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Twin Cylinder Steam Engine

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Patrick

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Had to put the Atlantic locomotive on the shelf for a while so in the mean time I decide to start building a stationary two cylinder reversing steam engine I drew up last winter. So far I have the cylinders bored but not yet honed, the crosshead guides are machined, valve plates are done and I have the parts for the crankshaft machined. Hope to get the crank silver soldered up this week and move on to other parts. I think it should work out OK, I will use walchert reversing gear, on paper all looks well, but then there is reality. Time will tell
Regards
PatP1020393.JPG
 

Hawkeye

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Now that's the kind of build I like to see, Pat. I'll be watching.
 

bpratl

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Looking good! Can't wait to see this project come along as I have a real soft spot for steam engines. Bob
 
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I will be following along as well, should be a good project!
 

Andy Rafferty

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Hope those aren't 2-56 socket heads. Keep posting and include some sizes so I can envy in the proper scale. Good Work!
 

Patrick

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Well this week I got the crank shaft made, the pedestals for the crank, and started on the flywheels. The crank has a 1 3/4" stroke, shaft is 1/2" silversoldered together with 56% silver, supposed to be 70,000 lb tensile strength. Flywheels are 5 1/2" dia. made from schedule 80 steam pipe with aluminum hubs.
Andy, the screws used on the crosshead support are 4-40, I am not following any perticular scale, I do my layout on autocad and adjust the size of the components to my satisfaction. Bore is 1 1/4" and the stroke is 1 3/4". The fasteners on the center pedestal are temporary, I ran out of 6-32 all thread.P1020429.JPG P1020430.JPG
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gbritnell

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Hi Patrick,
I have never seen a crosshead support quite like you have. How does it support the end of the piston shaft to connecting rod joint?
gbritnell
 

34_40

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Not sure how I've been missing this thread.. it won't happen any longer!

Great project.
 

T Bredehoft

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How does it support the end of the piston shaft to connecting rod joint?

With any luck at all, the Crosshead is cylindrical on its OD, tapped for a piston rod (just a straight piece of steel with threads on both ends) on one end and slotted to accept the connecting rod on the other. The crosshead guide is bored to match the OD of the Crosshead.
 

Patrick

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gbritnell, attached is a picture of the drawing showing the cylinder assembly, the connecting rod attaches to the crosshead and the crankshaft. The crosshead guide will either have bronze bearings or ball bearing, haven't made up my mind as of yet but leaning toward bronze.
Hope this will help.
Regards
PatrickP1020449.JPG
 

Patrick

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This past weekend was a little productive, got the oak base glued up and trimmed out, the flywheels are done, and got the eccentric cams machined, not shown in this picture.
Need to check around the shop for more material to keep going.
Thanks for your interest
Pat
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Hawkeye

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I like what I see. Very nice!
 

34_40

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It's gonna be a beauty!
 

Patrick

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Moving along, got the pistons, piston rings, con-rods made and fitted the components to the cylinders. So far all is well
Thanks again
Patrick

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kvt

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That all looks nice, what did you make the rings out of.
 

T Bredehoft

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When I was making steam engines we packed the rings with gland packing, a string stuff embedded with graphite. I have also made them from mehanite iron. I'm not sure what it really is....(Google it)

"The Meehanite process which when followed will produce, according to Meehanite, cast iron with uniform soundness, consistent physical and mechanical properties and dependable performance in service." Courtesy Wikipedia.

There you go, a truly uniform iron.
 

kvt

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Thanks, In one pic they looked like normal steel, and in another they looked more like the ones the I use in normal engines. I was thinking something like a good plastic or something might make a good seal on the pistons. The few steam engines I have done had no rings and had a bunch blow by.
 
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Piston rings are normally made of cast iron, Meehanite being one type of cast iron. It doesn't matter whether it be gas engines or steam or diesel, they are usually made of cast iron. The high percentage of graphite in the iron helps with lubrication, especially when used with cast iron cylinders. Plastic rings probably would disintegrate in short order, the temperatures are elevated by the steam in the first place, plus the added heat of friction would cause the plastic rings to melt at the ring face where it meets the cylinder wall. Plastic rings might work for a short time if the engine is run only using compressed air, but steam would probably not work very well at all.

