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Thread: Atlantic Make and Break Fabrication Project @MIT

  1. #141
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Continuing to chip away at the Atlantic. I have one student working on it with support from lab staff Bill.

    Boring out the connecting rod main (it gets babbited):



    Couldn't resist putting components together.



    Machined base. Still needs flash ground out and babbiting, but otherwise done:



    Next up is a new set of patterns for the upper base. That's an interesting part and we're uncertain how it was originally done, but I have a plan. With the upper base, we can pour the bearings and hoping this can get done by February.

  2. #142
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Peter Kinley came to town and brought the records book for the M&B engines - customers, serial numbers, configuration, etc. Really cool. It looks to cover all engines through 1969. Note the tabs for the various horsepower engines.



    Also, our student, Tom, who is now a grad student here, continues to work on the piston when taking a break from more heady researchy things. Happy to have him!


  3. #143
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Very cool!

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  4. #144
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Back in the saddle (sort of) after an 18 month hiatus from campus. Tough to pour iron on zoom.

    After shaking out cobwebs and going through the class storage area, we found our material and I have a student who will dive into the manifold. This class is now totally out of sequence and we've lost the continuity of our rotating bench of juniors and seniors, so this activity is now a volunteer side activity for our students - at least through January.
    The manifold is actually a little bugger of a part with its cores, but we now have a strategy of which I'm reasonably optimistic. Basically, we ought to pour this part vertically. To facilitate this, we made a three part flask - a standard cope and drag, but with a bottom that allows us to add proper runners and gates. This arrangement should make filling the internal passages much easier. We'll see.






  5. #145
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Good to see it progressing!
    Thank's for keeping us in the loop

  6. #146
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Excited to see this thread/work come back!

  7. #147
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Yes! Great to see you up and going again.

  8. #148
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    setting up the piston for the wrist pin




    There were two versions of the wrist pin. One was to bush the wrist pin holes and clamp the pin itself onto the bronze connecting rod. The other was to set screw the wrist pin to the piston's internal bosses (an approach to which I'm allergic). In the latter, the connecting rod rotates on the pin. We decided to go with clamping the pin to the rod, but no bush. That is, we have a CRS pin clamped by the connecting rod and rotating in the cast iron hole. We'll see how it goes. We can always bush later.








  9. #149
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Beautiful!!!

  10. #150
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Beautiful work! (I want to build something now...)
    Your students are getting great experience, which they will remember for a lifetime.

    Is that fixture for the piston Delrin and how does the wrist pin get lubrication?

    (Engines that use a connecting rod pinch bolt (typically) use a groove or notch in the wrist pin for the pinch bolt itself to "key" the pin and prevent said pin from ever contacting the cylinder walls... If you have seen the damage from a wrist pin dragging on the cylinder you will know why, it is ugly. Pinch bolts are notoriously unreliable in that application and often safety wired)

  11. #151
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    That's a serious big chunk of cast iron to be hurtling up and down a bore - I didn't realise how big until I saw the pics above. Looking at the big-end of the con rod, I can't help but think that the little hinge pin looks small, but I guess it never really sees much load if this is a two stroke.

    Pete
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  12. #152
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Quote Originally Posted by Canoeyawl View Post
    Is that fixture for the piston Delrin and how does the wrist pin get lubrication?
    Thanks! The fixture is delrin - we have buckets of it for our classes.
    Good question about lubrication. There were no provisions in the drawings! I am tempted to drill a couple holes in the inner piston bosses. I'm open to suggestions.

    Interesting comment about the groove and the pinch bolt. Kind of like a tailstock lock. I get it. Yeah, there are no details in the drawings about this, but the pinch bolt is moused with wire. I'll consider a way to lock the pin laterally.

  13. #153
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Quote Originally Posted by epoxyboy View Post
    That's a serious big chunk of cast iron to be hurtling up and down a bore - I didn't realise how big until I saw the pics above. Looking at the big-end of the con rod, I can't help but think that the little hinge pin looks small, but I guess it never really sees much load if this is a two stroke.

    Pete
    The pin diameter is to the print, though we put in a shorter pin just for machining the rod's faces. Hate to whack it with our precious shell mill.
    It is a 4hp two stroke, so we're running with that.

    The journal end will be babbitted and its bolt moused like the clamp bolt at the wrist pin.

    Correction: I just looked at the print. The bolt at the crankshaft end will be longer than what we (temporarily) used and will have a castle lock nut and cotter pin.
    Last edited by DoctorB; 09-26-2021 at 09:32 PM.

