SCRM got a nice donation this weekend -- a completely operational model of a sawmill, powered by a Coles single-cylinder steam engine. Only the working parts were modeled, mostly filling a 4x8 sheet of plywood. I plan to use this as the core of an exhibit on South Carolina logging railroads (I already have Thomas Fetters' book).

Several years ago, a small stationery steam engine showed up at the Museum. It and the Coles powering the sawmill are about the same size and configuration, although the two engines are quite different in details. The one we had is black with red rods and flywheel. The Coles is blue. I don't know who built the black one, it may be a lower-end Coles.

The blue engine came with a full set of drawings. It's got a 1 1/4 x 2 1/8 cylinder and a D valve. The black engine appears to have a slightly longer stroke, and has a piston valve. Both engines have problems, which showed up when I ran them on air.

The D valve in the blue one is blowing buy something awful. It runs, but has very little power. I'm a bit past my expertise on this, what can I do to fix this problem? I think the bvalve is not seated properly, and inlet pressure is leaking into the exhaust chamber. It does run (poorly), but there's almost no pulse to the exhaust.

The black engine has a piston valve and runs much better. However, the machine screws holding one bearing block in place have sheared off, and the eccentric strap is broken. I can easily replace the bolts (that's on my list for later this week). Since there's no real strain on the eccentric crank, I'm pretty sure the strap will hold with only the one screw securing it. I'd like to be able to replace it, however. Also, I need an oiler for the inlet line and oil or grease cups for the crosshead and bearings. Where can I find such parts? Any help would be appreciated!

The South Carolina Railroad Museum
mconrad@compuzone.net

Off to California for a few days but I will be back in a week or so. Drop me a line then and I think I can troubleshoot both your engines in the Savannah shop.

Dave

irondave@bellsouth.net

> SCRM got a nice donation this weekend -- a
> completely operational model of a sawmill,
> powered by a Coles single-cylinder steam
> engine. Only the working parts were modeled,
> mostly filling a 4x8 sheet of plywood. I
> plan to use this as the core of an exhibit
> on South Carolina logging railroads (I
> already have Thomas Fetters' book).

> Several years ago, a small stationery steam
> engine showed up at the Museum. It and the
> Coles powering the sawmill are about the
> same size and configuration, although the
> two engines are quite different in details.
> The one we had is black with red rods and
> flywheel. The Coles is blue. I don't know
> who built the black one, it may be a
> lower-end Coles.

> The blue engine came with a full set of
> drawings. It's got a 1 1/4 x 2 1/8 cylinder
> and a D valve. The black engine appears to
> have a slightly longer stroke, and has a
> piston valve. Both engines have problems,
> which showed up when I ran them on air.

> The D valve in the blue one is blowing buy
> something awful. It runs, but has very
> little power. I'm a bit past my expertise on
> this, what can I do to fix this problem? I
> think the bvalve is not seated properly, and
> inlet pressure is leaking into the exhaust
> chamber. It does run (poorly), but there's
> almost no pulse to the exhaust.

> The black engine has a piston valve and runs
> much better. However, the machine screws
> holding one bearing block in place have
> sheared off, and the eccentric strap is
> broken. I can easily replace the bolts
> (that's on my list for later this week).
> Since there's no real strain on the
> eccentric crank, I'm pretty sure the strap
> will hold with only the one screw securing
> it. I'd like to be able to replace it,
> however. Also, I need an oiler for the inlet
> line and oil or grease cups for the
> crosshead and bearings. Where can I find
> such parts? Any help would be appreciated!

If you have all of the parts you should be able to braze the strap back together and make the repair almost invisible. I suggest you contact the people who put on the show at Denton, NC for a source of the oilers and grease cups. They may even have some on hand.

Are you sure the engine with the blow by problem is not out of time bad enough to cause loss of power. If it is not out of time you need to be sure the valve seat is flat and the valve lapped to it. The folks at Denton should be able to advise you on this problem too.

jhbohon@yahoo.com

> Are you sure the engine with the blow by
> problem is not out of time bad enough to
> cause loss of power. If it is not out of
> time you need to be sure the valve seat is
> flat and the valve lapped to it. The folks
> at Denton should be able to advise you on
> this problem too.

It could be out of time. The crank was slipping on the axle because a key was missing. We made a new key from a piece of coat hanger wire (Gawd I love that stuff!). There was a choice of two spots to put the crank, 180 degrees apart. Correct me if I'm wrong here, but shouldn't the crank work in either position? Won't the engine just run the opposite way if the crank is 180 degrees off?

I did notice that when the eccentric is on quarter (main crank on dead center), the valve isn't perfectly centered between the ports. This appears to be deliberate because there isn't enough room in the steam chest for a full stroke if it were centered when the crank is on quarter. I don't understand the reason for this. It's not the cause of the blowing by, though.

