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IndustryArena Forum > MetalWorking > MetalWork Discussion > Drilling 1/16" diameter 5" long offset hole into 3/8" Aluminum Hex Stock
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  1. #1
    Join Date
    Feb 2018
    Posts
    7

    Drilling 1/16" diameter 5" long offset hole into 3/8" Aluminum Hex Stock

    What is the best course to drill a 1/16" diameter 5" long offset hole into the length of a piece of 6061 aluminum hex bar?

    I tried using an extra length aircraft drill bit, but it wobbles too much because of the small diameter of the bit. I was using a drill press, made a jig, and the bit broke from being too aggressive. The bit also wobbled the whole time. I am wondering if I could use a bit with 3" flute length and drill from either side. I have an old South Bend lathe and am wondering if it would be better do try this sort of thing on the lathe, rather than the drill press.

    Is there any way to drill an off-center hole like this with a six-jaw chuck? If so, how would I do it?

    Or is there some other way to drill this long of a hole that I may not be thinking of?

    What is the best drill bit for doing this. I've read parabolic bits are best for cutting aluminum, but was wondering if any of you have done this and what bit I should buy?
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  2. #2
    Join Date
    Sep 2006
    Posts
    6463

    Re: Drilling 1/16" diameter 5" long offset hole into 3/8" Aluminum Hex Stock

    use a series of shorter drills consecutively....IE, start with a 1" long drill and then one a bit longer.....drill from both ends.....best of luck meeting the first hole in the middle.....peck the hole with short pecks and use kerosene for a lube...…..use a lathe or drill press, it doesn't matter.


    If you want to use a drill press mark the centre of the hole offset on each end....ACCURATELY...…...then set it in an angle block upright on the drill press table.
    Ian..

  3. #3
    Join Date
    Jun 2015
    Posts
    4131

    Re: Drilling 1/16" diameter 5" long offset hole into 3/8" Aluminum Hex Stock

    hi jesset there may be alignment issues with the drill press

    whatever machine you choose, you should be sure that tools are coaxial with the spindle, and the linear movement of the machine is paralel with the tool

    at such small diameters, is better to rotate the tool then to rotate the part; rotating the part will put more stress on the tool

    use more tools, starting from short to long ( just like handlewanker said ), and also check the machine alignment before begining

    pecking is critical, and you should use a thin wire & air to clean the hole, so to be sure that there are no chips inside ( it helps if the part is clamped in a horizontal position )

    if you reach half of the desired depth, and you wish to flip the part, then you need to check the alignment of your fixture, and it may be better to don't flip the part, but to continue to reach the full depth

    try a classical mill with horizontal spindle, and someone with a gentle hand so to feel the cutting ... kindly
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

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