How to make a reamer cut a little smaller? - Page 2
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  1. #21
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    Quote Originally Posted by Dualkit View Post
    Something tells me he doesn't want to wait for something from McMaster to show up on Tuesday.
    Takes a body only a few minutes to make any-size yah want of "D" reamer, under quatah inch especially. So.... yazz...


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    Glad you got it fixed. I like leaving 2% of finish hole diameter for a reamer. You were leaving near 20%. Reamers aren't precision tools at that much material removal, just high flute count drills.

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  4. #23
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    Quote Originally Posted by Bobw View Post
    ....

    The spin it backwards and hit it with a stone works, or I use a diamond file, usually
    doesn't take long, or much to bring it in a couple tenths.

    .......
    Actually I'd run it forward and stone it.
    If done backwards you will cam the OD grind more like an endmill so you will need to remove more.
    Rounding or dulling the front 45s with a stone or deburr wheel also helps. Ideally the real cutting actions occurs here.
    One thing to think of is also heat in the cut.
    If you can make the material hot as it is being cut it will shrink afterwards. This is why such tools need backtaper to avoid seizing.
    Since there is, or should be a backtaper you only need to work or modify the front end and a small side section.
    With a glass or microscope you should be able to see the offending action on the margins near the tip.
    The downside of rubbing is material welding to the margin or OD grind making the tool in fact oversize while working.
    That welded AL is very happy to become part of the cutting tool. You will see this action with not so clean and shiny finish in the hole.
    This is a SFM or lube problem, or perhaps surface finish on the tool itself.

    Withdraw should be done very fast or even non-rotating
    Bob

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  6. #24
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    If it was metric A m6 dowel pin with a H7 reamer wil give the proper fit

    Peter

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    normally you use .001 smaller reamer when you want a press fit and a .001 bigger reamer when you want a easy sliding fit. you get more accurate hole if you use taping fluid reaming hole compared to dry. if tool got runout the beginning of hole is almost always oversize or bell mouthed
    .
    use spring roll pin if loose. normally then contract .005 to .010 smaller going in hole

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    all reamed holes are bell mouthed or oversize on hole beginning. if you ream shallow like only .1" or .050" deep, quite often have to use a much smaller reamer like -.004"
    .
    reamers usually can get every .0005" in size
    .
    hand reaming often done going from -.004 to a more accurate size. hand reamers usually have a taper on end like a hand starting tap. hand reamers usually have opposite square end for going in a hand tap holder. hand reamer often has longer flute lengths. deep holes are not always straight done with a normal chucking reamer. reamer tends to follow the drilled hole which often is not straight

  9. #27
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    I have reduced reamer size with reaming a hole in a 1/2 " bar stock , splitting to the reamed hole with a saw cut, adding a screw so able to tighten the reamed hole, then with rouge or diamond compound back turned the reamer to make it smaller.
    A loaded up reamer might cut over the micrometer size in aluminum.
    Reamers have a back taper going away from the tip/end, so cutting off and inch and re-sharpening will often reduce size .0002.
    A reamer can not ream smaller than its micrometer size or it would just stick in the hole.
    I like to turn reamer slow and draw out not under power if needing very close.
    Most often a properly sharp reamer will cut about .0002 over measure size.
    I like about .006 to .016 stock for most reaming.
    A common drill will ream to its size + a few tenths if a pre-drill hole is made.
    Sharpening a reamer is best done with the reamer held in a bushing as poor sharpening can have only one or two flute ends doing all the work.
    The holding for sharpening bushing can be made with reaming a slug with the intended reamer. Yes sharpening between centers is also good.

    I have not checked bargain reamers for sharpening quality, but suspect it is not very good. Even .0003 off center sharpening would be disaster for holding size at the start of the hole. likely the hole would straighten out going deep in steel but perhaps not in aluminum.
    Likely I could sharpen HSS reamers to 1" for $6.00 each and make very good profit...If I felt like working.

    Wow! go figure
    Reamer Sharpening Service – Nation Aviation Tools

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    Oil thickness will change hole size also. WD40 as opposed to say Moly Dee can make as much as .001 hole size difference.