  14. #154
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    I put a 5hp Atlantic (NOS) in a boat (Danish Seine Boat). Talking to a man from the Lunenburg Foundry, he said the 5hp is more like 18hp in reality.

  15. #155
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Quote Originally Posted by Thad View Post
    I put a 5hp Atlantic (NOS) in a boat (Danish Seine Boat). Talking to a man from the Lunenburg Foundry, he said the 5hp is more like 18hp in reality.
    It took me a sec to realize you were saying "New Old Stock" rather than "Nitrous Oxide". I was briefly thinking "Holy cow!!" You were, right?

  16. #156
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    New Old Stock, yes.

  17. #157
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Quote Originally Posted by Thad View Post
    New Old Stock, yes.
    Nitrous would be amazing though.

  18. #158
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Third attempt at the manifold. First vertical pour. We shake it out on Friday. For now its a wrapped present under the tree.


    You're looking at the upside-down mould with its bottom removed. We have a two-part cope (left and right side), and a single piece drag. Runners were carved in the drag on either side of the two-part-cope's parting line. Had we done the cores differently, we could have easily have a runner in the parting plane with vertical gates. The core was made in March 2020, that crazy week we evacuated our students. It is pretty well cured.





    First pour of this academic year. 30# and uneventful - just as we like it. It was fun to wake up the equipment and remind ourselves how this stuff worked. "Where'd I put those gloves?" "You have a thermocouple?" "Where's the refractory? "Where's the sodium silicate? "Is the chainfall working?" "Where's the sand?" We took our time and got our bearings. It was like being reunited with the dusty Millennium Falcon.

  19. #159
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Good question about lubrication. There were no provisions in the drawings! I am tempted to drill a couple holes in the inner piston bosses. I'm open to suggestions.
    Are there oil drain holes from the ring grooves? If so, perhaps drill one to the wrist pin boss/bore. Or does that bottom ring act as oil control, so this wouldn't work?

    Depending on splash lubrication that deep into the piston looks a bit iffy to me.

    And to prevent the pin from moving laterally: teflon buttons at the ends of the wrist pin are sometimes used.

  20. #160
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Quote Originally Posted by robm View Post
    Are there oil drain holes from the ring grooves? If so, perhaps drill one to the wrist pin boss/bore. Or does that bottom ring act as oil control, so this wouldn't work?

    Depending on splash lubrication that deep into the piston looks a bit iffy to me.

    And to prevent the pin from moving laterally: teflon buttons at the ends of the wrist pin are sometimes used.
    It's a two stroke, so the lubricating oil is mixed with the fuel - there is no sump or splashing oil or oil control ring.
    The closest thing to this that I've owned was a 1950's Daimler-Steyr-Puch scooter. That had circlips to retain the wrist pin, and a bronze bushing in the con rod.
    There were about 5 1/16" holes spaced around maybe 90 of arc on the con rod, and a slit cut around the bushing that lined up with the holes to get some oil into the middle of the pin. If the wear on the pin and bushing were anything to go by, it wasn't a hugely effective system. 150cc, 5hp - one of these ugly beasts FWIW
    Puch-1959-Scooter.jpg

    Pete
    I have one troll on ignore

  21. #161
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    With a fixed wrist pin the only thing I can come up with is a hole right through each boss on the piston to allow lubrication to enter top and bottom.
    A healthy chamfer or slot won't hurt anything and would act as a funnel although the upper one may have to be cut by hand or with a sexy cutter with a removable head. I dream these things up while I'm sleeping...

    (I do know that many/most of these old slow turning engines suffer from wrist pin to piston lubrication)
    A chamfer on the inside of the piston wrist pin bore might encourage a bit of mix in there ?

  22. #162
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    Default Re: Atlantic Make and Break Fabrication Project @MIT

    Nice scooter!
    For lubrication, we'll drill some holes in the piston bosses. Other than that, we'll stick to the prints - it worked for Lunenburg, it'll work for us. Plus, we're not exactly running rum downeast.

    Here we are unwrapping our little box. Turned out pretty good. Some grinding and machining is next.








    Internal passages look good:




    There's some swell and a couple little defects from sand collapsing. But nothing a little welding can't solve. I may weld up a steel flask similar to the original cylinder flask from Lunenburg. It will be simpler to pack and still be a vertical pour - which I think is so important for this type of part. Our apprentice, Chiaki, is doing this on a volunteer basis. I'll post as the finish work progresses.

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