The South Carolina Railroad Museum
mconrad@compuzone.net

First off Coles Power Models is still in business in CA and may be of help with spare parts or advice. I've dealt with them in the past (not recently though) and the service was very good. They are a source for things like lubricators and the like. See the below link for their website.

Another firm, P.M. Research of Wellsville, NY (www.pmresearchinc.com) offers various parts (lubricators, scale-size valves and piping, etc.) as well--I had great service from them as well.

As said, check the mating of the valve to the steam chest port surface. Lapping the valve face to the port surface may be needed (perhaps it was never done when the engine was built). Also check for a bent valve rod that could lift the valve off the port surface. The valve timing could be off--it doesn't hurt to play around a little with adjustment. I once spent a whole weekend playing with valve adjustments to get my 1 1/2 inch scale live steam 0-4-0T (Stephenson gear/D valves) to be "just right" in my eyes. I'm also wondering about the piston rings being worn or even missing. Not sure what Coles uses... graphite yarn, Teflon thread, or acutal rings. You could be blowing past the rings and losing power that way. As for the piston valve engine with the loose eccentric, you are correct in that if you rotate the eccentric 180 degrees on the crankshaft the engine will run in other direction.

Good luck and let us know how you made out.

Regards,
Jim Robinson



Coles Power Models

> Good luck and let us know how you made out.

Progress:

Thanks for the Coles link. I'm going to order their parts catalog.

I went to the hardware store and got some bolts for the black engine, which had the loose bearing block. If I ever get my hands on the genius who used soft brass bolts to hold the bearing block next to the crank... Needless to say, the bolts I replaced them with are STEEL.

I reassembled the bearing and now there's a bind. Apparently, it wore unevenly while the bearing was loose. Either that or drilling the old brass bolts out moved the holes slightly. I'm going to have to fiddle a bit to make it work right. I only fussed with it for about an hour after work yesterday, I'll work on it more later. I may bring it home and mess with it at the house.

The broken eccentric strap is holding. We've got an expert metal worker in the museum, I may give it to him and ask him to repair or replicate it.

Haven't messed with the blue engine that came with the sawmill yet. Can somebody explain lapping the valve?

The South Carolina Railroad Museum
mconrad@compuzone.net

Coles' has a lot of stuff in their catalog that he can no longer get. For many small things like grease and oil cups AMES in Valparaiso Fla might be a better solution.

My advice? Take some pics of what you have and ask the fellows on Chaski's "Live Steam" board for input.

http://www.chaski.com/ubb/postlist.php? ... =livesteam


Live Steam Board

> Can somebody
> explain lapping the valve?

It's the "fitting" of the valve face to the valve port surface within the steam chest. A very mild abrasive media (a "lapping compound")(some folks even use ordinary toothpaste) is introduced between the two surfaces, which are then worked together to produce a tightly mated fit between the surfaces.

One nice thing about D (slide) valves is they tend to usually "wear in" during operation, ie: the valve face and port surfaces continue to fit themselves to each other during operation. On at least model engines, usually you find more problems with piston valves wearing out over time then with D valves wearing out. Makes me wonder if there's something funky with the timing or something else is wrong.

Rereading your first post, you mentioned you had drawings for this engine, so you should be able to see how it was assembled. Sounds to me like you're going to have to do some disassembly to find out "wuzzup" with the little beast. Remove the valve and inspect both the valve face and the steam chest port surface for problems (gouges, burrs, uneven wear, etc). Depending on how the valve and valve rod is designed, it's possible (though unlikely) that the valve rod could be bent or otherwise out of alignement causing the valve not to seat properly during its travel. It's something else to check.

As I mentioned earlier, it's possible that the piston ring(s) may be shot and allowing for blow-by past the piston. This certainly can cause a loss of power. If it turns out that the valve isn't the problem, check into the ring(s). Study the drawing--it shouldn't be too involved to pull the cylinder head and remove the piston/piston rod assembly from cylinder. Again, I'm not sure what Coles provided or spec'ed out for the piston ring(s). With a 1 1/4 inch bore, it could be a piece of Teflon or even a rubber O-ring. Or perhaps something like graphited yarn if the engine is a really old example. Word of caution if you find an O-ring--they don't last long if you run the engine (especially on air) without proper cylinder lubrication!

Sounds like fun! Keep at it, you'll get it worked out!

Regards,
Jim Robinson

Thanks for the useful ideas!

Additional info: the engine was very poorly treated before it was donated. Someone had let water sit in it. The piston was frozen, penetrating oil and some tapping with a wood stick got it moving again. There was also rust in the valve chest. I cleaned it out and the engine ran worse. Will lap the valve with some toothpaste as you suggest.

