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Thread: Power tapping in the lathe

  1. #1
    Join Date
    Sep 2008
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    UK
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    329

    Default Power tapping in the lathe

    When power tapping in the lathe I would put the tap in the drill chuck, add a squirt of oil and with slowest speed get started and let it draw itself in, then reverse out.


    Trouble is the chuck soon runs out of grip. Hard steel against hard steel.

    Then I have to resort to the handle to complete.

    So what do you use to hold your taps when power tapping....up to M12 or 1/2" or even bigger?

    Thanks
    "...do you not think you have enough machines?"

  2. #2
    airsmith282 Guest

    Default

    i dont do power tapping on the lathe, i have a little jig i built from one i had seen and it works perfect to get things started so its all lined up on the lathe then once ihave a few threads in i take it out fininsh by hand, , that or i just do it manuley from the start never fails me ,,

  3. #3
    Join Date
    Sep 2004
    Location
    Brisbane, CA
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    442

    Default

    Quote Originally Posted by Davidhcnc
    Trouble is the chuck soon runs out of grip. Hard steel against hard steel.
    As you've discovered, drill chucks and taps are not that good of a match.

    I use ER collet holders for taps in both my lathe and mill. You can get ER chucks with MT shanks on them.

    Paul T.
    www.power-t.com

  4. #4
    Join Date
    Aug 2006
    Location
    Beaverton, OR
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    7,187

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    I have had good luck using albrecht chucks. I power tapped 5/8-11 the other night. Though when you reverse the chuck will come loose. At that point I just use a crescent wrench to pull it out.

  5. #5
    Join Date
    Mar 2009
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    804

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    All we use are Bilz tap collets and a holder with a 1" shank. You will ruin your drill chucks from the tap slipping. The Bilz tap collets have a square hole that prevents slipping, that slippage can break the tap.

  6. #6
    Join Date
    Feb 2010
    Location
    Spokane
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    When holding a tap in a Jacobs chuck, I always used the "spin factor" as a poor man torque limiter. Now, this is using a ball bearing style Jacobs chuck, tightened about as hard as I can twist the key.

    It seemed to work out about right that when the tap starts spinning in the chuck, I am doing something wrong; pushing too hard, not pushing hard enough, flutes packed full, dull tap, hole too small etc.

    If I really need to twist the tap harder for 1 or 2 holes, I will start the tap with the chuck to establish alignment and then finish with a tap wrench.

    Dave

  7. #7
    Join Date
    May 2006
    Location
    Phoenix, AZ
    Posts
    3,214

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    I bought some Jacobs collet chucks off ebay (and the first from a local friend). They are intended for tapping machines. They have an appropriate sized Rubber Flex collet to hold the tap coaxial, and a clamp arrangement to hold/drive the square drive of the tap. These work great when held in my 18N (3/4" Super Chuck) and can easily handle large taps. I think the largest I've run is 5/8, which is at the upper range of the largest chuck I have. Larger than that and I generally single point it, too cheap to buy taps.

    Smaller taps I just use my one of my smaller Super Chucks. Gripping taps is where the ball bearing chucks really excel. And I don't allow them to spin, I've rebuilt several that were ruined by allowing it to do so. For actual drilling, I prefer the plain bearing Jacobs (from before Danaher killed the quality) or Albrechts.
    Russ
    Master Floor Sweeper

  8. #8
    Join Date
    Nov 2009
    Location
    Ontario
    Posts
    973

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    Quote Originally Posted by becksmachine
    When holding a tap in a Jacobs chuck, I always used the "spin factor" as a poor man torque limiter. Now, this is using a ball bearing style Jacobs chuck, tightened about as hard as I can twist the key.

    It seemed to work out about right that when the tap starts spinning in the chuck, I am doing something wrong; pushing too hard, not pushing hard enough, flutes packed full, dull tap, hole too small etc.

    If I really need to twist the tap harder for 1 or 2 holes, I will start the tap with the chuck to establish alignment and then finish with a tap wrench.

    Dave
    I agree, but what do I know?
    When the tap slips in the chuck, hand turning the chuck in neutral, I know it's time to back out, clean out the chips and go in again with the tap handle.
    Thanks Dave for articulating this. If my chuck grabbed the tap hard enough, it might break. New problem.
    Mike

    My Dad always said, "If you want people to do things for you on the farm, you have to buy a machine they can sit on that does most of the work."

  9. #9
    Join Date
    May 2003
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    52N 122W Western Kanuckistan
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    The tap won't break if it is of good quality and the hole is the right size and the material is within the capability of the tap. You need to make some tap holders like this:



    The hex shaft is just an old screw driver bit driven into a slightly undersize hole in the short piece of mild steel bar. The tap has a small flat ground on it opposite the markings. I wouldn't be without them in the common sizes. Great for freehand drill tapping too.
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

  10. #10
    Join Date
    Aug 2004
    Location
    Barrie ontario Canada
    Posts
    193

    Default Power Tapping in the lathe

    Evan, that is a slick tool you made up.
    I now have a new project this weekend, thanks for showing.
    Allways things to learn from you!

    Paul
    Paul

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