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Thread: Advice on proper use on reamers sought

  1. #1
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    Default Advice on proper use on reamers sought

    I could use some "rules of thumb" regarding the proper use of straight flute, chucking reamers.

    I have had some sadly mixed results as of late using new (and different brand) chucking reamers in various materials (steel, bronze, aluminum). I use the reamers both in my mill and lathe. I have tried different rotational and feed speeds, lubricants, different size holes (< 1"), etc. The only things I know for sure, is to not reverse reamer rotation while the flutes are engaged and to drill the "to be reamed" hole within several thousandths under the reamer size. My reamed holes are frequently; tapered, rough cut, oversized and in general, an affront to the general machining community.

    My machinist text books don't really address methodology of use, just identification and general application. I could use some direction, please.

    Thanks!

  2. #2
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    Kind of difficult to list ALL situations here. Here are some basic "rules":

    Reamer quality: Cheap reamers are as common a cheap drills. Buy the highest quality you can afford.

    Size of the reamers: Under 1/2" Drill 1/64" Undersize, Over 1/2" 1/32" drill oversize is what I learned with. Harder materials, you may want to diminish these allowances.

    Speeds / feeds: Half the speed of drilling, twice the feed of drilling.

    Dull or damaged reamers will give you poor results. Store them where the flutes won't be damaged.

    A slightly damaged reamer (i.e. nicked flute) MAY be able to be salvaged by stoning the offending area.

    Liberal lubrication, Clear flutes frequently, NEVER turn them backwards.

    Here is a little more guidance in selection: http://www1.mscdirect.com/CGI/NNPDFF...=216&PMCTLG=00

    Also, Try screw machine reamers where you reaming jobs are not deep. Thier shorter length will add to thier rigidity.

    Tapered or oversize holes tell me somthing is not turning, or mounting (ed) true, or the length of the reamer is allowing it to "wobble" more than you would like.
    Last edited by ERBenoit; 01-05-2009 at 03:45 PM.
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  3. #3
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    Quote Originally Posted by Pherdie
    to drill the "to be reamed" hole within several thousandths under the reamer size.
    There are a million different takes on reamers. I like to leave a good chunk of material for the reamer to chew on, seems to self center better and hold size easier. Say a B or a C drill for a .250 hole instead of a D.

    Also, I'll disagree politely with ERBenoit, you don't want a reamer to be "rigid", there is a reason the shanks are so long and skinny, its so they can flex and follow the hole, if they were rock solid and rigid, they would bore their own hole and a couple of tenths of runout at the collet or chuck would leave with a very oversized hole. I've gone so far as to turn the shanks down further on big reamers to make them even floppier.

    A floating holder can also help a lot, especially on a lathe where alignment can be much more of an issue than on a mill.

    Also don't baby it, you need to feed it and give it something to do, otherwise it finds its own thing to do and you end up with oversized holes.

  4. #4
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    Quote Originally Posted by bobw53
    Also, I'll disagree politely with ERBenoit, you don't want a reamer to be "rigid", there is a reason the shanks are so long and skinny, its so they can flex and follow the hole, if they were rock solid and rigid, they would bore their own hole and a couple of tenths of runout at the collet or chuck would leave with a very oversized hole. I've gone so far as to turn the shanks down further on big reamers to make them even floppier.
    To disagree is OK.

    Looking at my post again, I didn't word what I wanted to correctly. Interperet as follows: Reamed holes with a very short depth. (i.e. 3/8" hole reamed in 3/8" plate). If you're drilling / reaming a 3/8" hole in 3/8" plate, chances are the drill won't wander very far. Thus the OAL, and the "why so" of a normal chucking reamer becomes moot. You don't have a very deep hole to follow.

    I use screw machine reamers regularly when shallow or thin material reaming. If you're reaming any significant depth, a screw machine reamer will probably be shorter than the depth of the hole anyway.

    You could also start with a screw machine reamer then swicth over to a chucking reamer as well.
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  5. #5
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    Thanks for the responses.

