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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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General help with reamers needed
I am looking for basic info and advice on using reamers. I have a few
questions: 1. What types of reamers exist? The ones that I have herd of are D-bits, non adjustable straight flute, adjustable straight flute, and taper. 2. If and when should reaming be done under power? I know that you are not supposed to ever turn them backwards. 3. Should the reamer be allowed to "float" or should it be rigidly supported? 4. I believe that that reamers are for a finishing cut and not to remove large amounts of metal. Is this correct? Any help would be greatly appreciated. Thank You |
#2
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"John Albers" wrote in message om... I am looking for basic info and advice on using reamers. I have a few questions: 1. What types of reamers exist? The ones that I have herd of are D-bits, non adjustable straight flute, adjustable straight flute, and taper. Two classes are of concern. Chucking, or hand. There are variations of flute design, one of which you left out is the helical flute. 2. If and when should reaming be done under power? I know that you are not supposed to ever turn them backwards. When using a chucking (machine) reamer. 3. Should the reamer be allowed to "float" or should it be rigidly supported? Unless a (chucking) reamer is 100% in dead alignment with the hole being reamed, it is very best to float it. That permits the reamer to seek center. Imagine reaming from a tailstock of a lathe that is somewhat low, a common condition on older lathes. If one does not have a floating device, to minimize the amount of influence a reamer has over the hole that is reamed, it's a good idea to hold the reamer by a short distance of the shank (¼") so it can easily center on the hole. When chucked that short, they can move about freely, yet hold for reaming under all but the most severe conditions without spinning in the chuck. 4. I believe that that reamers are for a finishing cut and not to remove large amounts of metal. Is this correct? Yes, that is correct. Most reamers have little ability to deal with chips, so they accumulate in the flutes (unlike drills, which tend to discharge them via the helical flute). A fully loaded reamer is troublesome, and flutes have limited capacity, so leaving too much to ream is a bad choice. Best is to remove a maximum of .015", and less can be better. The larger the cut, the more influence it can have over the finish diameter, often the result of one tooth of a reamer being dull, deflecting the cut away. That tends to yield tapered holes. The less material left behind to ream, the better the chance the hole won't clean up, due in part to drill's ability to drill anything but a straight, round hole. Any help would be greatly appreciated. Thank You The best help I can offer is for you to learn to bore holes instead of ream them, assuming you have a mill from which you perform your work. Reamers are, at best, not a great tool. They have the potential to do good work, but are not predictable. They often yield holes that are multi-sided or tapered, and don't have the ability to locate a hole where it is desired, unlike a boring head. A well bored hole won't display any of these tendencies. Further, (fixed, not adjustable) reamers are good for one size, and one size only. A boring head will yield any size desired. I suggest the use of reamers for certain operations, one of which is when building tools with dowel pins. I rarely rely on reamers for critical dimensions otherwise. Harold |
#3
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On Mon, 22 Nov 2004 11:31:10 -0800, "Harold & Susan Vordos"
wrote: "John Albers" wrote in message . com... I am looking for basic info and advice on using reamers. I have a few questions: 1. What types of reamers exist? The ones that I have herd of are D-bits, non adjustable straight flute, adjustable straight flute, and taper. Two classes are of concern. Chucking, or hand. There are variations of flute design, one of which you left out is the helical flute. 2. If and when should reaming be done under power? I know that you are not supposed to ever turn them backwards. When using a chucking (machine) reamer. 3. Should the reamer be allowed to "float" or should it be rigidly supported? Unless a (chucking) reamer is 100% in dead alignment with the hole being reamed, it is very best to float it. That permits the reamer to seek center. Imagine reaming from a tailstock of a lathe that is somewhat low, a common condition on older lathes. If one does not have a floating device, to minimize the amount of influence a reamer has over the hole that is reamed, it's a good idea to hold the reamer by a short distance of the shank (¼") so it can easily center on the hole. When chucked that short, they can move about freely, yet hold for reaming under all but the most severe conditions without spinning in the chuck. 