How to make a reamer cut a little smaller? - Page 3
Close
Login to Your Account
Page 3 of 3 FirstFirst 123
Results 41 to 53 of 53
  1. #41
    Join Date
    May 2007
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    2,599
    Post Thanks / Like
    Likes (Given)
    3052
    Likes (Received)
    479

    Default

    I have rotated the reamer backwards and polished it with fine sandpaper. You have to go slowly and mic the reamer after a few seconds to see what is happening. It is good when you get a reamer right to tape it and write on the tape what size it reams to. It is always good to have a good supply of readers when you have to alter them. Also one can ding a reamer slightly and it can oversized a hole. Just tricky stuff.

    A reamer that reams oversized generally will smoothe out and ream to size. A temporary solution.

  2. #42
    Join Date
    Jun 2012
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    9,956
    Post Thanks / Like
    Likes (Given)
    3358
    Likes (Received)
    3566

    Default

    The reamer axial feed rate is like a thread that it has a helix angle effect. Axial cutting tools need additional clearance because of the effect. This is the reason most/many drills are cleared at 12*. Most reamers should be primary cleared at 10 to 15 degrees. Aluminum perhaps more. Every reamer end tooth need be very accurate perhaps only tenths difference.

    screw thread helix angle chart - Yahoo Image Search Results

    A very tight reamer might cut +.0001. most cut about +.0002 . Often altering the flute spacing and odd number of flutes can make a reamer run closer to size.

    Finish grinding a reamer OD with wheel turning into to the cutting edge flute diameter, or into the heal can make a very slight difference in the cutting action. A very slight roll-off edge is made when the wheel contacts the part (reamer). this effect is so slight it takes a needle indicator point and tenths or Um indicator to see it. I discovered it with running one way, then bluing -up the reamer and then further spark-out running the other way. Grinding into the flute OD top edge would make a reamer cut tighter size (<.0002) but would have increased heat and less tool life, grinding into the heal would make looser (perhaps .0002/.00025) with less heat and longer tool life..
    The same happens and effects grinding mill cutters when leaving a flat or circular land as for cast iron carbide cutting tools. Yes few grinder hands or engineers have discovered this effect in finish grinding reamers and land-finish cutting tools. Guess I could write a paper on it.

  3. #43
    Join Date
    Dec 2008
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    10,032
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    2609

    Default

    straight flute reamers sometimes vibrate and you get a lobed hole especially shallow depth holes. not perfectly round and low spots might be undersize.
    .
    if it vibrates more it reaches a point hole dia is bigger. thick cutting oil can effect vibration and hole smoothness. softer part of aluminum a reamer that has tool holder runout hole can be bigger cause part is too soft to steady or reduce the tool tip runout. sometimes a drill bushing is used and or part is thicker, when reamed, then part milled thinner where hole beginning or bellmouthed is later milled off. basically if reamer has .005" runout or wobble and you shallow depth ream soft material like aluminum you will get oversize holes. you can use a -.001" reamer and still easily get oversize holes
    .
    lobed hole is small amounts like .0005" and between a deep hole not being always straight you can do 10 parts with some have problems with a long Go or NoGo pin gage
    .
    spiral flute reamers often can handle hardness variations much better. for example a hole in a pulley with a keyway. the spiral flutes will span the keyway gap vastly better than a straight flute reamer. spiral flute will span hard to soft variations in metal better usually vibrate less

  4. #44
    Join Date
    Oct 2005
    Country
    CANADA
    State/Province
    Ontario
    Posts
    1,009
    Post Thanks / Like
    Likes (Given)
    194
    Likes (Received)
    337

    Default

    Quote Originally Posted by Spinit View Post
    I have rotated the reamer backwards and polished it with fine sandpaper. You have to go slowly and mic the reamer after a few seconds to see what is happening. It is good when you get a reamer right to tape it and write on the tape what size it reams to. It is always good to have a good supply of readers when you have to alter them. Also one can ding a reamer slightly and it can oversized a hole. Just tricky stuff.

    A reamer that reams oversized generally will smoothe out and ream to size. A temporary solution.