Coles speced cast iron rings on this engine, believe it or not. I thought it would be the valve that was blowing by, but now that you mention it, I guess it could be the piston as well. As soon as I get my Coles catalog I'll order new rings for it.

The drawings for the engine have a date of 1980, BTW.

I managed to get the other engine, the black one we had, repaired except for the eccentric strap. I took it home and fussed with it last night. Haven't tested it on air yet (left my compressor at the museum) but it seems to turn freely now. If I ever get hold of the guy who used soft brass screws on that bearing...

The South Carolina Railroad Museum
mconrad@compuzone.net

Hearing that the engine was stuck and had water and rust inside the steam chest probably means the interface between the valve face and port surface is certainly none-too-perfect anymore. Definitely remove the valve, clean up the mating surfaces, relap the valve, clean everything out real good (especially the all of the ports), and reassemble. I've only used commerical lapping compound, but people have said that toothpaste does work (I have no idea what kind works best). Whatever you do use, make sure you clean it out really well.

I'm not too surprised that the engine has actual cast iron rings. Alternate materials used for rings (O-rings, Teflon bands, etc) seem to be more common in smaller bore models (under 1" bore) and/or in newer vintage models. BTW, as you go down in size (approaching the size of "toy" engines) often there are no rings used--the best you might get is some "oil retaining grooves" machined into the piston. While I'm pretty sure the rings are in less-than-perfect condition having been rusted fast to the cylinder wall, you'll probably find the problem is with the fit of the valve. Are you getting a steady flow of air from the exhaust when you try to run the engine?

Regards,
Jim Robinson

> I'm not too surprised that the engine has
> actual cast iron rings. Alternate materials
> used for rings (O-rings, Teflon bands, etc)
> seem to be more common in smaller bore
> models (under 1" bore) and/or in newer
> vintage models. BTW, as you go down in size
> (approaching the size of "toy"
> engines) often there are no rings used--the
> best you might get is some "oil
> retaining grooves" machined into the
> piston. While I'm pretty sure the rings are
> in less-than-perfect condition having been
> rusted fast to the cylinder wall, you'll
> probably find the problem is with the fit of
> the valve. Are you getting a steady flow of
> air from the exhaust when you try to run the
> engine?

Yes, she's got almost no chug whatsoever. Just a steady hiss of air. The engine DOES run, just very poorly.

The South Carolina Railroad Museum
mconrad@compuzone.net

Y'all said you wanted updates...

This weekend, I got the steam supply lines run to both engines. I had both engines running simultaneously for about a minute. Running on air on a regular basis has been pretty well scuttled, since the best the Museum's compressor could maintain was about 18 psi with both engines (sorta) running. Hopefully the boiler will be able to supply enough steam for both engines.

Any suggestions for an insulation material for the supply lines? The run to the engine that's going to power the saw blade is pretty long, about 6'. I'm a bit concerned that the steam is going to condense on the way to the engine.

I replaced the gaskets in the valve chest on the blue engine. That helped a lot, but there's still a blow by somewhere. The valve and its seat seem to be pretty smooth. In the process of timing it I managed to break the eccentric rod (I applied too much force in the wrong direction). I still have to order my Coles catalog, hopefully they have a replacement. If not, we've got a metal worker in the Museum, so I can give him the broken rod to repair or replicate.

The South Carolina Railroad Museum
mconrad@compuzone.net

> Any suggestions for an insulation material
> for the supply lines? The run to the engine
> that's going to power the saw blade is
> pretty long, about 6'. I'm a bit concerned
> that the steam is going to condense on the
> way to the engine.

Matt,

If your steam pressure is reasonably high (I'm thinking >50 psi) condensation of the steam in the line should not be a problem, especially if you have even a little fiberglass wrapped around it. At only 6' you probably won't need any at all.

Realize that at chemical plants (when steam is often produced at one facility, and used at another), runs of several hundred feet are commonplace. There is a steam line that runs from a power plant in Lake Charles to the chemical plant about a mile away; then you have the runs through all of the piping inside the plant. Granted, the steam left the plant at 850psi IIRC, but that is at least a mile or more versus six feet.

I don't think you have anything to worry about. If you do want to insulate it; the ordinary kind of insulation you wrap around pipes to keep them from freezing will work fine.

-James Hefner
Hebrews 10:20a


Surviving World Steam Project
james1@pernet.net

> "Hopefully the boiler will be able to supply
> enough steam for both engines.

> Any suggestions for an insulation material
> for the supply lines? The run to the engine
> that's going to power the saw blade is
> pretty long, about 6'. I'm a bit concerned
> that the steam is going to condense on the
> way to the engine. "

You should install a drop leg section of pipe just before the steam lines enter the engines. This drop leg should have either a manual drain valve or a steam trap, which will automatically drain out any condensate.

>

sinnh1@asme.org