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Thread: Herreshoff Steam Engine Fabrication @MIT

  1. #71
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by DoctorB View Post
    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)
    Wicking is used to reduce contamination, the holes are effectively sealed from debris. It is surprising how little lubrication is needed for a surface film of oil. Often the round felt wick is installed with a tail left in the box sump and the rest of the box filled or stuffed with cotton waste. I have seen the "wicks" bent and captured into a small hand carved longitudinal slot in the bearing to insure oil contact with the shaft.
    I have done a bit of Babbitt work and suspect that these above would be cast from the outboard end. I often make up a shaft or mandrel with a collar to both establish the thrust face and center the shaft, and a sometimes elaborate "Tinkers dam" of "Moistbestos" or fabricated metal to facilitate the pour. As Asbestos is now verboten I have no idea what you would use today.
    A shim stack can be economically and perfectly cut these days with a water jet, .002" brass shim packs are available. These should be in place before the pour, maybe a 1/16" and can be peeled off as needed to adjust the bearing clearance. (old fashioned "steam" cylinder and journal oils are "different" than modern internal combustion engine oil... http://steamenginelube.com/lubeuse.html)

    https://www.mcmaster.com/#shim-stock/=1bq5alg

    High grade hard felt and wicking is also available from McMastebr />
    https://www.mcmaster.com/#felt/=1bq5b6g

    Edit to add; I still have a universal line boring fixture for Babbit main bearings, some hand scrapers, and maybe ten pounds of Babbitt metal...
    (Think Model T Ford, and most other reciprocating engines up to mid 1930's.
    http://www.fordgarage.com/pages/kwikwayinstructions.htm)
    Last edited by Canoeyawl; 02-25-2018 at 03:12 PM.

  2. #72
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Super input Canoeyawl, thanks!
    Regarding babbit - I've never done it. Here's a newbie question for you: Is the babbit poured using the actual crankshaft, or is it common practice to pour over some type of master arbor/shaft ? Making the thrust faces using a test shaft or similar seems way easier than pouring using the real McCoy.
    (I follow you on the shim comments. We did same on the eccentric for the Atlantic ignition system.)

  3. #73
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    It can be done either way and I have done it both ways. But - often the complexity and weight of the original shaft can hinder locating it and pouring around it. (And you hate to risk damaging it!) If you have the tooling to make a temporary shaft and then accurately machine (Line bore) the babbitted assembly to fit, you may choose to use a simple mandrel with shoulders or placed between centers or some other means of "accurately" locating it for the pour. With mandrels and tooling you can cast the caps and block separately by just pouring into the void, dress the flats, chase the oil grooves, then shim and finish it as an assembly. I have a modest machine shop so for me it is often more effective to make up mandrels and fixtures to pour it, then machine, blue, scrape, and assemble (countless times!)
    Today there is much available online, videos and etc., but when I learned the knowledge was handed down to me as a sort of "How clever are you?", but like any casting it is fun and rewarding, usually!
    You are going to want a Vixen file, a chisel for cutting oil grooves and a scraper or two. McMaster has these, or you can make them. Many of these tools are made for the task at hand.
    Perhaps a field trip is in order, there must be a shop doing this work near you...

    The old Linsay Publications book is helpful, there are repops of it.
    Title: Babbitt Bearing Techniques, Publisher: Lindsay Publications,

    and these two...

    http://wiki.vintagemachinery.org/Get...aring_Book.pdf

    http://www.boatregister.net/Library/...dBearing_1.pdf

  4. #74
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    That Magnolia book is a gem.
    The Atlantic M&B crankcase print specifically identifies "magnolia" on their drawing.
    I think the mandrel with retaining caps/dams will make for a much easier job. Our schedule has the bed plate and crankshaft coming together late March. I'll start practice pouring and making jigs in anticipation. We have four bearings to babbitt. The two main bearings of the bed plate, the eccentric rod shells and the power piston rod shells. No time like the present - this ought to be fun.

  5. #75
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    You might want to take a look at these...
    ebay

    edit to add

    https://www.ebay.com/itm/MOUND-TOOLS...EAAOSwL9paZ2Dq
    Last edited by Canoeyawl; 02-27-2018 at 02:18 AM.

