Two Cylinder Double Acting Steam Engine Build

Discussion in 'A Work In Progress' started by vederstein, Oct 7, 2018.

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  1. Oct 7, 2018 #1

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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    Now that my (failed) Essex Stirling is over, I'm starting my next project.

    This steam engine is of my own design.

    90 degree, two cylinder, and double acting. It will use barstock and aluminum castings. The castings will be the crosshead frame, cylinder, and steam chest. The rest is aluminum, brass, and steel barstock.

    Bore is 1-1/8 inches with a 1 inch stroke.

    I've shown this animation in another thread, but it's appropriate to show it here:



    Let the build commence!!!

    ...Ved.
     
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  2. Oct 7, 2018 #2

    vederstein

    vederstein

    vederstein

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    I started with the engine block which was a 4 inch diameter x 4 long piece of solid 6061 aluminum. It took 45 minutes to cut this think on my 4x6 bandsaw.

    DSC02143.JPG

    First I faced it off and turned down 0.20 to clean up the outside.

    DSC02144.JPG

    Next was to progressive drill out the center so I wouldn't have to bore out as much.

    DSC02145.JPG DSC02146.JPG

    Then I bored it out to 2.75 inches diameter.

    DSC02147.JPG

    I flipped the part in the lathe and the machined out the rear boss. I took some very heavy cuts...

    DSC02148.JPG

    Then I bored out the opposite end for the rear crankshaft bearing. (1.125 diameter)

    DSC02151.JPG

    The amount of chips after hogging out this chuck of aluminum was significant.

    DSC02152.JPG

    Then off to the mill (next post in this thread)...
     

    Attached Files:

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  3. Oct 7, 2018 #3

    vederstein

    vederstein

    vederstein

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    After indexing the part into the rotary table, I cut the two faceted sides 90 degrees apart.

    DSC02153.JPG
    DSC02154.JPG
    DSC02155.JPG

    Then on one face, I drilled out the holes to mount the crosshead frame and the milled a pocket for connecting rod clearance.

    DSC02155.JPG DSC02158.JPG

    Rotating the part 180 degrees, I milled out the slots for access to the connecting rod bearing caps.

    DSC02159.JPG

    Rotating to the other face, the same operations were then performed. The operations were offset from the first set though because the 2nd cylinder is offset from the first. Then I drilled and counterbored the holes to mount the front crankshaft bearing housing. Rotating the part 180 degrees to do the same operation to the other side.

    DSC02160.JPG

    With the lathe work in the previous post, this was about 4-1/2 hours of work.

    DSC02161.JPG

    Until next time...

    ...Ved.
     

    Attached Files:

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  4. Oct 13, 2018 #4

    vederstein

    vederstein

    vederstein

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    I could've make the front bearing housing simple, a round disk with a bored center hole. But nope. Let's make it DIFFICULT!!!

    I found a piece of scrap on the shelf. (Not scrap anymore) and after blueing the approximate center, I chucked the part into the four jaw. The I commenced to drill / bore the bearing journal.

    DSC02168.JPG
    DSC02169.JPG
    DSC02170.JPG

    Then I switched the four jaw to the three jaw and made a mandral to slide the bore over. I held the part against the mandral with a live center and a piece of scrap. Then I could commence with turning the outside radius.

    DSC02171.JPG

    DSC02172.JPG

    At this point I could've had a useable part. But this is where I made it difficult: Off to the mill:

    Using my rotary table, I milled the perimeter close to print. It's just for looks and access to oil the connecting rods, so I wasn't super careful on getting the dims exactly right. The result looks pretty good through.

    DSC02175.JPG

    DSC02176.JPG

    DSC02178.JPG

    There's some holes to drill/tap into the ends of the bearing housing, but I'll wait on putting those in because I have my mill set up with the rotary table and I don't want to tear it down when I have more parts there will require the table.

    So that's it for this part.

    I also made some crankshaft components, but they're pieces of stepped roundstock and aren't really interesting.

    ...Ved.
     
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  5. Oct 14, 2018 #5

    vederstein

    vederstein

    vederstein

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    Today I had an apparently successful pour of one of the two cylinders and crossheads:



    ...Ved.
     
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  6. Oct 14, 2018 #6

    vederstein

    vederstein

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    Much of the order of parts has to do with what material I have laying around and not wanting to tear down my rotary table. So on to the eccentrics.

    I had a small piece of 1" diameter 12L14 barstock (perfect for the eccentrics). So first it was facing off the stock then turning the diameter.

    DSC02187.JPG

    Then parting off...

    DSC02188.JPG

    Then the part was flipped and the opposite side cleaned up.

    DSC02186.JPG

    After making a second part and some discs for the eccentric covers, it was off to the mill. The shoulder on the eccentric made it easy to hold in the rotary table. Then it was a matter of drilling / tapping / reaming the part. When I started tapping, it just didn't feel right. I tried a new tap and it was still stiff. I was afraid of breaking the tap so I changed the design for a through bolt and nut design. I may not be a pretty, but the risk was too high.

    DSC02189.JPG DSC02190.JPG DSC02191.JPG

    The Eccentric covers had the same drilling and reaming operations. The only thing noteworthy is that the "teeth" in the rotary table's jaws made it pretty easy to hole the thin disc.

    DSC02192.JPG

    There's a drilling / tapping operation still to be done, but that's for later when the rotary table is torn down.

    DSC02194.JPG
     
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  7. Oct 20, 2018 #7

    vederstein

    vederstein

    vederstein

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    Today I worked on the cylinder heads and piston rod glands. Both are very similar (2.125 dia x .25 thick plates). I had a chunk of 2-1/2" aluminum round form which to make the parts. So I turned the material to the correct diameter then parted off the two cylinder heads.

    DSC02195.JPG DSC02196.JPG

    Then I drilled/reamed the material for the Piston Rod Glands.

    DSC02198.JPG

    The design calls for a .375 x .030 countebore for the O-ring pocket. On other projects I've had variable success with boring tools and endmills.

    A couple of years ago I was visiting a garage sale and the guy was selling old counterboring tools. I purchased the entire box for $20 or something like that. Until now, I've never used them.

    Rummaging through the bag of tools, I found a .375 cutter that worked wonderfully. If anyone can tell me what this tool is actually meant for, I'd appreciate it.

    DSC02199.JPG DSC02200.JPG

    Then I parted off the part. Do this three more times and off to the mill.

    I used my rotary table setup to drill the bolt circles. Unfortunately, I assembled the jaws incorrectly and the first part's bolt circle was jacked. So I re-drilled it. I can use the part in a position on the engine where the error won't be noticeable or impact engine performance, so the part isn't totally ruined. Repeat five more times.

    DSC02201.JPG

    DSC02204.JPG

    And that's enough for the day.

    Next time, machining some aluminum castings I think.

    ...Ved.
     
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  8. Oct 20, 2018 #8

    johnmcc69

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    Looks like some pretty good progress! Nice work!

    John
     
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  9. Oct 21, 2018 #9

    vederstein

    vederstein

    vederstein

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    I'm glad to see that someone is watching. I was wondering if anybody had interest in this thread or if I was documenting for no purpose whatsoever.

    ...Ved.
     
  10. Oct 22, 2018 #10

    reubenT

    reubenT

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    It's nice work. I'm glad someone is still interested in steam engines. I want to make a twin double acting someday, maybe 20 HP in size, and pretty much all in cast iron. (put the charcoal cupola to work) Haven't decided on exact configuration, whether side by side or opposed or V twin. And what kind of valves to use, maybe invent my own style valve. Maybe a modified gridiron type would fit my ideas. One to drive another steam truck with a yarrow boiler. I just love the whole concept of driving around and doing work on firewood power, and blowing off steam.
     
  11. Oct 22, 2018 #11

    vederstein

    vederstein

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    20HP is a big engine. The steam tractors I've seen in that power range typically have a single, double acting piston around 10" diameter. But they ran quite slowly.

    Given a project as you suggest, It would seem prudent to have a smaller, but high speed engine. The pistons pistons should be oriented in such a way to minimize vibration (horizontally opposed, inline at 180 degrees, or something like that). A high speed engine (~2500 rpm) would allow the use of power transmission equipment from automotive sources lessening the issue of the rest of the machine.

    As for valves, again look at automotive technology. Poppets which are well suited to higher speeds would be my first thought. Second thought would be a rotary valve. Third would be a D-valve, but those aren't the most thermally efficient.

    Just a few comments...

    ...Ved.
     
  12. Oct 23, 2018 #12

    reubenT

    reubenT

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    Yah. The old medium size engines usually run around 250 RPM. I've considered many options. Kind of settled on about 5" piston size and maybe 1000 RPM. Direct coupled to transmission of a 4x4 truck. Thought about using poppet valves too. Slide valves don't like much over 200 PSI. If I use slide or rocker valves I like independent intake and exhaust controls. Tied together as in the various forms of D valves it's hard to control inlet cutoff while maintaining full exhaust venting. I have a book full of all manner of creative solutions the steam engineers came up with in the 1800's. The original gridiron valve minimized valve motion but still had intake and exhaust actions tied together. I thought about doing the gridiron with independent control for each end, although it's still a slide valve. Poppet might be better. The truck I just got working has the old Westinghouse high speed engine on it, 2 cy single acting. (600 rpm is high speed when everything else was much slower) I will have to start using it to see how well it pulls the truck. I had it going once and it seemed to drive around on the level OK. If it doesn't climb a hill with a load I will lower the chain ratio to the transmission to give it lower gears. Been busy rebuilding a semi transmission, haven't found time to play with it.

    Now on the original topic here, I've heard that aluminum and steam don't mix very well. But I'm assuming that has to do with wear surfaces in valve and cylinder. I'm assuming everything but cylinder and valves would be fine in Al. Even an aluminum cy would probably be ok with a cast iron or brass liner. I was going to try using an aluminum piston once, since ideally the piston doesn't really bear on the cylinder wall, only the rings do. but didn't get further than collecting the parts for that one. (the Westinghouse engine came along before I put it together, so I used it instead)
     
  13. Oct 23, 2018 #13

    vederstein

    vederstein

    vederstein

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    For what I'm doing, aluminum will be fine. We're talking about an engine meant to last for hours, not even tens of hours before requiring a rebuild. If wear does become an issue, I'll press in a liner and have a slightly smaller piston.

    Your project, requires real thought to those items.

    ...Ved.
     
  14. Oct 24, 2018 #14

    Rickl

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    Have enjoyed your work. Looking forward to your progress.

    Rick
    Sth Australia
     
  15. Oct 28, 2018 #15

    vederstein

    vederstein

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    On to the first cylinder casting.

    I used the nub left over from the casting process to hold the part and then I could center drill the opposite end for a live center. Then I could machine the outside diameter and face off the first end.

    DSC02221.JPG DSC02222.JPG

    I left a bit of material so I count grip on it for machining the opposite end.

    DSC02224.JPG DSC02225.JPG DSC02226.JPG

    I then gripped the part in the lathe chuck via the OD and drilled / bored the cylinder.

    DSC02227.JPG DSC02228.JPG

    Off to the mill. I set the rotary table to zero degrees then eyeballed the steam chest porting face. I then used a long endmill to cut the face 1.75" off the center.

    DSC02229.JPG

    Then I could drill/tap the two flanges. Note that when I flipped the part, I used a dial test indicator to locate the casting square.

    DSC02229.JPG DSC02230.JPG

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    And that's the first cylinder until I tear down the rotary table.

    ...Ved.
     
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  16. Oct 28, 2018 #16

    swarfrat

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    That tool is, indeed, a counterbore without a pilot. Normal usage would have a properly sized pilot in the end to keep the cutting tool aligned with the existing hole.
    Craig
     
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  17. Oct 28, 2018 #17

    vederstein

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    I also tried to machine the first crosshead casting. When I flipped the part, I didn't use a live center to support the end. I should have and will next time...

    (The video is about four minutes. If you want to see all hell break loose, go to time 3:40.)

     
  18. Nov 3, 2018 #18

    vederstein

    vederstein

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    I made another crosshead casting and machined the second part up to the point in the video (prior post) where I screwed up. This time I ensured I used a live center to support the end. I also placed some thin brass between the casting and the jaws to protect the machined casting finish. It helped, but I still have some marks on the OD of the surface. :(

    DSC02234.JPG

    Then I could flip the part and drill out for reaming. This is the same 1.000" reamer I used for the Essex Hot Air Engine cooling fin castings. On that engine I had a terrible finish, but I didn't know if it was the material or if the reamer was just plain shitty. Here I had a better finish with far less (but still some) chatter. So I guess my previous bad finish was mostly due to the material, but my setup also can have some blame.


    DSC02237.JPG

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    Next was off to the mill for drilling the holes in the flanges. This process was similar as on the earlier parts, but here, the clocking of the holes in both flanges is critical.

    DSC02239.JPG

    To do so, I drilled through the clamped (lower flange) in one position.

    DSC02240.JPG

    This allowed me to pin-locate the casting for drilling the opposite side when the part was flipped. (I couldn't drill all the way through in one setup because then I'd be drilling into the chuck jaws in some of the positions.

    DSC02241.JPG

    From there, I stopped for the day except I felt the need to do a dry fit before I machined the 2nd cylinder parts. All holes appeared to line up. Yea!!

    DSC02242.JPG

    That's all for now...

    ...Ved.
     
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  19. Nov 18, 2018 #19

    vederstein

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    I machined one of the connecting rods today. It was surprisingly difficult and my results are serviceable but certainly not where I wanted it to be.

    After squaring the material destined to be the upper and lower ends of the conrod, I drilled/tapped and bolted the two pieces together.

    DSC02254.JPG

    Then I indicated the big end center and drilled/reamed the upper and big end journals.

    DSC02255.JPG DSC02256.JPG DSC02257.JPG DSC02258.JPG

    I shifted the part over in the vise and milled the "neck" down. Then I rotated the part and milled the necked portion the remaining length.

    DSC02259.JPG DSC02261.JPG

    I disassembled the big end and milled it down to the proper thickness (.500")

    DSC02263.JPG

    After a bit of filing, I have a serviceable connecting rod. (Proper length screws will come later).

    DSC02265.JPG

    The description here doesn't fully convey how hard this part was to make, but it's the general idea.

    ...Ved.
     
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  20. Nov 18, 2018 #20

    vederstein

    vederstein

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    Today I also finished up the outer bearing housing. First I located the first threaded hole per the print. Then I installed the bearing in the housing and the block.

    DSC02248.JPG

    With one end secured to the block and a solid shaft going through both bearings, I transferred punched the other end of the bearing housing to locate the thread. I figured is anything was off, this procedure would compensate.

    DSC02249.JPG

    Then I could drill/tap the punched side. The bearings were just a bit loose in their housings, so I reassembled the parts and secured the bearings in the housings with some red loctite.

    ...Ved.
     
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