4. I believe that that reamers are for a finishing cut and not to remove large amounts of metal. Is this correct? Yes, that is correct. Most reamers have little ability to deal with chips, so they accumulate in the flutes (unlike drills, which tend to discharge them via the helical flute). A fully loaded reamer is troublesome, and flutes have limited capacity, so leaving too much to ream is a bad choice. Best is to remove a maximum of .015", and less can be better. The larger the cut, the more influence it can have over the finish diameter, often the result of one tooth of a reamer being dull, deflecting the cut away. That tends to yield tapered holes. The less material left behind to ream, the better the chance the hole won't clean up, due in part to drill's ability to drill anything but a straight, round hole. Any help would be greatly appreciated. Thank You The best help I can offer is for you to learn to bore holes instead of ream them, assuming you have a mill from which you perform your work. Reamers are, at best, not a great tool. They have the potential to do good work, but are not predictable. They often yield holes that are multi-sided or tapered, and don't have the ability to locate a hole where it is desired, unlike a boring head. A well bored hole won't display any of these tendencies. Further, (fixed, not adjustable) reamers are good for one size, and one size only. A boring head will yield any size desired. I suggest the use of reamers for certain operations, one of which is when building tools with dowel pins. I rarely rely on reamers for critical dimensions otherwise. Harold Good answer and I know nothing about reamers and someone asked... I figured that the hole is drilled then reamed without moving the set up or by hand , I like the partial chuck part. |
#4
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Another approach - in case it's of interest:
An experience motor mechanic showed me another way to finish holes. His method of making bushes was to turn it in a chuck, OD +.001 , ID spot on. When pressed into placed (in this case a conrod small end) the ID would get smaller, and this was dealt with by honing with a small brake cylinder hone in a hand drill. Whilst that doesn't sound like a precise method, I found it to be better than hand-reaming, which always left a 6-sided hole. I used to have to ream on the tight side, and let it bed in. Embedded abrasive doesn't seem to be an issue. Jordan |
#5
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"Jordan" wrote in message u... Another approach - in case it's of interest: An experience motor mechanic showed me another way to finish holes. His method of making bushes was to turn it in a chuck, OD +.001 , ID spot on. When pressed into placed (in this case a conrod small end) the ID would get smaller, and this was dealt with by honing with a small brake cylinder hone in a hand drill. Whilst that doesn't sound like a precise method, I found it to be better than hand-reaming, which always left a 6-sided hole. I used to have to ream on the tight side, and let it bed in. Embedded abrasive doesn't seem to be an issue. Jordan Having worked with flexible hones as well as rigid hones, (think Sunnen) I can't recommend, in good conscience, a flexible hone, although I have to agree that the suggested method, where one leaves very little to remove, is likely a very nice way to go, certainly better than reaming. Honing a reamed hole quickly exposes all the problems of reaming. Rigid hones are capable of making *perfectly* round and straight holes from those that are not. It's inherent in the mandrel design. Flexible hones simply follow the hole, and have a propensity for bell mouthing each end, especially when not applied well. Harold |
#6
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"John Albers" wrote in message om... I am looking for basic info and advice on using reamers. I have a few questions: Since you've already gotten some very good advice about reamers, here's a bit more. In the Bedsider Reader Guy mentions the drills that should be reserved for each size reamer. reamer size drill size 1/4 letter "D" = 0.2460 5/16 7.80mm = 0.3071 3/8 9.40mm = 0.3701 7/16 11.0mm = 0.4331 1/2 12.5mm = 0.4921 Hope this is helpful. Bernd A real patriot is the fellow who gets a parking ticket and rejoices that the system works. -- unknown |
#7
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From a somewhat limited viewpoint, the questions you are asking implies you
have already decided that a reamer is the tool to use. Quite often, the process flow has a big bearing on the situation. Backing up a bit, what are the size, location, and finish parameters? Quantity required has a big influence on decision also. You'll also find reamers in larger sizes somewhat expensive. Other posters have mentioned honing. Another method for exact hole size/finish requirements is burnishing. Another important factor is condition and type of equipment available to do the work. All of which brings to mind the "instructor" showing his mastery of a turret lathe producing bushings with an I.D. of .750 inch nominal. Manually, he could change diameter by as much as .005 inch by varying speed/feed??? I guess that means skill level of operators?? Good luck! "John Albers" wrote in message om... I am looking for basic info and advice on using reamers. I have a few questions: 1. What types of reamers exist? The ones that I have herd of are D-bits, non adjustable straight flute, adjustable straight flute, and taper. 2. If and when should reaming be done under power? I know that you are not supposed to ever turn them backwards. 3. Should the reamer be allowed to "float" or should it be rigidly supported? 4. I believe that that reamers are for a finishing cut and not to remove large amounts of metal. Is this correct? Any help would be greatly appreciated. Thank You |
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