2 cylinder inside-out steam engine

[cfellows]

I ran across this video on youtube and was impressed with the way it runs and sounds. Also liked all the movement so thought I'd take a whack at making something similar.

[ame=http://www.youtube.com/watch?v=P4UrQFhxf7A]http://www.youtube.com/watch?v=P4UrQFhxf7A[/ame]

This is a drawing of what I have so far. Not complete, but gives you a good idea of what I'm aiming for.

So far I've got the flywheel turned and the 2 cylinders made. The latter are made from aluminum tubing, 1 1/16" OD x 15/16" ID. The flywheel is from Martin Models and is 5.5" diameter.

Chuck

 

[Path]

Chuck ...

This going to be a fun project to follow.
In fact, I would like to make one. Anything I can do to help?

Pat

 

[cfellows]

Thanks, Pat, think I got everything under control for the moment.

The original engine shown in the video uses rotary valves in the crankshaft. In my engine, the valving will be operated by the cylinder. As it moves from one end to the other, it will push the piston and the hollow piston support shaft left and right to alternately connect one end and the other with the air supply coming up through the end supports. Although not shown, I will have to install stops on each end to limit the axial travel of the piston support shaft.

Here is a picture showing my current plan for the air supply and valve operation. I have some concerns about my ability to get the piston support shafts to move freely left and right and still seal well in the end supports. Have to see how that goes. My engine will be reversible, and, although it should be self starting, I'm guessing it will always start in the same direction it was last going.

Chuck

 

[lathe nut]

Chuck that is neat, depend on you to find something like that, explain it so easy then draw it, that is so good of you to share your knowledge and great skills, here I go again another copy and paste for a future project, thought that I could get you and Brains projects done in a few hundred years now looks like its going to take several thousand, will follow this one, thanks, Lathe Nut

 

[Captain Jerry]

That is a really interesting design and your innovation of moving the valve rod by piston contact adds to the interest. It also adds to the number of problems to overcome, but that's the whole purpose of this activity (I hate to use the word "hobby"). This project will keep you thinking and will keep the rest of us entertained. I had been trying to figure out the purpose of the o-rings in your first drawing. Did not see this coming.

I know how much you like the exhaust puff of poppet valves and this design should lead to a really sharp PUFF!

Jerry

 

[cfellows]

Chuck that is neat, depend on you to find something like that, explain it so easy then draw it, that is so good of you to share your knowledge and great skills, here I go again another copy and paste for a future project, thought that I could get you and Brains projects done in a few hundred years now looks like its going to take several thousand, will follow this one, thanks, Lathe Nut

Thanks, Lathe Nut. I'm always looking for ways to simplify things, so projects can get done quicker!

That is a really interesting design and your innovation of moving the valve rod by piston contact adds to the interest. It also adds to the number of problems to overcome, but that's the whole purpose of this activity (I hate to use the word "hobby"). This project will keep you thinking and will keep the rest of us entertained. I had been trying to figure out the purpose of the o-rings in your first drawing. Did not see this coming.

I know how much you like the exhaust puff of poppet valves and this design should lead to a really sharp PUFF!

Jerry

Thanks, Jerry. The purpose of the large o-rings is just to cushion the cylinder contacting the piston and sound of metal on metal.

Chuck

 

[BillTodd]

The purpose of the large o-rings is just to cushion the cylinder contacting the piston and sound of metal on metal.

Chuck,

Have you considered closing off the exhaust hole inside the cylinder (i.e. moving the exhaust hole further away from the piston so it's partially covered by the cylinder gland) to provide an air cushion instead_of/as_well_as the o-ring?

Bill

 

[Florian]

Hey Chuck

You may also find that one interesting:
[ame]http://www.youtube.com/watch?v=ZexzL-WrqqU[/ame]

Cheers Florian

 

[cfellows]

Chuck,

Have you considered closing off the exhaust hole inside the cylinder (i.e. moving the exhaust hole further away from the piston so it's partially covered by the cylinder gland) to provide an air cushion instead_of/as_well_as the o-ring?

Bill

That is a possibility worthy of consideration.

Thx...
Chuck

Hey Chuck

You may also find that one interesting:
http://www.youtube.com/watch?v=ZexzL-WrqqU

Cheers Florian

That's a pretty engine. Uses a more complex valving operation, tho.

Chuck

 

[cfellows]

I got some more work done on my engine yesterday and today. I've been working on the design as well as some house projects, so haven't spent much time in the shop lately. Hopefully I can start getting really serious about this engine.

Here is the engine base. It's a piece of aluminum about 8" long, 2.25" wide, and used to be about 3/8" thick. However, it had a bit of a bow in it, so I flattened both sides with a flycutter in my end mill. It's now about .335" thick, but it is nice and flat. I will probably cut down the length some.

Here are the cylinder assembly support blocks. I gang drilled the holes to make sure they were in as perfect alignment as I could get them. They are 2" wide, 1.375" tall, and 3/4" thick.

Here is a partial assembly of what I have so far. The cylinder support rods are 3/8" diameter. Probably could have gotten by with smaller rods, but didn't want to push it. I'm quite happy with the alignment and the fit of the cylinder support rods... nice, close sliding fit. We'll see if that's still the situation after I screw the end blocks to the base plate... :-\

Next, I will fasten the cylinder support blocks to the base plate. Once I get all the air passages and mounting holes drilled in the end blocks, I may mill them down some so they don't look so "blocky".

