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Thread: Simple draft and full mold patterns

  1. #171
    motzingg, The Excelsior link is neat, thanks.<br>
    <br>
    I tested the pocket pattern and the plug for the core box. The pocket was a little large, I may have added too much material for the shrink because the gap around the core pattern is excessive, but the fins pulled OK and the exhaust core mated with the core print. This flask is too small for this casting, but it is quick to ram up for these trials. <br>
    <br>
    <img src="http://www.alloyavenue.com/vb/attachment.php?attachmentid=16509&amp;stc=1" border="0" alt="">
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    Last edited by sandcrab; 08-17-2017 at 03:35 AM.
    If you think you can't do it, you're right!

  2. #172
    Moderator DavidF's Avatar
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    OK, another stupid question....But where is the intake??
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  3. #173
    This is only the pocket. It will be cast in the cope. The combustion chamber is in the center and the projection on the right above the exhaust is the intake core. The intake valve, seat, spring and rocker arm are carried in an assembly that locks into the head with a retaining ring. Look back at the previous photos of the pattern for the head and intake pocket. They will be molded in the drag. This is just the start, and the rear head is different as far as the exhaust port angle is concerned.
    If you think you can't do it, you're right!

  4. #174
    @DavidF

    I believe this is an atmospheric valve engine, the pushrod drives the exhaust open and closed from a single cam, and the intake valve opens automatically on a light spring to draw air through the carburetor on the down-stroke which is not the power stroke. Like a hit-and-miss only without the governor mechanism so it fires every revolution.


    Sandcrab, do you do a plaster test-pour the way BobS has shown in pictures, or do you just measure/eyeball the cavity? I think i need to build a small molding flask for exactly the purpose you are describing here- less overburden that you need to pack, move and worry about. I naturally assumed my first patterns would pull right out of the sand and work perfectly on the first try, and I have found that to not be the case, ha ha!

  5. #175
    Splendid work Sandcrab.
    I found that trying to find what I need and then make it work with what I have, is more trouble than designing what I want and doing it.
    me

    "Quick decisions are unsafe decisions."
    Sophocles

  6. #176
    I moved this project down to "1914 Indian heads". Moar pictures.
    If you think you can't do it, you're right!

  7. #177
    I'm back working on the blower pattern. I started with a core print to support the cores and then made a removable insert to form the fins on the base and reduce the amount of material there. The inlet and outlet stack on the insert so the complete core can be inverted in the mold. I used linseed oil bonded core sand and spent a day baking up a pair. The first pour had a little drop where the core touched at the end, but it gives me a blank to start machining the bores and deciding on the rotor shape.
    Pattern and core ready to be placed.
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    Last edited by sandcrab; 08-25-2017 at 02:22 AM.
    If you think you can't do it, you're right!

  8. #178
    Good to see you are still at it.

    Donk
    Needs must while the devil rides.

  9. #179
    Moderator DavidF's Avatar
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    That is going to be sweet!!
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  10. #180
    Poured the rear plate. I added dogs so I would be able to machine it without having to make a fixture. I did make a fixture to hold the blower in the vertical slide for the line boring.
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    If you think you can't do it, you're right!

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