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  1. #21
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    Thanos:

    The setup went like this....
    First setup the case as far from the machine column as practical.
    Align the case using the crank as the reference , making the axis of the crank dead parallel with the
    horizontal spindle.

    Indicate to the center of the crank using short tooling.
    Move the position of the spindle to reflect the factory center to center distance from the crank....Average the vertical height using the opposite fan shaft bores and the crank bore to
    project the height of the counter shaft bore...the side to side location as stated is taken from a factory drawings (lucky to have this)

    Use short tooling to true up the rear housing bore, face the register surfaces both inside and out for the flanges of the bearing carrier. Set control registers to zero....

    Remove short tooling, fit long bar. Indicate as shown using the just finished bore as a datum.
    Note difference in position from first dial up and bore with short tooling.
    Calculate droop of bar using the change in position to indicate true, proportion for the additional length of the bar, move to make that correction and set the registers to zero.

    Bore inner housings.....Have beer....
    Cheers Ross

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  3. #22
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    Do you do anything to compensate for the indicator possibly reading differently right side up vs upside down?

  4. #23
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    In this case i don't...use the same indicator (Interapid) so i believe the error is balanced between the short and long setup.
    Have the same issues with the line boring machine setting the bar....The interapid indicators are pretty good on the gravity change aspect...
    Cheers Ross

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  6. #24
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    Quote Originally Posted by AlfaGTA View Post
    .... Indicate as shown using the just finished bore as a datum.
    Note difference in position from first dial up and bore with short tooling.
    Calculate droop of bar using the change in position to indicate true, proportion for the additional length of the bar, move to make that correction and set the registers to zero.
    ...
    Many thanks for that! Will try to keep it in mind!

    BR,
    Thanos

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    How precise is spindle axis movement ? I mean if you put test mandrel to collet, dial indicator on table and move axis in and out.

  8. #26
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    I always have loved your posts, Ross... So much to learn there!

    I have to say that you have nerves of steel though. I think I'd be having a heart attack on each and every one of those revolutions to cut... Let's see.... 60 heart attacks a minute (60RPM) times whatever.... I'm pretty sure I'd be dead.

    I'm kind of stunned that it all worked out so well, especially since you had to shorten the bar at some point, I assume. but doing this would change the sag. which would require a change in the cutter offset or you'd have a different diameter. It must have been a pain to get that perfect.... Or maybe I'm missing something.

    Alan

  9. #27
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    Posted this some time back. Thought some might be interested in the short update.
    Entire lower end was finished for all machine work. Bearings fitted and all clearances checked.
    Rods assembled with new OS bearings (made for this job) all clearances checked.
    Crank assembled and end thrust set. Crank checked for freedom of rotation...

    Job sent to Porsche America (LA) for final assembly and run in...
    Finished engine on Dyno ready for test running...awaiting performance reports.



    Cheers Ross

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  11. #28
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    Ross, did you end up using the autocollimator for any portion of the alignment?

  12. #29
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    Dave:
    No I did not use any optical alignment . Stuck with things i felt more comfortable with.
    Did all alignments mechanically. Test bars, indicators plus purpose built fixturing....

    An autocollimator would have been a good way to get things true, but i did not feel good about devising a good method to employ the instrument.
    Actually did the alignment for the main boring three times....First go,the derived location of the boring bar relative to the front main housing bore was far enough different it made me suspect my approach.
    Changed my method and did the setup again with similar results...Did it a third way and when the results repeated i figured that i had it properly aligned....Just wanted to be sure.

    Cheers Ross

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  14. #30
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    "Trust, but verify"...
    Thanks for sharing this with us.

  15. #31
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    Default jack screws

    Ross
    any chance you would know maker of leveling screws in Porsche dyno cell?
    Attached Thumbnails Attached Thumbnails 9879hui.jpg   98yh.jpg  

  16. #32
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    Sorry ,no clue, but i would wager that they are German.....
    Cheers Ross

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