Stuart Turner S9

[Ian S C]

5th October, a friend dropped in this little engine, or bits of it anyway.

[Ian S C]

And now heres the results, I made a new eccentric strap, from cast iron, 2 piston rings, cast iron. The cast iron came from an old brake disc.  I made the balls for the governor by annealing a pair of 1/2' bearing balls, and drilled them, made up the arms for the governor, and rivitted the balls on the arms.  When I got the engine it was assebled, sort of. It was so stiff, it could not be turned over, and it had no rings at that stage.  One thing needed was shims under the main bearing on the flywheel side. Another thing needed was the guide strips for the (I'll call it) slipper on the con rod, more brake disc CI.   Even had to make the butterfly for the governor, easier than I thought it would be.   The engine runs quite well, when run on my compressor, it starts at about 10psi (thats when the auto-drain on the water trap closes), the governor starts to close around 20psi, and holds the revs to a bit over 30psi.   A bit of a tidy up, and some paint, and things look a little better than they did.

[steamer]

Nice Job Ian!    I always liked the 9!

Dave

[b.lindsey]

You did a bang up job on that Ian. Quite a transformation indeed!!

Bill

[Ian S C]

Thanks Dave and Bill, It will be hard to let the engine go, but my friend has a little museum about 100 yards down the road, so it won't be too far away.
  The thing was in a horrible mess, and it's far from perfect, but it looks OK, and runs OK, But it sure uses a lot of air, mind you my compressor has a fairly small capacity, it's an old freezer compressor.   Ian S C

[Don1966]

That looks great Ian, you did a jam up job on it.

Don

[Ian S C]

Not knowing anything about steam, what size boiler would an engine this size need, I'm not going to build one, just interested.  The owner says that there was one for it, but the scrap man got there first, and if the state of the boiler was similar to the engine, its proberbly best the scrappy got it, it proberbly would'nt hold water anyway!!    Ian S C

[Stilldrillin]

You've done a crackin' job there, Ian! 

Very well sorted..... 

David D

[Walsheng]

Just perusing through the different sections here and I cam across this thread.
I am getting close to finishing a Stuart #9 and one of the last things I need to do is machine the piston and need to find out how deep to machine the piston ring grooves. It is not on the prints and I am told it is not in Tubal Cain's book.
I have been told a couple of thousandths smaller than the ring ID and have also been told 0.010"/0.020" smaller.
Now I am no mathematician but I do know there is considerable difference between a couple of thou and 0.020".
Anybody know the real answer?

And by the way, nice job on the refurbishing job Ian.

John

[b.lindsey]

John, i wouls say .005 to .010 should be enough. The minor dia. of the ring groove mainly lets gasses (from combustion or steam) in behind the rings to help force them out against the cylinder wall.
Bill

[Ian S C]

John, The groove on my engine had been done by the origional owner, mine has one groove, 1/4" wide, and to a depth to take rings 1/16" thick, it was a bit scarey putting them on,but it prooved much easier than I thought it would be. If you don't want cast iron rings, you could use teflon tape.  Ian S C

[Walsheng]

John, i wouls say .005 to .010 should be enough. The minor dia. of the ring groove mainly lets gasses (from combustion or steam) in behind the rings to help force them out against the cylinder wall.
Bill

Thanks Bill.  I'm sure it's nothing magical but I've only build an S10 in the past, far distance past, about 35 years ago, and that did not have rings.  As a matter of fact I don't even recall what the piston was made of. I know there should be some clearance under the rings and I'm not sure how critical it is.

John, The groove on my engine had been done by the origional owner, mine has one groove, 1/4" wide, and to a depth to take rings 1/16" thick, it was a bit scarey putting them on,but it prooved much easier than I thought it would be. If you don't want cast iron rings, you could use teflon tape.  Ian S C

Thank you Ian.  The kit comes with cast iron rings so I think I would like to give them a try.  And also the print was not clear if there is one groove or two although it appears to be one.  I also don't think there is enough room for two separate grooves.  The webs in between and to the outside would be extremely thin.

John

[Jo]

John,

Don't be frightened putting on the rings they have been heat treated so they will be a lot more forgiving than you will expect. And they have been designed to go over the piston diameter so you should have no problem just keep the amount you try to stretch them to the diameter of the piston

Jo

[Walsheng]

Thanks Jo.  I am thinking of turning up a fixture to polish the OD of the rings.
You know I thought I was getting close to finishing but as I look at all the little things that need to be done, maybe not so much.
Little things like I bought a bunch of 6-32 nuts and they are terrible.  Half the threads in the nuts are stripped on most of them.  I have some 3/16" hex stock so I guess I will just make some.

John

[b.lindsey]

John, though it may make no difference in a steam or air powered engine, I wouldn't polish the rings. just a good machined surface...the let them seat themselves in the cylinder bore. Polishing could round the surface slightly and lessen the seal they provide. Just my 2 cents.

Bill

[Walsheng]

John, though it may make no difference in a steam or air powered engine, I wouldn't polish the rings. just a good machined surface...the let them seat themselves in the cylinder bore. Polishing could round the surface slightly and lessen the seal they provide. Just my 2 cents.

Bill

Thanks Bill.  Maybe I will grind the OD to get a nice finish. I imagine the edges should be slightly broken so they don't pick up.
So much to learn, so much to learn.  And I am enjoying every bit!

John

[Ian S C]

John, the piston on mine is 3/8" thick, and even then the ring groove is not central.  The rings I had to make myself, quite a few bits have gone missing over the many years of neglect, imade them a few thou over thick, about .128" and polished the sides to .125", I left theouter diameter as machined, the old brake disc I used turned up very well.  I expanded the gaps 1/4", and heated them with the gas torch for a few miniutes.  Put the rings in the cylinder, and check the gap, if its only ever to be run on air, the gap can be almost nil, but we don't know what might happen 50 or 100 years from now, and they could well be around much longer than that, so I made the gap about .005", if it leaks air, it leaks air, so what.  I used teflon plumbers tape in all glands, including the govenor, on air you could get away without sealing that.   Ian S C

[Walsheng]

Thank you Ian. These ring things are all new to me.  Just using them let alone building them.  Maybe one of these days I will try to build some.
I have a Stuart 504 boiler in progress so I plan to run it on steam at some point. And considering I've had these kits now for 20+ years and I am just getting around to building them, 50 or 100 years does not sound all that long!
I have some string packing my old boss gave me back in 1975 that I might try.  It has been in a sealed container since then so I will add a little oil and give it a try.  If it doesn't do the trick I will try the teflon tape. The tape is one of those items I seem to accumulate.  For years every time I would go to use it I would not be able to find it so I would buy another.  Now they are everywhere. In the sock drawer, under the sofa, in the freezer...

John