide chunks of iron to use for other parts like steam chests and cylinder heads. Hogging away the heavy portions on the saw will make easy work for your CNC to finish up the outside profiles. Once this is done and before finishing the delicate work, a good coarse sand or bead blasting, turns the smooth surfaces into a true cast look. Cast iron bar is really not that expensive and if you're only going to make one set of cylinders, it negates the pattern making step which could run the cost up over the desired "build budget".

PS. I see you might be going to Cabin Fever. If you get there a day early, you might stop by Dura-Bar at 180 Roosevelt Ave in York (practically around the corner from the fair grounds) to see what they have in their "drop" rack. Let them know you're a hobbyist and your building a livesteamer.

[Harold_V]

"From solid" would have been better than using "billet". I really hate that word....

You are not alone. I can't think of a word that is misused more. Billet. It's all billet at some point in its life, so the comment is meaningless. The only thing I can conclude is that the term is used to distinguish items made from bar stock (or plate) as opposed to being cast. A catch phrase for those that wish to be seen as being knowledgeable. Sort of backfires, doesn't it?

Harold