Two classes are of concern. Chucking, or hand. There are variations of flute design, one of which you left out is the helical flute.
When using a chucking (machine) reamer.
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.
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.
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.
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.
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.
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??
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