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Hi my name is Emily and I am working on the Herreshoff with DoctorB. I'm a senior MechE at MIT and currently I'm working on the bed plate bearing caps for this engine construction.

    Progress so far!
    Patterns and core boxes machined and ready for packing for sand casting. We decided that the top could be milled to accommodate the thin wall when casting.

    Casting came out so well! There was a bit of a scare that it didn't fill completely but it ended up filling up just enough, and being a great quality casting. The surface finish turned out really nice also.

    Moving forward I will be finish machining this part to match the specs in the original Herreshoff drawing! Stay tuned!

  7. #77
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Nice castings Emily! Good work.
    Are you going to line bore these with the foundation?
    If so you may want to do it with cast iron shims representative of the Babbit shims.
    An interupted cut will be a pain...

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    beginner's luck

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    DoctorB, what kind of encouragement is that? LOL
    Question about the wicks used to lubricate. I think the idea is pretty neat, keeps things oiled but keeps dirt out. Why do we no longer lubricate things that way? Automation? More technologically advanced seals so no need? I imagine you'd tend to use up oil that way but without the wick using sealed bearings, you'd not lose any? Just spitballing here.
    If one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours.
    -Henry David Thoreau-

  10. #80
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Opinion; I think wicks are still used with high quality ball bearings like the abec higher classes-$$$. My experience is milling machine, lathe, precision grinders and other accurate spindles are often shielded ball bearings with wick lubrication. Ball bearings don't need much oil until you are using it for cooling, and really precise bearings don't have clearance for grease.

    Capillary action significantly reduces the chance of contamination. The "reservoir" or oil cup is often positioned below the bearing.

  11. #81
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    When I was in school we didn't do anything nearly as cool as this - but then again, I was an EE

    -Steve
    MIT BSEE '86
    1949 Alden Malabar Jr - "Nixie"

    "The greatest enemy of knowledge is not ignorance; it is the illusion of knowledge." - Stephen Hawking

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Canoeyawl View Post
    Are you going to line bore these with the foundation?
    If so you may want to do it with cast iron shims representative of the Babbit shims.
    An interupted cut will be a pain...
    We don't have a line borer, but have considered an offset boring head on the mill, and boring once assembled to the bed (with shims for the reason you mentioned). The annular clearance for the Babbitt, however, is 3/16", so we're hoping to avoid boring altogether. The dimension and surface finish from the resin bonded core seem fine. Any reason to bore if we are babbitting with such a large gap?

  13. #83
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by sejman View Post
    When I was in school we didn't do anything nearly as cool as this - but then again, I was an EE

    -Steve
    MIT BSEE '86
    Mens et Manus (with a side of Cor)

  14. #84
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    No, my thinking was only to establish concentricity, if needed.
    (Do you have a boring and facing head?)

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Canoeyawl View Post
    I have done a bit of Babbitt work and suspect that these above would be cast from the outboard end. I often make up a shaft or mandrel with a collar to both establish the thrust face and center the shaft, and a sometimes elaborate "Tinkers dam" of "Moistbestos" or fabricated metal to facilitate the pour. As Asbestos is now verboten I have no idea what you would use today.
    A shim stack can be economically and perfectly cut these days with a water jet, .002" brass shim packs are available. These should be in place before the pour, maybe a 1/16" and can be peeled off as needed to adjust the bearing clearance. (old fashioned "steam" cylinder and journal oils are "different" than modern internal combustion engine
    Just a suggestion, silicone rubber when cured is ridiculousy heat tolerant, and can be used for molding those little metal war-gaming figurines. If push comes to shove, it might be worth having a play with a tube of silicone RTV, and some molten Babbit metal, to see what happens.

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

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Canoeyawl View Post
    No, my thinking was only to establish concentricity, if needed.
    (Do you have a boring and facing head?)
    Yep, we have boring and facing heads

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by DoctorB View Post
    Yep, we have boring and facing heads
    Excellent!
    (I have an "extra" R-8 Wohlhaupter, and was thinking of a donation. They don't get used very often!)

