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Re: large hole making

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  • leasingham_connelly
    ... hole ( ... circle.. I was ... idea??? ... You beat me to the punch there as I was going to suggest the same except I would suggest at least two holes to
    Message 1 of 34 , Feb 1, 2005
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      --- In mill_drill@yahoogroups.com, cmiller231@a... wrote:
      > Maybe this would not be worth the trouble but how about drilling a
      hole (
      > 3/8" appox) inside the 2" circle so that it just touches the 2"
      circle.. I was
      > thinking that this would allow chips to fall through. Good or bad
      idea???
      > Chris

      You beat me to the punch there as I was going to suggest the same
      except I would suggest at least two holes to clear the chips. I
      don't know if is the case but I would worry about the holesaw being
      pushed off line by a single hole on one side. Where I work the pipe
      fitters use carbide tipped on stainless pipes. The curved surface
      helps clear chips at the start of the cut and the saw breaks thru
      quite early on so that the chips clear. They cut up to 4.5" diameter
      with a large radial drill, M5 spindle with reducing sleeve to
      Starrett morse taper adaptor size. The arbor is one with a nut that
      screws down to lock the holesaw solidly. These only work on holesaws
      over 30mm but I would not recommend arbors that do not have this
      feature for any holes that require accuracy of size and position or
      a good finish.

      We also use an industrial annular cutter 63mm diameter for one job
      requiring high accuracy of hole size. This is used with a large
      drill bush to stop it from wandering as there is no pilot drill to
      steady it otherwise. It is used slow and steady as it straddles the
      pipe wall and we do not want to chip it.

      Martin
    • leasingham_connelly
      ... lutz48@a... ... more ... As a production engineer in a turbine construction and accoustic enclosure packaging department (19 years) I am in the lucky
      Message 34 of 34 , Feb 2, 2005
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        --- In mill_drill@yahoogroups.com, "Alan E. Lutz" <lutz48@a...>
        wrote:
        > your opinion
        > ---- leasingham_connelly <martin.connelly@i...> wrote:
        >
        > =============
        >
        >
        >
        >
        >
        >
        >
        > --- In mill_drill@yahoogroups.com, "Alan E. Lutz"
        lutz48@a...
        > wrote:
        > Chris,
        >
        > This would create an interupted cut that puts greater strain on
        > the the cutter(s).  In the case of the hole saw, you would be
        more
        > likely to break teeth IMO.
        >
        > AEL
        >
        >
        >
        > It is not an interupted cut unless there is only one tooth on the
        > holesaw, there will always be some teeth cutting otherwise. A pair
        > of clearance holes is no different to using these tools on the
        > curved surface of a piece of pipe. I can confirm that cutting
        > without a chip clearance hole in 3/4" thick cast steel causes chip
        > build up leading to holesaw breakage and the debris is a bitch to
        > get out. I can also confirm that clearance holes help with
        > successful use of holesaws in thick metal. If you think a blast of
        > air will clear chips out of this narrow deep curved slot then you
        > obviously have not tried it.
        >
        > Martin
        >

        As a production engineer in a turbine construction and accoustic
        enclosure packaging department (19 years) I am in the lucky position
        of being able to try various methods of doing jobs like drilling 2"
        holes at someone else's expence in time and tooling. So please do
        not make the mistake of confusing opinion with experience. When I
        offer an opinion I will state it as such.

        Martin Connelly
        BEng(Hons)
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