Graphited string packing, as mentioned earlier, works well in small steam engines, but once you start getting into cylinder bores of about one inch or more, the string packing just does not work too well.

Some individuals have had good luck using neoprene O-rings for compressed air engines, but Viton O-rings seem to work much better, especially if running on steam. When using O-rings it is important to remember that the o-ring does not need to be 'squeezed' into the bore, it should not fit overly tight.

Regardless of what material you are using for rings, it is important to remember that you do not need the high ring pressures with steam or compressed air that we are used to seeing with internal combustion engines. The rings merely need to seat and close the gap all the way around the piston, but do not need to exert the sealing pressure that is typically used with gasoline engines. I read a very interesting article on this somewhere, though I do not remember where. If I can find it I will post a link to it if it is available online.
 
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Not trying to hijack the thread here, but merely offering pertinent information on a sub topic of this engine build. I found the article I was thinking about, and it can be read on Jerry Howell's web site. The article discusses wall pressures exerted by the ring on the cylinder wall and also discusses some methods for making your own rings. Here it is for those who might be interested: http://jerry-howell.com/PistonRings.html
 
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bpratl

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Terry, thanks, that's good input on the rings. Bob
 

34_40

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Thanks for making the time to share the build and the pics. That's a very interesting rig you made/use to hold the dremel tool. A very good idea indeed!
 

Patrick

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KVT, the rings are made of grey cast iron which is readily available from most metal/iron suppliers in the USA. They are then heat treaded to provide the amount of spring resistance to the cylinder wall and the end gap clearance set. Finally, I run them over a piece fine emery paper on top of a piece of glass glued to a plywood base to achieve the side clearance in the ring grove.
In my opinion, using Meehanite cast iron would be great if I were building a full size steam engine to be used on a daily basis for some type of heavy work. In my case, a model steam engine will perform for a long time, (beyond my existance), with grey cast. I have also used viton o-rings in the past and they too will work just fine since the steam generated in a model boiler will not be super heated nor will the pressures exceed 100lbs. My wife is into knitting bigtime, so I have used graphite inpregnated yarn on occasions for rings, but doesn't last. I still use some of this for packing gland seals which seems to work out just fine. Since this is a hobby, anything that you can dream up to try is worth the effort, after all, isn't this how we got to where we are today.
Regards
 

kvt

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Thanks for the info, The build looks great and should last like you said. It will be fun to watch
 

Patrick

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34-40, the dremel tool holder works out really well, you just have to be gentle when feeding the cutoff wheel. It also helps to have a spare set of bearings around as the nose bearing takes alot of pressure from the cross slide. "Patience here is critical"

Is that your ride in the picture? looks super, when I was younger, I built a 1929 ford 2 door and a 1932 Chev 5 window, wish I still had one of them.
O-well, foolish boy let money overcome my better judgment.
Regards

1-1929 Ford Model A.jpg 2-1929 Ford Model A.jpg 1932 Chevrolet Coupe.jpg
 

34_40

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Thank you for the reply Patrick. I can see where the bearings take a beating, especially with the rpm's those things turn!

Yes, that's my car.. 347 stroker SBF Auto OD and a whole list of goodies. Thanks for posting the pics of yours too!

I've made some bits and pieces of a motor.. they were really "studies" if you will, just wanted to see if I can do "it", and this thread is more inspiration!

Thanks Again for making the time to share the build!
 

Patrick

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Progress on the steam engine is coming along, have the eccentric straps, the pedestals for the expansion links, and the links made. Waiting on some 4mm x 7mm x 3mm ball bearings for the expansion links to pivit on. Maybe I'll start on the steam chest while I wait for the bearings.

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kvt

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Looks nice. Keep up the good work on it.
 

Patrick

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Getting close to seeing if it will run in one direction let alone reverse. Need to make the steam chest valves and linkage and then test the functionality. if all goes well, will finish the reverse linkage and steam piping.

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34_40

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Man oh man,, it'll be beautiful!
 

Patrick

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Summer time and there seems to be no end to the work that needs to get done outside. Therefore all work in the shop has to stop until I get the weeds and the honey-do list completed. The attached picture is where I am for now, the engine runs well on air pressure both forward and reverse. Will get back to the fun stuff in the fall.
Regards

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