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Thread: Herreshoff Steam Engine Fabrication @MIT

  1. #36
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by kbowen View Post
    Years ago I read in a biography that Herreshoff was already inventing his own valve opening curves before going to MIT and astounded his classmates by commenting that he had already used one of the curves that the Professor was discussing. True / False?
    I also have a question, we're these splash pan lubrication on the cranks, or pressure with reuse, or pressure one-shot? I remember as late as the early 60's the Kahlenberg diesels on the Great Lakes were one-shot systems and left an oil slick whenever they pumped the bilge.
    Ken
    Regarding the valves and MIT, I asked Kurt (Hart Nautical Museum) and this was his reply:
    Like many times, story is partially true.

    A detailed handwritten account of this is in the minutes of the MIT Society for the Arts in MIT archives. The minutes recount that NGH demonstrated some sort of rotary valve at a formal presentation of a Society meeting. This was a sort of adult education forum early in MIT history. They had some very big names and it seems quite unusual for a student to be a presenter. Story L.F. Herreshoff tells in his book is that N.G. showed his professor a curve he had used to design a valve for an engine (LFH says curve used for valve settings for a rotary engine somewhat like small model airplane engines much later and that he was 16 at the time). Apparently, the analytical geometry professor was somewhat amazed because curves were not used for that purpose then and invited NGH to bring the engine and demonstrate for MIT Society of Arts meeting, which was attended by President Barton Rogers!

    Kurt has the written meeting minutes, and when I have time I may try to decipher the technical information.

    Re: lubrication. I have been a little perplexed by this myself. The base of this particular engine has an open bottom, so no sump or splash. The upper halves of the main journals do seem to have a built in reservoir with holes through the shell to the babbitt. It looks like it would make a mess, and I'm not convinced my understanding is correct.

  2. #37
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by DoctorB View Post
    Re: lubrication. I have been a little perplexed by this myself. The base of this particular engine has an open bottom, so no sump or splash. The upper halves of the main journals do seem to have a built in reservoir with holes through the shell to the babbitt. It looks like it would make a mess, and I'm not convinced my understanding is correct.
    [/FONT]
    The engines with unenclosed cranks always seem to have open base bottoms. Drip pans are installed separately beneath the engines. There's a reason the lowest rate in the engine room just below the "oiler" is the "wiper," or so it would seem.

  3. #38
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Thanks Bob - great piece of information. Funny you mention the oiler. One of our techs was just talking about the oiler position at the MIT power plant.

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Now that I have photobucket out of my life, I can start getting caught up on posting. Here's a photo-synopsis of the cylinder:

    CAD was shown from post 24, and I'm reposting the cylinder patterns and core boxes:

    Patterns being CNC'd. This is the first adaptive tool path for fast material removal.


    After a few more toolpaths, the final result:



    Coreboxes using the same CNC method:


    I'm particularly fond of the way Colleen jigsaw puzzled the core box for the cavity that connects the valve cylinder to the power cylindebr />
    Last edited by DoctorB; 03-13-2018 at 11:35 AM.

  5. #40
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    more...




    Last edited by DoctorB; 03-13-2018 at 11:46 AM.

  6. #41
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    packing the flask and placing the core:





    and voila:


    We only run the program in the spring, but I have to complete this engine by end of May, so some the staff here and I are going to do work on it ourselves along with one of my students. There will be plenty for the students to do once the course starts up again. I'll take some pics of the machined cylinder later this week. There are some defects on the the flange, and other places here and there, but they seem mainly cosmetic and some grinding and brazing will clean things up. We already bored the two cylinders and faced the top and bottom. There were no voids to speak of. So far so good.
    Last edited by DoctorB; 03-13-2018 at 11:51 AM.

  7. #42
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Before one of fall classes gets into full swing, we thought we'd take a stab at finishing some parts. The cylinder is now "done", awaiting honing, filling some areas, and grinding and filing casting artifacts.
    After facing and boring most of the way, Bill made a fixture to locate the bores. Then he flipped the part over and completed them from the other side. check out the tap handle for the 1" NPT steam inlet.
    Notice the chatter marks from the long boring bar. We'll address that later.




    Last edited by DoctorB; 03-13-2018 at 11:54 AM.

