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    Default Boring a hole

    What is the best way to bore a 1-1/4” dia hole all the way through a 3” cube of 6160. The hole once bored will have a second hole on top 1-1/2” dia and 1” down. Best using 3 axis or 4th axis with a rotary table. I ask this whether I should be considering purchasing a 3 or 4 axis mill. The cube will require other machining operations like face milling and edges round over as well and 12 6mm tapped holes.

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    As a turner I’d clamp in four-jaw chuck, push through an EcoCut, turn the bigger diameter with same tool, then locate by the bore on the milling machine’s table, supported, make the cube to specs on five sides, and flip. As a miller I’d push through a twist drill or a two-inserts boring tool and turn out the bigger diameter with a fly cutter. You can also plunge mill the entire story.

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    I’m now an old enough codger to say the thing every old codger told me when asking such questions:

    What’s the tolerance?

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    If it's a fractional dimension I assume a fractional tolerance unless otherwise specified.(std. +/- 1/64")

    So stick it in a vise on parallels, punch an 1-1/4" drill thru, drop in an end mill and interpolate the c'bore.

    Want better advise? Provide more information...

    6160???

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    The 1-1/2” hole will be holding a pressed in bearing so better tolerance than .015 I would think. The 1-1/4” hole could be .015 tolerance. The sides of the cube need to be .005. I was not planning on obtaining a lathe to do this. So would this be doable on a 3 axis mill or should I be looking for a 4 axis mill. I have very little machining experience, hence the needed advice.

    Yes 6160 because its available in 3x3 bar.

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    Quote Originally Posted by Ot1 View Post
    The 1-1/2” hole will be holding a pressed in bearing so better tolerance than .015 I would think. The 1-1/4” hole could be .015 tolerance. The sides of the cube need to be .005. I was not planning on obtaining a lathe to do this. So would this be doable on a 3 axis mill or should I be looking for a 4 axis mill. I have very little machining experience, hence the needed advice.
    .
    every pressed in bearing bore tolerance i have done was like -.0002" to -.0010 press fit so it requires holding a +/-.0002" size of your target size
    .
    there is a learning curve even with boring bars. feeds and speeds, depth of cut, etc.
    .
    many ream holes to size. be aware often reamers cut bigger than the reamer size

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    If you have the option of affording a 4th, then get it. There are only more things you can do with more Axes, not the other way around. But you can build that part with 3 very easily. You don't need a Rotary just to flip a part. But you need some Set-up skill.

    R

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    working with a rotary table requires some skill. grid shift and center of index calibration is needed
    .
    programing can become complex too. that alone requires some training

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    Quote Originally Posted by Ot1 View Post
    What is the best way to bore a 1-1/4” dia hole all the way through a 3” cube of 6160. The hole once bored will have a second hole on top 1-1/2” dia and 1” down. Best using 3 axis or 4th axis with a rotary table. I ask this whether I should be considering purchasing a 3 or 4 axis mill. The cube will require other machining operations like face milling and edges round over as well and 12 6mm tapped holes.
    How many pieces?
    Is it already a cube?
    What is the tolerance of the bore?

    The BEST (and quickest) way to get the holes in there is on a lathe. You could turn an O.D. large enough to make the cube, drill and bore the holes on the lathe and face to length.
    Then head to the mill and turn it into a cube.

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    Quote Originally Posted by DMF_TomB View Post
    .
    every pressed in bearing bore tolerance i have done was like -.0002" to -.0010 press fit so it requires holding a +/-.0002" size of your target size
    ^^^ I was wondering this too ?

    What bearings are happy for
    Quote Originally Posted by Ot1 View Post
    The 1-1/2” hole will be holding a pressed in bearing so better tolerance than .015 I would think. The 1-1/4” hole could be .015 tolerance. The sides of the cube need to be .005.
    Are those like skateboard bearings ?

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    Quote Originally Posted by Mtndew View Post
    How many pieces?
    Is it already a cube?
    What is the tolerance of the bore?

    The BEST (and quickest) way to get the holes in there is on a lathe. You could turn an O.D. large enough to make the cube, drill and bore the holes on the lathe and face to length.
    Then head to the mill and turn it into a cube.
    Or just do the whole damn thing on a Lathe; Holes, Square, Round edges be done. It's really a Turners part.

    R

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    Quote Originally Posted by cameraman View Post
    Are those like skateboard bearings ?
    Skateboard bearings are more like 22mm OD x 8mm ID. Same with those fidget spinner things.

    R

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    Quote Originally Posted by Ot1 View Post
    The 1-1/2” hole will be holding a pressed in bearing so better tolerance than .015 I would think. The 1-1/4” hole could be .015 tolerance. The sides of the cube need to be .005. I was not planning on obtaining a lathe to do this. So would this be doable on a 3 axis mill or should I be looking for a 4 axis mill. I have very little machining experience, hence the needed advice.

    Yes 6160 because its available in 3x3 bar.
    Ok, since you don't have a lathe, yes this can be done on a 3 axis mill.
    If I was limited on tooling I would be reaming that hole for the bearing press, and then just interpolate the counterbore(s).
    You don't need a 4 axis rotary to cut this part, but if you have one at your disposal of course that would make it easier.

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    Circular interpolate with a .750 Ripper mill or similar right down through and rough out the same way with the mill stepped over for the 1.5" c'bore, blast coolant to flush chips, leaving .01-.015" material for a finish ream or interpolate with a carbide em doing extra spring pass to get as round as possible ,depending how good the mill is for circular paths and still won't be an exact round hole but should be good enough for most . 2 tools unless you chamfermill of course .


    .
    Last edited by jjxtrider; 11-27-2018 at 05:11 PM.

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    Quote Originally Posted by Mtndew View Post
    How many pieces?
    Is it already a cube?
    What is the tolerance of the bore?

    The BEST (and quickest) way to get the holes in there is on a lathe. You could turn an O.D. large enough to make the cube, drill and bore the holes on the lathe and face to length.
    Then head to the mill and turn it into a cube.
    number of pieces is unknown, but for production. The cube is close but not to size and requires some face milling including fillet, possibly weight reduction milling, and 12 holes with tapping. Large hole tolerence was mentioned .0002.
    Maybe I am misunderstanding you but turning an OD large enough to make a 3 inch cube would require a 4.5” cylinder. Making the cube rough on a lathe will waste too much material.

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    Radial bearing

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    Quote Originally Posted by litlerob1 View Post
    Or just do the whole damn thing on a Lathe; Holes, Square, Round edges be done. It's really a Turners part.

    R
    You could only do the center holes on a lathe but the other 12 are not on center and will be tapped. And then there are 6 faces to mill.

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    Quote Originally Posted by Ot1 View Post
    You could only do the center holes on a lathe but the other 12 are not on center and will be tapped. And then there are 6 faces to mill.
    And? Oh ye of little imagination.

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    Quote Originally Posted by litlerob1 View Post
    And? Oh ye of little imagination.

    I'm not sure Op knows what a Turner's cube is nor how it's made, nor necessarily the limits of what you can put on a face plate (as an asymmetric/off center part).


    However the weight reduction complex milled pockets would be a different matter.


    __________________________________________________ ____________________________________

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    Quote Originally Posted by cameraman View Post
    I'm not sure Op knows what a Turner's cube is nor how it's made, nor necessarily the limits of what you can put on a face plate (as an asymmetric/off center part).


    However the weight reduction complex milled pockets would be a different matter.


    __________________________________________________ ____________________________________
    I did not know what a turners cube was, but had an idea it was turned on a lathe, I looked it up, yes on a lathe, but only a mill is in the budget for now. I realize I have much to learn.

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