Center drilling mill question
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    Default Center drilling mill question

    I have some jobs with a lot of different diameter small holes.

    We're talking 4.6mm 5.0mm 5.2mm 6.0mm 6.8mm diameter in the same part.

    So obviously I wanna reduce the number of tools.

    I can always drill the smallest diameter and then switch to a mill to widen them all as needed but are there any good "drills that mill" or "mills that drill"? The tool needn't be very good at the milling, only need 0.2mmR to get from 4.6 to 5.0 f.ex.

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    Is this being done on a cnc mill? There are center cutting end mills available. Redrilling, and only removing a small amount, like 4.6 to 5 mm is hard on drills, best to go with the right size to begin with. And why drill it twice?

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    Quote Originally Posted by Tichy View Post
    I have some jobs with a lot of different diameter small holes.

    We're talking 4.6mm 5.0mm 5.2mm 6.0mm 6.8mm diameter in the same part.

    So obviously I wanna reduce the number of tools.

    I can always drill the smallest diameter and then switch to a mill to widen them all as needed but are there any good "drills that mill" or "mills that drill"? The tool needn't be very good at the milling, only need 0.2mmR to get from 4.6 to 5.0 f.ex.
    .
    some places sell end mills with 90 degree point or ends for drill, chamfer and milling. obviously it depends on length to diameter ratio
    .
    typically when over 3x or over 3x dia in length tool rigidity goes down by cube of length change. 2x longer (2x2x2) is 1/8 as rigid and 3x longer (3x3x3) is 1/27 as rigid.
    .
    so obviously say a 6mm dia hole 100mm deep you aint going to circular mill. sure some toy makers have small parts and only shallow drill depths. depends on what you are making of course.

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    unless you mean interpolating all of the larger sizes how are you going to reduce tool number with a small drill and a number of different different mills?

    if you can interpolate them, sure, why not. but you would not be asking...

    what are we missing?

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    You are missing that all I ask for is the best possible tool to drill a 4.6mm hole and then widen it to 6.0mm. that would help a lot.

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    Quote Originally Posted by Tichy View Post
    You are missing that all I ask for is the best possible tool to drill a 4.6mm hole and then widen it to 6.0mm. that would help a lot.
    A 4.6mm Drill, and an endmill smaller than or equal to 6.0mm would do the job nicely.

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    Quote Originally Posted by PocoLoco View Post
    Is this being done on a cnc mill? There are center cutting end mills available. Redrilling, and only removing a small amount, like 4.6 to 5 mm is hard on drills, best to go with the right size to begin with. And why drill it twice?
    Exactly right: double the time making tools traverse the same path is eminently inefficient. On a tool change frequency optimization basis, multiple parts could/should be fixtured to make the tool do more work.

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    Quote Originally Posted by HuFlungDung View Post
    Exactly right: double the time making tools traverse the same path is eminently inefficient. On a tool change frequency optimization basis, multiple parts could/should be fixtured to make the tool do more work.
    And this is exactly my question.

    I am asking if you know of tools that could reasonably effectively drill a hole of a certain diameter and then widen it, perhaps with a spiraling motion, to another diameter.

    This is not at all purely theoretical. We could be talking about big details and then I can not mount more than one in my machine.

    As someone noted above, what I'm after is basically good end mills with angled points and I wonder if people have had success with that.

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    Quote Originally Posted by DMF_TomB View Post
    .
    some places sell end mills with 90 degree point or ends for drill, chamfer and milling. obviously it depends on length to diameter ratio
    .
    typically when over 3x or over 3x dia in length tool rigidity goes down by cube of length change. 2x longer (2x2x2) is 1/8 as rigid and 3x longer (3x3x3) is 1/27 as rigid.
    .
    so obviously say a 6mm dia hole 100mm deep you aint going to circular mill. sure some toy makers have small parts and only shallow drill depths. depends on what you are making of course.
    Can you link to any specific tool for reference?

    I'm not talking very deep holes, I'm not that suicidal. 2xd tops. (Okay maybe 2.5...)

    Let me take a specific part. 8mm thick stock, 1450x80mm. 4.6mm, 6mm depth bottom hole plus thru hole. 5.0mm thru hole. 5.2mm thru hole. 6.2mm thru hole. 10.2mm thru hole. Rapid traverse is F15000. Tool change is maybe 15 seconds, I'll have to time it. Stainless 304/304L.

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    I think this may have been covered by Larry in post #4 above, but if not...
    NC spotting drill

    -Marty-

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    Could this be what you seek?

    Industrial Supply Equipment from MSC Industrial Supply

    It drills! It mills! It countersinks! It chamfers! Sizes start at 1/16" diameter and go to 3/4". But it has a 90 degree point and the length of the flutes is rather short, as it should/must be. You may need to use two sizes to cover your range of holes.

    So, as others have hinted at, IT DEPENDS ON THE DETAILS YOU HAVE LEFT OUT!

    Blind or thru hole?

    If blind, is the conical bottom OK or does it need to be flat?

    And the kicker, HOW DEEP?

    Another thought would be an ordinary, CENTER CUTTING end mill which can be used as a drill. It would probably be easier to get one of those in a metric size.

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    Quote Originally Posted by EPAIII View Post
    Could this be what you seek?

    Industrial Supply Equipment from MSC Industrial Supply

    It drills! It mills! It countersinks! It chamfers! Sizes start at 1/16" diameter and go to 3/4". But it has a 90 degree point and the length of the flutes is rather short, as it should/must be. You may need to use two sizes to cover your range of holes.

    So, as others have hinted at, IT DEPENDS ON THE DETAILS YOU HAVE LEFT OUT!

    Blind or thru hole?

    If blind, is the conical bottom OK or does it need to be flat?

    And the kicker, HOW DEEP?

    Another thought would be an ordinary, CENTER CUTTING end mill which can be used as a drill. It would probably be easier to get one of those in a metric size.
    Blind 6mm through 8mm sizes 4.6-10mm. conical okay.

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    This one of those threads that make you go "hmmm "

    Is there a tool to "widen" a hole? Yes, it is called an endmill.

    Now to be more serious, get an endmill maybe 3-4mm diameter and just helix bore all the holes. Going 10-12mm deep will be a snap. What tolerances on the holes? If it is tight (relatively speaking), I would rough bore with one end mill, then finish with a different one to control size better.

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    Then one or perhaps two of the tools that I suggested would probably work.



    Quote Originally Posted by Tichy View Post
    Blind 6mm through 8mm sizes 4.6-10mm. conical okay.

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    Default Misplaced post - sorry

    Quote Originally Posted by Marty Feldman View Post
    I think this may have been covered by Larry in post #4 above, but if not...
    NC spotting drill

    -Marty-
    Posted in the wrong place. Meant to post in mnl's 11/9/19 post "1/16 spotting drills".

    -Marty-

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    Quote Originally Posted by Mike1974 View Post
    This one of those threads that make you go "hmmm "

    Is there a tool to "widen" a hole? Yes, it is called an endmill.

    Now to be more serious, get an endmill maybe 3-4mm diameter and just helix bore all the holes. Going 10-12mm deep will be a snap. What tolerances on the holes? If it is tight (relatively speaking), I would rough bore with one end mill, then finish with a different one to control size better.
    No tolerances to speak of for these ones.

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    My take on the subject:

    You have 5 different size holes in you example. 15 sec toolchange is 1 minute of toolchange after you load the first tool. It seems interpolating all the bigger sizes with one tool would take longer than the extra minute of toolchange time.

    I'd get some really good drills for for your matl and just blast the hole with the right size drill.


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