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Canoeyawl View Post
    Excellent!
    (I have an "extra" R-8 Wohlhaupter, and was thinking of a donation. They don't get used very often!)
    we have a couple of imports and an older Bridgeport head, but not a Wohlhaupter. I'd love to try it. If not for the main bearings, we still have the main connecting rod shells and the eccentric shell - though those are also babbitted.
    We'd be happy to borrow and test drive for a while.
    thanks for considering!

  19. #89
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by DoctorB View Post
    we have a couple of imports and an older Bridgeport head, but not a Wohlhaupter. I'd love to try it. If not for the main bearings, we still have the main connecting rod shells and the eccentric shell - though those are also babbitted.
    We'd be happy to borrow and test drive for a while.
    thanks for considering!
    I wasn't aware that Bridgeport made a facing head.
    Assume your machine is R-8?
    P.M. sent...

  20. #90
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Canoeyawl View Post
    I wasn't aware that Bridgeport made a facing head.
    Assume your machine is R-8?
    P.M. sent...
    R8, yes.

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Hi everyone, I'm Sam - one of the students working on this project. I am making the piston and valve parts and am stumped by some details on Herreshoff's drawings, I wonder if anyone can shed some light. The details are of the valve rings and piston rings.

    Valve Rings
    The valve ring drawings (first and second drawing attached) show a cast iron ring that has been split in three places with what appear to be little bronze clips that, as far as I have figured, are for preloading the ring against the cylinder wall. The cast iron ring, however, is not shown with notches or any other feature to allow the clips to fit in - has anybody seen this detail before or have any idea of what would typically be done?





    Piston Rings
    The only indication of a piston ring detail is the note in the third attached drawing, which refers to a pattern number. It seems strange to me to have a single thick ring (as shown on the drawing) and I do not know how Herreshoff would have split it to assemble it around the piston. I am contemplating straying from the drawing and making two thin rings (similar to gas engine piston rings) that are split by fracturing with a hammer while holding the ring in a vice (as done by Fair Weather Foundry https://youtu.be/dl55OCUol20). The rings would be separated by a small distance and would sit in separate grooves. Thoughts on either this new approach or what Herreshoff might have originally done with the piston rings?




    Thank you!
    Sam

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    I could inspect the rings in the tripple, that we are overhauling for "Vapor", and let you know how they were set up as, they are original at this time.
    Jay

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    [QUOTE=DoctorB;5491293]Super input Canoeyawl, thanks!
    Regarding babbit - I've never done it. Here's a newbie question for you: Is the babbit poured using the actual crankshaft, or is it common practice to pour over some type of master arbor/shaft ? Making the thrust faces using a test shaft or similar seems way easier than pouring using the real McCoy.
    (I follow you on the shim comments. We did same on the eccentric for the Atlantic ignition system.)[/QUOTE

    While any deviation from the original Herreshoff drawings is probably anathema to most everybody, might I be so bold as to suggest that if it is at all possible, consistent with the design, you consider substituting ball bearings for the babbit ones. Sometimes somebody comes along with some new-fangled invention that really does render the older technology obsolete. Ball bearings should substantially reduce your concerns about keeping the babbet bearings lubricated, I'd expect. https://www.timken.com/products/

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    [QUOTE=Bob Cleek;5510290]
    Quote Originally Posted by DoctorB View Post
    Super input Canoeyawl, thanks!
    Regarding babbit - I've never done it. Here's a newbie question for you: Is the babbit poured using the actual crankshaft, or is it common practice to pour over some type of master arbor/shaft ? Making the thrust faces using a test shaft or similar seems way easier than pouring using the real McCoy.
    (I follow you on the shim comments. We did same on the eccentric for the Atlantic ignition system.)[/QUOTE

    While any deviation from the original Herreshoff drawings is probably anathema to most everybody, might I be so bold as to suggest that if it is at all possible, consistent with the design, you consider substituting ball bearings for the babbit ones. Sometimes somebody comes along with some new-fangled invention that really does render the older technology obsolete. Ball bearings should substantially reduce your concerns about keeping the babbet bearings lubricated, I'd expect. https://www.timken.com/products/

    Hang on Bob, let me lift myself back into my chair. Now, what were you suggesting?