    ERBenoit wrote, "Clear flutes frequently"

    So if I'm reaming a 3' long bore, do I 'peck" at it repeatedly, thus clearing the flutes often, or will repeated 'pecking" lead to taper???

  6. #6
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    Quote Originally Posted by Pherdie
    Thanks for the responses.

    ERBenoit wrote, "Clear flutes frequently"

    So if I'm reaming a 3' long bore, do I 'peck" at it repeatedly, thus clearing the flutes often, or will repeated 'pecking" lead to taper???
    3' WOW! Thats a long bore and even longer reamer! Yes '"pecking" is what I was referring to. You don't want to pack the flutes with chips. Doing so may cause scoring of the "reamed" hole, or even worse. Flutes with severley impacted chips may break right off. Especially the smaller diameters.

    Pecking shouldn't lead to the tapering of the hole. Just asking, Is "tapering" what is really happening, or is the hole drifting off center, or outside of your tolerance limits? If the hole is drifting, that's not a problem caused by, nor will be remedied by any reamer.
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    If you "peck" you spend a lot of time with the reamer at the hole mouth, or being fed into the hole.

    Seems like that would be a recipe for "bell-mouthing", if not tapering, with reamers as well as grinders. Seems to turn out that way for me.

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    Quote Originally Posted by J Tiers
    If you "peck" you spend a lot of time with the reamer at the hole mouth, or being fed into the hole.

    Seems like that would be a recipe for "bell-mouthing", if not tapering, with reamers as well as grinders. Seems to turn out that way for me.
    Reaming: At twice the feed of drilling, you shouldn't be spending too much time at the mouth of the hole, or anywhere along the length of the hole. Pecking doesn't nesessarily mean in 1/8" increments. You should be able to, depending upon hole (blind or through) chip space and amount of material left for reaming, "peck" nearly the length of the flutes.

    If you don't want to peck or at least minimize the number of pecks, you could try a reamer that will push the chips ahead (LHS/ RHC) in a through hole, or draw them out (RHS/RHC) of a blind hole. Straight flute reamers "should" only be used in through holes.
    Last edited by ERBenoit; 01-05-2009 at 10:22 PM.
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  9. #9
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    Default Three what???

    If you are going three feet deep you are using the wrong tool. That is gun drill territory or high pressure through the tool oil at the very least.

    I usually start a reamer (for steel) around 20 to 25 SFM and .001 to .0015 chip load per flute. It all depends on the thickness of what I am reaming, the depth I am reaming, the tolerance I am trying to hold, the diameter of the reamer, what I am using for a lubricant.

    If I can, I float the reamer by just barely holding on to the shank in a drill chuck, the less you hold the better, or if you are lucky enough to have a floating reamer holder game on. Others might say to dial in the reamer… I agree to a point.

  10. #10
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    Quote Originally Posted by J Tiers
    If you "peck" you spend a lot of time with the reamer at the hole mouth, or being fed into the hole.

    Seems like that would be a recipe for "bell-mouthing", if not tapering, with reamers as well as grinders. Seems to turn out that way for me.
    Sometimes you do pack them up with a reamer, and I've also found that you can end up with some tapering and bell mouthing. Ran one about a month ago on the lathe, .625 supposed to be ±.0005, but as long as a .626- pin didn't go it was more than fine they epoxy the bushing in anyways, and I saw what they were getting before. 4.3" deep. drilled .030 under on the lathe.

    The chips were packing really bad and basically scoring and tearing the hell out of the bore and pushing it about .002 out(with huge tears and score marks much much deeper). Tried pecking at 2.5", still oversize, and a bit of a bellmouth, tried 1.3" pecks, a little better, but bellmouthed really bad (floating holder, with a few thou of float). Said screw it, left 1" of flutes and ground the rest back to about .400 diameter(by hand) and did it in one shot, some of the chips came out and the ones that didn't at least had a place to hang out without killing my bore. Came out great. The reamer looks like a hacked mutant, but it works good.

    Shouldn't be as big of a problem on a mill, better hole to reamer alignment and a good portion of the chips should fall ahead of the reamer.

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