Piston Ring Material?

G'Day All,

I am currently building a Hit & Miss engine & I am undecided on the best material for the piston rings. Details are;

Cylinder, cast iron & Ø30 mm: Piston stroke 40 mm: Rings, Ø30 OD, Ø27.5 ID & 1.25 mm wide: Engine speed possible 700 - 800 RPM.

I am not sure about cast iron rings in a cast iron bore & have been considering leaded bright mild steel. Could those members that are IC builders please comment.

Thanks in advance,

Don.

Edited By Don Brymer on 23/10/2012 00:53:23

Hi Don

Cast iron piston rings working with cast iron cylinders is probably the most commonly used combination for your type of application. I would recommend going for a good quality material like a grade 17 continually cast which has a very fine grain and uniform structure. I used this combination on my BR2 without any problem.

Because of it's free graphite content cast iron has the rare property of being a good bearing material with it's self, not so with most other materials.

Steel piston rings may be OK but I have no experience in this quarter.

Nigel

As Nigel says cast iron is the best there was a good article in ME some years ago about makeing them. must try and dig it out for you but sure you can use the free index to find it.

Regards
Bob

A good place to start - Volume 202, issue 4350, page 522.

Regards

Terry

Yes definately CI. I use the Trimble method of splitting and then heating others prefer to make the ring with a larger diameter and cut a section out.

Make a couple more than you need just incase of a mishap when fitting

These and these are some I have made

It would be hard to get steel to split in the same way you can cast iron and I'm not sure mild steel would hold the spring when heated.

J

__Hi Don,

I have made a lot of IC engines over the years and I mostly use continually cast c.i. for the cylinders and piston rings. For slow revving engines I use c.i. for the pistons too. I use the George Trimble method to make the rings. This method appeared in the Strictly I.C. magazine February - July 1989.Oil control rings made by this method give also good results and with some care you never break a ring. On the photos you see my diesel piston (not run-in yet) and my Holt engine with oil control rings.

Good luck with your engine.

Regards, Johan.

Just made a pair of rings for a ST no 9, it's a horizontal steam engine with 1.5:" bore and stroke, I used the cast iron from an automotive brake disc, they seem OK, it may be some time till they get tryed in action. Made one years back for a twin cylinder Continental industrial engine from the rim of a cast iron V-pully, that one was somewhere between 3" and 4". Ian S C

Johan,

I think (and I could be wrong) that when you post pictures side-by-side, as above, it makes the text for the whole of the page extend sideways so that the stupid advertising panel hides a chunk of it. Yes, I know, even the average 10-year old could probably design a web site less cack-handed than this one, but still, it's kinder to all of us if you just try to post them one above the other.

David,

Any chance your web people could .... no, I suppose not.

David

Edited By David Littlewood on 23/10/2012 10:40:10

Thanks David. I keep it in mind for the next time.

We had a brand new 27.5Kva generator delivered and the man in charge could not wait to start it up.

This genny is air start but of course it had no air in the tank until it had been started. It was started with the attached starting handle and the air pump engaged and then when 600lb was in the tank the engine was switched down. Later it was started up again using the air start motor which made a funny noise but no one took notice. At that point I started a service of the machine and found no oil in the air start motor. Decided to strip it and found one piston with a broken ring so decided to make another as there was no chance of spares.

I found one of those racking base stands and gave it a rub with a file and it seemed soft enough so turned up a new ring and split it and heated it up and then put it on the piston and re-assembled the motor. Remembering to put oil in as well ! Started up again with no funny noise and as far as I know still going strong.

clive

G'Day Don,

On all the big ship main engines I worked on, the cylinder liners were cast iron and the piston rings were also cast iron. Cast iron works well against cast iron, I would go for C.I.

Regards, Chris

G'Day All,

Thanks everyone for your input.

Problem resolved as regards to the most suitable material for the rings. I will need to source some suitable C.I.

With regard to the manufacture of the rings, I initially plan to use the method described by Tom Schwartz in issue 27 of the Model Engine Builder Magazine as I do not have access to the other articles mentioned.

Thanks & regards,

Don.

G'Day All,

Thanks everyone for your input.

Problem resolved as regards to the most suitable material for the rings. I will need to source some suitable C.I.

With regard to the manufacture of the rings, I initially plan to use the method described by Tom Schwartz in issue 27 of the Model Engine Builder Magazine as I do not have access to the other articles mentioned.

Thanks & regards,

Don.

For my rings (1.5" dia) made from old brake disc cast iron. The disc was one of the ones with two faces with a gap between for cooling, I split the discs with the bandsaw, and faced the rough side with the vertical milling machine, cut out a square, cut the corners of that, bored the inside diameter. made a mandrel to fit the bored hole, and put the ring on with a bit of super glue, turnd it down to the required diameter. I tryed knocking the ring off the mandrel with an aluminium punch without heating, it did two things---it came off, and it split the ring, I was wondering how I was going to do that! Ian S C

The MEB method will be fine, its not that different to the Trimble method.

J

My latest homemade cast iron dykes ring on a cast iron piston is running in a steel cylinder and I have also used them in cast iron cylinders as well.

They are both a good combination of materials as 122.91 mph over 500metres with my flash steamer last month has proved.

11,000rpm plus at times with little wear apart from the odd mark caused by scale?

Lubrication is splash and the cylinder has a burnished appearance.

Being steam it has to be stripped after every meeting to stop corrosion setting in but with IC it should not be too big a problem.

I also coat the piston and cylinder with Graphogen graphite paste it does help running in.

Windy