CNC holes are widening - Page 2
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  1. #21
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    Quote Originally Posted by Mike1974 View Post
    Thanks tom, you covered about every bad situation that can happen, but somehow did not help the OP..??
    So.... the usual?

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  3. #22
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    Quote Originally Posted by J.Caraher View Post
    If you don't mind, please close the thread with a result. So often the search function turns up dead ends since the OP never comes back with the resolution.
    yeah, i was about to do that. thanks for the help.

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    Quote Originally Posted by J.Caraher View Post
    If you don't mind, please close the thread with a result. So often the search function turns up dead ends since the OP never comes back with the resolution.
    how do i close down a thread?

  5. #24
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    Just post what you did to resolve the problem.

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    Good to buy a loop for about $5 to $20.

    Then practice looking at cutter wear lands. in a short you will know what a .002/ .005 /.010 what-ever wear looks like and for certain jobs and materials gauge your sharpness with a quick look..

    Dont bang end mill cutters together ..when dull wrap a slip of paper around and save in size grups to save for the shapening.

    Have a note pad and keep track of how many good holes/parts you get..makes a better you if you know a little about cuttes. Agree things can go hey wire and you don't get the expected number of parts.

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    to the OP
    all great given advice these guys are pro's
    my advice is this
    Aluminum has a high thermal coefficient, in others words, dimensionally it will change rapidly as it heats up.
    take the over sized parts and let them cool , and re verify the bores with a bore gage. calibrated to gage blocks.
    misting like others said is not keeping the tool and part cool enough,
    also surely the is at least a 5x magnifier, look at the tools very close, and switch to a new sharp tool.
    look at the condition of the bore from acceptable parts to the last run, is there any visual smearing , tool marks, or any change.
    re que all tools and change any worn tools, or just let it sit until the owner returns, don't continue to run bad parts.
    he will get pissed , but he will get over that. he won't be happy if you to continue to run bad parts.

    remember to verify critical dimensions after the parts cool.

  8. #27
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    Quote Originally Posted by Mike1974 View Post
    Thanks tom, you covered about every bad situation that can happen, but somehow did not help the OP..??

    I can't believe we still didn't hear about his spreadsheet and salary.........

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  10. #28
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    Quote Originally Posted by ChipSplitter View Post
    I can't believe we still didn't hear about his spreadsheet and salary.........
    Please don't bait him.

  11. #29
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    To the Op
    I will confess I have not run a machine in a while. But it's like writing a bicycle.
    Back to basics
    The holders precision hydraulic or standard holders.
    Are end mill high precision or standard non precision end mills.
    Did you indicate the end mills at near the cutting edge w/I .0002-.0005? While mounted in the mill.
    Is milling fixture re tramed in?
    Are you cleaning and lightly cleaning
    All the holders , collets, and milling tools.
    Loaded question did you bump the spindle
    On any other object?
    Make sure every thing clean , bed of the machine is stoned with no Nick's, burrs, ECT. Same with the fixtures
    Again make sure the holders are clean and lightly oiled, no wobble at the end mills.
    Use a .ooo5 indicator with mag base
    And verify run-out. May be the cutter
    Moved or the holder.or fixturing.

  12. #30
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    Each tool change will require re indicating for run out,
    How are the tools being pre set?
    Some of the pros can jump in about that.

  13. #31
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    Thermal expansion? On a .472 bore? It'd be a puddle of liquid before it went out of tolerance.

    Besides, the hole is getting bigger.

    Assuming there's a tool change involved, I'd be looking at crap on the taper as others have noted.

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  15. #32
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    Quote Originally Posted by 1953chevB View Post
    Each tool change will require re indicating for run out,
    How are the tools being pre set?
    Some of the pros can jump in about that.
    No youtube link this time?

    https://m.youtube.com/watch?v=gQXUQRFNhUw

  16. #33
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    ya good point hole does not change much at .472 diameter but for future reference to the OP good to keep note.
    what temperature are the parts heat up to with just mist.. most likely a tool issue.
    but have to eliminate all right.

    My earlier post
    Each tool change will require re indicating for run out,
    How are the tools being pre set?

    edit need to clarify better
    I for got to add if he cuts the holes to low limit in the machine , verifies it pulls the parts
    now it cools the hole is under size .0003-.0005 on diameter is that problem.
    let it cool then verify actual size, tool cutter compensate good as gold.
    ya there over size but aluminum has to cool, what if it was 2.00 dia hole.

  17. #34
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    no but that was a funny video.


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