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    Quote Originally Posted by mc3608 View Post
    Run a stone at about 45deg to dull a little. Don't ream any more than .005.
    run slow feed fast, use cutting oil.
    If that doesn't work run spindle backwards and hold a hard stone against it to make a little smaller.
    That's the way I was shown, then mark the reamer to suit as altered.

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    Quote Originally Posted by Terry Keeley View Post
    . . .Hole is blind so burnishing with a steel ball won't do. . .
    Terry, I may have misunderstood Bob's post (#9) but I got the impression the ball merely reduced the hole diameter near the top, sort of like staking. Full depth burnishing would enlarge the hole, not shrink it. Right? Seems like that might have provided the light press fit for you since the rest of the hole was an accurate fit.

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    Quote Originally Posted by Gordon Heaton View Post
    Terry, I may have misunderstood Bob's post (#9) but I got the impression the ball merely reduced the hole diameter near the top, sort of like staking. Full depth burnishing would enlarge the hole, not shrink it. Right? Seems like that might have provided the light press fit for you since the rest of the hole was an accurate fit.
    Correct, but Bob was being sarcastic anyway. That method does not reduce the hole diameter, it mishapes it. Making it passable by Quality, if it were going on an Airplane, and someone did that, that person would be Terminated.

    R

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    One more for future reference: try using coolant for lubricant and dropping your SFM to around 20. You will get a significantly smaller hole without altering the reamer. I have done back to back testing with this method, first with oil then with coolant. The same pin just slips into the one reamed with oil, needs to be tapped into the one reamed with coolant. Didn't measure the holes though.

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    I don;t know what kind of drugs some of you are smoking. If a Reamer is measured across the flutes as .5000000000000" it CANNOT make holes under that size. 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.

    But you cannot magically make a square hole with a round peg. You cannot make a .495" hole with a .5" Reamer, it's against the laws of Physics. If the Reamer is a POS, I can't attest to that, but if it's normal......

    R

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  21. #34
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    do not know if you have been suggested this or not but it might work
    heat the part couple hundred degrees ream and let cool might give you what you want... hope it works for you....

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    Quote Originally Posted by litlerob1 View Post
    I don;t know what kind of drugs some of you are smoking. If a Reamer is measured across the flutes as .5000000000000" it CANNOT make holes under that size.
    R
    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.

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    I suppose one might have a dull reamer at end cutting flutes that burnishes as much as cutting, or so wore out it is tapered the wrong way with front taper and with getting the part so hot the part is expanded from heat so that the reamer does not lock in the hole..
    and so making a tight to the reamer fit.

    Yes with the part cooled the reamer would not go back into the hole..

    Most likely the reamer would break so ending up with no sized hole ans no reamer
    Last edited by michiganbuck; 06-18-2019 at 08:36 AM.

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    It only takes a tenth or two difference to make a pin go from slip fit to tap fit. Obviously you're not going to get a huge diameter change...(At least I thought that would be obvious?) In my own example, when used with oil the reamer could be put back in the hole and removed again by hand. Not so when using coolant. Whether that reamer I used in the aforementioned test was in great shape I couldn't say, but it was in good enough shape to cut freely and produce chips when used with cutting oil. I've also used that method more than once with other reamers - with the same result.

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    There are floating reamer holders, they help.

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    Quote Originally Posted by litlerob1 View Post
    I don;t know what kind of drugs some of you are smoking. If a Reamer is measured across the flutes as .5000000000000" it CANNOT make holes under that size. 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.

    But you cannot magically make a square hole with a round peg. You cannot make a .495" hole with a .5" Reamer, it's against the laws of Physics. If the Reamer is a POS, I can't attest to that, but if it's normal......

    R
    and what if the cutting edges of the reamer do flex inwards a little due to the cutting forces?
    4.99999999999999 would be quite possible

  28. #40
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    Quote Originally Posted by janvanruth View Post
    and what if the cutting edges of the reamer do flex inwards a little due to the cutting forces?
    4.99999999999999 would be quite possible
    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


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