    Yup. I've made a reamer cut oversize a bit by raising a burr with a carbide insert on one of the flutes. Temporary but it does work for a few holes.

  5. #45
    Join Date
    Jun 2012
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    9,956
    Post Thanks / Like
    Likes (Given)
    3358
    Likes (Received)
    3566

    Default

    A reamer should be sharp and cut a hole about +.0015 to about .0002 over its micrometer size. If a different size is needed then that size reamer should be bought. It is not uncommon to have 3 or more reamers for a given size, from press to running fit. Any hacking on a reamer is just a temporary fix and shortens the life of the reamer.
    Cut off shorter and proper resharpening is a proper size change to make smaller size. Often .0002 per inch of cut off, but micrometer check to be sure.

    A slip of abrasive paper taped to a rod used in a drill press can open a reamed hole. The length of the abrasive paper strip can gauge the size very close. Yes this is best for a through hole.

  6. #46
    Join Date
    Aug 2008
    Location
    near Cleveland
    Posts
    813
    Post Thanks / Like
    Likes (Given)
    55
    Likes (Received)
    104

    Default

    I've had some success running the reamer backward and stoning it. Not leaving excessive ream stock, making certain the reamer runs true, running it slow with just enough feed-you should feel it cut lots of oil. If you bump the bottom of the hole, you just lost.

    If all else fails, leave appropriate offering at the altar of the reamer god.

  7. #47
    Join Date
    Jan 2007
    Location
    Flushing/Flint, Michigan
    Posts
    7,601
    Post Thanks / Like
    Likes (Given)
    378
    Likes (Received)
    6350

    Default

    Quote Originally Posted by metlcutr55 View Post
    I have run a reamer thru a hole and not been able to pass it back thru the hole by hand whilst not rotating. and passed it thru the hole 2 or 3x rotating, same result. tight, squeaky. cutting oil thru bronze if I remember. 1/4 inch range reamer. and yes, one that had seen many holes. regarding the drugs, its been a while, best guess white widow.
    The fact that you have "screw" it in leaves a hint as to what happens.
    Probably have to screw it in at just about the withdraw thread rate.
    A reamer threads in just like a tap but there is no cutting action past the tip so it tries to burnish until enough backtaper clears.
    The stock being cut may still be in plastic so will spring back and not permanently deform. It may totally deform, partiality deform or come back at you like a crazy person.
    Hence you get a hole actually smaller than the reamer itself.
    Margin size moves this action around but material characteristics, speed and stock removal also play a big roll.
    Lubes make a difference as they change the temps and the pressure on that critical feed per flute up the margin to get you to the elastic limit. (The point where the metal stays where it should)

    Drills can have the same problem.
    Bob

  8. Likes mtlhe liked this post
  9. #48
    Join Date
    Jan 2007
    Location
    s w NH
    Posts
    320
    Post Thanks / Like
    Likes (Given)
    223
    Likes (Received)
    118

    Default

    Quote Originally Posted by CarbideBob View Post
    The fact that you have "screw" it in leaves a hint as to what happens.


    Bob
    I see no screwing in my post ?? this would be on a "Bridgeport", and hand reaming. the old reamer goes in tight and pulls out tight, and no evidence of cutting, and I mean tight, forcing it thru and back. multiple times no hole size change. probably trying to burnish but just not happening. by the time it gets to that point coolant or oil changes don't seem to matter. and have seen this effect in other metals too.

    regarding the OP, if you stone (or any other process) your reamer to make the right size hole, tag it for that job only, and use it only there. I really prefer carbide reamers, a high speed reamer wears and changes so much quicker. if you get that reamer working well, repeat exactly what you've done before, and your chances of getting good holes are decent. so many factors involved, wear and tear, how you are chucking the reamer, does it run out? are you holding it the same way and by the same length on the shank? a shorter reamer chucked on a lot of the shank has less chance to follow the hole than a longer one chucked on just a couple shank diameters. jmho ymmv. and in your initial setting up, fool with coolants or oil and type of oil, speed and feed. all can make a difference.