    Ahhhh, yes - ball bearings. I totally get it, but on this one, for the time being, we're staying with Babbitt. It's not something the students have encountered, and probably not something most will ever have the chance to try again. (Plus, I've never poured them, and want to give it a try.)

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Jay Greer View Post
    I could inspect the rings in the tripple, that we are overhauling for "Vapor", and let you know how they were set up as, they are original at this time.
    Jay
    Thanks, Jay! That would be a great reference to have.

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Hello,
    I recieved this letter from my friend Chris McMullen of McMullen Wing Co. NZ. Chris has built an entire Herreshoff thirty foot launch plus the Herreshoff engine and boiler. He wanted me to edit this post but I have left it just as it came to me as I feel it is just fine as it is.
    Chris is one of the finest boat builders I have ever had the pleasure of knowing!
    Jay

    Hello Jay
    Tonight, I had some spare time and looked at the wooden boat forum. I knew I have been mentioned on this forum, I am not a member and don’t really want to get world wide exposure to my long winded spare time project. I have a 45 foot wooden classic
    launch to cruise and maintain and that takes a lot of my time. Building the steam launch, boiler and machinery has been a challenge and possibly the most interesting project I have ever done.
    I am interested to read the circulating engine crank shaft was made from aluminium bronze. All the castings on my engine are this material other than the steam cylinders and pistons. These were made from Cast Iron. Nothing has been fabricated.
    My Crank Shaft was cast off a pattern in so called SG iron. It was designed to be made from a steel casting. I chose to use SG Iron as the contraction of this metal is minimal compared with steel or aluminium bronze. The foundry delayed the pour for some reason and the casting is little better than cast iron. Otherwise, it was a good casting and I machined it and fitted the crank to the engine that has been run but not under load. A huge disappointment when I had the metal tested.
    Three more casting were made but all had faults. The three crank casting with overhanging balance weights is very difficult to mould and pour. There is no tolerance! If the casting is too long or too short it simply won’t fit between the two bearing blocks in the engine. The whole design is very compact. NGH signed off the drawings but I am sure they were drawn by his draftsmen based on sketches done by the master. Certainly, the engine was not made for easy manufacture.
    In the latest Funnel Magazine put out by the “Steam Boat Association of Great Britain” There is an very well written article on NG Herreshoff. It comments that his engines look almost as if a brilliant engineer,never having seen any one else’s efforts, had worked out how to build engines him self from scratch.
    I have just had my engine apart to fit the lagging castings. I am ignoring the crank problem for now.
    Jay, you can give JB my address if you wish.
    Cheers
    Chris

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    [QUOTE=DoctorB;5510313]
    Quote Originally Posted by Bob Cleek View Post


    Hang on Bob, let me lift myself back into my chair. Now, what were you suggesting?

    Ahhhh, yes - ball bearings. I totally get it, but on this one, for the time being, we're staying with Babbitt. It's not something the students have encountered, and probably not something most will ever have the chance to try again. (Plus, I've never poured them, and want to give it a try.)
    And, from all reports, not something they'll ever want to try again, although, in all honesty, my experience with pouring them is second-hand and related to Aeromotor windmills. You know, the ones that go "squeak, squeak, squeak" all day long out on the farm! LOL

  28. #98
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Quote Originally Posted by Jay Greer View Post
    Hello,
    I recieved this letter from my friend Chris McMullen of McMullen Wing Co. NZ. Chris has built an entire Herreshoff thirty foot launch plus the Herreshoff engine and boiler. He wanted me to edit this post but I have left it just as it came to me as I feel it is just fine as it is.
    Chris is one of the finest boat builders I have ever had the pleasure of knowing!
    Jay