  8. #43
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    DoctorB, how do you get started with the facing on a rough casting? I've always been curious how that works, without any clean datum points to begin with.

    Pete
    Don't underestimate the power of stupid people in large numbers!

  9. #44
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by epoxyboy View Post
    DoctorB, how do you get started with the facing on a rough casting? I've always been curious how that works, without any clean datum points to begin with.

    Pete
    Figuring out "where to start" is sometimes a head-scratcher. The decision largely depends on the relationship among the machined features. In our case, the relative location of the bores was important, as was perpendicularity with the flange and position of the bolt pattern. We simply hand ground enough of the flash and crap on one face - enough for the cylinder to stand upright without wobbling and pointing vertically (measured with a square) - and clamped it to the mill. Then we faced the top, removing a minimum amount of material, establishing a datum. Once we had this datum, the part was flipped over again, and fully faced the flange, bored the cylinders, and drilled the bolt pattern. Flip and repeat.

    No doubt, raw castings start as blobs. For a one-off like this, we don't worry about fixtures. We size it up, shrug our shoulders, and go for it.

  10. #45
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Anyone have any great ideas or experience related to forging connecting rods? Our hammer isn't large enough to die forge the whole rod.

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Herreshoff had the advantage of having his laptop located between his ears! The man was amazing in his ability to visualize that which was needed without a calculator or drafting table. When we first started working on "Vapor", LFH was still alive. He confessed to me, during a phone conversation, that his father was the only person who could answer some of the questions we had about the valving. What an amazing project you people at MIT have taken on! Bravo! "Vapors" crank is splash lubed.
    jay
    Last edited by Jay Greer; 10-12-2017 at 11:13 AM.

  12. #47
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Core box and patterns for the exhaust cylinder are ready. We might pour tomorrow.






    Using removable end plates makes removal of the core easier. I ran the piece through the table saw with a 1 1/2 degree blade angle to get the necessary draft. It also, of course, matches the draft of the pattern's core print. The are MDO - super smooth and flat.

  13. #48
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Here's our first attempt at packing the flask for the exhaust cylinder. I like how the runners connect to the flanges, but realized that it would be hard to vent the core because the sprue is too close to the core print at the steam exhaust flange. So rather than continue, executive decision was made to repack and move the sprue to other side of the cylinder.


    Second packing. The sprue was moved to the far side of the cylinder (bottom right), to permit venting of all three core prints. Notice the tiny vent holes on the cope. We've learned that this is essential and have developed this habit (we do it with welding rod) - no reason not to vent. Our friends at Lunenburg Foundry turned us on to generous venting.








    Notice the "S" mark for sprue. Do this to avoid pouring into the core vents - don't ask how I know.

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Fascinating to watch you progress!
    Jay

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Jay Greer View Post
    Fascinating to watch you progress!
    Jay
    Yes, indeed!
    There is nothing quite as permanent as a good temporary repair.

  16. #51
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Thank you for posting...fascinating stuff!

  17. #52
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    I busted out the exhaust cylinder from the flask and ran it over to our friends at MIT Central Machine to clean it up and fill some voids at the flanges. It seems that the lowest part of the mold is a great collector of crap, creating pits and voids. Instead of recasting the part, central machine welded in some filler, ground the excess, and generally cleaned things up. Moving forward, we're going to make better wells near the sprue and runners and may even add wells at the lowest-most areas of the molds, in the areas near flanges, for instance.

    One awesome artifact is that the core print leaked and iron filled the core vent, hence that weird internal tee thing - the part that makes the cylinder look like it's throwing up (or worse). I hate to cut it out because it's such a great teaching piece. Notice the machining marks from the pattern - those are residual marks from a scalloping operation using a 3/16 ball end mill. We'll finish machine the part in the lab - facing the flanges and adding a bolt pattern to the exhaust port...and cutting out that tongue thing.







    Here's a money shot of the cleaned up main cylinder. Notice the oops on the bottom threaded hole. No big deal.


  18. #53
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Next up: One of our rising seniors makes the column and I'll make the bed plate.

  19. #54
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Happy Holidays everyone.
    Below is the model of the "column". This is one of two parts that support the cylinders, and the bearing surface for the connecting rods' linear bearings. You can see the part in context in the first post.



    There is an interesting story to this part (so says the nerd). The original part drawing shows a web that runs the length of the front of the column, making the column an I beam, rather than the T section shown above. When we made the pattern, it seemed that it would be difficult to remove the part from the packed sand. We nonetheless packed a flask to see what would happen. Indeed, the sand broke rather easily.




    We could have increased the draft angle, and tried again, but when we looked closely at the assembly drawing (that was drawn a week after the part drawing) we noticed the drawing showed a T-section instead. We went to the archives and saw similar T-section columns on a few other engines. Long story short, we ran with that knowing it would be easier to cast. New pattern below:



    The packing was certainly easier.

    Last edited by DoctorB; 12-30-2017 at 05:24 PM.

  20. #55
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Very nice! I’m looking forward to seeing the pour.

    It is interesting the way the part doesn’t match the design.

  21. #56
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    We found the discrepancy interesting too - it's all part of the story, and the type of technical-sleuthing students remember.
    The pour was good - almost too good. I hope the student, Elizabeth (Bibit), doesn't think they're all this easy. Notice the far-side riser and vents running down the length of the column. I see no reason not to be generous with venting.



    The setup for machining was a bit cumbersome, but for a one-off was fine. The strategy was to get two parallel edges on the bearing feature, and a perpendicular edge on the upper flange. Then, we could fixture the part using a vice with large jaws (seen below), and the holes and other facing becomes standard practice. (Though we did a couple of foo-bars, nonetheless).




    In retrospect, instead of using the level on the casting, we should have used two height indicators at the centerline positions of the top and bottom mounting flanges (right and left flanges, as photographed below). We ended up with a little tilt, which meant the mounting holes were off-center approximately 0.100" relative to the flange. It's really just aesthetic - the relative hole locations on the flanges and parallelism and perpendicularity of the bearing surface are all spot on (I think).



    Then we faced it with a new kick-ass shell mill.






    (Those threads on the bottom holes were a misinterpretation and got drilled out, no problem)
    Last edited by DoctorB; 12-30-2017 at 06:11 PM.

  22. #57
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Still at it, though remember that exhaust cylinder? Well, it didn't turn out that great after all. In retrospect, I should have added risers to the end flanges. Oh well, we're re-pouring this one in a week or so. The great news is I have nine seniors cranking away on parts. The stuffing boxes are being turned, the connecting rods are getting cut on the waterjet and finish machined, and a number of parts are in the queue for casting over the next several weeks. Patterns and coreboxes are rolling off the production floor.


  23. #58
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    While I'm here, can someone tell me the purpose of that funky little box-like structure on top of the bearing shells?
    (Plans courtesy MIT Museum, used with permission)

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by DoctorB View Post
    Jay, we'll be watching the Vapor project. I'm curious to know how Chris make the crankshaft.

    Here's a new pattern rolling off our production line. It is the bottom half of the top cap. This is the second of three toolpaths.


    There's a little handwork to do - some toolpath figments were overlooked, but the material sands very easily.
    Interesting project, good luck. This looks like around 12-15 lbs urethane. Nice material, we using it often.
    Maybe the picture was taken too early in the process, but if you parallel finish / radial finish it, going up-downhill with around 14-16 % step-over, you almost don't have to sand it. But - as I said, maybe you already did, the picture was from before.

    All the best
    T.
    Every time you say the word "just", you've just doubled my work.(me)

  25. #60
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    I believe those “little boxes” will be drilled down through the bottom, and through the babbet, and are lubrication reservoirs (grease/oil). My 1905 bandsaw has similar reservoirs on its main bearings.

  26. #61
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Very impressive work !.
    We have just moved to a new area , and I've found that the young bloke living behind us , and his family are right in to steam.
    They have steam launches , traction engines , and he is making from scratch a small traction engine for his young children to drive.
    I've seen it , it is almost finished , painting stage , and only about 8 ft long.
    Again , very impressive work.
    Regards Rob J.

