Loading ...
Sorry, an error occurred while loading the content.

Re: [MedievalSawdust] dril bit tracking tricks? [1 Attachment]

Expand Messages
  • powell.sean@comcast.net
    From a metal fabrication sense I can say that we have similar problems on deep bores. One solution is gun-drilling but I doubt that you have the capability of
    Message 1 of 7 , Jan 20, 2010
    View Source
    • 0 Attachment

      From a metal fabrication sense I can say that we have similar problems on deep bores. One solution is gun-drilling but I doubt that you have the capability of spinning the workpiece in the opposite direction simultaneous to spinning the drill-bit.

       

      Lacking that a smooth sided bit is the next best. The longer the sides the better. A fostner is probably your best off-the-shelf solution unless you know someone who can mill you a twist drill with no radial relief. Actually it would be fairly trivial to take a 1 3/8 twist drill and grind it down to 1 1/4 and remove the radial relief if you have the correct tools.

       

      The final option is to drill a smaller diameter hole and then ream it out to the correct size. Reamers should have at least 4" of cutting flutes and some are likely to have 6". A reamed hole will be straight for the length of the reamer and usually for quite a bit more.

       

      Luck!

      Sean


      ----- Original Message -----
      From: "Conal O'hAirt Jim Hart" <baronconal@...>
      To: medievalsawdust@yahoogroups.com
      Sent: Wednesday, January 20, 2010 7:52:29 AM GMT -05:00 US/Canada Eastern
      Subject: [MedievalSawdust] dril bit tracking tricks? [1 Attachment]

      [Attachment(s) from Conal O'hAirt Jim Hart included below]

      I'm going to be drilling a larger hole ( 1 1/4" )through the width of a 6" piece of yellow
      pine.  see attached file. this piece is going to be glued up along the same plane as the hole
      and the hole will be centered on the glue joint.
       
      I've had some issues with the drill bit wandering off course even in my drill
      press.
       
      What I am wondering is what tricks do you guys know to help keep the bit
      cutting where I want it to without drifting around when it hits harder and softer
      areas of the wood?
       
      Pre drilling with a smaller bit is only a partial solution unless I buy an extra long
      smaller bit. Drilling slower and using a new bit I know will help....
       
      But I figured I'd ask just in case someone out here knows I trick/technique I
      do not.
       
       
       

       
      Baron Conal O'hAirt / Jim Hart

      Aude Aliquid Dignum
      ' Dare Something Worthy '


      Attachment(s) from Conal O'hAirt Jim Hart

      1 of 1 Photo(s)

    • John LaTorre
      ... ... You didn t say how tight the tolerances have to be, but I m guessing that you have a little wiggle room. The only thing I can think of is to use
      Message 2 of 7 , Jan 20, 2010
      View Source
      • 0 Attachment
        Conal O'hAirt wrote:

        >
        > I'm going to be drilling a larger hole ( 1 1/4" )through the width of a 6" piece of yellow
        > pine. see attached file. this piece is going to be glued up along the same plane as the hole
        > and the hole will be centered on the glue joint.
        >
        >
        >

        <snip>
        > But I figured I'd ask just in case someone out here knows I trick/technique I
        > do not.
        >

        You didn't say how tight the tolerances have to be, but I'm guessing
        that you have a little wiggle room. The only thing I can think of is to
        use a Forstner bit instead of a spade bit and take it slow. If you
        really, really trust the trueness of your drill table and your
        marking-out skills, you could bore halfway through on one side, flip the
        work over, and drill the rest of the way from the other side. I've done
        that when boring center hubs for spoke tents. (But in that case, I
        didn't want a tight fit, and if it came off a little wrong, a bit of
        work with a rasp would make the offset go away.)

        Good luck!

        Johann von Drachenfels
        West Kingdom
      • conradh@efn.org
        ... Johann s idea here sounds good to me, along with his warning about careful layout. I d add only that if the hole were made undersize to begin with, from
        Message 3 of 7 , Jan 20, 2010
        View Source
        • 0 Attachment
          On Wed, January 20, 2010 11:36 am, John LaTorre wrote:
          > Conal O'hAirt wrote:
          >
          >
          >>
          >> I'm going to be drilling a larger hole ( 1 1/4" )through the width of a
          >> 6" piece of yellow
          >> pine. see attached file. this piece is going to be glued up along the
          >> same plane as the hole and the hole will be centered on the glue joint.

          >
          > You didn't say how tight the tolerances have to be, but I'm guessing
          > that you have a little wiggle room. The only thing I can think of is to use
          > a Forstner bit instead of a spade bit and take it slow. If you really,
          > really trust the trueness of your drill table and your marking-out skills,
          > you could bore halfway through on one side, flip the work over, and drill
          > the rest of the way from the other side. I've done that when boring center
          > hubs for spoke tents. (But in that case, I didn't want a tight fit, and if
          > it came off a little wrong, a bit of work with a rasp would make the
          > offset go away.)

          Johann's idea here sounds good to me, along with his warning about careful
          layout. I'd add only that if the hole were made undersize to begin with,
          from both sides as Johann suggests, then the rasp work could correct any
          centering errors without taking the hole over size. Once the hole has
          been correctly adjusted to the desired centerline, enlarge it to final
          size with a big twist drill or reamer. If you're worried about rough
          breakout at the exit wound, do your reaming from both sides as well.

          Another possibility just occurred to me, though I haven't tried it.
          (Which means you should try it on some scrap first!):

          What if you laid out your centerline on each of the mating faces first,
          and then scored it with a saw kerf all along each line? That should keep
          the center point tracking properly through the assembled block.

          Ulfhedinn
        Your message has been successfully submitted and would be delivered to recipients shortly.