    Hello Jay
    Tonight, I had some spare time and looked at the wooden boat forum. I knew I have been mentioned on this forum, I am not a member and don’t really want to get world wide exposure to my long winded spare time project. I have a 45 foot wooden classic
    launch to cruise and maintain and that takes a lot of my time. Building the steam launch, boiler and machinery has been a challenge and possibly the most interesting project I have ever done.
    I am interested to read the circulating engine crank shaft was made from aluminium bronze. All the castings on my engine are this material other than the steam cylinders and pistons. These were made from Cast Iron. Nothing has been fabricated.
    My Crank Shaft was cast off a pattern in so called SG iron. It was designed to be made from a steel casting. I chose to use SG Iron as the contraction of this metal is minimal compared with steel or aluminium bronze. The foundry delayed the pour for some reason and the casting is little better than cast iron. Otherwise, it was a good casting and I machined it and fitted the crank to the engine that has been run but not under load. A huge disappointment when I had the metal tested.
    Three more casting were made but all had faults. The three crank casting with overhanging balance weights is very difficult to mould and pour. There is no tolerance! If the casting is too long or too short it simply won’t fit between the two bearing blocks in the engine. The whole design is very compact. NGH signed off the drawings but I am sure they were drawn by his draftsmen based on sketches done by the master. Certainly, the engine was not made for easy manufacture.
    In the latest Funnel Magazine put out by the “Steam Boat Association of Great Britain” There is an very well written article on NG Herreshoff. It comments that his engines look almost as if a brilliant engineer,never having seen any one else’s efforts, had worked out how to build engines him self from scratch.
    I have just had my engine apart to fit the lagging castings. I am ignoring the crank problem for now.
    Jay, you can give JB my address if you wish.
    Cheers
    Chris
    What would it take to get you to share some pictures, Chris? I know, I know, you're a bit of a hermit in Hobbit Land down there, but we'd love to see the progress you've made and promise not to pester you!

  29. #99
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    I will ask him Bob.
    Jay

  30. #100

    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Hello Sam
    I have another drawing of typical Herreshoff piston rings. The rings are cut into three equal segments and notched to fit the bronze keepers. Right or wrong I used phosphor bronze for my rings. Mine are loaded with thin flat spring steel laid in the groove prior to assembly . The rings in my engine are slightly wider. Only yesterday I had the pistons out and could have taken a photo. It's all on the drawing but the notches are an omission.
    The pistons and spring loaded segmented rings are tricky to assemble. I used a hose clamp and shim stock. The rings foul the undercut and steam passage. On my engine they are at the same level. On your engine the undercut is lower so it will be easier. Just wobble the piston and they go in. I note the piston is cast steel. Mine are cast iron. A great project, Pleased I can help. Chris M from New Zealand

  31. #101

    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Hello Bob
    I am not really a hermit but the expectations of others is the worst part of this project. My friend Jay Greer blew my cover some years ago. Sure it has taken a long time but procrastination has helped. When I started there was no internet. No abom79 on youtube. I went to library's and read every old engineering book I could find. As a woodworker, I had to learn to think like an engineer. Not so much machine work but setting up the work to make every thing square.
    There were omissions on the drawings that had me bluffed. Herreshoff did so many things his way. The omissions on the drawings were standard work shop practice, at HMC the fitters and machinists knew what to do or I guess they could ask their Boss. I never had that luxury.
    I think my work is pretty close to how it was done. Does it matter? I guess not but to me it did and I have enjoyed the research and learning to do some seemingly impossible tasks. I have a good workshop but most of my machines are obsolete and I saved them from being scrapped. Some required rebuilding. I am not an expert at anything but I am persistent. I will post some photos on this site. Thank you for your interest. Chris New Zealand.

