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  1. #1
    Join Date
    Aug 2004
    Location
    Perth Western Australia
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    63
    Posts
    183

    Default Sharpening expandable reamers

    This project was inspired by a youtube video tube which I can't find again, the finger tool is my contribution.
    Unfortunately I have to shim the magnetic vee blocks to suit each the particular reamer.
    The finger tool is hinged so the reamer can be rotated anti-clock wise then back against the next blade to index it.
    Not perfect but with careful technique it will revitalize my blunt reamer collection.
    Ive only sharpened one so far and I haven't tested it, but I know it will cut once again.
    Mark
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    I've become a tool of my tools.

  2. #2
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
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    70
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    5,146

    Default

    VERY NICE WORK. Any chance of some better pics of the finger tool, like what's on the other side, PLEASE?? How does it rotate to allow the next blade through, please?
    Kryn
    To grow old is mandatory, growing up is optional.

  3. #3
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
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    71
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    3,009

    Default

    Hi Mark.
    Ingenious and nicely executed.
    I too have a collection of blunt reamers - and have a small tool & cutter grinder and access to a surface grinder.
    Can you explain a little about the geometry of your grinds?
    My understanding is that adjustable reamers have a very slightly tapered section to around a third of the length of the blades and then are dead parallel for the remaining two thirds.
    I am also under the impression that their cutting edges are relieved slightly. I thought that this was a curved relief.
    Very interested to learn more about the geometry and how their shape is restored.
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  4. #4
    Join Date
    Aug 2004
    Location
    Perth Western Australia
    Age
    63
    Posts
    183

    Default Geometry?

    Joe I had no idea about the geometry I didn't give it much thought.
    I clocked it and sharpened it parallel now I will have to re- mount it and cut a taper.
    The reamer I used was so blunt it was useless so I had nothing to lose.
    Mark
    I've become a tool of my tools.

  5. #5
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    5,402

    Default

    Hi Guys,

    I've just had a look at one of my adjustable reamers ! I can't measure any taper on this one at all, it appears to be parallel along its length. So I took a blade out and measured it it does have a taper on the back ! About fifteen thou or so.

    I was going to measure it at each end, but dropped it and it shattered into several pieces. However it does have a flat relief behind the cutting edge. Also the blade looks to be more like carbide than HSS, probably explaining why it shattered so easily !

    06-02-2022-001.jpg 06-02-2022-002.jpg

    These are pictures of the end bit, it was the only bit I found !
    Best Regards:
    Baron J.

  6. #6
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    732

    Default

    I have often thought of sharpening some of my Sutton expanding reamers but because of the geometry or profile of the cutting edge I always shy away from it. The only way I can describe the shape of profile of the blades is "Barrel Shaped" with the highest point/largest diameter being about 1/3 of the way along the edge.

  7. #7
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
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    71
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    Default

    I finally found something on the geometry of adjustable reamers - on the Narex site:
    https://www.narex.tools/en/e-shop-catalog/vystruzniky
    Looks like these are indeed parallel across opposing cutting edges. Their pic also shows the sharpening angles:
    vystruzniky_vykresy.png
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  8. #8
    Join Date
    Oct 2008
    Location
    Cairns, Q
    Posts
    666

    Default

    [QUOTE=Techo1;1994432 "Barrel Shaped" with the highest point/largest diameter being about 1/3 of the way along the edge.[/QUOTE]

    I remember checking one of mine years ago - blades were as described by Techno 1.

    Frank.

  9. #9
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    55
    Posts
    2,163

    Default

    Quote Originally Posted by jhovel View Post
    I finally found something on the geometry of adjustable reamers - on the Narex site:
    https://www.narex.tools/en/e-shop-catalog/vystruzniky
    Looks like these are indeed parallel across opposing cutting edges. Their pic also shows the sharpening angles:
    vystruzniky_vykresy.png
    Interesting about the irregular angular spacing of the blades "to achieve perfectly round holes".
    Not something I've come across before.

    Steve

  10. #10
    Join Date
    Mar 2014
    Location
    South of Adelaide
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    1,008

    Default

    Quote Originally Posted by OxxAndBert View Post
    Interesting about the irregular angular spacing of the blades "to achieve perfectly round holes".
    Not something I've come across before.

    Steve
    I would imagine it is to stop it chattering, most good quality carbide endmills have that to reduce chatter now days.

  11. #11
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    732

    Default

    Quote Originally Posted by snapatap View Post
    I would imagine it is to stop it chattering, most good quality carbide endmills have that to reduce chatter now days.
    Yes, it's also done on some reamers and countersinks.

  12. #12
    Join Date
    Aug 2004
    Location
    Perth Western Australia
    Age
    63
    Posts
    183

    Default

    At last I have found time to get back to this project, I'm finishing a telescoping gantry project which is taking up most of my time.
    I looked at the geometry of my adjustable finger and realized when I moved the fine adjustment screw it rotated the finger horizontally instead of lifting it.
    Dumb ass! so I reconfigured it. Its still a pain to set up but it better.
    I remounted my reamer and ground a taper on the lower third of the blade, I hope to test it in the next few days.
    I have taken more photos as requested.
    I hope you can see the finger is located in a V groove which allows it to move back to allow the blade to pass when the reamer is rotated anti-clockwise (Yes the direction depends on which end you view it from.) then it locks back against its stop once the blade has passed.
    Mark
    Attached Images Attached Images
    I've become a tool of my tools.

  13. #13
    Join Date
    Jun 2020
    Location
    Geelong VIC
    Age
    65
    Posts
    25

    Default

    Quote Originally Posted by Poloris View Post
    At last I have found time to get back to this project, I'm finishing a telescoping gantry project which is taking up most of my time.
    I looked at the geometry of my adjustable finger and realized when I moved the fine adjustment screw it rotated the finger horizontally instead of lifting it.
    Dumb ass! so I reconfigured it. Its still a pain to set up but it better.
    I remounted my reamer and ground a taper on the lower third of the blade, I hope to test it in the next few days.
    I have taken more photos as requested.
    I hope you can see the finger is located in a V groove which allows it to move back to allow the blade to pass when the reamer is rotated anti-clockwise (Yes the direction depends on which end you view it from.) then it locks back against its stop once the blade has passed.
    Mark
    Keep old skills alive, and good tools live on! BTW I do mine (adj. and m/c reamers) between centers... and after initial full blade grind... pack up the "lead in" end center table mount at the back with shim (12th), and had good results to date. I think on smaller sizes (up to 1/2") the 12th gives a bit to much taper. On the bigger ones is seams ok, as they have a longer blade? One thing I have noticed is the smaller the ream the more critical the "primary clearence and land size" has to be to stop chatter... especially in brass! I have also found you get the best results if you first strip and clean the reamer (adj) and "set" the blades, by turning the reamer backwards in an "on-size" bush, after "nipping" up the collers. Steve.

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