Guide to Reaming Holes - Page 3
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  1. #41
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    Quote Originally Posted by litlerob1 View Post
    I don't care if you like working with Tools from the 70's. There is a time and place for Reamers, but it is very rarely in modern CNC equipment. I can do whatever you think you need to do without a Reamer. They are garbage, and belong there.

    I wasn't comparing a Drill to a Reamer (though I could) I just wasn't, in that post. I was comparing a Drill to a Boring tool used for a straight hole. The only benefit of a Reamer is that they are fast. So using a Boring Tool to straighten your hole or make it Round or whatever is a baby's waste of time. And you say that you can't make a Straight hole with a Boring Tool anyway, so you are talking in circles my friend. In your example, you would Drill a hole, Bore it (with taper) then Ream it???!!! Hell man, 6mm hole Inches deep is your reference feature. What are you pressing a locating pin in there? OH you mean it's a through hole--burn it.

    R
    With comments like these, I'm afraid I'll need to block you from any future reading or posts. Nonsensical!
    I

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    Quote Originally Posted by litlerob1 View Post
    I don't care if you like working with Tools from the 70's. There is a time and place for Reamers, but it is very rarely in modern CNC equipment. I can do whatever you think you need to do without a Reamer. They are garbage, and belong there.

    I wasn't comparing a Drill to a Reamer (though I could) I just wasn't, in that post. I was comparing a Drill to a Boring tool used for a straight hole. The only benefit of a Reamer is that they are fast. So using a Boring Tool to straighten your hole or make it Round or whatever is a baby's waste of time. And you say that you can't make a Straight hole with a Boring Tool anyway, so you are talking in circles my friend. In your example, you would Drill a hole, Bore it (with taper) then Ream it???!!! Hell man, 6mm hole Inches deep is your reference feature. What are you pressing a locating pin in there? OH you mean it's a through hole--burn it.

    R
    .
    .
    reamers used every day on modern cnc equipment. unless you are a toy maker there are always length to diameter ratios where boring a hole is not practical due to vibration where a reamer work very good usually.
    .
    if you got a .3937 hole thats over 2.0" deep much easier to ream. i never get oversize holes except at start of hole and maybe .03" depth. as chucking reamer in hole enough it quickly reams to reamer size. hand reamers reaming a .001" are used where even the hole start or top of hole needs to be within .0001" thats normal. there is a very small percentage of lobed holes and curved holes where a long gage pin will not go in. spiral flute reamers are often better than straight flute reamers for longer holes
    .
    lobed holes and curved holes are usually related to hardness variations and vibration during reaming. sure there are 5% of parts where the hole is not within .0001 and gage pin not going in all the way easily. same hardness variations do similar to bored holes often why same boring bar not adjusted can do slightly different size holes. .0001 or .0002" differences i have seen many hundreds of times easily
    .
    seen many times a dozen parts same gage pin wont go in easily and parts made before and after those parts gage pin goes in ok. most metal is not perfectly uniform. its not like molten metal is mixed with a blender. also oxidized metal as it deoxidises it changes. often parts are only partial deoxidized and small areas the carbon, silicon, manganese, etc ratios are a bit off

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    Quote Originally Posted by CalG View Post
    With comments like these, I'm afraid I'll need to block you from any future reading or posts. Nonsensical!
    I

    I would block me too, if I could. Some of what I say is Chutney slang and some of it is pure Trolling the topic of Reamers. But it's not wrong. I VERY rarely use Reamers, and I still get the job done efficiently, that's all.

    R

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    This topic has been argued about in the past and I will chime in again. I have reamed thousands of holes, manually and cnc for ejector pins for plastic injection molds. This is what I know. Most guys leave WAY to much stock to take out, on a .250" dia hole, I would only leave .0015-.002 per side material to remove, also cutting oils will cut larger holes compared to coolant. For example, if your holes are just slightly oversize, try coolant, if your already using coolant leave less stock or switch reamer size.

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    One thing to try that I didn't see mentioned. Place a 2 second dwell at the bottom of the hole. On our machines the sudden torque on the servo from going in the reverse direction can cause the hole to go big. Our usually setup is to use a cam drill, zip tool and reamer. Can get at least 20 parts on cast Inconel. Holding a +/-.0005 diameter. (Machining Datums)

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    Quote Originally Posted by 5 axis Fidia guy View Post
    This topic has been argued about in the past and I will chime in again. I have reamed thousands of holes, manually and cnc for ejector pins for plastic injection molds. This is what I know. Most guys leave WAY to much stock to take out, on a .250" dia hole, I would only leave .0015-.002 per side material to remove, also cutting oils will cut larger holes compared to coolant. For example, if your holes are just slightly oversize, try coolant, if your already using coolant leave less stock or switch reamer size.
    I agree with this and hold this tolerance all day with carbide MA Ford Tru Size reamers only.

    .251 +/-.0002 we drill .246

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    One can improve on straightness—cylindricity—by pulling the reamer instead of pushing it through the work. It’s more often done with hand reamers than on machines but it’s feasible. The tool needs to have a rear lead in, of course.

    It’s like pull turning, the way gun barrels are hollowed out.

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    Quote Originally Posted by KristianSilva View Post
    Hi!

    I have some holes to ream and every time I have ever reamed holes in the past (once or twice), they have always come out oversize. Does anyone know of a "guide to successful reaming"? I couldnt find one using the search.

    Or if anyone would be so helpful to write a quick step by step guide, do's and donts etc, I would massivley appreciate the help.

    Thanks in advance!

    P.S Im reaming a 6mm H7 hole in mild steel.