  32. #102

    Default Re: Herreshoff Steam Engine Fabrication @MIT

    I am aware my Herreshoff Steam Launch Replica has been mentioned on this forum, I am not sure I am a member and never really want to get world wide exposure to my long winded spare time project. I have a 45 foot wooden, eighty year old classic launch to cruise and maintain and that takes a lot of my time.I am interested in what JB and the students are doing. A huge learning curve!
    Re the Babbitt or White metal.
    This was poured round a lined up shaft or a dummy shaft. The metal retained by a special clay. This eliminated the need to line bore the bearings. It is over twenty years since I used the method but it worked. I forget how you achieve a spit bearing. The method is well documented in some old Engineering books.
    Building the Replica Herreshoff Steam Launch, boiler and machinery has been a challenge and possibly the most interesting project I have ever done.
    I was interested to read , (on the forum) the circulating engine crank shaft was specified to be made from aluminium bronze.
    All the castings on my Triple Expansion Engine are this material other than the steam cylinders and pistons. These were made from Cast Iron. Nothing has been fabricated.
    My crank shaft was cast off a pattern in so called SG iron. It was designed to be a steel casting. I chose to use SG Iron as the contraction of this metal is minimal compared with Steel or Aluminium Bronze. The foundry delayed the pour for some reason and I later found the casting is little better than cast iron. A huge disappointment. Prior to having the metal tested, I machined it and fitted the crank to the engine, the engine has been run on steam but not under load.
    Three more casting were made but all had faults.
    The Three Crank casting with overhanging balance weights is very difficult to mould and pour. There is no tolerance! If the casting is too long or too short it simply won’t fit between the two bearing blocks in the engine. The whole design is very compact.
    I have just had my engine apart to fit the lagging castings. I am ignoring the crank problem for now. If I use a different metal it will require a new pattern. Aluminium Bronze is not the easiest metal to cast or machine but a better option than steel.
    Further, to avoid unnecessary correspondences.
    The crank was designed to be cast. I have investigated having it fabricated or machined from a billet. I have a Solid Work drawing. I am not saying it is impossible but any way is make this crank is going to be expensive. In my opinion a casting is still the best option. For those interested, the pattern is really just a core print. There is no room for draft (taper) as on a regular pattern. The crank can never be ground due to the overhanging balance weights and requires specially shaped lathe tools to machine the journals.
    NGH signed off the drawings of my engine but I am sure they were drawn by his draftsmen based on sketches done by the master. Certainly, the engine was not made for economic manufacture.
    In the latest Funnel Magazine put out by the “Steam Boat Association of Great Britain” There is an very well written article on NG Herreshoff. It comments that his engines look almost as if a brilliant engineer,never having seen any one else’s efforts, had worked out how to build engines him self from scratch. Further, compared with British Designs, the light weight Herreshoff engines were designed for fast boats and they would likely have a short but Merry life.



    Chris Auckland New Zealand

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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Welcome aboard Chris!
    Jay

  34. #104
    Join Date
    Jun 2003
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    Central Coast, Ca
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    Default Re: Herreshoff Steam Engine Fabrication @MIT

    I would enjoy seeing the drawing or pictures of that crankshaft...

    I can't imagine how the crank could be originally ground with overhanging counterweights.
    Many years ago I rebuilt a 1921 Packard six that was a fully babbitted 7 main bearing crank with counterweights overhanging each rod journal and I came up against this same issue. Could not grind the journals. It turned out that Packard had bolted the counterweights on, but done it in such a way as to be "invisible". They used shouldered bolts that were an interference fit into the counterweight itself with the heads left proud. (the crankshaft was drilled and tapped parallel to the throw, the weight mounted on a machined flat perpendicular to and at the end of each throw, two bolts per wieght) After grinding and finishing the journals, the weights were attached, the crankshaft with the weights was turned in the lathe, machining the heads of the bolts off while finishing the O.D. of all the counterweights. It was clever, and precise leaving no trace of the join, but what a pain! Removing them to grind the crank was problematic, the weights and bolts had to be destroyed, and recreated. The crankshaft appeared to be made entirely from a steel billet, no trace of forging or casting marks.

  35. #105

    Default Re: Herreshoff Steam Engine Fabrication @MIT

    Hello Canoeyawl
    My point was. Because of the cast balance weights the Herreshoff Crank design could never have been ground by HMC in 1898 or by any one in 2018. If you remove the weights the crank webs are too thin to hold the crank between centres. Be aware the Packard you talk about had seven main bearing. The Herreshoff Engine I am building has three cranks and two bearings.
    I know to some folk, what I am doing is stupid. And they are likely right.
    This project will never make sense to most people.
    In 2018 you can buy an electric or diesel motor to drive this boat for way less than I have spent. I could have employed a company with CNC capability and used ball bearings rather than Babbitt to build the engine. The sense of personal achievement would be missing. And that's the driving force. I am not out to prove anything accept to my self.
    The reason, I have joined this Forum is to help encourage the Engineering Students at MIT.
    Thank you for your interest Chris Auckland New Zealand

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