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RE: [mill_drill] Re: Undersized (5/8") drill bits...

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  • Bill
    It’s a beauty isn’t it? Bend in the shank….sure…..a little maybe….the shanks are generally not heat treated, but in the flutes….bend that far and
    Message 1 of 76 , Jun 23, 2013
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      It’s a beauty isn’t it? Bend in the shank….sure…..a little maybe….the shanks are generally not heat treated, but in the flutes….bend that far and not break? First for me.

       

      It was supposed to be a USA made index…..after one of the guys bent the first bit anyone used trying to drill a hole with a ½” 18V drill, turns out they sent us the wrong set, after further inspection. They shipped out the set I ordered when I sent ‘em that pic.

       

      Bill

       

      From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com] On Behalf Of Guenther Paul
      Sent: Sunday, June 23, 2013 3:36 AM
      To: mill_drill@yahoogroups.com
      Subject: Re: [mill_drill] Re: Undersized (5/8") drill bits...

       

       

      Bill

      The drill bit you are showing is like the rifle that shots around a corner

       

      GP

      From: Bill <bill_1955@...>
      To: mill_drill@yahoogroups.com
      Sent: Saturday, June 22, 2013 10:55 PM
      Subject: RE: [mill_drill] Re: Undersized (5/8") drill bits... [1 Attachment]

       

      You get…..what you pay for…..

       

      I stick with name brand made in USA drill bits anymore. Same for most cutting tools I buy, whether it’s carbide or HSS.

      Seems to be a lot of variance between batches of import cutting tools too.

       

      Harbor Freight has a couple of unique blends for tool & high speed steels.

       Some, use peanut butter in the blend, like the pic attached.

      The others use peanut brittle, and some glass, and will shatter if you drop it from a height of only 6”, on to your work bench.

       

      J

      Bill

       

      From: mill_drill@yahoogroups.com [mailto:mill_drill@yahoogroups.com] On Behalf Of rogers92026
      Sent: Saturday, June 22, 2013 7:23 PM
      To: mill_drill@yahoogroups.com
      Subject: [mill_drill] Re: Undersized (5/8") drill bits...

       

       

      I have 3 or 4 boxes of Harbor Fright(!) drill bit sets and all are a different level of quality.

      One of the sets in HSS is really good. One of the sets with TIn is really crummy. Of that really crummy set, one of the new bits was bent, a couple won't cut because they were ground incorrectly (not enough relief and they rub on the back of drill surface) and one taught me an important lesson (which I'll describe in the next paragraph). The worst set of bits I've ever run in to were from HF and were bought by my Father in law. They were so poorly sharpened that I couldn't even drill holes in wood. They too were rubbing on the trailing edge of the bit.

      My lesson: I had drilled a hole for tapping and I ended up with a realllly sloppy fit after tapping. When I mic'd the drill bit it seemed fine. But then I examined the cutting end and could visually see that the point wasn't in the center. It ended up cutting a hole that was 0.015 inch oversize for my M4 or M5 tap.

      The lesson that I learned is that when getting ready to drill a hole that will be tapped that it is worth the time to drill a "sample" hole in a similar piece of material and then check it with either a caliper or pin gauge, etc. This is especially true if you bought a cheaper set of HF drills.

      Bruce

      --- In mailto:mill_drill%40yahoogroups.com, Rick Sparber <rgsparber@...> wrote:
      >
      > GP,
      >
      > I agree. Buy the best quality you can afford AND keep them sharp. I use a Drill Doctor which centers the point. An off center point will cause the drill to cut oversized.
      >
      > Rick
      >
      > On Jun 22, 2013, at 2:46 PM, Guenther Paul <paulguenter@...> wrote:
      >
      > >
      > >
      > > Well all i can say buy good bits. Nor form HF or china. There are American made bits and are on size. I had some china bits they don't even drill hard wood don't know how i git them but they are in the junk now
      > >
      > > GP
      > > From: Dallas Richardson <classicpoints@...>
      > > To: "mailto:mill_drill%40yahoogroups.com" <mailto:mill_drill%40yahoogroups.com>
      > > Sent: Saturday, June 22, 2013 11:56 AM
      > > Subject: [mill_drill] Undersized (5/8") drill bits...
      > > Vern;
      > > I would take to heart what RICK was telling you about the Drill bits.
      > >
      > > I don't believe that you can buy a bit in a store that is "accurate". In
      > > that I mean to say within .003... If you stop and think about it? All
      > > of the drill bits and nuts and bolts that you buy now days in stores like
      > > Home Depot, Lowe's, Harbor Freight, are mass produced by the Gazillions
      > > and like the 5/8 bits are close.. That is the KEY Fraze here.. They are
      > > CLOSE. But, as Mr. Sparber said. To get right on, you need to go to
      > > a boring bar or a reamer..
      > >
      > >
      > >
      > >
      > > Dallas
      > >
      > >
      > > From: Rick Sparber <rgsparber@...>
      > > To: "mailto:mill_drill%40yahoogroups.com" <mailto:mill_drill%40yahoogroups.com>
      > > Sent: Saturday, June 22, 2013 9:27 AM
      > > Subject: Re: [mill_drill] Undersized (5/8") drill bits...
      > >
      > > Vern,Drills are for "knocking through holes". If you need precision, follow up with a boring bar. If you want smooth walls and precision, I follow the boring bar with a reamer. RickOn Jun 21, 2013, at 8:23 AM, Vern <mailto:n7gtb%40yahoo.com> wrote:> The other day, I had drilled a hole in an aluminum hub I had recently cast. When I attempted to fit it onto a 5/8" shaft, I discovered that the hole was undersized, so I measured the bit...I was surprised to find that it was 0.004" undersized. I later purchased a 'quality' HSS 5/8" bit from a local 'tool' supplier, thinking this would be better than the previous one from the big box hardware store. It too was undersized at 0.6225"...> > The second bit cost, was as much as the entire set that had the first, but doesn't appear to be any closer tolerance than the first. Is this a consequence of overseas production, or am I simply making false assumptions here?> > Thanks,> -Vern> > Sent from my iPhone> > ------------------------------------> > Yahoo! Groups Links> > >
      > >
      > >
      > >
      > >
      >

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      Checked by AVG - www.avg.com
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      Internal Virus Database is out of date.

    • leasingham_connelly
      BS328 part 1 (Specification for twist drills), which is equivalent to a number of ISO standards, gives the cutting diameter of a drill as measured across the
      Message 76 of 76 , Jun 28, 2013
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        BS328 part 1 (Specification for twist drills), which is equivalent to a number of ISO standards, gives the cutting diameter of a drill as measured across the lands at the outer corners as h8. Back taper is between 0.0002mm and 0.0008mm per millimetre linear distance from the outer corner towards the shank. The total back taper not to exceed 0.25mm. Below 6.0mm back taper is not a requirement.

        I imagine that all other drill standards will be the same as, or very similar, with regards to these dimensions. Just divide by 25.4 for inch equivalents and you should be close to USA standards.

        Martin

        --- In mill_drill@yahoogroups.com, Goran Hosinsky <hosinsky@...> wrote:
        >
        > Searching Ebay (the German one) for a missing drill size (metric) I find
        > that they offer two types of HSS drills: Rolled or ground, the second
        > one being the more expensive. Might there be a difference in precision
        > between the two types - and could that be the explanation of the start
        > of this thread?
        >
        > Goran
        >
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