  27. #62
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by nedL View Post
    I believe those “little boxes” will be drilled down through the bottom, and through the babbet, and are lubrication reservoirs (grease/oil). My 1905 bandsaw has similar reservoirs on its main bearings.
    Thanks Ned.
    I was also thinking the shell itself was drilled through to receive babbet. I wuoldn't know how to fill it otherwise.
    We were figuring something along those lines, but were stumped by two things:
    1. Why would the through holes for oil be at that elevation?
    2. Casting the thin wall seems difficult - they are only 0.09" thick and quite tall. (I typically use 0.125" welding rod to punch vent holes through the highest points of the cavity, which would be the rim of the walls.)

    Now that I'm thinking about it, does the extra babbet fill most of that cavity up to the oil holes +/- ?

  28. #63
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    The "Vapor" project has sadly slowed down due to the owner's having health problems. The boat is ready but the engine is not.
    I believe Chris McMullen machined his crank out of a solid billet.
    Keep up the good work, we are all fascinated!
    Jay

  29. #64
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Sorry to hear that Jay. Once we are done with this engine, I have the Atlantic Make & Break to finish. Perhaps we can help Vapor's engine along somehow. Keep me posted.

    Our crank is being made of Aluminum Bronze (C95400), mostly pieced together. The eccentric will be turned off center relative to the aft centered shaft as one piece. Everything will be interference fit and cross pinned. Should be fun. We're doing it on our Hardinge toolroom lathe, which is an absolute joy to use.

  30. #65
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by nedL View Post
    I believe those “little boxes” will be drilled down through the bottom, and through the babbet, and are lubrication reservoirs (grease/oil). My 1905 bandsaw has similar reservoirs on its main bearings.
    Common to "old" engines these often have a round felt wick leading into the bearing journal itself and felt waste in the "box". A small hinged iron lid was also common. (Many machine tools were fitted out in a similar manner with capillary action through wicks the only lubrication supply)

    Last edited by Canoeyawl; 02-24-2018 at 02:55 PM.

  31. #66
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Awesome, thanks.
    Our plan is to leave the pattern solid in the box area and machine it out. I just think we're asking for problems with incomplete filling and bubbles for that thin walled section.

  32. #67
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    1. Why would the through holes for oil be at that elevation?
    .........

    I saw that and thought it very odd too.
    I like your idea of cast it solid, then deal with it.

  33. #68
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Canoeyawl View Post
    Common to "old" engines these often have a round felt wick leading into the bearing journal itself and felt waste in the "box". A small hinged iron lid was also common. (Many machine tools were fitted out in a similar manner with capillary action through wicks the only lubrication supply)
    Ahhh - a wick! Makes sense that the holes are now longer. Thanks.

  34. #69
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by DoctorB View Post
    Sorry to hear that Jay. Once we are done with this engine, I have the Atlantic Make & Break to finish. Perhaps we can help Vapor's engine along somehow. Keep me posted.

    Our crank is being made of Aluminum Bronze (C95400), mostly pieced together. The eccentric will be turned off center relative to the aft centered shaft as one piece. Everything will be interference fit and cross pinned. Should be fun. We're doing it on our Hardinge toolroom lathe, which is an absolute joy to use.
    Well Dr. B thank you for the offer to help! I look forward to getting "Vapor" operational in the foreseeable future! Intersting to see that your chose aluminum BZ for the crank! Tough stuff indeed! That Hardinge Lathe is a good work horse for the project. I have, recently become the steward of a Rivett 608 precistion bench lathe which is identical to the one that was used by NG Hereshoff.
    I really enjoy your photos and postings on your project!
    Jay

  35. #70
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Jay Greer View Post
    Well Dr. B thank you for the offer to help! I look forward to getting "Vapor" operational in the foreseeable future! Intersting to see that your chose aluminum BZ for the crank! Tough stuff indeed! That Hardinge Lathe is a good work horse for the project. I have, recently become the steward of a Rivett 608 precistion bench lathe which is identical to the one that was used by NG Hereshoff.
    I really enjoy your photos and postings on your project!
    Jay
    Al-Bz was called out in the print for the crank. It's the most specific material callout in the plans. Most other materials just say "bronze", "iron", "steel". 954 has 60% machinability, so we should be okay, though we will have an interrupted cut starting the eccentric. I'm not particularly looking forward to that thwump-thwump-thwump-thwump sound all day. We will start with HSS tool and maybe switch to carbide inserts once we're past the interrupted business.
    (At least it's not 863 Mg-Bz).

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