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  • Expansion reamers

    Please tell me about expansion reamers. What are they, how are they used, and what applications are they used for? How does a 5/8 expansion reamer differ from a 5/8 chucking reamer?

    Thank you.
    Gary


    Appearance is Everything...

  • #2
    You can adjust the dia.of reamer.It has a taper and expands the body.They aren't the best and are hard to hold sizes as the flighting can expand from chip load and cut over size.I personally wouldn't use them on anything important..

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    • #3
      I was always told that an adjustable reamer was only adjusted for resharpening not change the size.

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      • #4
        There is some ambiguity in reamer terminology. There are single size reamers designed for either machine or hand use with no adjustment possible. There are single size reamers with a very small adjustment range for adjusting fit or compensating for sharpening and these are sometimes called expansion reamers. Then there are the wide range reamers that have blades in a tapered body. They are generally called adjustable reamers but are also called expansion reamers. As j king said they are harder to get good results with and they vary in quality. A good adjustable reamer can produce sizes within a few ten-thousandths but it takes skill and patience.
        Don Young

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        • #5
          I have had very good results with some piloted adjustable reamers, like the "automotive" type, but with a pilot setup.

          If carefully set up they won't lose size, the blades are trapped by rings at each end, and cannot move. Of course in poorly made versions, they might not all be held tightly, and could slip around and throw off the size.
          CNC machines only go through the motions.

          Ideas expressed may be mine, or from anyone else in the universe.
          Not responsible for clerical errors. Or those made by lay people either.
          Number formats and units may be chosen at random depending on what day it is.
          I reserve the right to use a number system with any integer base without prior notice.
          Generalizations are understood to be "often" true, but not true in every case.

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          • #6
            Like J Tiers I too have had success with adjustable reamers, but as he mentioned they are more finicky. I used one to ream valve guides in a vintage engine that had slight variance in the replacement valves, but required a consistent spacing between guide and valve stem. In general, I try to avoid them because without a lot of experience and skill they are a pain to get accurate results with.

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            • #7
              We are using these and so are many other manufacturers. Not cheap but the best.
              Download the PDF for lots of info.

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              • #8
                I have a number of spiral flute reamers that are adjustable. They're more like over/under reamers since the adjustment goes from about .001 under to about .003 over. The adjustment is that fine and limited. You have to run them through or the hole will have a slight taper.

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                • #9
                  Since Tiffie's not around to do it: http://www.tools-n-gizmos.com/info/Reamer_Basics.html

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                  • #10
                    NOTE: Some sources of reamer information (e.g. TM 9-243) imply (or state outright) that expansion reamers are just another form of adjustable reamer (with a smaller adjustment range). Whereas, several manufacturers (e.g, Super Tool inc.) state that expansion reamers are not adjustable reamers. The expansion screw should NEVER be loosened or tightened in an attempt to use the reamer for a size other than that which it was finish ground. Expansion reamers are beneficial when the diameter wears down to the low limit. It can be expanded oversize and reground back to its original size. This can be done many times making the expansion reamer a very cost effective tool.
                    Thanks Rosco. That makes sense. The spiral expansion reamer in your link is exactly the type I have.

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                    • #11
                      Originally posted by Juergenwt View Post
                      We just bought one at work for an aerospace part. Something like $800 for the holder. Beats $500 a pop for the special end mill that were are using if it works.

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                      • #12
                        Originally posted by goose View Post
                        Please tell me about expansion reamers. What are they, how are they used, and what applications are they used for?
                        How does a 5/8 expansion reamer differ from a 5/8 chucking reamer?
                        On the chance that the OP may be refering to Adjustable Hand reamers

                        from a Taylor & Jones catalog, Pg. 26
                        OPERATION
                        Adjustment is a simple operation carried out by the loosening of one nut while tightening the other, thus
                        allowing the blades to progress along the taper bottomed slots resulting in an increase or decrease in the
                        Reamer diameter according to the direction of adjustment.

                        ADJUSTABLE HAND REAMERS
                        The Adjustable Hand Reamer is designed to fulfil the requirements of a section of the Engineering Industry
                        which has need of a versatile tool capable of reaming a small number of odd size holes.
                        The Reamer being simple in design and free from complications is easily adjusted to any diameter within the
                        limits of the expansion range and by use of a set of Reamers holes of any size and tolerance from 1/4" to
                        3-11/32" or 6,35mm to 84,93mm can be obtained, or in the case of Taylor & Jones B47 patent blade type 3/8"
                        to 3-11/32" or 9,52mm to 84,93mm.

                        Here's what Taylor & Jones Adjustable Hand Reamers look like.
                        As can be seen, each size has a broad working range.





                        The price tag on the H12 model dates back at least to the 70's.

                        .

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                        • #13
                          I found that if you remove the blades and fit them in backwards, you get a very good tool for opening out holes in thin sheet without leaving a burr. I used mine to drill out a steel head gasket for bigger bolts
                          Peter - novice home machinist, modern motorcycle enthusiast.

                          Denford Viceroy 280 Synchro (11 x 24)
                          Herbert 0V adapted to R8 by 'Sir John'.
                          Monarch 10EE 1942

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                          • #14
                            Adjustable reamers, in my experience, are dangerous in the hands of the inexperienced. Good example: I watched a friend ruin 8 NOS Ford flathead V-8 wrist-pin bushings with a set of Horror Fright adjustable reamers. The bushings should have been sized in a SunnenĀ® pin fitting machine, but he got in a hurry and reamed them out with a cordless drill....Now, all of his wrist pins in the engine are chattering away, and he is at a loss as to where the noise is coming from..("I put new piston pin bushings in it...")

                            I would say adjustable reamers, used carefully, in a pinch, would be OK. But if you need a precision diameter hole, a chucking reamer would be a far better choice.
                            No good deed goes unpunished.

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                            • #15
                              The hand expansion reamers work fine if turned by hand with a tap wrench as they were designed for. If set properly with a micrometer and used correctly they do a good job. As mentioned already some are much better quality than others. This is not a tool to cheap out on.
                              A chucking reamer is faster and easier to use because it is powered, but you can't always get every job on the mill. Sometimes you have to take the tools to the work.
                              Last edited by Toolguy; 09-14-2013, 09:04 PM.
                              Kansas City area

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