  10. #49
    Join Date
    Oct 2013
    Location
    netherlands Asten
    Posts
    803
    Post Thanks / Like
    Likes (Given)
    513
    Likes (Received)
    341

    Default

    Quote Originally Posted by litlerob1 View Post
    Show me the Data.

    I don't think that what you suggest is impossible. But it's more likely to fall under the category of POS tool, or weird hole.

    I realize that drugs are legal in the Netherlands, but they still effect the brain the same way.

    R
    Bob must be on drugs too?


    The stock being cut may still be in plastic so will spring back and not permanently deform. It may totally deform, partiality deform or come back at you like a crazy person.
    Hence you get a hole actually smaller than the reamer itself.
    Margin size moves this action around but material characteristics, speed and stock removal also play a big roll.
    Lubes make a difference as they change the temps and the pressure on that critical feed per flute up the margin to get you to the elastic limit. (The point where the metal stays where it should)

    Drills can have the same problem.
    Bob

  11. #50
    Join Date
    Nov 2013
    Country
    UNITED STATES
    State/Province
    Utah
    Posts
    4,374
    Post Thanks / Like
    Likes (Given)
    1170
    Likes (Received)
    2399

    Default

    Quote Originally Posted by litlerob1 View Post
    You can manipulate the working conditions and the material, you can make a weird hole, you can run a file down the inside of the hole to make a bushing stay in there

    R
    Read the above. At the moment of cutting, the hole is what it is. If something happens after, it is irrelevant. Until it isn't. There are Machining and handling techniques to deal with Plasticity.

    Quote Originally Posted by janvanruth View Post
    Bob must be on drugs too?
    I have no idea if he's on drugs, unless unnamed beer is a drug.

  12. #51
    Join Date
    Jan 2007
    Location
    Flushing/Flint, Michigan
    Posts
    7,601
    Post Thanks / Like
    Likes (Given)
    378
    Likes (Received)
    6350

    Default

    Reaming is a complicated process of both cutting and maybe even metal spinning wrapped in one package.
    If you want to confuse yourself on the way down this rabbit hole the following reads are recommended.
    https://www.amazon.com/Geometry-Sing.../dp/1849960526
    https://www.amazon.com/Metal-Cutting.../dp/0849318955
    Not easy reads and written by a sometimes competitor. He is very good at getting results. These books you have to read two or four times for much to make sense,..... at least I had to.
    Be aware that if your world has been Merchant's work or the rather simple orthogonal models you may not be happy at first as he is rather critical and somewhat outspoken on many things.
    He actually was here for a very brief time. If you think Gordon is controversial or argumentative you have never met this guy.

    I do wish I could "show the data" as I have lots.
    When you do this work for pay you sign NDAs up the wazoo. I can't "prove" any of it.
    Bob

  13. #52
    Join Date
    Apr 2017
    Country
    UNITED STATES
    State/Province
    South Dakota
    Posts
    9
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    0

    Default

    Quote Originally Posted by Evenglischatiest View Post
    Are you choking up on it? I try to leave reamers hanging out much longer than drills, to let them float better. It needs to follow the hole that's already there, instead of trying to make it's own. On that same note, are you spotting the pilot holes? If the drill goes in crooked, the reamer will start out off center, making the hole big, and probably tapered. Also, make sure you're drilling deep enough. If the reamer bottoms out on the pilot hole, or on the chips, the reamer will wobble a bit. It doesn't take much.

    As others have already said, try a bigger drill, a lower speed, and a higher feed. I usually spot drill to .070 diameter, and drill to #53, as deep as I can get away with. Then ream at 10 SFM, feeding at .01" per rev, no pecking.
    Like your thoughts! Which maid me think about the alignment of the tail stock to the head center as well.

  14. #53
    Join Date
    Feb 2013
    Location
    Madison, WI
    Posts
    954
    Post Thanks / Like
    Likes (Given)
    1094
    Likes (Received)
    613

    Default

    I didn't take the time to read through this, so it may have already been said. But i'd use a #53 drill then come in with the reamer, making sure the reamer spun true. The holes should come in spot on then.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •