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Ultra basics: Why are reamer shanks so loooooong?

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  • Ultra basics: Why are reamer shanks so loooooong?

    I feel a little stupid asking the question
    Just exactly why are the flute and shank lengths so generous in comparison to diameter? The standard ratio is huge!

  • #2
    I believe there is a standard governing this, may be in Machinery's Handbook. afaik its to ensure they have enough flex.....the reamer is supposed to accurately follow the hole not the path the drill chuck's pointing it in which could be several though off or eccentric.
    .

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    • #3
      Originally posted by Mcgyver
      I believe there is a standard governing this, may be in Machinery's Handbook. afaik its to ensure they have enough flex.....the reamer is supposed to accurately follow the hole not the path the drill chuck's pointing it in which could be several though off or eccentric.
      Oh yea! I have a one inch reamer and it is less than a foot long. I guarantee it will not flex much. It would have to be several feet long for that to work.

      I guess that works if the reamer is under 1/4" or so. But I suspect it if for reach, not flex. Perhaps for deep holes.
      Paul A.
      SE Texas

      Make it fit.
      You can't win and there IS a penalty for trying!

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      • #4
        Long can be good, but can also be a PITA. I've had to cut many so I have enough working height under my BP spindle.

        For the most part I'll go with the self aligning "flex" theory though...

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        • #5
          Paul Alciatore: Does nobody believe that all these tools are actualy all made of rubber? (At least, on the scales we deal with)

          I bet if you chuck that 1"x12" reamer up, put a TDI on the tip of it and push, 10lbs will easly deflect the reamer 0.002", Enough to make aligning it up with an existing hole MUCH easyer.
          Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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          • #6
            It occurs to me that keeping a long reamer aligned with the hole would be easier than doing the same with a short one. You can spot the .010 per inch that you are low much easier at 10 inches than you can at 2 inches.


            I could be totally off base.

            Dan
            At the end of the project, there is a profound difference between spare parts and extra parts.

            Location: SF East Bay.

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            • #7
              The longer shaft allows reaming a deeper hole. Lot cheaper adding length to the shaft than the flutes. Also easier to sharpen.

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              • #8
                This type of reamer (chucking) is primarily re-sharpened only at the face of the tip - not the flutes. Sharpening the flutes is possible, but that will change the dimension.

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                • #9
                  Arthur.Marks,

                  Actually, that's a very interesting question!

                  As a side note, I'm glad they are long as I make boring bars from them - especially the smaller diameters.

                  .
                  Last edited by Mike Burdick; 06-16-2010, 01:51 AM.

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                  • #10
                    The length is most likely for reach. If shorter is needed, cut it off. Much easier to shorten than lengthen.

                    Or, buy stub reamers.

                    Having a reamer flex to follow a hole would not give accurate size. If the reamer needs to follow a hole, use a floating holder.

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                    • #11
                      Originally posted by Paul Alciatore
                      Oh yea! I have a one inch reamer and it is less than a foot long. I guarantee it will not flex much. It would have to be several feet long for that to work.

                      I guess that works if the reamer is under 1/4" or so. But I suspect it if for reach, not flex. Perhaps for deep holes.
                      you don't think a 1" reamer is going to flex? everything made of metal flexes. I'm only talking a few thou; like as when lathe tailstock is a bit low or the drill chuck has a couple of thou run out. I've seen it numerous times with the reamer is visually turning eccentrically but upon starting the hole straightens out - something's flexing.

                      i can't buy the deep hole idea as why are reamer standards (length is ANSI defined) so out of step with standard drill lengths...also its a lot of extra material for the once in a life time need for a 6" deep 3/8" reamed hole. I think if it was for depth, there'd be a rarer extra long set and standard reamers would be the length of say jobber drills

                      I can't remember where i got the flex bit from, or maybe i just made it up....without being able to remember a source i sent an email to Dormer (butterfield) hoping they can shed some light ....i'll post if hear anything
                      .

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                      • #12
                        Originally posted by Mcgyver

                        I can't remember where i got the flex bit from, or maybe i just made it up....without being able to remember a source i sent an email to Dormer (butterfield) hoping they can shed some light ....i'll post if hear anything

                        I heard the same thing on this forum awhile ago. I'm very interested to hear what Dormer says.

                        I've seen solid carbide reamers that are short and stuby. I suppose one could argue that these need to be used with a floating holder while the long HSS ones don't need the floating holder, despite the fact that they are both marketed merely as "chucking reamers".
                        Last edited by Fasttrack; 06-16-2010, 12:06 PM.

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                        • #13
                          Originally posted by Fasttrack
                          I heard the same thing on this forum awhile ago. I'm very interested to hear what Dormer says.
                          maybe you heard it from me
                          .

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                          • #14
                            Maybe they are long (and flexible) to track the work better when mounted in the typical drill chuck...? I know mine have a heck of a lot more run-out than my colletts.

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                            • #15
                              I often wondered about this myself. I have two sets of reamers, and sometimes run into problems getting enough clearance between the work and the quill on my "mini-mill" because the shank of a reamer is way too long.
                              Several times I've ended up clamping the part to a faceplate or a four-jaw chuck and reaming with the lathe's tailstock. Worst case scenario I've had to resort to clamping a part in a vice and reaming it with a cordless drill.... I know, it's not good "shop etiquette", but it works. ( My brother and I reamed to size 8 wristpin bushings for a Ford flathead V-8 once, with a vice and a cordless drill. The engine is still running perfectly with over 40,000 miles on it since)

                              I've even considered cutting a couple of inches off the shank of some of my reamers. (I'll probably have to cut them off with a cutting torch, since they seem to be pretty hard steel)
                              No good deed goes unpunished.

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