Chuck

 

[smfr]

That video in your first post shows a really interesting collection of engines as it zooms in at the start!

This looks like a challenging, but very neat project. I'll be following along!

 

[cfellows]

I did a bit of head scratching today, trying to figure out how lash up the base plate and two cylinder support blocks so I could drill and tap the holes to hold them together. In the end, I mixed up a little bit of 5 minute epoxy and spread a very thin layer on the bottom of each cylinder support block. I placed the two cylinder support rods in the end blocks then carefully positioned the assembly on the base plate getting everything squared up, aligned and the right positioning. Then I just let the epoxy harden. After about an hour, the epoxy was nice and firm and the cylinder support rods still slid freely back and forth in the support blocks. So far, so good. I had already laid out and drilled the holes in the base plate, so now, I flipped the assembly over and drilled the pilot holes into the support blocks. After enlarging the holes in the base plate, I tapped all 4 holes 6-32 7/8" deep. I put in the cap screws, snugged them down then tested the fit of the cylinder support rods again. Everything still slides freely.

I'm a little concerned that if I take the screws out, break the epoxy bond and scrape off the epoxy, it might throw off the alignment enough to make the rods bind, but, as long as I don't have to, I won't take it apart.

Chuck

 

[cfellows]

Today I completed work on the cylinder support rods. The first task was to cut the grooves in the end of each rod. The grooves allow passage of the air regardless of how the rod rotates. I used a 1/8" cutoff tool and cut the grooves .050" deep. I realized later that they really only needed to be about .030" deep but, what's done is done.

Next, I drilled the center holes, 1/8" diameter and 2.875" deep from each end. I was a little nervous about drilling that small a hole that deep, but it was uneventful. I backed the bit out about every 1/16" to clear the chips. I used a standard length bit to drill as far as I could, but had to use a longer bit to drill the last 1/2" or so. Yup, that's a 12" long x 1/8" drill bit I'm using there. I bought it at Home Depot and I did have to sharpen it before I could use it! Guess I'll have to break down and buy a set of extra long aircraft bits one of these days.

Here's a picture of both rods with all 4 center holes drilled.

Finally, I drilled the radial port holes in both ends and one on either side of the piston in the middle.

Before the engine is completed, I'll have to plug the ends of the center holes, probably with something resembling a rivet. I'm planning to just use Loctite.

Chuck

 

[cfellows]

After lots of noodling, Thanksgiving, and seemingly endless honey-do items, I got back out in the shop today and made some chips. In fairness to SWMBO, I was kind of stuck on a couple of design issues so probably wouldn't have made much progress anyway! :-\

I decided to change the cylinder material from the thin walled aluminum to thicker walled brass. I was originally going to put screws through the side of the cylinder into the heads, but decided the convention method of screwing through the head into the end of the cylinder made more sense. So, I turned the brass cylinders from 1.125" brass rod. The heads are also turned from 1.125" brass rod. I will probably do some further shaping to the cylinder and perhaps the head at a later time.

I also made an aluminum crosshead guide that will fasten flat to the base. The crosshead will be comprised of either blocks or round rollers attached to the cylinder that fit into the slots in the guide.

Here are some pictures of the parts and partially assembled.

Chuck

 

[cfellows]

Work has been slow on this engine, mostly because I've been working on design issues. I'm trying to come up with an engine that will look good with nice proportions and not look like a bunch of parts just bolted together. Consequently, it has been kind of tough.

I did build and fit the pistons, added the cross head bearings and the connecting rod bosses to the cylinders, and made a steel base to hold both the cylinder assembly and the flywheel assembly. I plan to weld milled angle iron around the steel bed-plate to form the base. The other hurdle before me is to design the flywheel support and bearing assemblies.

I'm also playing around with different flywheel designs.

Chuck

 

[Harold Lee]

Looking real good Chuck!! Interesting that your base had a bow to it. I was looking through Rudy Kohoupt's plans on the Pioneer engine and he said that all extruded aluminum will have stress warpage and should be milled on both sides to relieve the stress. otherwise it will warp during machining. Was this something that you discovered on your own from experience?

Moving forward I will buy aluminum plate one thickness larger and mill it down like you did.

Watching your build with interest.

Harold

 

[cfellows]

Thanks for the comments, Harold. I really only noticed the bow on this piece because I knew it would have to be completely flat. The way this engine operates requires all the moving parts to be square and in pretty perfect alignment.

Chuck

 

[cfellows]

Got some more done today. I Finished making and mounting the flywheel support assembly. Here's a few pictures of everything assembled.

I feel like I'm in the home stretch now. Gotta finish the crank arms, connecting rod, and the external plumbing.

Chuck

 

[gbritnell]

Nice looking engine Chuck. Great job on the flywheel.
gbritnell

 

[Harold Lee]

I agree with gbritnell on your flywheel. The design of it perfectly matches the engine. I liked the martin model casting one you originally proposed but with the larger mass which was not required on this double acting two cylinder design, this one seems more "Victorian".