Steel Cylinder blocks

[westlin]

Hi, a general question, ive found a company that will make a set of cylinder blocks but they are machined out of steel, not cast. Ive never heard of steel blocks before only cast or gunmetal.

Welcome people thoughts

[andyhigham]

From a strength point of view I don't see anything wrong with steel for cylinders. However as the inner surface of the bore is also a bearing the material used for pistons and rings would need careful consideration, maybe cast iron for both piston and rings? Another consideration is corrosion, steel is much more prone to rusting than cast iron.
A possibility would be steel cylinder blocks with cast iron liners pressed in, the steam ports could be milled in the bore of the cylinder before the liner is fitted

[Roger]

I agree with Andy. The question surely is why that same company can't machine a set from solid cast iron stock instead?
You can buy that sort of this from this company.

Another possibility is to machine them from SAE660 bar, which is what I did. I can't see that it makes any sense to make them from Steel and then have to add liners when you can make them from something that will do both jobs. SAE660 bar isn't that expensive if you shop around. I bought mine from Leeds Bronze.

[andyhigham]

Did Joan make his cylinders from stainless steel?

[westlin]

Could high temperature o rings be a way forward

[terrier060]

If it is any help - I was going to prefabricate mine in steel for my Coronation Pacific using two end plates and two steel pipes. But I was going to line both pipes (cylinder bore and valves) with bronze or cast-iron liners - fixed with a suitable adhesive - the end covers will hold them in place but the adhesive seals them. I have seen this done on a model at the Bristol show and a very neat job it was. In some ways this has an advantage over a large solid cast-iron block as it will accept a lot more lagging. It also allows you to be more imaginative with steam passages and is a lot cheaper than buying castings.

I suspect with CNC the parts would fit together so accurately that there would be no need for complicated setups as is required when machining castings. The bores would be true and could be silver-soldered to the end plates. Perhaps a light cleaning-up of each bore may be required before assembling the liners.

I think there is a lot to be said for fabricating cylinders, particularly in larger gauges and I am sure that there is someone on this Forum that has done so with all the talent that is present here. I find it strange that so many talented engineers here still stick to purchasing castings for cylinders.
Ed

[92220]

My cylinders are fabricated in steel and silversoldered together, as exact replicas of the real ones. All I did to make them suitable as loco cylinders was to make cast iron liners and hone the bores to size.

Bob.

Edit.

I was going to add a photo but couldn't get into Photobucket. Managed it now:

[barlowworks]

If I recall correctly MrCrispin, on his You tube channel, machined his cylinders from steel. I'm not sure about the liners, it's some time since I checked him out.

Mike

[westlin]

Mike, could u share the you tube link. Thanks

[miketaylor]

here you are:

There are about 7 or parts to the cylinders.

He uses cast iron liners.

www.youtube.com/watch?v=vhvVQg19jgs

Mike (other Mike)

[barlowworks]

Saved me the trouble of having to work out how to post a link to You Tube, thanks Mike

Mike (first Mike)

[westlin]

Cheers guys

[dscott]

The SUPER Mr Crispin has gone very quiet lately!
We now watch Keith Appleton who is very entertaining!
Also This old Tony!!
David and Lily.

[terrier060]

Mar 1, 2019 12:43:57 GMT 92220 said:

My cylinders are fabricated in steel and silversoldered together, as exact replicas of the real ones. All I did to make them suitable as loco cylinders was to make cast iron liners and hone the bores to size.

Bob.

Edit.

I was going to add a photo but couldn't get into Photobucket. Managed it now:

Brilliant Bob - what a great job you made of them and they look so much better than castings.  It's a shame most of the hard work is not visible when the covers are on!
Ed

[runner42]

Mar 1, 2019 12:43:57 GMT 92220 said:

My cylinders are fabricated in steel and silversoldered together, as exact replicas of the real ones. All I did to make them suitable as loco cylinders was to make cast iron liners and hone the bores to size.

Bob.

Edit.

I was going to add a photo but couldn't get into Photobucket. Managed it now:

Hi Bob,

the cast iron liners are not shown, did you use a cast iron liner in the piston valve liner or was the piston valve made with some compatible material with steel. How did you establish the interface of the liner to the cylinder was it press fit for example and was this done before silver soldering? An excellent example of fabricating cylinders, I would encourage you to provide more details and photos if you have them.


Brian 

[92220]

Hi Brian.

I'm sorry, I never took a photo of the liners. They were machined as a tight slide fit in the fabrication, and sealed in place with high temperature Loctite, and then bored to 0.005" undersize. They were then honed to size. The cast iron piston rings were made by a guy in Birmingham to suit the honed bores of the cylinders and valves, but unfortunately I have lost his name and address in 2 house moves.

The BR drawings were used to base my own drawings for the piston valve and cylinder liners. Both liners have a number of small ports (as fullsize) cut to provide a bridge between ports for the piston rings to pass over without snagging in the port. The piston valves are made of mild steel but I didn't use piston rings on them. I machined 3 oil grooves along the periphery of each bobbin to provide sealing. The difficulty with using piston rings in the bobbins would be fitting the bobbins into the liners from one end, to assemble the motion.

Bob.


Edit:    I did contemplate using PTFE for the valve bobbins but that material really isn't suitable due to it's high thermal expansion. The bobbins would have had to be made very loose in the liners so that when they heated up they would seal. If made to a proper fit in the liners, they would have jammed the first time steam was admitted.

Bob

[stevep]

Bob,

I think PTFE is fine with two provisos. Firstly, the ring needs to be cut at a shallow angle, so that any circumferential expansion allows the two parts to slide past each other. The other is that there must be plenty of room UNDER the ring, so that the ring can expand downwards. (Some authorities advocate plenty of space under the ring anyway, to allow the steam to blow the ring against the cylinder wall).

I have PTFE rings like this on my Rob Roy, and they've lasted about 30 years. The original soft packing had disappeared when I gave it its first major overhaul after about 10 years.

[westlin]

Steve

What are your cylinders made of?

[stevep]

Gunmetal cylinders and pistons, with slide valves.

I also went through Martin Evans' book carefully, and noted that there was an error on the drawing, and all the locos in the photographs had an off-set valve crosshead. I corrected this by adjusting the distance of the valve face from the bolting flanges, and the position of the valve rod in the steam chest. My valve crossheads are straight.

[92220]

Hi Steve.

Piston valves or slide valves on your Rob Roy?

Bob.