    I use 4% as my base ratio for reaming stock to leave. So for a 6mm/.2362" inch diameter I leave .24mm/.0094" stock. You can use a under-size reground straight or ball end mill that is approximately .025mm/.001" undersize of the finish reamer size.
    The ball end mill has only to go down to centerline of radius.

    Another thing we did is regrind the front 45° lead angle so it wa concentric with the reamer OD, you'd be surprised how much off some reamers are from the factory.....I'm not talking the high end replaceable types, just your run of the mill product from a catalog house.

    Indicate the reamer so run-out or TIR is only a .005mm/.0002". This helps prevent an oversize hole and or bell mouthing at the top of the hole. This can be done by pushing on small diameter reamers that can be pushed, but larger diameter reamers you'll need an adjustable holder.....sorry?

    You can use a drill chuck to hold it as long as it is indicated in, but a more precision holder using a higher end collet works better....that can be adjusted radially. The smallest hole I've reamed using this method was 1.5mm/.0625" diameter for a tooth brush mold in S7 material. Holes were ± .005mm/.0002" true position accuracy over a 20mm/.780 length!

    After reaming "billions" of holes this way, it has always worked without any issues delivering a straight, round and on location hole.

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    maybe I woke up on the wrong side of the bed?
    How in the world is a gun barrel pull turned to hollow it out? That doesn't make any sense?!!


    I was under the impression that a single flute "gun drill" was used for rifles or anything else of that kind of length.
    Revolver or pistol cylinders and the barrels are drilled with a Carbide drill....at least thats how all the major gun manufacturers I've visited do it?

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    I dont ream anything above 3/4 or it has a micron tolerance regarding the size and or location.
    Then its jig grinder time.

    Its only a a crap shoot if you dont know how to use a reamer. I have never fed a reamer out of a hole or had it get pulled out of a holder rapiding out of the hole???
    I can only imagine that happening if you forgot to tighten the holder?

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    I can ream that hole faster, and better even with your chutney on it....by the way, what kind of chutney?

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    Quote Originally Posted by litlerob1 View Post
    Shit, I'm convinced now.

    But remember ALL the old timers were in the closet gays!!! Not saying there is anything wrong with that, but using Reamers is like that.

    My goats are missing.

    R
    What do these goats look like? Asking for a friend.

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    obviously if you got tool holders with a lot of runout you will get bellmouthed or tapered hole starts when reaming
    .
    often holes are reamed when surface just rough milled and when .020 of surface removed for finishing it removes most of hole starting taper
    .
    obviously if you got soft aluminum and a reamer with a lot of runout you are going to have to do things a bit different. many holes are rough reamed .001 to .005" undersized and hand reamed to finished size. thats needed more with softer metals

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    1. Spot drill
    2. Drill to 30% of finished diameter (can usually skip this step on small holes)
    3. Drill 60%
    4. Drill 97%
    5. Ream to size (reduce cutting speed and use cutting oil)


    I've only scanned this thread so sorry if this has already been said...

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    I just keep thinkin of that old saying, "Old Machinists never Die, they just loose their Reamers"

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    Quote Originally Posted by KristianSilva View Post
    Hi!

    I have some holes to ream and every time I have ever reamed holes in the past (once or twice), they have always come out oversize. Does anyone know of a "guide to successful reaming"? I couldnt find one using the search.

    Or if anyone would be so helpful to write a quick step by step guide, do's and donts etc, I would massivley appreciate the help.

    Thanks in advance!

    P.S Im reaming a 6mm H7 hole in mild steel.
    Are you reducing the speed by 1/4 of the drilling speed??? also if the hole is not round or true the reamer will follow the drilled hole, leave at least .010 thou for reaming better still single point bore the hole true and to size,

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    Unless I missed it (and that could very well be), there has been no mention of what machine is being used.

    Is this a mill, a drill press or a lathe?

    What can happen on a lathe is that if the tailstock is not perfectly lined up, the reamer can wobble and you end up with a conical hole.

    As long as you don't move the work between tool changes, you won't have that problem with a drilling-type machine.

    Steve

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    Just my 2 cents drill hole. 01 to. 015 small straight. reamer 800 rpm feed 7ipm stop the spindle a d draw it out.
    i peck reamers if the material heats up and squeeze the tool to produce holes bigger the deeper you go. If tool gets hot dwell between possible pecks to cool your Hole.
    I'm no word Smith do what you will with it
    Phil

    Sent from my SM-N950U using Tapatalk

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    Quote Originally Posted by Tom Lg View Post
    What do these goats look like? Asking for a friend.
    They look sexy, and delicious simultaneously.

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    Quote Originally Posted by SteveM View Post
    Unless I missed it (and that could very well be), there has been no mention of what machine is being used.

    Is this a mill, a drill press or a lathe?

    What can happen on a lathe is that if the tailstock is not perfectly lined up, the reamer can wobble and you end up with a conical hole.

    As long as you don't move the work between tool changes, you won't have that problem with a drilling-type machine.

    Steve
    That was my question too.

    I was having problems reaming(because it's faster)some parts I was finishing. I've done a thousand of them. All of a sudden my 1" reamer is reaming oversize to the point a seal doesn't just not stay in it doesn't even try. Might have been .010" over but might as well have been .100" I've Been doing this on a turret lathe with a collet. I took them over to a saddle lathe that I know has a spot on tail stock and just like that perfect 1" holes again. Best I can figure I had some wear on the turret lathe that got it out of whack. A reamer should give you a hole true to size. If not you most likely have an equipment problem. Now I just need to true up the turret lathe again. Not many people work on these things anymore.


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