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Thread: Helping Remake a 100 Year Old Engine out of Grey Iron

  1. #1

    Helping Remake a 100 Year Old Engine out of Grey Iron

    I'm working with a guy that will be CNC machining a cylinder head for a 100 year old engine. My part of the work is scanning and modeling the engine. Future videos will be the printing of the mold and CNC cutting the heads.


  2. #2
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    Nice toys you have to play with. Especially that scanning arm look forward to the next installment.

  3. #3
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    One of the things I have discovered about old engines (the one I have measured that I actually had the original plans for) is that the castings were not all that accurate.

    So while scanning an old engine block down to the 1/1000 th of an inch or so will give you an accurate scan of the casting, there can be shifts and offsets in the cores, bosses offset slightly from where they should be to center bolt holes on the boss, centerlines not consistent from duplicate items, etc.

    I find it better to try to capture the original geometry if possible by hand measuring, and then entering consistent geometry into the 3D program.
    I understand that scanning an object saves a lot of time, but 3D work is not that time consuming once you get the hang of it.

    And for patterns, I prefer to make them from wood or steel, but again 3D printing can save a lot of time if you have access to the equipment.
    Once you get good at pattern making, then making patterns by hand is not very time consuming either.

    And if you make your own patterns (correctly), then you have a much better chance of getting consistent wall thicknesses at water jackets and passages.
    On the other hand, if you make your patterns poorly (I have seen more than a few done poorly), then you end up with square corners without fillets, and sections that are too thin due to offset cores and such.
    These defects show up when a casting is sectioned, and also sometime show up when you start machining the casting.

    And I highly recommend bound sand for molds and cores.
    You can get very accurate work with bound sand.
    The resin-based binders work best with iron.

    Edit:
    Here is the website of a guy in germany who is casting a remake of an old german marine engine in cast iron.
    His photos show sections of the block.
    He uses the bound sand for the molds. Looks like he used sodium silicate, not the resin-based binder. If you use the ss type with a catalyst, then you don't need the CO2 to harden it.
    http://www.steamboating.de/kaiser/st...gine-03-10.php
    Last edited by cjcaster; 07-08-2017 at 06:30 AM.

  4. #4
    Moderator DavidF's Avatar
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    The triangle count on that scan would certainly crash my computer, I've dealt with a couple and it wasn't fun at all. That is a very cool project you have gotten yourself into. Looking forward to the next installment......
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

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